Cell biology and human body systems might seem complex, but... Show more
Biology396 views·Updated May 26, 2026·19 pagesComprehensive AQA Biology Paper 1 & 2 Mind Maps
M
Millie@milliexcarrots
1 / 10
1
of 10
Transport in Cells and Cell Division
Ever wonder how nutrients get into your cells or how you grow? It all comes down to three key transport processes that are happening in your body right now.
Diffusion is the net movement of particles from high to low concentration - think of how perfume spreads across a room. Temperature, concentration gradient, and surface area all affect how fast this happens. Your small intestine is brilliant at this because it has a massive surface area and thin walls.
Osmosis works similarly but specifically moves water molecules across partially permeable membranes from dilute to concentrated solutions. Active transport is different - it uses energy from respiration to move particles from low to high concentration, like root hair cells absorbing minerals.
Your chromosomes carry thousands of genes and come in 23 pairs in human body cells. Stem cells are undifferentiated cells that can become different cell types - embryonic ones can become any cell type, whilst adult stem cells are more limited. The cell cycle involves growth, DNA copying during synthesis, then mitosis where one cell divides into two identical daughter cells.
Key Practical: Test how different sugar concentrations affect potato tissue mass by placing equal-sized pieces in various solutions for 2 hours, then measuring the changes.
2
of 10
Cell Structure and Microscopy
Understanding cell structure is like getting the blueprint for life itself - and the differences between cell types tell us everything about how organisms function.
Animal cells contain a nucleus (controls the cell), mitochondria (where respiration happens), ribosomes (make proteins), cytoplasm (where reactions occur), and a cell membrane (controls what enters and leaves). Plant cells have all of these plus a cellulose cell wall for strength, chloroplasts for photosynthesis, and a permanent vacuole for support.
Bacterial cells are completely different - they're prokaryotic (genetic material not in a nucleus) whilst plant, animal and fungal cells are eukaryotic (genetic material in a nucleus). Bacteria have flagella for movement and plasmids that allow gene transfer between cells.
When using microscopes, remember that magnification = size of image ÷ size of real object, whilst resolution is the ability to distinguish between separate objects. Different units matter too: centimetres (1×10²), millimetres (1×10³), micrometres (1×10⁶), and nanometres (1×10⁹).
Microscope Practical: Always use low power first to locate cells, add stain like iodine for clarity, and include a scale line in your drawings.
3
of 10
Food Tests
Knowing what's in your food isn't just about reading labels - scientists use specific chemical tests to identify the main biological molecules, and you can do these tests yourself.
The Benedict's test detects sugars by adding Benedict's solution to your sample and heating in a water bath at 80°C. Blue means no sugar, whilst green, yellow, orange, and red show increasing sugar concentrations. For starch, add iodine solution - it turns from brown/orange to blue-black if starch is present.
Lipids are tested using Sudan III solution, which separates the mixture into two layers with the top layer turning red if fats are present. The Biuret test identifies proteins by adding Biuret solution - it changes from blue to purple if proteins are detected.
Before any test, you'll need to prepare your sample by breaking up the food, adding distilled water, stirring to dissolve, then filtering out solid bits. This gives you a clear solution to work with.
Remember: Always point test tubes away from you when heating, and use exactly 2cm³ or 5cm³ of solutions as specified for accurate results.
4
of 10
Specialised Cells
Your body contains incredibly specialised cells, each perfectly designed for their specific job - it's like having the ultimate toolkit where every tool is custom-made for one purpose.
Sperm cells are built for one mission: reaching the egg. They have a streamlined head for speed, an acrosome containing enzymes to penetrate the egg, loads of mitochondria for energy, and a tail for swimming. Nerve cells transmit electrical signals using their long axon, dendrites that receive signals from other neurons, and a myelin sheath that insulates and speeds up transmission.
Muscle cells are packed with mitochondria for energy and protein fibres that can contract to create movement. In plants, xylem cells form hollow tubes (end walls break down, no cytoplasm) strengthened with lignin to transport water and minerals one way only.
Phloem cells work differently - they keep their end walls with holes to allow sugar transport, work in both directions, and need companion cells for support. Root hair cells have a massive surface area for absorbing water by osmosis and loads of mitochondria to power active transport of minerals.
Top Tip: Each specialised cell has features directly linked to its function - learn the job first, then the adaptations make perfect sense.
5
of 10
Heart Structure and Function
Your heart is essentially a double pump that never stops working, and understanding its structure shows you exactly how it keeps you alive every single second.
The heart has four chambers: two atria that receive blood from veins, and two ventricles that pump blood into arteries. Blood flows from the vena cava into the right atrium, through the tricuspid valve to the right ventricle, then out via the pulmonary artery to the lungs.
After picking up oxygen in the lungs, blood returns via pulmonary veins to the left atrium, passes through the bicuspid valve to the left ventricle, then gets pumped out through the aorta to the rest of your body. This is called the double circulatory system because blood passes through the heart twice in each complete circuit.
The left ventricle has thicker walls than the right because it needs to pump blood around your entire body, whilst the right ventricle only pumps to your lungs. Valves prevent backflow and ensure blood only moves in one direction.
Memory Trick: Remember that arteries carry blood away from the heart, whilst veins carry blood back to the heart - the pulmonary vessels are the exception to the usual oxygenation rule.
6
of 10
Gaseous Exchange in Lungs
Every breath you take is part of an incredibly efficient system that gets oxygen to your cells and removes carbon dioxide - and it's all about maximising surface area for diffusion.
Air travels through your trachea (windpipe with cartilage rings to prevent collapse), splits into two bronchi, then divides into smaller bronchioles that end in tiny air sacs called alveoli. These millions of alveoli are where the magic happens.
Alveoli are perfectly adapted for gas exchange: they have a massive moist surface area, an excellent blood supply through capillaries, and extremely thin walls so gases only need to diffuse a short distance. Oxygen diffuses from alveoli into blood whilst carbon dioxide diffuses from blood into alveoli.
The heart sends deoxygenated blood to lungs via the pulmonary artery, and oxygenated blood returns via pulmonary veins. This constant circulation ensures fresh oxygen reaches every cell in your body whilst waste carbon dioxide gets removed.
Key Point: The entire respiratory system is designed around one principle - maximising the surface area available for diffusion whilst minimising the distance gases need to travel.
7
of 10
Immune System and Disease Prevention
Your body is under constant attack from pathogens, but you've got an amazing defence system that works 24/7 to keep you healthy - and understanding it helps you make better health decisions.
Your body has non-specific defences that work against all pathogens, including physical barriers and white blood cells. These cells defend you through phagocytosis (surrounding and digesting pathogens), producing antibodies that attach to antigens on pathogens, and making antitoxins that neutralise poisonous toxins.
Antibiotics kill bacteria but are useless against viruses. Antibiotic-resistant strains like MRSA are increasing because antibiotics are overused. Doctors shouldn't prescribe them for viral infections or minor bacterial ones.
Vaccination works by injecting dead or inactive pathogens, stimulating your white blood cells to produce antibodies and develop immunity. If the same pathogen enters later, your immune system responds quickly. New drugs go through double-blind trials where neither patients nor doctors know who gets the real drug versus a placebo.
Important: Antibiotics only work on bacteria, never viruses - that's why they won't cure your cold or flu.
8
of 10
Pathogens and Disease Types
Disease-causing microorganisms are everywhere, but knowing how they work and spread gives you the power to protect yourself and understand why certain treatments work.
Pathogens cause infectious diseases and spread through direct contact, water, air, or vectors (organisms that carry pathogens without getting sick). You can reduce infection through good hygiene, destroying vectors, isolating infected people, and vaccination.
Viral diseases occur when viruses reproduce rapidly in body cells, damaging them. Measles causes fever and rash, spreading through droplets from breathing, sneezing, or coughing. HIV spreads through sexual contact or bodily fluids, initially flu-like, then attacks immune cells leading to AIDS. Tobacco Mosaic Virus affects plants, reducing chlorophyll and affecting photosynthesis.
Bacterial diseases damage cells directly or produce toxins. Salmonella food poisoning causes fever, cramps, and vomiting from contaminated eggs or chicken. Gonorrhoea is an STD causing yellow discharge, treated with antibiotics like penicillin. Malaria is caused by protists spread by mosquito vectors.
Prevention Tip: Many diseases are preventable through simple measures like good hygiene, safe food handling, and barrier contraception.
9
of 10
Respiration and Energy Release
Every movement you make, every thought you think, every heartbeat requires energy - and that energy comes from respiration, a process happening in every single one of your cells right now.
Respiration is an exothermic reaction that releases energy from glucose for chemical reactions, movement, and keeping you warm. Aerobic respiration uses oxygen: glucose + oxygen → carbon dioxide + water. This happens in all organisms and provides the most energy.
When oxygen runs out, anaerobic respiration takes over. In animals, glucose breaks down to lactic acid without producing carbon dioxide. In plants and yeast, glucose forms ethanol and carbon dioxide - this process in yeast is called fermentation and is used to make bread and alcohol.
Metabolism is all the chemical reactions in your body controlled by enzymes. This includes converting glucose to starch, glycogen, and cellulose; forming lipids from glycerol and fatty acids; making amino acids and proteins; and breaking down excess proteins to urea for removal.
Exercise Connection: During intense exercise, your muscles can't get enough oxygen, so anaerobic respiration creates lactic acid, causing muscle pain and creating an oxygen debt that must be repaid afterwards.
10
of 10
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Biology396 views·Updated May 26, 2026·19 pagesComprehensive AQA Biology Paper 1 & 2 Mind Maps
M
Millie@milliexcarrots
Cell biology and human body systems might seem complex, but they're actually about understanding how life works at its most basic level. From how substances move in and out of cells to how your heart pumps blood around your body,... Show more
1
of 10Sign up to see the content. It's free!
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Transport in Cells and Cell Division
Ever wonder how nutrients get into your cells or how you grow? It all comes down to three key transport processes that are happening in your body right now.
Diffusion is the net movement of particles from high to low concentration - think of how perfume spreads across a room. Temperature, concentration gradient, and surface area all affect how fast this happens. Your small intestine is brilliant at this because it has a massive surface area and thin walls.
Osmosis works similarly but specifically moves water molecules across partially permeable membranes from dilute to concentrated solutions. Active transport is different - it uses energy from respiration to move particles from low to high concentration, like root hair cells absorbing minerals.
Your chromosomes carry thousands of genes and come in 23 pairs in human body cells. Stem cells are undifferentiated cells that can become different cell types - embryonic ones can become any cell type, whilst adult stem cells are more limited. The cell cycle involves growth, DNA copying during synthesis, then mitosis where one cell divides into two identical daughter cells.
Key Practical: Test how different sugar concentrations affect potato tissue mass by placing equal-sized pieces in various solutions for 2 hours, then measuring the changes.
2
of 10Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Cell Structure and Microscopy
Understanding cell structure is like getting the blueprint for life itself - and the differences between cell types tell us everything about how organisms function.
Animal cells contain a nucleus (controls the cell), mitochondria (where respiration happens), ribosomes (make proteins), cytoplasm (where reactions occur), and a cell membrane (controls what enters and leaves). Plant cells have all of these plus a cellulose cell wall for strength, chloroplasts for photosynthesis, and a permanent vacuole for support.
Bacterial cells are completely different - they're prokaryotic (genetic material not in a nucleus) whilst plant, animal and fungal cells are eukaryotic (genetic material in a nucleus). Bacteria have flagella for movement and plasmids that allow gene transfer between cells.
When using microscopes, remember that magnification = size of image ÷ size of real object, whilst resolution is the ability to distinguish between separate objects. Different units matter too: centimetres (1×10²), millimetres (1×10³), micrometres (1×10⁶), and nanometres (1×10⁹).
Microscope Practical: Always use low power first to locate cells, add stain like iodine for clarity, and include a scale line in your drawings.
3
of 10Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Food Tests
Knowing what's in your food isn't just about reading labels - scientists use specific chemical tests to identify the main biological molecules, and you can do these tests yourself.
The Benedict's test detects sugars by adding Benedict's solution to your sample and heating in a water bath at 80°C. Blue means no sugar, whilst green, yellow, orange, and red show increasing sugar concentrations. For starch, add iodine solution - it turns from brown/orange to blue-black if starch is present.
Lipids are tested using Sudan III solution, which separates the mixture into two layers with the top layer turning red if fats are present. The Biuret test identifies proteins by adding Biuret solution - it changes from blue to purple if proteins are detected.
Before any test, you'll need to prepare your sample by breaking up the food, adding distilled water, stirring to dissolve, then filtering out solid bits. This gives you a clear solution to work with.
Remember: Always point test tubes away from you when heating, and use exactly 2cm³ or 5cm³ of solutions as specified for accurate results.
4
of 10Sign up to see the content. It's free!
- Access to all documents
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Specialised Cells
Your body contains incredibly specialised cells, each perfectly designed for their specific job - it's like having the ultimate toolkit where every tool is custom-made for one purpose.
Sperm cells are built for one mission: reaching the egg. They have a streamlined head for speed, an acrosome containing enzymes to penetrate the egg, loads of mitochondria for energy, and a tail for swimming. Nerve cells transmit electrical signals using their long axon, dendrites that receive signals from other neurons, and a myelin sheath that insulates and speeds up transmission.
Muscle cells are packed with mitochondria for energy and protein fibres that can contract to create movement. In plants, xylem cells form hollow tubes (end walls break down, no cytoplasm) strengthened with lignin to transport water and minerals one way only.
Phloem cells work differently - they keep their end walls with holes to allow sugar transport, work in both directions, and need companion cells for support. Root hair cells have a massive surface area for absorbing water by osmosis and loads of mitochondria to power active transport of minerals.
Top Tip: Each specialised cell has features directly linked to its function - learn the job first, then the adaptations make perfect sense.
5
of 10Sign up to see the content. It's free!
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Heart Structure and Function
Your heart is essentially a double pump that never stops working, and understanding its structure shows you exactly how it keeps you alive every single second.
The heart has four chambers: two atria that receive blood from veins, and two ventricles that pump blood into arteries. Blood flows from the vena cava into the right atrium, through the tricuspid valve to the right ventricle, then out via the pulmonary artery to the lungs.
After picking up oxygen in the lungs, blood returns via pulmonary veins to the left atrium, passes through the bicuspid valve to the left ventricle, then gets pumped out through the aorta to the rest of your body. This is called the double circulatory system because blood passes through the heart twice in each complete circuit.
The left ventricle has thicker walls than the right because it needs to pump blood around your entire body, whilst the right ventricle only pumps to your lungs. Valves prevent backflow and ensure blood only moves in one direction.
Memory Trick: Remember that arteries carry blood away from the heart, whilst veins carry blood back to the heart - the pulmonary vessels are the exception to the usual oxygenation rule.
6
of 10Sign up to see the content. It's free!
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Gaseous Exchange in Lungs
Every breath you take is part of an incredibly efficient system that gets oxygen to your cells and removes carbon dioxide - and it's all about maximising surface area for diffusion.
Air travels through your trachea (windpipe with cartilage rings to prevent collapse), splits into two bronchi, then divides into smaller bronchioles that end in tiny air sacs called alveoli. These millions of alveoli are where the magic happens.
Alveoli are perfectly adapted for gas exchange: they have a massive moist surface area, an excellent blood supply through capillaries, and extremely thin walls so gases only need to diffuse a short distance. Oxygen diffuses from alveoli into blood whilst carbon dioxide diffuses from blood into alveoli.
The heart sends deoxygenated blood to lungs via the pulmonary artery, and oxygenated blood returns via pulmonary veins. This constant circulation ensures fresh oxygen reaches every cell in your body whilst waste carbon dioxide gets removed.
Key Point: The entire respiratory system is designed around one principle - maximising the surface area available for diffusion whilst minimising the distance gases need to travel.
7
of 10Sign up to see the content. It's free!
- Access to all documents
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Immune System and Disease Prevention
Your body is under constant attack from pathogens, but you've got an amazing defence system that works 24/7 to keep you healthy - and understanding it helps you make better health decisions.
Your body has non-specific defences that work against all pathogens, including physical barriers and white blood cells. These cells defend you through phagocytosis (surrounding and digesting pathogens), producing antibodies that attach to antigens on pathogens, and making antitoxins that neutralise poisonous toxins.
Antibiotics kill bacteria but are useless against viruses. Antibiotic-resistant strains like MRSA are increasing because antibiotics are overused. Doctors shouldn't prescribe them for viral infections or minor bacterial ones.
Vaccination works by injecting dead or inactive pathogens, stimulating your white blood cells to produce antibodies and develop immunity. If the same pathogen enters later, your immune system responds quickly. New drugs go through double-blind trials where neither patients nor doctors know who gets the real drug versus a placebo.
Important: Antibiotics only work on bacteria, never viruses - that's why they won't cure your cold or flu.
8
of 10Sign up to see the content. It's free!
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Pathogens and Disease Types
Disease-causing microorganisms are everywhere, but knowing how they work and spread gives you the power to protect yourself and understand why certain treatments work.
Pathogens cause infectious diseases and spread through direct contact, water, air, or vectors (organisms that carry pathogens without getting sick). You can reduce infection through good hygiene, destroying vectors, isolating infected people, and vaccination.
Viral diseases occur when viruses reproduce rapidly in body cells, damaging them. Measles causes fever and rash, spreading through droplets from breathing, sneezing, or coughing. HIV spreads through sexual contact or bodily fluids, initially flu-like, then attacks immune cells leading to AIDS. Tobacco Mosaic Virus affects plants, reducing chlorophyll and affecting photosynthesis.
Bacterial diseases damage cells directly or produce toxins. Salmonella food poisoning causes fever, cramps, and vomiting from contaminated eggs or chicken. Gonorrhoea is an STD causing yellow discharge, treated with antibiotics like penicillin. Malaria is caused by protists spread by mosquito vectors.
Prevention Tip: Many diseases are preventable through simple measures like good hygiene, safe food handling, and barrier contraception.
9
of 10Sign up to see the content. It's free!
- Access to all documents
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Respiration and Energy Release
Every movement you make, every thought you think, every heartbeat requires energy - and that energy comes from respiration, a process happening in every single one of your cells right now.
Respiration is an exothermic reaction that releases energy from glucose for chemical reactions, movement, and keeping you warm. Aerobic respiration uses oxygen: glucose + oxygen → carbon dioxide + water. This happens in all organisms and provides the most energy.
When oxygen runs out, anaerobic respiration takes over. In animals, glucose breaks down to lactic acid without producing carbon dioxide. In plants and yeast, glucose forms ethanol and carbon dioxide - this process in yeast is called fermentation and is used to make bread and alcohol.
Metabolism is all the chemical reactions in your body controlled by enzymes. This includes converting glucose to starch, glycogen, and cellulose; forming lipids from glycerol and fatty acids; making amino acids and proteins; and breaking down excess proteins to urea for removal.
Exercise Connection: During intense exercise, your muscles can't get enough oxygen, so anaerobic respiration creates lactic acid, causing muscle pain and creating an oxygen debt that must be repaid afterwards.
10
of 10Sign up to see the content. It's free!
- Access to all documents
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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.
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Explore the key differences between aerobic and anaerobic respiration in this concise summary. Understand the processes of cellular respiration, including the role of glucose, oxygen, and the byproducts of each type. Learn about metabolism, energy transfer, and the significance of fermentation in yeast and plants. Ideal for biology students studying bioenergetics and cellular metabolism.
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Explore key criminology theories and their implications on crime and deviance. This comprehensive summary covers biological, psychological, and sociological perspectives, including labelling theory, right realism, and the impact of social campaigns on policy development. Ideal for A-Level criminology students seeking to understand the complexities of criminal behaviour and the factors influencing crime prevention strategies.
129,737211
English LiteratureRomeo and Juliet: Key themes
Key Romeo and Juliet themes and analysed quotes
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English LiteratureMacbeth: Guilt and Ambition
Explore the complex themes of guilt and ambition in Shakespeare's 'Macbeth'. This analysis covers key characters, including Macbeth and Lady Macbeth, their moral dilemmas, and the tragic consequences of their ambition. Ideal for students studying character motivations, thematic elements, and the psychological impact of power. Includes insights on the natural order, manipulation, and the descent into madness.
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cell structures
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