B1-B4 Biology covers the fundamental concepts of how living things...
Biology1,304 views·Updated Jun 1, 2026·5 pagesComprehensive Biology Revision: Paper 1 Foundation & Higher
D
Darcy Smyth@darcysmyth_aadg
1 / 5
1
of 5
Cells and Transport
Every living thing is built from cells - think of them as biological building blocks with specific parts doing different jobs. Animal cells have a nucleus (containing genetic material), cytoplasm (full of enzymes), cell membrane (controlling what enters and exits), and mitochondria (powering the cell through respiration).
Plant cells have all these parts plus some extras: a cell wall for support, a vacuole filled with cell sap, and chloroplasts for photosynthesis. Some cells, like stem cells found in bone marrow, haven't specialised yet and can become any type of cell - that's why they're so useful in medicine.
Substances move around cells through different processes. Diffusion happens when particles spread from areas of high concentration to low concentration naturally. Osmosis is similar but specifically for water moving across membranes. Active transport is different - it moves molecules against the concentration gradient, which requires energy from the cell.
Quick Tip: Remember that plant cells have everything animal cells have, PLUS extra structures - never the other way around!
2
of 5
Organs and Enzymes
Your body's organs are perfectly designed for their jobs through specialised exchange surfaces. The lungs have tiny air sacs called alveoli with huge surface areas and thin walls for efficient gas exchange. Your small intestine has villi - finger-like projections that massively increase surface area for absorbing nutrients quickly.
Enzymes are biological catalysts that speed up reactions without being used up themselves. The main digestive enzymes you need to know are amylase (breaks down starch into sugars), protease (breaks down proteins into amino acids), and lipase (breaks down fats into glycerol and fatty acids).
Your heart pumps blood around your body through three types of blood vessels. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries are tiny vessels where substances are exchanged with tissues.
Exam Focus: Learn the enzyme names and what they break down - this comes up frequently in tests!
3
of 5
Disease and Defence
Pathogens are microorganisms that cause disease, and they come in four main types. Bacteria reproduce rapidly and release toxins, viruses live inside cells and damage them, fungi grow and spread on organisms, and protists are parasites that live off other organisms.
Your body has brilliant defence mechanisms against disease. Physical barriers like skin, hair, and mucus stop pathogens entering. If they do get in, white blood cells either consume the invaders or produce antibodies that attack specific pathogens.
Vaccination works by injecting small amounts of dead or inactive pathogens, making your immune system familiar with the disease so it can fight it off quickly if you encounter it again. Antibiotics kill bacteria but don't work against viruses - that's why doctors won't give them for colds or flu.
Real World: Antibiotic-resistant bacteria develop when people don't complete their antibiotic courses, so always finish the full prescription!
4
of 5
Respiration and Photosynthesis
Respiration happens in every living cell to transfer energy from glucose - it's how your body powers everything from muscle contractions to maintaining body temperature. Aerobic respiration uses oxygen and happens in the mitochondria, whilst anaerobic respiration happens without oxygen but only provides energy for short periods.
Photosynthesis is how plants make their own food using the equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Plants use the glucose produced for respiration, making cellulose for structure, or storing it as starch for later.
The rate of photosynthesis depends on limiting factors - whichever factor is in shortest supply limits the whole process. These are light intensity, carbon dioxide concentration, and temperature. Farmers use greenhouses to control these factors and maximise crop growth.
Memory Trick: Photosynthesis and respiration are basically opposite processes - one makes glucose using CO₂, the other breaks down glucose producing CO₂!
5
of 5
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Protein
7Most popular content in Biology
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
Biology1,304 views·Updated Jun 1, 2026·5 pagesComprehensive Biology Revision: Paper 1 Foundation & Higher
D
Darcy Smyth@darcysmyth_aadg
B1-B4 Biology covers the fundamental concepts of how living things work, from the tiny cells that make up everything to the complex processes that keep organisms alive. You'll explore how substances move in and out of cells, how organs are...
1
of 5
Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Cells and Transport
Every living thing is built from cells - think of them as biological building blocks with specific parts doing different jobs. Animal cells have a nucleus (containing genetic material), cytoplasm (full of enzymes), cell membrane (controlling what enters and exits), and mitochondria (powering the cell through respiration).
Plant cells have all these parts plus some extras: a cell wall for support, a vacuole filled with cell sap, and chloroplasts for photosynthesis. Some cells, like stem cells found in bone marrow, haven't specialised yet and can become any type of cell - that's why they're so useful in medicine.
Substances move around cells through different processes. Diffusion happens when particles spread from areas of high concentration to low concentration naturally. Osmosis is similar but specifically for water moving across membranes. Active transport is different - it moves molecules against the concentration gradient, which requires energy from the cell.
Quick Tip: Remember that plant cells have everything animal cells have, PLUS extra structures - never the other way around!
2
of 5Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Organs and Enzymes
Your body's organs are perfectly designed for their jobs through specialised exchange surfaces. The lungs have tiny air sacs called alveoli with huge surface areas and thin walls for efficient gas exchange. Your small intestine has villi - finger-like projections that massively increase surface area for absorbing nutrients quickly.
Enzymes are biological catalysts that speed up reactions without being used up themselves. The main digestive enzymes you need to know are amylase (breaks down starch into sugars), protease (breaks down proteins into amino acids), and lipase (breaks down fats into glycerol and fatty acids).
Your heart pumps blood around your body through three types of blood vessels. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries are tiny vessels where substances are exchanged with tissues.
Exam Focus: Learn the enzyme names and what they break down - this comes up frequently in tests!
3
of 5Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Disease and Defence
Pathogens are microorganisms that cause disease, and they come in four main types. Bacteria reproduce rapidly and release toxins, viruses live inside cells and damage them, fungi grow and spread on organisms, and protists are parasites that live off other organisms.
Your body has brilliant defence mechanisms against disease. Physical barriers like skin, hair, and mucus stop pathogens entering. If they do get in, white blood cells either consume the invaders or produce antibodies that attack specific pathogens.
Vaccination works by injecting small amounts of dead or inactive pathogens, making your immune system familiar with the disease so it can fight it off quickly if you encounter it again. Antibiotics kill bacteria but don't work against viruses - that's why doctors won't give them for colds or flu.
Real World: Antibiotic-resistant bacteria develop when people don't complete their antibiotic courses, so always finish the full prescription!
4
of 5Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Respiration and Photosynthesis
Respiration happens in every living cell to transfer energy from glucose - it's how your body powers everything from muscle contractions to maintaining body temperature. Aerobic respiration uses oxygen and happens in the mitochondria, whilst anaerobic respiration happens without oxygen but only provides energy for short periods.
Photosynthesis is how plants make their own food using the equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Plants use the glucose produced for respiration, making cellulose for structure, or storing it as starch for later.
The rate of photosynthesis depends on limiting factors - whichever factor is in shortest supply limits the whole process. These are light intensity, carbon dioxide concentration, and temperature. Farmers use greenhouses to control these factors and maximise crop growth.
Memory Trick: Photosynthesis and respiration are basically opposite processes - one makes glucose using CO₂, the other breaks down glucose producing CO₂!
5
of 5Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: Protein
7Most popular content in Biology
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user