Let's explore the exciting pea plant experiment by Mendel
More free lessons & practice -https://www.khanacademy.org/sc....ience/in-in-class9th

Khan Academy is a nonprofit organization with the mission of providing free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's learn the 5 major plant hormones and how we can remember their functions.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organisation with the mission of providing free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore the law of independent assortment
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

In this video, we talk about population density and how difficult it can get to estimate sometimes. We find out how to count tiger populations and that population density isn't always about the number of individuals in the area.

Timestamps:
00:00 - What is population density?
01:46 - Purpose of population density
02:49 - How to count tigers?
04:58 - Biomass density as an alternative
07:27 - Summary

Practice this concept: https://www.khanacademy.org/sc....ience/in-in-class-12

Master the concept of Organisms and their Environments through practice exercises and videos: https://www.khanacademy.org/sc....ience/in-in-class-12

Check out more videos and exercises on Organisms and Populations: https://www.khanacademy.org/sc....ience/in-in-class-12

To get you fully ready for your exam and help you fall in love with biology, find the complete bank of exercises and videos for Class 12 Biology here: https://www.khanacademy.org/sc....ience/in-in-class-12

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy!


Subscribe to our YouTube channel: https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Sulagna Das

In this video, we explore how today's population can help us predict how it will be like in the future. And, talk about the showrunner of this prediction: the age pyramids.

Timestamps:

00:00 - What is an age pyramid?
01:52 - Expanding age pyramid
05:44 - Declining age pyramid
07:48 - Stable age pyramid
09:32 - India's age pyramid

Practice this concept: https://www.khanacademy.org/sc....ience/in-in-class-12

Master the concept of Organisms and their Environments through practice exercises and videos: https://www.khanacademy.org/sc....ience/in-in-class-12

Check out more videos and exercises on Organisms and Populations: https://www.khanacademy.org/sc....ience/in-in-class-12

To get you fully ready for your exam and help you fall in love with biology, find the complete bank of exercises and videos for Class 12 Biology here: https://www.khanacademy.org/sc....ience/in-in-class-12

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy!


Subscribe to our YouTube channel: https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Sulagna Das

In this video, we explore the concept of adaptations and how different types of adaptations have allowed organisms to survive in the most bizarre environments without a glitch.

Timestamps:
01:42 - Structural adaptations
07:20 - Physiological adaptations
09:15 - How Tibetans can live 13,000 feet in the mountains?
12:02 - Behavioural adaptations
14:15 - Definition of adaptation

Practice this concept: https://www.khanacademy.org/sc....ience/in-in-class-12

Master the concept of Organisms and their Environments through practice exercises and videos: https://www.khanacademy.org/sc....ience/in-in-class-12

Check out more videos and exercises on Organisms and Populations: https://www.khanacademy.org/sc....ience/in-in-class-12

To get you fully ready for your exam and help you fall in love with biology, find the complete bank of exercises and videos for Class 12 Biology here: https://www.khanacademy.org/sc....ience/in-in-class-12

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy!


Subscribe to our YouTube channel: https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Sulagna Das

In this video, we explore the possible reactions living organisms have towards non-living factors, like temperature and salt concentration.

Timestamps:
00:00 - Homeostasis
01:43 - Regulators
02:56 - Conformers
04:31 - Partial regulators
05:12 - Response graph
07:15 - Migration and suspension

Practice these concepts:

https://www.khanacademy.org/sc....ience/in-in-class-12

https://www.khanacademy.org/sc....ience/in-in-class-12

Master the concept of Organisms and their Environments through practice exercises and videos: https://www.khanacademy.org/sc....ience/in-in-class-12

Check out more videos and exercises on Organisms and Populations: https://www.khanacademy.org/sc....ience/in-in-class-12

To get you fully ready for your exam and help you fall in love with biology, find the complete bank of exercises and videos for Class 12 Biology here: https://www.khanacademy.org/sc....ience/in-in-class-12

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy!


Subscribe to our YouTube channel: https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Sulagna Das

Drawing diagrams in biology could be tricky! Watch this video to know how to use a mnemonic to remember the anatomy of a dicot stem, and to learn the different parts of dicot and monocot stems and their functions.

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy.


Subscribe to our YouTube channel - https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Nivedhitha Suresh

How are frogs able to see clearly in the dark and hear event faint whispers to hunt prey? How is a frog's body controlled? Watch this video to learn more about control and coordination in frogs!

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.


Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy.


Subscribe to our YouTube channel - https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Nivedhitha Suresh

Let's learn how placenta helps in nourishing the fetus
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore the physical changes in humans at puberty.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore how fertilisation takes place in flowers.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore pollination, its types and agents.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore the unisexual and bisexual flowers
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's see how the DNA number is maintained in sexual reproduction.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore how sexual reproduction speeds up variations
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore vegetative propagation with examples & advantages.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Hydra, yeast, spirogyra, planaria, starfish, rhizopus reproduction. More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!Created by Mahesh Shenoy

Let's explore binary & multiple fission with examples.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore what variation is and it's need
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore reproduction at cellular level.
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

Let's explore why most living things reproduce
More free lessons & practice -https://www.khanacademy.org/sc....ience/class-10-biolo

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Created by Mahesh Shenoy

How are the architecturally diverse pollen grains or microspores produced in flowering plants? What role do each part of the male reproductive structure in plants serve? Watch this video to understand the process of pollen formation.

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.

Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy.


Subscribe to our YouTube channel - https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Nivedhitha Suresh

What will happen if we wrap a poly bag around a leaf and leave it overnight? Let's find out!

Khan Academy is a free learning platform for Class 1-12 students with videos, exercises, and tests for maths, science, and more subjects. Our content is aligned to CBSE syllabus and available in Hindi, English, and many more regional languages.

Experience the joy of easy, seamless, accessible learning anywhere, anytime with Khan Academy.


Subscribe to our YouTube channel - https://www.youtube.com/c/khanacademy

As a 501(c)(3) nonprofit organization, we would love your help!
Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc

Created by Vibhor Pandey

The ability to accurately observe, dissect and record an organism is a key skill for biology students. Many students are intimidated by the idea of making a scientific drawing, and struggle to develop their skills in this area.

This video will guide you through how to complete a dissection and scientific drawing of a flower. We recommend using Alstroemeria, as they are regularly available in supermarkets. However, there is an alternative version in which students follow in the footsteps of Darwin, making careful observations and dissections of primulas. Primulas are available in garden centres through much of the late autumn, winter and spring months, and flower in the garden in spring.

0:00 Credits
0:17 Step 1 - remove sepals
0:45 Step 2 - remove petals
1:11 Step 3 - remove stamens opposite sepals
1:54 Step 4 - remove stamens opposite petals
2:21 Step 5 - bissect the ovary
2:58 Step 6 - identify the line of symmetry in the flower
3:16 Step 7 - slice along the line of symmetry
3:32 Step 8 - continue slicing through the petals
4:00 Step 9 - arrange the parts for drawing
4:21 Step 10 - observe the flower parts
4:55 Step 11 - produce anatomical flower drawing

Follow our channel for biology practicals and more.
Teaching and technical notes plus student sheets: https://www.saps.org.uk/dissection
#saps #alevelbiology #flowers

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

This is part of the IB's NEW Biology syllabus, which means you have exams in May 2025 or later. The videos were designed and recorded by Cheryl Hickman

In this video, we step into the world of honey bees and find out why some of them don't have fathers, while everyone has grandfathers!

More free lessons & practice: https://www.khanacademy.org/sc....ience/in-in-class-12

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Created by Sulagna Das

In this episode , we look at how the body is able to regulate blood glucose.This episode can be good for both ordinary and advanced levels

The regulation of blood glucose, also known as blood sugar, involves complex mechanisms that ensure the body maintains stable glucose levels. Here is an overview of the process:

1. Role of Pancreas: The pancreas plays a central role in blood glucose regulation through the secretion of two important hormones - insulin and glucagon.

2. Insulin:
- When blood glucose levels rise after a meal, cells in the pancreas called beta cells secrete insulin into the bloodstream.
- Insulin facilitates the uptake of glucose from the bloodstream into cells, particularly in the liver, muscle, and adipose tissue.
- Insulin promotes the storage of excess glucose as glycogen in the liver and muscles, lowering blood glucose levels.

3. Glucagon:
- In contrast to insulin, when blood glucose levels drop too low, alpha cells in the pancreas release glucagon into the bloodstream.
- Glucagon stimulates the liver to break down stored glycogen into glucose, releasing it into the bloodstream to increase blood glucose levels.

4. Liver's Role:
- The liver plays a vital role in blood glucose regulation. It stores glucose as glycogen and can release or generate glucose through glycogenolysis and gluconeogenesis, respectively.
- During periods of fasting or prolonged exercise, glucagon stimulates the liver to convert stored glycogen or other molecules (amino acids, lactate) into glucose for energy.

5. Hormonal Regulation:
- Several hormones affect blood glucose levels. Besides insulin and glucagon, other hormones such as cortisol, epinephrine, and growth hormone influence glucose metabolism.
- These hormones can raise blood glucose levels by stimulating glucose production through gluconeogenesis or by reducing glucose uptake in certain tissues.

6. Role of Adipose Tissue:
- Adipose tissue, or fat cells, also contribute to blood glucose regulation.
- They release fatty acids into the bloodstream in response to insulin, which provides an alternative source of fuel for cells instead of glucose.
- Fatty acids spare glucose, allowing it to be available for tissues that primarily rely on glucose for energy.

7. Feedback Loop:
- Blood glucose regulation involves a complex feedback loop system. Specialized cells in the pancreas sense the glucose levels in the blood and release insulin or glucagon accordingly.
- As blood glucose levels rise, insulin is released to facilitate glucose uptake and reduce glucose production.
- Conversely, when blood glucose levels decrease, glucagon is released to stimulate glucose production and maintain glucose homeostasis.

These processes work together to maintain blood glucose levels within a narrow range, as excessive or insufficient glucose can have detrimental effects on various organs and bodily functions. Blood glucose regulation is crucial for energy production, cellular function, and overall metabolic health.

Sodium ions keep the body fluids in normal balance. Sodium ions regulate blood pressure and volume. Sodium ions also play an important role in nervous transmission.Therefore maintaining a constant level enables different metabolic processes to proceed normally.
The regulation of sodium ions in the body involves several processes that ensure a balance between sodium intake and excretion. Here is a step-by-step explanation of these processes:

1. Sodium Intake: Sodium ions enter the body primarily through dietary sources, such as table salt (sodium chloride) and processed foods. The average daily sodium intake is around 3,400 mg.

2. Filtration in the Kidneys: As blood passes through the kidneys, a filtration process occurs in the glomeruli, where sodium ions are filtered out of the blood along with other waste products.

3. Sodium Reabsorption in the Proximal Tubules: In the renal tubules, around 65-70% of the filtered sodium ions are reabsorbed back into the bloodstream in the proximal tubules through passive diffusion.

4. Hormonal Control:
a. Renin-Angiotensin-Aldosterone System (RAAS): When the body senses a decrease in blood volume or low blood pressure, specialized cells in the kidneys release an enzyme called renin. Renin converts angiotensinogen (a protein produced by the liver) into angiotensin I, which is then converted to angiotensin II by an enzyme called ACE (angiotensin-converting enzyme). Angiotensin II stimulates the release of aldosterone from the adrenal glands. Aldosterone acts on the distal tubules and collecting ducts of the nephrons, promoting the reabsorption of sodium ions back into the bloodstream, leading to water retention and increased blood volume and pressure.

b. Antidiuretic Hormone (ADH): ADH, also known as vasopressin, is released by the pituitary gland in response to increased plasma osmolality (concentration of solutes in the blood) or decreased blood volume. ADH acts on the collecting ducts of the nephrons, increasing the permeability of the ducts to water. This causes increased reabsorption of water back into the bloodstream, indirectly affecting sodium ion concentration and maintaining water balance.

5. Other Factors Influencing Sodium Regulation:
- Blood Pressure: Sodium plays a key role in maintaining blood pressure. Increases in sodium intake lead to an increase in blood volume, which can raise blood pressure. Conversely, decreased sodium intake can lower blood pressure.
- Atrial Natriuretic Peptide (ANP): Released by the heart's atria in response to increased blood volume and pressure, ANP acts as a natural antagonist to aldosterone. It promotes the excretion of sodium in the urine, leading to decreased blood volume and pressure.

6. Sodium Excretion: The remaining sodium ions that are not reabsorbed in the renal tubules are eliminated from the body through urine. The rate of sodium excretion depends on the balance between sodium intake and the efficacy of sodium reabsorption.

These processes work together to regulate the concentration of sodium ions in the body, maintaining electrolyte balance, blood pressure, and overall homeostasis.



Here are some precise notes on the regulation of sodium ions in the body:

1. Importance of Sodium Ions:
- Sodium ions (Na+) are essential for many physiological processes in the body, including nerve function, muscle contraction, and maintenance of fluid balance.
- Sodium ions also play a crucial role in maintaining blood volume, blood pressure, and pH balance.

2. Kidney Function in Sodium Regulation:
- The kidneys play a key role in regulating sodium concentration in the body by adjusting its reabsorption and excretion.
- Sodium reabsorption primarily occurs in the renal tubules.

3. Sodium Reabsorption:
- In the proximal tubules of the nephrons, around 65-70% of the filtered sodium is reabsorbed passively.
- Active reabsorption occurs in the distal tubules and collecting ducts, under hormonal control.

4. Hormonal Control:
a. Aldosterone:
- Aldosterone, a steroid hormone produced by the adrenal glands, plays a pivotal role in sodium regulation.
- It promotes the reabsorption of sodium ions in the distal tubules and collecting ducts of the nephrons.
- Aldosterone enhances sodium retention while simultaneously increasing potassium and hydrogen ion excretion.

b. Renin-Angiotensin-Aldosterone System (RAAS):
- The renin-angiotensin-aldosterone system is a hormonal cascade that regulates sodium balance and blood pressure.
- When blood pressure decreases or sodium levels decrease, renin is released from the kidneys, leading to the activation of angiotensin I and angiotensin II, ultimately triggering the release of aldosterone.

c. Antidiuretic Hormone (ADH):
- Another hormone involved in sodium regulation is ADH, also known as vasopressin.
- ADH is released by the pituitary gland in response to high plasma osmolality or decreased blood volume.
- ADH acts on the collecting ducts of the kidneys, promoting water reabsorption, which indirectly affects sodium concentration.

5. Osmoregulation and Water Balance:
- Sodium regulation is closely linked to water balance in the body.
- The movement of sodium ions drives osmosis, affecting the movement of water across cell membranes and in and out of the blood vessels.
- Imbalances in sodium levels can lead to improper water distribution and dehydration or overhydration.

These notes provide a concise overview of the regulation of sodium ions in the body.

DID U KNOW THATUp to 60% of the human adult body is water. According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water.This video explains to you very well what the body does in order to ensure that water in your body is neither in excess nor inadequate.

Water regulation in the body is essential for maintaining proper cellular function, blood volume, and electrolyte balance. Several organs and hormones work together to regulate water in the body. Here are some key aspects of water regulation:

1. The hypothalamus: The hypothalamus in the brain senses changes in blood osmolality, or the concentration of particles in the blood. When the osmolality increases, the hypothalamus stimulates the release of antidiuretic hormone (ADH) from the pituitary gland.

2. ADH: ADH, also known as vasopressin, is a hormone that regulates water reabsorption in the kidneys. ADH acts on the kidneys to increase the reabsorption of water, leading to decreased urine output and increased water retention. When blood osmolality decreases, ADH release is inhibited, and the kidneys excrete more water, leading to increased urine output and decreased water retention.

3. Kidneys: The kidneys play a critical role in regulating water balance in the body. The kidneys filter waste products and excess water from the blood, which is then excreted as urine. The amount of water reabsorbed in the kidneys is regulated by ADH, as described above.

4. Thirst mechanism: The sensation of thirst is an important mechanism for regulating water balance. When dehydration occurs, the body senses a decrease in blood volume, which triggers the release of hormones that stimulate thirst, leading to increased water intake.

5. Electrolyte balance: Regulating water balance also involves maintaining electrolyte balance. Electrolytes, such as sodium, potassium, and chloride, are essential for proper cellular function, and their concentrations are carefully regulated by the kidneys and several hormones.

Disruptions to the regulation of water balance can lead to various disorders, such as dehydration or overhydration, which can have significant effects on electrolyte balance and cellular function.

Watch, and learnThe parathyroid hormone (PTH), secreted by the parathyroid glands, is responsible for regulating blood calcium levels; it is released whenever blood calcium levels are low. PTH increases blood calcium levels by stimulating osteoclasts, which break down bone to release calcium into the blood stream



Calcium ions play a vital role in numerous physiological processes in the body, including muscle contraction, nerve signaling, and bone health. The regulation of calcium ions in the body is achieved through a complex series of mechanisms involving several organs and hormones. Here are some key aspects of calcium ion regulation:

1. Parathyroid hormone (PTH): When the calcium levels in the blood are low, the parathyroid glands, located in the neck, release PTH. PTH acts on the bones, kidneys, and intestines to increase calcium levels. It stimulates bone resorption, where calcium is released from the bones, and enhances the reabsorption of calcium in the kidneys and the absorption of calcium from the intestines.

2. Calcitonin: Released by the thyroid gland, calcitonin opposes the actions of PTH. It promotes the deposition of calcium into the bones, inhibits bone resorption, and reduces the reabsorption of calcium in the kidneys.

3. Vitamin D: Often known as the "sunshine vitamin" because it can be synthesized in the skin upon exposure to sunlight, vitamin D plays a critical role in calcium regulation. Vitamin D enhances the absorption of calcium from the intestines by stimulating the synthesis of calcium-binding proteins.

4. Kidneys: The kidneys regulate calcium levels by controlling its reabsorption and excretion. PTH stimulates the kidneys to reabsorb more calcium, preventing its loss through urine. Conversely, high blood calcium levels can trigger the kidneys to excrete excess calcium.

5. Bones: Calcium is stored in the bones and can be released or deposited depending on the body's needs. PTH and vitamin D influence bone cells called osteoclasts, which break down bone to release calcium, and osteoblasts, which build bone and incorporate calcium.

Disruptions to the regulation of calcium ions can lead to various disorders such as hypercalcemia (high blood calcium) or hypocalcemia (low blood calcium), which can have significant effects on muscle and nerve function, among other physiological processes.

Proteins are broken down to peptides in stomach and duodenum after which the peptides are broken down finally to amino acids in the ileum.When amino acids are in excess the body, the body does not store them but rather breaks them down in a process called deamination which involves removal of amino group from amino acid to form ammonia.Ammonia is a toxic product especially for mammals which do not have enough water in their bodies ( unlike organisms like bony fish). Therefore mammals turn the toxic ammonia into less toxic product called urea through a series of reactions in the ornithine cycle as discussed aboveOrnithine, arspatate, arginine are all amino acids.


The ornithine cycle, also known as the urea cycle, is a metabolic pathway that takes place in the liver and other tissues. It is responsible for the synthesis of urea and the detoxification of ammonia, which is a byproduct of protein metabolism. The liver plays a crucial role in this cycle by converting ammonia into urea, which can then be excreted by the kidneys.

Deamination is another important process in protein metabolism, which involves the removal of the amine group from an amino acid. This process also generates ammonia, which can be toxic to the body if it accumulates. Once again, the liver plays a critical role in removing ammonia from the body by converting it into urea, which can be safely excreted in urine.

Overall, the liver is essential for maintaining the body's nitrogen balance and preventing accumulation of toxic ammonia. Dysfunction of the liver, such as in liver disease or damage, can result in impaired ornithine cycle and deamination, leading to harmful levels of ammonia buildup in the body.

Nucleic Acids such as DNA and RNA are very important molecules in the bodies of living organisms.

This video gives an introduction looking at the monomers of nucleic Acids which are nucleotides ie the components of nucleotides, how the components combine to form nucleotides, and finally how the nucleotides combine to form nucleic Acids.

The next episodes will be about specific nucleic Acids ie RNA and DNA. So please subscribe so that you are notified whenever I post.

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Bone tissue is a type of connective tissue that forms the skeletal system of the body. It is a hard and dense tissue that provides support, protection, and movement to the body, as well as housing and protecting vital organs.

Bone tissue is made up of specialized cells, called osteocytes, embedded within a matrix composed of collagen fibers and mineral salts, predominantly calcium and phosphate. This combination of organic and inorganic materials gives bone its unique properties of strength and hardness.

Bones are classified into two types: compact bone and spongy bone. Compact bone makes up the outer layer of bones and provides strength and protection, while spongy bone is found in the interior of bones and provides structural support. Both types of bone tissue contain osteons, which are cylindrical structures composed of concentric layers called lamellae that surround a central canal containing blood vessels and nerves.

Bone tissue undergoes continuous remodeling throughout life in a process called bone remodeling. This involves the removal of old or damaged bone tissue by cells called osteoclasts and the formation of new bone tissue by cells called osteoblasts. This constant remodeling allows bones to adapt to mechanical stress, repair damage, and maintain optimal strength and structure.

In addition to its mechanical functions, bone tissue also serves as a reservoir for minerals, such as calcium and phosphate, which are essential for various physiological processes in the body. When blood calcium levels are low, bone tissue releases calcium into the bloodstream to maintain homeostasis.

Overall, bone tissue plays a crucial role in providing support and protection to the body, facilitating movement, and contributing to mineral homeostasis.

Parts of flowers, pollen grain and ova formation, structures of mature pollen grain and ovum, pollination and fertilization, agents of pollination, advantages of sexual reproduction, means employed by plants to limit self-fertilization, dispersal and agents of dispersal, seed dormancy, causes of seed dormancy, how to break seed dormancy.

Male and female reproductive systems, spermatogenesis, oogenesis, fertilization, advantages of internal fertilization, menstrual cycle, events in pregnancy, the function, structure, and adaptations of placenta, hormonal control of birth, causes of infertility in male and female




Reproduction in animals refers to the biological process through which animals produce offspring, ensuring the continuation of their species. There are various modes of reproduction in animals, including sexual reproduction and asexual reproduction.

1. ****ual Reproduction:
****ual reproduction involves the fusion of genetic material from two parents, typically a male and a female, to produce offspring. This process includes several steps:

- Mating: The male and female individuals come together for copulation, either through direct contact or via specialized reproductive organs.
- Fertilization: The fusion of sperm and egg, resulting in the formation of a zygote.
- Development: The zygote undergoes embryonic development and eventually matures into a new individual.
- Gestation: In many species, particularly mammals, the female carries and nourishes the developing embryo/fetus internally before giving birth.

****ual reproduction contributes to genetic diversity as offspring inherit a combination of traits from both parents.

2. Asexual Reproduction:
Asexual reproduction involves the production of offspring without the involvement of gametes (sperm and egg) or the fusion of genetic material from two parents. Types of asexual reproduction include:

- Binary Fission: The parent organism divides into two equal-sized daughter cells. This is commonly observed in microorganisms such as bacteria.
- Budding: A small outgrowth or bud forms on the parent organism and eventually detaches to become a new, genetically identical individual. It is seen in organisms like hydra and yeast.
- Fragmentation: The parent organism breaks into fragments, with each piece regenerating into a complete new individual. This is observed in some invertebrates such as starfish and planarians.
- Parthenogenesis: Offspring are produced from unfertilized eggs, where the female gamete develops into an embryo without fertilization. It is seen in some reptiles, insects, and fish.

Asexual reproduction typically leads to offspring that are genetically identical or very similar to the parent.

The mode of reproduction in animals varies across different species and is influenced by factors such as environmental conditions, availability of mates, and evolutionary adaptations. ****ual reproduction is more common among animals as it promotes genetic diversity, increasing the chances of survival in changing environments.

Temperature regulation in animals is the process by which animals maintain their internal body temperature within a narrow range to match the external environment. This is crucial for survival and maintaining proper bodily functions. There are two main types of animals in terms of temperature regulation, endotherms and ectotherms.

1. Endotherms:
Endotherms, also known as warm-blooded animals, are those that maintain a constant internal body temperature by generating heat through metabolic processes. Examples of endotherms are mammals and birds. These animals have a complex system of thermoregulation that enables them to maintain their body temperature within a narrow range, regardless of the external temperature.

Endotherms have several mechanisms for temperature regulation, such as:
- Shivering: Muscular contractions generate heat and raise body temperature.
- Sweating: Evaporation of sweat cools the body down.
- Vasodilation and vasoconstriction: The dilation and constriction of blood vessels regulate heat loss or gain.
- Behavioral regulation: Seeking shade or exposure to the sun to regulate body temperature.

2. Ectotherms:
Ectotherms, also known as cold-blooded animals, are those that rely on the external temperature to regulate their body temperature. Examples of ectotherms are reptiles, amphibians, and fish. These animals do not generate heat internally but instead rely on the environment to provide heat or to facilitate heat loss.

Ectotherms have different ways of regulating their body temperature, such as:
- Basking: Exposure to the sun to increase body temperature.
- Burrowing: Going underground to avoid high temperatures.
- Constriction and dilation: Constricting or dilating blood vessels to regulate blood flow and heat loss.

In summary, animals use different mechanisms to regulate their body temperature depending on whether they are endothermic or ectothermic. Both types of animals have adaptations to maintain their internal body temperature within a narrow range to ensure proper bodily functions and survival in their respective environments.

Significance of temperature regulation, types of temperature regulation, endotherms, warm blooded, ectoderms,, cold blooded, skin, responses of humans to cold and hot environment, behavioral responses, temperature regulation in plants, lower and upper critical temperatures, lower and upper lethal temperatures

Temperature regulation in animals is the process by which animals maintain their internal body temperature within a narrow range to match the external environment. This is crucial for survival and maintaining proper bodily functions. There are two main types of animals in terms of temperature regulation, endotherms and ectotherms.

1. Endotherms:
Endotherms, also known as warm-blooded animals, are those that maintain a constant internal body temperature by generating heat through metabolic processes. Examples of endotherms are mammals and birds. These animals have a complex system of thermoregulation that enables them to maintain their body temperature within a narrow range, regardless of the external temperature.

Endotherms have several mechanisms for temperature regulation, such as:
- Shivering: Muscular contractions generate heat and raise body temperature.
- Sweating: Evaporation of sweat cools the body down.
- Vasodilation and vasoconstriction: The dilation and constriction of blood vessels regulate heat loss or gain.
- Behavioral regulation: Seeking shade or exposure to the sun to regulate body temperature.

2. Ectotherms:
Ectotherms, also known as cold-blooded animals, are those that rely on the external temperature to regulate their body temperature. Examples of ectotherms are reptiles, amphibians, and fish. These animals do not generate heat internally but instead rely on the environment to provide heat or to facilitate heat loss.

Ectotherms have different ways of regulating their body temperature, such as:
- Basking: Exposure to the sun to increase body temperature.
- Burrowing: Going underground to avoid high temperatures.
- Constriction and dilation: Constricting or dilating blood vessels to regulate blood flow and heat loss.

In summary, animals use different mechanisms to regulate their body temperature depending on whether they are endothermic or ectothermic. Both types of animals have adaptations to maintain their internal body temperature within a narrow range to ensure proper bodily functions and survival in their respective environments.

Excretion is the process by which organisms remove waste products from their bodies to maintain homeostasis. It is an essential function that helps regulate the internal environment of living organisms.

1. Purpose of Excretion:
- Elimination of metabolic waste: Cells produce waste products as a result of their normal metabolic processes. Excretion removes these waste substances, such as carbon dioxide, urea, and excess ions like ammonia, to prevent their accumulation and toxicity.
- Maintenance of osmotic balance: Many organisms excrete excess water and salts to maintain proper osmotic balance within their bodies. This helps prevent dehydration or electrolyte imbalances.

2. Organs and Systems involved in Excretion:
- Kidneys: In most vertebrates, including humans, kidneys play a key role in excretion. They filter blood, remove waste products, regulate water and electrolyte balance, and produce urine.
- Lungs: In humans and many other organisms, the lungs excrete carbon dioxide and water vapor during the process of breathing.
- Skin: Sweating helps remove water, salts, and some nitrogenous wastes like urea from the body.
- Liver: The liver is involved in the excretion of certain waste products, like bilirubin and some drugs, as part of its detoxification functions.

3. Excretion in Plants:
- Plants excrete waste products through various mechanisms, including the shedding of leaves, bark, and fruit.
- Some plants also excrete excess salts through salt glands in leaves.

4. Excretion in Single-celled Organisms:
- Single-celled organisms, like bacteria and protists, excrete waste products directly into their environment.
- Amoebas, for example, excrete metabolic wastes through the cell membrane.

5. Importance of Excretion:
- Eliminating waste products helps maintain proper internal balance and prevent toxic buildup.
- Rebalancing water and ion levels is crucial for cellular functioning and overall homeostasis.

In summary, excretion is the process by which organisms eliminate waste products. It involves various organs and systems, including kidneys, lungs, skin, and liver. Excretion is important for maintaining internal balance and preventing toxin buildup in organisms.

Fully discussed revision questions

Fully discussed revision questions

Excretion and osmoregulation in marine invertebrates and vertebrates, excretion and osmoregulation fresh water animals and fish, excretion and osmoregulation in insects, excretion in plants, adaptations of xerophytes and halophytes


Excretion and osmoregulation are closely related processes that work together to maintain the balance of water and dissolved substances, such as salts, inside an organism's body.

1. Excretion:
Excretion is the process of removing metabolic waste products from an organism's body. These waste products include substances like carbon dioxide, urea, ammonia, and excess ions. Excretion helps prevent the accumulation of toxic substances and maintains the proper functioning of an organism. Examples of organs involved in excretion are the kidneys, lungs, skin, and liver.

2. Osmoregulation:
Osmoregulation is the process by which an organism regulates the balance of water and dissolved substances in its body fluids. It ensures that the concentration of solutes inside the body remains within a certain range, maintaining homeostasis. Osmoregulation involves mechanisms for retaining or excreting water and salts to maintain the proper balance.

3. Relationship between Excretion and Osmoregulation:
Excretion and osmoregulation are interconnected processes that work together to maintain the internal balance of an organism.
- Waste products, such as urea and ammonia, are excreted by the kidneys, which also play a significant role in regulating the concentration of water and ions in the body.
- The lungs, through respiration, eliminate carbon dioxide and also help regulate the body's acid-base balance.
- The skin excretes water and salts through sweating, which helps cool the body and maintain proper levels of hydration.
- The liver is involved in excreting waste products, such as bilirubin and drugs, and plays a role in maintaining the balance of various nutrients and metabolites.

Osmoregulation ensures that the concentration of water and dissolved substances in the body is maintained within a narrow range. This is achieved through various mechanisms, including the control of water intake and output, ion regulation, and adjustment of excretory processes. Excretory organs, such as the kidneys, play a vital role in osmoregulation by filtering and selectively reabsorbing substances to maintain water and salt balance.

In summary, excretion and osmoregulation are interconnected processes that work together to maintain the balance of water and dissolved substances in an organism's body. Excretion removes waste products, while osmoregulation regulates the water and solute content to maintain proper internal balance, ensuring the overall health and well-being of the organism.

definition of prokaryotic and eukaryotic cell. differences between prokaryotic and eukaryotic cells

⁣Prokaryotic and eukaryotic cells are two types of cells that make up all living organisms. They differ in their structural complexity and organization.

1. Structure:
- Prokaryotic cells: Prokaryotic cells are generally smaller and simpler in structure compared to eukaryotic cells. They lack a nucleus and membrane-bound organelles. Instead, their DNA is present in a region called the nucleoid, and they have few internal structures called ribosomes.
- Eukaryotic cells: Eukaryotic cells are larger and more complex. They contain a well-defined nucleus that houses the DNA. In addition, eukaryotic cells possess various membrane-bound organelles, such as mitochondria, endoplasmic reticulum, golgi apparatus, and others.

2. DNA Organization:
- Prokaryotic cells: Prokaryotes have a single, circular DNA molecule floating freely in the cytoplasm. It lacks the organization into chromosomes seen in eukaryotic cells.
- Eukaryotic cells: Eukaryotes have linear DNA molecules that are organized into multiple chromosomes, typically found within the nucleus.

3. Membrane-bound Organelles:
- Prokaryotic cells: Prokaryotes lack membrane-bound organelles. They have some specialized regions within their cytoplasm, such as ribosomes for protein synthesis, but these structures are not surrounded by membranes.
- Eukaryotic cells: Eukaryotes possess membrane-bound organelles that perform specific functions. These include the nucleus (DNA storage and transcription), mitochondria (energy production via cellular respiration), endoplasmic reticulum (protein synthesis and lipid metabolism), and golgi apparatus (modifying, sorting, and packaging proteins).

4. Complexity:
- Prokaryotic cells: Prokaryotes are simpler in structure and organization, lacking compartmentalization. They can be found as unicellular organisms, such as bacteria and archaea.
- Eukaryotic cells: Eukaryotes are more complex, with compartmentalization provided by membrane-bound organelles. They can be found as both unicellular (e.g., yeast) and multicellular organisms (e.g., plants, animals, fungi).

In summary, prokaryotic cells are smaller, simpler, lack a nucleus, and lack membrane-bound organelles. Eukaryotic cells are larger, more complex, contain a nucleus, and possess membrane-bound organelles.

1. What is locomotion in animals?
2. What are the different methods of locomotion employed by vertebrates?
3. How do mammals move about using their legs?
4. What adaptations do animals have for movement in extreme environments?
5. How do invertebrates like insects and spiders move about?
6. Why is locomotion important for animals?
7. Can animals switch between methods of locomotion?

Answers:
1. Locomotion is the ability of living organisms to move around from one place to another.
2. Vertebrates use various methods of locomotion. For instance, birds and bats have wings that enable them to fly, while fish have fins and tails that help them swim. Mammals, including humans, have legs that allow them to walk, run, or climb.
3. Mammals move by contracting their muscles to move their leg bones. They also adjust their gait and speed depending on the terrain, incline, or other factors.
4. Animals have specific adaptations to move in extreme environments. For instance, polar bears have large, webbed paws that help them walk on ice, and animals in the desert can drink water from their food sources to conserve energy and reduce water loss.
5. Invertebrates use a variety of methods to move. For example, jellyfish and sea anemones contract and expand their muscles to propel themselves through the water, and insects and spiders have multiple legs that enable them to walk, run, or jump.
6. Locomotion is important for animals to find food, escape predators, and navigate their environments. Animals that cannot move well usually do not survive long.
7. Yes, animals can switch between methods of locomotion. For instance, some reptiles can walk or crawl on land and also swim in water.

Biceps and triceps, stability and locomotion in tetrapod, locomotion in fish, stability in fish and how it is counteracted, locomotion in birds, adaptations of birds to locomotion, fine structure of muscles, how muscles contract.

Types of skeleton, locomotion in earthworm, locomotion in insects, human skeleton, function of bones, types of muscles and their differences and joints.

Locomotion is the ability of living organisms to move around from one place to another. Animals have developed different mechanisms and body structures to enable them to move in different environments.

Vertebrates, or animals with backbones, employ various methods of locomotion. Birds and bats, for example, have wings that enable them to fly, while fish have fins and tails that help them swim. Mammals, including humans, have legs that allow them to walk, run, or climb. Other animals like snakes use their body muscles to crawl or slither.

Invertebrates, or animals without backbones, use a variety of methods to move. Jellyfish and sea anemones contract and expand their muscles to propel themselves through the water. Insects and spiders have multiple legs that enable them to walk, run, or jump.

Some animals have specific adaptations that allow them to move in extreme environments. For example, polar bears have large, webbed paws that help them walk on ice. Kangaroos use their powerful hind legs to hop across vast distances in the Australian outback.

Overall, locomotion is essential for animals to find food, escape predators, and navigate their environments.

Well discussed structured questions from national exams

Terminologies (gene, allele, dominant gene, recessive genes, homozygous, heterozygous, back cross, test cross), monohybrid inheritance, sex determination and multiple alleles (ABO blood groups)

6 A-level paper 2 revision questions for photosynthesis


Photosynthesis is the process by which green plants make their own food using sunlight, carbon dioxide, and water. During photosynthesis, chlorophyll absorbs light energy and converts it into chemical energy which is stored in the form of glucose. Oxygen is also produced as a byproduct of photosynthesis. This process plays a significant role in maintaining the balance of oxygen and carbon dioxide in the atmosphere. The equation for photosynthesis is: 6CO2 + 6H2O + sunlight energy → C6H12O6 + 6O2.

Coordination in animals 30 objective revision questions and answers

This video is about practicals for food tests.Please enjoy.

Title: Food Tests Practicals - Episode One: Test for Starch

Introduction:
Welcome to the first episode of Food Tests Practicals! In this episode, we will be conducting a simple test to detect the presence of starch in food items. Starch is a complex carbohydrate that is commonly found in foods such as potatoes, rice, bread, and pasta. By performing this test, we can identify if a particular food item contains starch.

Materials Needed:
1. Food items for testing (recommended: potato, bread, and rice)
2. Iodine solution
3. Test tubes
4. Dropper or pipette
5. Beaker or container for water bath
6. Water

Procedure:
1. Start by setting up a water bath. Fill a beaker or container with water and heat it until it reaches a gentle simmer.
2. Take the food items you wish to test (potato, bread, and rice) and cut small pieces of each. Ensure that the pieces are roughly the same size.
3. Label your test tubes with the names of the food items you are testing.
4. Place a piece of each food item into their respective labeled test tubes.
5. Add a few drops of iodine solution to each test tube using a dropper or pipette.
6. Observe the color change that occurs. Starch reacts with iodine to produce a dark blue or black color.

Results and Interpretation:
Positive Result - If the color of the solution changes to dark blue or black, it indicates the presence of starch in the tested food item.
Negative Result - If the color of the solution remains unchanged (brown or yellow), it suggests the absence of starch in the tested food item.

Conclusion:
In this episode of Food Tests Practicals, we performed a test to detect the presence of starch in food items using iodine solution. By observing the color change in the solution, we can determine if a food item contains starch. Starch is an essential carbohydrate in our diet, providing energy and serving as a storage form of glucose in plants. Stay tuned for more practical episodes on food tests to expand your knowledge of food science!

Questions are skillfully selected test and enhance understanding

Definition of homeostasis, mechanisms of homeostasis (negative feedback and positive feedback), components of efficient negative feed back mechanism, homeostasis of glucose, role of pancreas in homeostasis of glucose (i.e. production of insulin) and diabetes mellitus



Homeostasis is the ability of an organism or system to maintain a stable and constant internal environment despite changes in the external environment or physiological conditions. In other words, homeostasis is the process by which the body regulates and maintains equilibrium or balance within its internal environment, including temperature, pH, fluid levels, and energy metabolism.

The mechanisms of homeostasis involve feedback loops that continuously monitor and adjust internal conditions to maintain stable levels. Negative feedback loops, for example, are used to detect and correct deviations from normal conditions, such as fluctuations in body temperature or blood glucose levels. Positive feedback loops, on the other hand, amplify changes in the internal environment and are involved in processes such as childbirth and blood clotting.

The body's major organ systems work together to maintain homeostasis. The nervous system, for example, uses sensors in the body to detect deviations from normal conditions and sends signals to coordinate responses. The endocrine system uses hormones to regulate various physiological processes, including metabolism, growth and development, and fluid and ion balance. The immune system also plays a role in maintaining homeostasis by fighting off infections and other threats to the internal environment.

Dysfunction in homeostasis can lead to diseases and health problems. For example, diabetes results from a failure in the body's ability to regulate blood sugar levels, while dehydration occurs when there is an imbalance in fluid and electrolyte levels. Understanding homeostasis and its mechanisms is thus crucial in preventing and treating various health conditions.

central nervous system, reflex arc, conditioned reflex, part and functions of parts of the brain, sympathetic and parasympathetic systems, position of endocrine glands in the body, hormone and their function, mechanism of hormone action



⁣Differences between Nervous and Endocrine Systems:

1. Communication:
- Nervous System: Uses electrical impulses (action potentials) for rapid communication.
- Endocrine System: Uses chemical messengers called hormones for slower, long-distance communication.

2. Mode of Transmission:
- Nervous System: Transmits information through neurons via synapses.
- Endocrine System: Releases hormones into the bloodstream to target specific tissues or organs.

3. Speed of Response:
- Nervous System: Responds rapidly, enabling quick reflexes and immediate reactions.
- Endocrine System: Responds more slowly, with effects taking minutes to hours, but lasts longer.

4. Duration of Effect:
- Nervous System: Effects are short-lived.
- Endocrine System: Effects are long-lasting.

Action Potential:
- An action potential is a rapid electrical impulse that allows neurons to transmit signals throughout the nervous system.
- It is generated when the membrane potential of a neuron depolarizes, reaching a threshold level, causing a cascade of voltage-gated ion channels to open and initiate the action potential.
- The action potential propagates down the axon of a neuron, allowing for long-distance transmission of signals.

Impulse:
- An impulse refers to the rapid transmission of an action potential along the length of a neuron.
- It involves the depolarization and repolarization of the neuron's membrane.
- The impulse allows for the efficient and coordinated communication of signals in the nervous system.

All-or-None Law:
- The all-or-none law states that once a neuron's membrane potential reaches the threshold level, an action potential is generated and transmitted along the neuron.
- The size or intensity of the stimulus does not affect the amplitude or speed of the action potential; it either fires completely or does not fire at all.

Refractory Period:
- The refractory period is a brief period of time following an action potential when the neuron cannot generate another action potential.
- It allows the neuron to recover and reset its ion channels before firing again, ensuring proper signal transmission and preventing continuous firing.

Synapse:
- A synapse is a junction between two neurons or between a neuron and an effector cell (such as a muscle or gland).
- It is the site where communication occurs between these cells.
- At the synapse, the electrical signal of the presynaptic neuron is converted into a chemical signal in the form of neurotransmitters.

Transmission at the Synapse:
- Transmission at the synapse involves the release of neurotransmitters from the presynaptic neuron, which diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron or effector cell.
- This binding triggers a response in the postsynaptic neuron or effector cell, propagating the signal across the synapse.

Neuromuscular Junction:
- The neuromuscular junction is a specialized synapse between a motor neuron and a muscle fiber.
- It is responsible for transmitting signals from the motor neuron to the muscle, leading to muscle contraction.

Functions of Synapses:
- Mediating the transmission of signals between neurons, allowing for communication within the nervous system.
- Integrating and processing incoming signals, allowing for complex and coordinated responses.
- Modulating and amplifying signals, enabling effective communication and control of bodily functions.
- Allowing for synaptic plasticity, which is crucial for learning, memory formation, and neural adaptability.

Differences between nervous and endocrine system, action potential, impulse, none or nothing law, refractory period, synapse, transmission at the synapse, neuromuscular junction, functions of the synapses.




Differences between Nervous and Endocrine Systems:

1. Communication:
- Nervous System: Uses electrical impulses (action potentials) for rapid communication.
- Endocrine System: Uses chemical messengers called hormones for slower, long-distance communication.

2. Mode of Transmission:
- Nervous System: Transmits information through neurons via synapses.
- Endocrine System: Releases hormones into the bloodstream to target specific tissues or organs.

3. Speed of Response:
- Nervous System: Responds rapidly, enabling quick reflexes and immediate reactions.
- Endocrine System: Responds more slowly, with effects taking minutes to hours, but lasts longer.

4. Duration of Effect:
- Nervous System: Effects are short-lived.
- Endocrine System: Effects are long-lasting.

Action Potential:
- An action potential is a rapid electrical impulse that allows neurons to transmit signals throughout the nervous system.
- It is generated when the membrane potential of a neuron depolarizes, reaching a threshold level, causing a cascade of voltage-gated ion channels to open and initiate the action potential.
- The action potential propagates down the axon of a neuron, allowing for long-distance transmission of signals.

Impulse:
- An impulse refers to the rapid transmission of an action potential along the length of a neuron.
- It involves the depolarization and repolarization of the neuron's membrane.
- The impulse allows for the efficient and coordinated communication of signals in the nervous system.

All-or-None Law:
- The all-or-none law states that once a neuron's membrane potential reaches the threshold level, an action potential is generated and transmitted along the neuron.
- The size or intensity of the stimulus does not affect the amplitude or speed of the action potential; it either fires completely or does not fire at all.

Refractory Period:
- The refractory period is a brief period of time following an action potential when the neuron cannot generate another action potential.
- It allows the neuron to recover and reset its ion channels before firing again, ensuring proper signal transmission and preventing continuous firing.

Synapse:
- A synapse is a junction between two neurons or between a neuron and an effector cell (such as a muscle or gland).
- It is the site where communication occurs between these cells.
- At the synapse, the electrical signal of the presynaptic neuron is converted into a chemical signal in the form of neurotransmitters.

Transmission at the Synapse:
- Transmission at the synapse involves the release of neurotransmitters from the presynaptic neuron, which diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron or effector cell.
- This binding triggers a response in the postsynaptic neuron or effector cell, propagating the signal across the synapse.

Neuromuscular Junction:
- The neuromuscular junction is a specialized synapse between a motor neuron and a muscle fiber.
- It is responsible for transmitting signals from the motor neuron to the muscle, leading to muscle contraction.

Functions of Synapses:
- Mediating the transmission of signals between neurons, allowing for communication within the nervous system.
- Integrating and processing incoming signals, allowing for complex and coordinated responses.
- Modulating and amplifying signals, enabling effective communication and control of bodily functions.
- Allowing for synaptic plasticity, which is crucial for learning, memory formation, and neural adaptability.

structure, adaptations and functions of photosynthesis, chemistry of photosynthesis(light harvesting, electron transport and Calvin cycle), C3 and C4 plants, advantages of C4 plants over C3 plant, differences between respiration and photosynthesis.



Structure and Adaptations of Photosynthesis:
- Photosynthesis occurs in the chloroplasts of plant cells.
- Chloroplasts contain a green pigment called chlorophyll, which captures sunlight.
- The chloroplasts have an inner membrane, outer membrane, and thylakoid membranes, where the various stages of photosynthesis take place.
- The thylakoid membranes are arranged in stacks called grana, and the fluid-filled space surrounding the grana is called the stroma.
- Adaptations of photosynthesis include the presence of large surface areas with abundant chloroplasts in leaves, and the arrangement of chlorophyll molecules in the thylakoid membranes to maximize light absorption.

Functions of Photosynthesis:
- Conversion of sunlight energy into chemical energy in the form of glucose.
- Production of oxygen as a byproduct, which is released into the atmosphere.
- Biosynthesis of carbohydrates and other organic compounds necessary for the plant's growth and maintenance.

Chemistry of Photosynthesis:
1. Light Harvesting: Chlorophyll absorbs photons of light energy, exciting electrons and initiating the process.
2. Electron Transport: Excited electrons are passed through a series of electron carriers within the thylakoid membranes, generating ATP and reducing NADP+ to NADPH.
3. Calvin Cycle: This occurs in the stroma and involves a series of enzyme-mediated reactions that use ATP and NADPH to convert carbon dioxide into glucose.

C3 and C4 Plants:
- C3 plants: Common plants like wheat, rice, and oats that directly use the C3 pathway in photosynthesis. In this pathway, carbon dioxide is initially fixed into a three-carbon compound.
- C4 plants: Plants like corn, sugarcane, and sorghum that have an additional step before entering the C3 pathway. They first fix carbon dioxide into a four-carbon compound, helping them adapt to hotter and drier environments.

Advantages of C4 Plants over C3 Plants:
- C4 plants have a higher rate of photosynthesis and can better withstand high temperatures and low carbon dioxide conditions.
- Their unique carbon fixation process allows them to efficiently use water and nutrients, promoting their growth in arid conditions.
- C4 plants often exhibit better water use efficiency compared to C3 plants.

Differences between Respiration and Photosynthesis:
1. Respiration occurs in all living cells, while photosynthesis occurs only in plants, algae, and some bacteria.
2. Respiration involves the breakdown of glucose to produce ATP, releasing carbon dioxide as a byproduct, while photosynthesis fixes carbon dioxide to produce glucose, releasing oxygen as a byproduct.
3. Respiration occurs continuously, while photosynthesis typically occurs during daylight hours.
4. Respiration releases energy, while photosynthesis stores energy.

types of autotrophic nutrition, conditions necessary for photosynthesis, limiting factors of photosynthesis

Purpose, types and adaptations to different types of heterotrophic nutrition
digestion and adaptation of digestive canal
control of digestions

Properties, and uses of acids, bases, water, carbohydrates, lipids, proteins, and vitamins

Aerobic respiration, anaerobic respiration, glycolysis, Krebs cycle, basal metabolic rate, fermentation

⁣Cellular respiration is the process by which cells convert nutrients into energy in the form of ATP (adenosine triphosphate). It is a series of metabolic reactions that occur in the presence of oxygen (aerobic respiration) or in the absence of oxygen (anaerobic respiration).

In aerobic respiration, the process takes place in the mitochondria and consists of three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle or TCA cycle), and the electron transport chain.

Glycolysis occurs in the cytoplasm and breaks down glucose into two molecules of pyruvate. This process yields a small amount of ATP and NADH.

Next, pyruvate enters the mitochondria where it undergoes the Krebs cycle. During this cycle, pyruvate is further broken down, releasing carbon dioxide and producing NADH, FADH2, and ATP.

The final stage is the electron transport chain, which occurs in the inner mitochondrial membrane. NADH and FADH2 produced in previous stages donate electrons to the chain, creating a flow of electrons that generates a proton gradient. This gradient drives ATP synthesis through oxidative phosphorylation.

Anaerobic respiration occurs in the absence of oxygen and includes processes such as alcoholic fermentation and lactic acid fermentation. These processes allow cells to continue generating small amounts of ATP without oxygen but are less efficient than aerobic respiration.

Overall, cellular respiration is a crucial process for organisms to obtain energy from nutrients and sustain various cellular activities.

properties of enzymes, factors affecting enzymes, lock and key hypothesis, enzyme inhibitors, anabolic reactions, catabolic reactions

Diffusion, osmosis, active transport, phagocytosis and pinocytosis for A-level students

This episode breaks down skeletal tissue starting with cartilage. Please learn, and ensure that you note down.

Structure, Functions, and adaptations of parenchyma, collenchyma, sclerenchyma, xylem and phloem for A -level students

epithelial and connective tissues, squamous, cuboidal, columnar tissue, endocrine tissue, connective tissues

Drawings of plants and animal cell; functions of parts of plants and animal cells, differences between plants and animal cells. suitable for advanced level and institutions.



Although plants and animals are both living organisms, there are significant differences between the cells found in each of them.

Plant cells have some unique features that distinguish them from animal cells:

1. Cell wall: Plant cells have a rigid cell wall made of cellulose, which provides structural support and protection for the cell. Animal cells do not have a cell wall.

2. Chloroplasts: Plant cells contain chloroplasts, which are responsible for photosynthesis. Chloroplasts contain the pigment chlorophyll and convert sunlight into energy. Animal cells do not have chloroplasts.

3. Large central vacuole: Plant cells have a large central vacuole that occupies a significant portion of the cell. The vacuole stores water, nutrients, and waste products and helps maintain cell turgidity. Animal cells may have smaller vacuoles, but they are not as prominent as in plant cells.

4. Plasmodesmata: Plant cells are interconnected by tiny channels called plasmodesmata, which allow for the transport of nutrients and signals between adjacent cells. Animal cells do not have plasmodesmata.

In contrast, animal cells have some distinguishing features:

1. Centrioles: Animal cells often contain centrioles, which are involved in cell division and the formation of spindle fibers. Plant cells lack centrioles.

2. Lysosomes: Animal cells have lysosomes, which are membrane-bound organelles that contain digestive enzymes. Lysosomes break down waste materials and cellular debris. Plant cells may have vacuoles with some similar functions but do not have true lysosomes.

3. Cilia and flagella: Animal cells often have cilia or flagella, which are hair-like structures involved in cellular movement. Plant cells do not have cilia or flagella, although some algae, which are plant-like organisms, may have similar structures.

Despite these differences, plant and animal cells also share many similarities. Both types of cells have a nucleus that contains the genetic material (DNA), as well as similar membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Both plant and animal cells are eukaryotic cells, meaning they have a true nucleus and membrane-bound organelles.

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. This energy is then stored as potential energy and used by organisms for various metabolic activities.

The process of photosynthesis can be divided into two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle).

Light-dependent reactions: These reactions occur in the thylakoid membrane of the chloroplasts and require light energy. The key steps involved in this stage are:

1. Absorption of light: Chlorophyll and other pigments in the thylakoid membrane absorb photons of light. This energy is used to excite electrons in chlorophyll.

2. Electron transport chain: Excited electrons from chlorophyll are passed along a series of electron carriers, losing energy in the process. This energy is used to pump hydrogen ions (H+) across the thylakoid membrane, creating a proton gradient.

3. ATP synthesis: The proton gradient created is used to drive ATP synthase, an enzyme that synthesizes ATP from ADP and inorganic phosphate. This process is called chemiosmosis.

4. Generation of reducing power: Excited electrons from chlorophyll are also used to reduce NADP+ to NADPH, another molecule that stores energy.

Light-independent reactions (Calvin cycle): These reactions occur in the stroma of the chloroplasts and do not require light directly. The key steps involved in this stage are:

1. Carbon fixation: CO2 from the atmosphere is captured and added to a 5-carbon molecule called ribulose bisphosphate (RuBP), forming an unstable 6-carbon molecule. This process is catalyzed by the enzyme rubisco.

2. Reduction: The 6-carbon molecule is quickly split into two 3-carbon molecules called 3-phosphoglycerate (PGA). ATP and NADPH from the light-dependent reactions are used to convert PGA into a 3-carbon sugar called glyceraldehyde-3-phosphate (G3P).

3. Regeneration: Some G3P molecules are converted back into RuBP, while others are used to synthesize glucose and other organic molecules.

Overall, photosynthesis is a crucial process for sustaining life on Earth as it provides oxygen for respiration and serves as the primary source of energy for most living organisms.

Organs of neck and muscles on the chest, abdominal structures in undisturbed form, veins from digestive system, arteries to digestive system, urinogenital system, diaphragm, visceral structures of the chest in undisturbed form and blood vessels in the neck and chest region.

classification, external structures functions and adaptations, Ecology

Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose (a simple sugar) and oxygen. It is a crucial biological process that occurs in the chloroplasts of plant cells.

During photosynthesis, light energy is absorbed by pigments in the chloroplasts, primarily chlorophyll. This energy is used to power a series of chemical reactions that take place in two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle).

In the light-dependent reactions, light energy is converted into chemical energy in the form of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). These energy carriers are used in the next stage of photosynthesis.

In the light-independent reactions, also known as the Calvin cycle, ATP and NADPH are utilized to convert carbon dioxide into glucose. This process involves a series of chemical reactions that use enzymes to catalyze the formation of glucose. The glucose produced can be used by the plant as an energy source or stored as starch for later use.

Photosynthesis not only provides energy-rich glucose for the plant but also produces oxygen as a byproduct. This oxygen is released into the atmosphere and is vital for supporting aerobic respiration in many organisms.

Overall, photosynthesis is an essential process that allows plants, algae, and certain bacteria to convert sunlight into chemical energy in the form of glucose. It plays a crucial role in sustaining plant life and maintaining the balance of oxygen and carbon dioxide in the Earth's atmosphere. Additionally, photosynthesis acts as the primary source of energy for most ecosystems on our planet.

Autotrophic nutrition is a mode of nutrition in which an organism synthesizes its own food using simple inorganic substances, such as carbon dioxide and water, with the help of energy from sunlight or inorganic chemical reactions. Autotrophs are organisms that have the ability to produce organic compounds from inorganic sources.

There are two main types of autotrophs: photoautotrophs and chemoautotrophs. Photoautotrophs use sunlight as a source of energy and are able to convert carbon dioxide and water into organic compounds by the process of photosynthesis. Examples of photoautotrophs include plants, algae, and cyanobacteria.

Chemoautotrophs, on the other hand, obtain their energy from chemical reactions involving inorganic compounds, such as sulfur, nitrogen, or iron. They can use the energy from these reactions to convert carbon dioxide into organic compounds. Examples of chemoautotrophs include some bacteria and archaea.

Autotrophic nutrition is important for the biosphere because it forms the basis of the food chain. Autotrophs are the primary producers that provide the energy and organic compounds essential for the survival of all other organisms. Through photosynthesis, autotrophs also release oxygen into the atmosphere, which is utilized by many organisms for respiration.

Overall, autotrophic nutrition is a unique mode of nutrition that enables organisms to produce their own food without relying on other organisms. It plays a vital role in sustaining life on Earth and maintaining ecological balance.

Created by @hakimtheblackbutterfly #tiktok #trending #shortsfeed #newvideo #youtubeshorts #instagram #subscribe @youtubecreater47 @youtubecreators @rkcreationsvlog @Biology made easy#biology#cytology

This video talks about the definition of the standard enthalpy of combustion. It also helps us identify the relationship between the standard enthalpy of combustion and the calorific value for a given fuel. This helps us compare different fuels.

00:00- Introduction
2:14- Is combustion enthalpy always negative?
2:34- Comparing fuels using combustion enthalpy values.
4:13- Calculating enthalpy of formation using combustion enthalpy values.

Practice this concept - “https://www.khanacademy.org/sc....ience/physical-chemi

Check out more videos and exercises on “Thermodynamics” - https://www.khanacademy.org/sc....ience/physical-chemi

To get you fully ready for your exam and help you fall in love with “Chemistry”, find the complete bank of exercises and videos for “Class 11 Chemistry” here -https://www.khanacademy.org/sc....ience/class-11-chemi

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Created by
Jitin Nair

This episode gives you a detailed introduction of a subtopic Histology under a topic of Cell Biology with more emphasis on Simple Epithelial Tissue.

This episode is setting a pace for a series of episodes that are about the same topic subtopic that u need to watch to get a complete doze of content.

May you subscribe(if you haven't), like the videos,comment and share the links with friends

This video breaks down areolar tissue as the simplest connective tissue.please Enjoy.

In this video, we explore more about a unique type of animal tissue called connective tissue with more focus on the breakdown of the different types.

Please enjoy, watch other episodes, and Share with colleagues and friends

Talk to Tr OSBERT NUWARINDA
+256705353517/+256779114179
osbertnuwa94@gmail.com

Get yourself a copy of biology book written by Tr.OSBERT NUWARINDA
1. Ordinary biology Made Easy (Good biology book for research for O'level)
2. Advanced Biology Demystified vol1 &vol 2 ( With good precise but enriching content of Advanced Level Biology)

In this episode, we expound more on the compound Epithelial Tissue. Just watch till the end and I tell you what,! you need to watch out for the next episode is really waoo.

watch, enjoy, and share. don't forget to subscribe Incase you haven't.

@nuwarindaosbertug9724

In this episode, we breakdown glandular tissue, types, examples and look at the structures of different glands. you don't have to miss it. I know you are going to enjoy it like never before.

Next video is about connective tissue also explained in totality. Just sit and enjoy the learning.

The ability to pass Biology exams lies in writing and rewriting notes, questions and answers to internalise the concepts, improve on spellings and writing.

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Chemicals of life

⁣In biology, the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body. A cell has three main parts: the cell membrane, the nucleus, and the cytoplasm. The cell membrane surrounds the cell and controls the substances that go into and out of the cell.

Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.

⁣an insoluble substance which is the main constituent of plant cell walls and of vegetable fibers such as cotton. It is a polysaccharide consisting of chains of glucose monomers.

starch, a white, granular, organic chemical that is produced by all green plants. Starch is a soft, white, tasteless powder that is insoluble in cold water, alcohol, or other solvents. The basic chemical formula of the starch molecule is (C6H10O5)n.

Amylopectin, the counterpart of amylose, is the major component of starch by weight and one of the largest molecules found in nature. It also is composed of linear chains of (1→4) linked α-d-glucopyranosyl units but with a much greater extent of α-(1→6) branching than amylose.

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