Biology

IGCSE · 42 topics available

Chapter 1 · Characteristics and Classification of Living Organisms

Characteristics of Living Organisms

The seven life processes (MRS GREN) that all living organisms share and how they differ from non-living things.

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Classification and the Binomial System

How organisms are grouped into a hierarchy of taxa and named using the two-part binomial system.

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Dichotomous Keys

How a series of paired either/or questions about observable features is used to identify an unknown organism.

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Chapter 2 · Organisation of the Organism

Cell Structure

The structures inside animal and plant cells, their functions, and the features that make plant cells different.

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Specialised Cells, Tissues and Organs

How cells become specialised for their jobs and are organised into tissues, organs and organ systems.

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Chapter 3 · Movement into and out of Cells

Diffusion and Osmosis

How particles and water move passively down concentration gradients, and the factors that affect the rate of movement.

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Active Transport

Movement of particles against a concentration gradient using energy from respiration and carrier proteins in the cell membrane.

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Chapter 4 · Biological Molecules

Carbohydrates, Proteins and Fats

The elements and building blocks of the three main food molecules, and their functions in living organisms.

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Food Tests

Simple chemical tests to identify starch, reducing sugars, protein and fat in food by their colour changes.

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Chapter 5 · Enzymes

Enzyme Action

Enzymes are protein catalysts that lower activation energy and act on specific substrates via the lock-and-key model.

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Factors Affecting Enzyme Activity

How temperature, pH and substrate concentration affect enzyme reaction rate, including denaturation.

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Chapter 6 · Plant Nutrition

Photosynthesis

How green plants use light energy in chloroplasts to make glucose from carbon dioxide and water, releasing oxygen.

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Leaf Structure and Mineral Requirements

How the internal tissues of a leaf are adapted for photosynthesis, and why plants need nitrate and magnesium ions.

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Chapter 7 · Human Nutrition

A Balanced Diet

The nutrients the human body needs, their functions, and the deficiency diseases caused by not eating a balanced diet.

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The Human Digestive System

The organs of the alimentary canal and the associated glands, and the journey food takes from ingestion to egestion.

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Digestion and Absorption

How enzymes break large food molecules into small soluble ones, the role of bile, and how the villi absorb the products.

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Chapter 8 · Transport in Plants

Xylem and Water Uptake

How roots take up water and mineral ions, and how xylem is adapted to carry them up to the leaves.

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Transpiration and Translocation

What transpiration is, the factors that affect its rate, and how phloem translocates food from sources to sinks.

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Chapter 9 · Transport in Animals

The Circulatory System and Heart

How the four-chambered heart and double circulation move blood around the body.

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Blood and Blood Vessels

The components of blood and how arteries, veins and capillaries are adapted to their jobs.

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Chapter 10 · Diseases and Immunity

Pathogens and Transmissible Diseases

What pathogens are, how transmissible diseases spread, and ways to control them.

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The Immune System

How white blood cells, antibodies and vaccination defend the body against pathogens.

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Chapter 11 · The Human Gas Exchange System

The Human Gas Exchange System

The path of air to the alveoli, how gases are exchanged, and how breathing works.

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Chapter 12 · Aerobic and Anaerobic Respiration

Aerobic and Anaerobic Respiration

How cells release energy from glucose with and without oxygen, and what each produces.

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Chapter 13 · Excretion and the Kidneys

Excretion and the Kidneys

How the kidneys remove urea and balance the body's water and salts through filtration and selective reabsorption.

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Chapter 14 · Coordination and Response

The Nervous System and Reflexes

How neurones, synapses and reflex arcs let the body detect stimuli and respond rapidly and automatically.

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Hormones and Homeostasis

How hormones from the endocrine system and negative feedback keep the internal environment, such as blood glucose, constant.

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Tropic Responses in Plants

How plants use phototropism, gravitropism and the hormone auxin to grow towards light and roots down to water.

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Chapter 15 · Medicinal and Misused Drugs

Medicinal and Misused Drugs

How medicines such as antibiotics work, why resistance develops, and how alcohol and tobacco harm the body.

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Chapter 16 · Reproduction

Asexual and Sexual Reproduction

Comparing reproduction with one parent producing clones and with two parents and gametes producing genetic variation.

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Sexual Reproduction in Plants

How flowering plants reproduce sexually: flower structure, pollination, fertilisation and seed formation.

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Sexual Reproduction in Humans

Human reproductive systems, gametes, fertilisation, and how the placenta supports the developing fetus.

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Chapter 17 · Inheritance

Chromosomes, Genes and Proteins

How DNA, chromosomes and genes store information and control characteristics by coding for proteins.

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Mitosis and Meiosis

The two types of nuclear division: mitosis for growth and repair, meiosis for producing gametes.

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Monohybrid Inheritance

Inheritance of one characteristic: dominant and recessive alleles, genotypes, phenotypes and genetic crosses.

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Chapter 18 · Variation and Selection

Variation

Differences within a species: continuous and discontinuous variation, and their genetic and environmental causes.

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Natural and Artificial Selection

How mutation, competition and selection pressures shape populations, and how humans use selective breeding.

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Chapter 19 · Organisms and their Environment

Food Chains, Webs and Energy Flow

How energy from the Sun passes through producers and consumers, and why so much is lost at each trophic level.

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Nutrient Cycles and Populations

The carbon and nitrogen cycles, the microbes that drive them, and how populations grow along a sigmoid curve.

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Chapter 20 · Human Impact and Conservation

Human Impact and Conservation

How human activity damages ecosystems through deforestation, pollution and eutrophication, and how conservation protects them.

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Chapter 21 · Biotechnology and Genetic Modification

Biotechnology

How microorganisms and enzymes are used to make bread, alcohol, medicines and industrial products in fermenters.

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Genetic Modification

How genes are cut, carried by plasmid vectors and inserted into bacteria to make insulin and improve crops.

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