Edexcel International GCSE Biology (4BI1)
Video lessons · IGCSE Biology revision notes · IGCSE Biology past papers
Every topic of Edexcel International GCSE Biology (4BI1) in short video lessons with diagrams, clear revision notes and all past papers with mark schemes.
The first 5 lessons of every chapter are free.
1 Life processes
- The characteristics of living organisms
- Animal and plant cells under the microscope
- The light microscope and magnification
- Temperature, pH and denaturing
- Practical: measuring enzyme activity
- Anaerobic respiration and how it differs from aerobic
- Practical: enzymes and food
- Aerobic respiration and ATP
- Practical: showing that respiring seeds give out carbon dioxide and heat
- Diffusion
- Osmosis
- Active transport
- What changes the rate of movement
- Stem cells and differentiation
- Cells, tissues, organs and systems
- Enzymes and the active site
2 The variety of living organisms
- Plants, animals, fungi, protoctists and bacteria
- Features of plants and animals
- Fungi, protoctists and bacteria
- Viruses and the main pathogen groups
3 Breathing and gas exchange
- The parts of the breathing system
- Ventilation- ribs, intercostals and diaphragm
- Alveoli and how they are adapted
- Comparing inspired and expired air
- The effect of exercise on breathing
- The effects of smoking on the lungs and the circulation
4 Food and digestion
- Carbohydrates, proteins and lipids
- Testing for starch, sugars, protein and fat
- The seven parts of a balanced diet
- What changes how much energy you need
- The parts of the digestive system
- Teeth, chewing and peristalsis
- Amylase, protease and lipase
- Bile, the liver and emulsifying fat
- The villus and absorption
- Practical: measuring the energy in a food sample
5 Blood and circulation
- Why small organisms manage without a transport system and large ones cannot
- Double circulation
- The structure of the heart
- How the heart beats
- Coronary arteries and heart disease
- How heart rate changes during exercise and under adrenaline
- Adrenaline and the body's response
- Arteries, veins and capillaries
- Plasma, red cells, white cells and platelets
- Phagocytes, antibodies and clotting
- Vaccination, memory cells and the secondary response
6 Coordination
- Central and peripheral nervous system
- Comparing nervous and hormonal control
- The three types of neurone, and the synapse
- The structure of the eye
- Focusing on near and distant objects
- Bright light and dim light
- Reflex actions
7 Chemical coordination
- The endocrine system
- Insulin, glucagon and the pancreas
- Testosterone, oestrogen and puberty
- Controlling the water content of the blood
8 Homeostasis and excretion
- Homeostasis and negative feedback
- Lungs, kidneys and skin as excretory organs
- Stomata and guard cells
- Kidneys, ureters and bladder
- Ultrafiltration and selective reabsorption
- Sweating, shivering and blood vessels
9 Reproduction in humans
- Sperm, egg and fertilisation
- Runners, tubers and cuttings
- The human reproductive systems
- The placenta and the developing fetus
- Hormones and the menstrual cycle
10 Plants and food
- Practical: light, carbon dioxide and chlorophyll
- Practical: the starch test
- The photosynthesis reaction
- How a leaf is adapted
- Light, carbon dioxide and temperature
- Practical: the effect of light on net gas exchange in a leaf
- Nitrate, phosphate, potassium and magnesium
11 Transport in plants
- Root hair cells and water uptake
- The transpiration stream
- Where the tissues sit in the plant
- The two transport tissues
- Moving sugars from source to sink
- Practical: what changes the rate
12 Chemical coordination in plants
13 Reproduction in plants
- The parts of a flower
- Insect and wind pollination
- The pollen tube and fertilisation
- Seed structure and germination
14 Ecosystems
- Habitat, population, community, ecosystem
- Practical: quadrats and transects
- What biodiversity means and how it is measured
- Food chains and food webs
- Decomposers and decay
- Pyramids of number, biomass and energy
- Why energy is lost between levels
- The carbon cycle
- The nitrogen cycle
15 Human influences on the environment
- Glasshouses and polythene tunnels, and why they raise yield
- How fertilisers increase crop yield
- Pesticides and biological control
- Feeding people without emptying the sea
- Greenhouse gases and global warming
- How acid rain forms and what it does
- Sewage, carbon monoxide and sulfur dioxide
- The effects of cutting down forests
- Fertiliser, algae and dead water
- Sustainable resources and conservation
16 Chromosomes, genes and DNA
- How the nucleus, chromosome, gene and DNA fit together
- Genes, alleles and the genome
- The double helix and base pairing
- Transcription and translation
- Mutations and what causes them
- Allele, genotype, phenotype, dominant, recessive
17 Cell division
- Mitosis and growth
- Meiosis and gametes
- Telling the two apart in the exam
- Continuous and discontinuous variation
18 Genes and inheritance
- Punnett squares
- Ratios, and what they do not promise
- Reading a pedigree
- When neither allele wins
- X and Y chromosomes
- Why most characteristics are controlled by many genes
19 Natural selection and evolution
20 Selective breeding
- Breeding animals and crops for a purpose
- Comparing artificial and natural selection
- Micropropagation and cloning animals
- Transgenic organisms and using cloned animals to make human proteins
21 Using microorganisms
- Yeast, anaerobic respiration and bread
- Beer, wine and yoghurt
- Growing microorganisms at scale
- Practical: aseptic technique