Pearson Edexcel · International GCSE

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Handouts, exercise sheets and slides

Shared topic documents retain their source course and topic titles. Use your chosen board’s specification for coverage, tier and exam requirements.

Handouts · ⁨Supports de cours⁩ · IGCSE Biology · ⁨Biologie IGCSE⁩ (21)

Exercise sheets · ⁨Fiches d'exercices⁩ · IGCSE Biology · ⁨Biologie IGCSE⁩ (76)

Presentation slides · ⁨Diaporamas de présentation⁩ · IGCSE Biology · ⁨Biologie IGCSE⁩ (21)

Course units and learning goals · ⁨Unités de cours et objectifs d'apprentissage⁩

These lessons teach selected course objectives. Check the remaining coverage gaps; the material is not a complete preparation programme. · ⁨Ces leçons abordent des objectifs de cours sélectionnés. Vérifiez les lacunes restantes en couverture ; ce matériel ne constitue pas un programme d'entraînement complet.⁩

Lessons · ⁨Leçons⁩ →Vocabulary practice · ⁨Pratique du vocabulaire⁩ →

1 · The nature and variety of living organisms

Image length divided by actual length.
A scale bar provides a known real distance in the same image. Convert the image length and real length to the same unit before dividing. Magnification is a ratio and has no unit.
Focus a prepared slide at low power first. Move to a higher power and use fine focus. Make a clear line drawing, label structures with straight lines, and record the scale rather than shading the image.

magnification: Image length divided by actual length
resolution: Ability to distinguish two close points

2 · Structures and functions in living organisms

Net water movement through a partially permeable membrane.
Use percentage change to compare samples with different initial masses. A zero percentage change estimates a solution concentration with no net water movement. This is an estimate from a trend, not proof that water molecules stop moving.
Use equal-length cylinders from similar tissue, fixed solution volume, temperature and immersion time. Blot each cylinder in the same way before weighing. Repeat each concentration and plot mean percentage change against concentration.
A biological catalyst.
Measure rate using product formed per unit time or a fixed endpoint. For an endpoint test, 1/time is a rate proxy if the same amount of product or substrate change defines the endpoint each time.
For starch digestion, equilibrate enzyme and starch in a water bath, control pH with buffer, mix measured volumes, and test samples with iodine at fixed intervals. Use a clean spot for each test. Do not put iodine into the reaction mixture.
Breakdown of large food molecules.
Absorption moves soluble products into blood or lymph. Thin exchange surfaces and a large surface area shorten diffusion paths and increase transfer. Enzyme activity and transport are different processes.
Use Benedict reagent with controlled heating for reducing sugars, iodine for starch, Biuret reagent for protein, and the ethanol emulsion test for lipids. Keep ethanol away from flames. Use positive and negative controls.
A factor whose shortage restricts rate.
Change only one factor when testing a limiting factor. At low light, extra light may increase rate. At a plateau, the changed factor is no longer the main limit in that range; the graph alone does not identify which other factor is limiting.
Measure collected gas volume over a fixed time instead of assuming all bubbles have the same volume. Control temperature, plant size and carbon dioxide supply. Allow the plant to adjust before each reading and repeat.
Cell reactions that transfer energy from substrates.
Anaerobic respiration releases less energy per glucose than aerobic respiration. In human muscles it produces lactic acid; in yeast it produces ethanol and carbon dioxide. Breathing supplies oxygen but is not itself respiration.
A respirometer can measure oxygen uptake when carbon dioxide is absorbed. Control temperature with a water bath and use a comparison containing inert material. Keep absorbent separated from organisms and follow the school risk assessment.
Maintenance of suitable internal conditions.
When blood glucose is high, insulin helps increase glucose uptake and storage as glycogen. When it is low, glucagon supports release of glucose from stores. These responses are coordinated, not identical effects of two hormones.
Interpret a time graph by identifying the initial disturbance, the response and the return toward the normal range. Mark the delay before a response. Do not assume a graph shows an instantaneous correction.

osmosis: Net water movement through a partially permeable membrane
control variable: A factor kept constant for a fair comparison
enzyme: A biological catalyst
denaturation: A structural change that disrupts function
digestion: Breakdown of large food molecules
absorption: Movement of soluble products into the body
limiting factor: A factor whose shortage restricts rate
photosynthesis: Light-driven formation of carbohydrate
respiration: Cell reactions that transfer energy from substrates
ATP: A molecule that couples energy transfers in cells
homeostasis: Maintenance of suitable internal conditions
negative feedback: A response opposing the original change

3 · Reproduction and inheritance

A variant of a gene.
In a simple monohybrid cross Aa × Aa, gametes carry A or a. Combining independent gametes gives AA, Aa, Aa and aa. The predicted probabilities describe many possible fertilizations, not a fixed order of children.
Write parental genotypes and gametes before making the grid. State the inheritance model and phenotype key. Use a pedigree to check consistency with a model; do not infer certainty from a small family alone.

allele: A variant of a gene
genotype: The alleles an organism carries

4 · Ecology and the environment

A defined area used for sampling.
Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
Choose coordinates with random numbers before visiting the patches. Record quadrat area and counting rules. For a transect, use fixed distances and measure a relevant abiotic variable. Do not damage habitats or sample unsafe locations.

quadrat: A defined area used for sampling
population: Organisms of one species in a defined area

5 · Use of biological resources

An agent that causes disease.
After vaccination, memory cells can support a faster secondary response. Antibiotic resistance arises through heritable variation and selection; an individual bacterium does not choose to become resistant because it needs to survive.
Use published infection data to compare rates per equal population size. Distinguish prevalence at a time from new cases over a period. In school, use safe simulations or approved cultures rather than collecting unknown pathogens.

pathogen: An agent that causes disease
antigen: A structure recognized by a specific immune response

Preparing for this qualification · ⁨Préparation à cette qualification⁩

This is linear 4BI1, not the separately coded modular qualification.
Paper 1B: 110 marks, 2 h, 61.1%; Paper 2B: 70 marks, 1 h 15 min, 38.9%. No Foundation/Higher tiers.
Retain every B-suffixed objective: it distinguishes separate Biology from Double Award; practical methods are assessed in writing.

Teaching coverage still needed · ⁨Couverture pédagogique encore nécessaire⁩

Characteristics of life, groups and specified pathogen examples need full coverage.
Full plant/human transport, gas exchange, excretion and coordination objectives, including B-suffixed separate-science statements, remain.
Plant/human reproduction, DNA/protein synthesis and selection objectives including B extensions remain.
Cycles, pollution and organism interdependence require complete statement mapping.
Food production, fish farming, fermentation, genetic modification and cloning need dedicated coverage; infection case covers microbiological evidence only.

Specifications and sample documents · ⁨Spécifications et documents d'échantillon⁩

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Course materials · ⁨Matériel pédagogique⁩

Course preparation · ⁨Préparation du cours⁩

Documents are available. Board-specific notes, assessments and interactive past-paper practice are not yet available for every course. · ⁨Les documents sont disponibles. Les notes spécifiques au conseil, les évaluations et la pratique interactive des anciens sujets ne sont pas encore disponibles pour tous les cours.⁩

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