Contents

Characteristics and classification of living organisms

Organisation of the organism

Cells under the microscope

Movement into and out of cells

Biological molecules

Food tests

Enzymes

Enzymes

Plant nutrition

Human nutrition

Transport in plants

Transport in animals

Diseases and immunity

Pathogens and disease spreadBeing prepared
Immunity and vaccinationBeing prepared

Gas exchange in humans

Gas exchange and breathing

Respiration

Respiration

Excretion in humans

Excretion and the kidneys

Coordination and response

Drugs

Antibiotics

Reproduction

Asexual and sexual reproductionBeing prepared
Flowers and pollinationBeing prepared
Fertilisation and germinationBeing prepared
Human reproductionBeing prepared
Puberty and the menstrual cycleBeing prepared
Sexually transmitted infectionsBeing prepared

Inheritance

Chromosomes, genes and allelesBeing prepared
From gene to proteinBeing prepared
Mitosis and meiosisBeing prepared
Monohybrid crossesBeing prepared
Family trees, blood groups and sex linkageBeing prepared

Variation and selection

Variation and mutationBeing prepared
Adaptation and selectionBeing prepared

Organisms and their environment

Food chains and websBeing prepared
Ecological pyramids and energyBeing prepared
Energy flow and nutrient cyclesBeing prepared
PopulationsBeing prepared

Human influences on ecosystems

Food supply and habitat lossBeing prepared
PollutionBeing prepared
ConservationBeing prepared

Biotechnology and genetic modification

BiotechnologyBeing prepared
Genetic modificationBeing prepared

Part 3 of 3

Page 03

Auxin: the message from the tip

identify

Try it yourself

Supplement: where in a shoot is auxin made?

identify: name or select.

Choose one answera.In the shoot tip.b.In the roots.c.In the region below the tip, where the curve forms.d.In the leaves, by photosynthesis.

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Scope and sources

Cambridge IGCSE Biology 0610 · 2026–2028 v3 · Original learning materials.

Plant responses (14.5.1–14.5.5): gravitropism and phototropism as growth responses towards or away from gravity and light, and investigating them in shoots and roots; and, for the Supplement, gravitropism and phototropism as examples of the chemical control of plant growth, with auxin made in the shoot tip, diffusing through the plant and stimulating cell elongation, and unequal auxin explaining the bending of shoots.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus