Theme C: Interaction and interdependence
How living systems interact and depend on each other: enzymes and metabolism, respiration and photosynthesis, chemical and neural signalling, how body systems are integrated, defence against disease, and the flow of energy and matter through ecosystems.
Molecules
C1.1 Enzymes and metabolism
How does an enzyme's shape let it speed up one particular reaction?
C1.2 Cell respiration
How do cells capture energy from food molecules in a form they can spend?
C1.3 Photosynthesis
How does a leaf turn light into the chemical energy stored in sugar?
Cells
C2.1 Chemical signalling
How can a cell pick out one chemical message among the many it is exposed to?
C2.2 Neural signalling
How does a neuron create and send an electrical signal using only ions?
Organisms
C3.1 Integration of body systems
How do nerves and hormones work together so the body acts as one coordinated whole?
C3.2 Defence against disease
How does the body tell invaders apart from its own cells and destroy them?
Ecosystems
C4.1 Populations and communities
What keeps a population from growing forever?
C4.2 Transfers of energy and matter
Why do atoms cycle round an ecosystem while energy passes through and is lost?