Concept of an Ecosystem

Classify ecosystems and analyse the abiotic and biotic factors that decide what lives where; sample an ecosystem and treat the data statistically; follow energy through trophic levels with productivity and ecological efficiency; trace the water, carbon, nitrogen and phosphorus cycles; and evaluate human impact, pollution and conservation, using Akagera, Nyungwe and the Rugezi wetland as cases.

2

Population and Natural Resources

Describe a population by its size, density, distribution and age structure, and estimate it by sampling and mark–release–recapture; model exponential and logistic growth and carrying capacity; analyse the density-dependent and density-independent factors that regulate populations; and evaluate how Rwanda uses and conserves its forests, water, land, minerals and energy.

3

Circulatory System in Animals

Explain why large animals need mass transport, and compare open and closed, single and double circulations; relate the structure of the mammalian heart to its function, analyse the cardiac cycle, its pressure changes and the ECG, and explain how heart rate is controlled; compare arteries, veins and capillaries, and explain tissue fluid and lymph; interpret oxygen dissociation curves and the Bohr shift; and explain blood clotting and cardiovascular disease.

4

Cellular Respiration

Explain why organisms need energy and how ATP, NAD, FAD and coenzyme A work; relate the structure of the mitochondrion to its role; follow glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation with their ATP yields; compare aerobic and anaerobic respiration and their efficiencies; and measure respiration and the respiratory quotient with a respirometer.

5

General Principles of Reception and Response in Animals

Explain why animals must respond to changes inside and outside the body; classify sensory receptors by the stimulus they detect, by their position and by their structure; explain how a receptor converts a stimulus into a generator potential and nerve impulses, and how receptors adapt; and relate the structure of the eye, the ear, taste buds and skin receptors to their functions.

6

Nervous Coordination

Describe how the mammalian nervous system is organised and how the structure of sensory, relay and motor neurones suits their functions; explain the resting potential, the action potential and the refractory period in terms of ion movements; explain how impulses are conducted, and why myelin, axon diameter and temperature change the speed; describe transmission across a cholinergic synapse and the roles of synapses; and relate reflex arcs to the other forms of response in animals.

7

Hormonal Coordination in Animals

Describe the human endocrine system and how hormones reach and act on their target cells; identify the main endocrine glands, their hormones and effects, including the hypothalamus–pituitary link; explain negative and positive feedback with blood glucose and thyroxine as examples; analyse the effects of hormonal imbalance such as diabetes and goitre; and compare hormonal with nervous coordination.

8

Human Reproduction

Relate the structure of the male and female reproductive systems to their functions; compare spermatogenesis and oogenesis; explain the hormonal control of the menstrual cycle; describe fertilisation, implantation and early development, the roles of the placenta, the changes of pregnancy, birth and parental care, and how twins arise; and evaluate the causes of infertility, in-vitro fertilisation, methods of family planning, and the prevention of sexually transmitted infections and HIV.

9

Skeleton, Muscle and Movement

Compare hydrostatic skeletons, exoskeletons and endoskeletons; relate the structure of cardiac, smooth and skeletal muscle to how each works; explain the ultrastructure of striated muscle and the sliding filament theory; and analyse how joints, antagonistic muscles and levers produce locomotion.

10

Principles and Applications of Gene Technology

Explain how restriction enzymes, ligase and plasmid vectors make recombinant DNA; describe artificial DNA synthesis, PCR and the transfer of genes into cells; analyse gel electrophoresis and microarray results; and weigh the applications of gene technology against its risks and ethical concerns.

11

Variation and Selection

Explain the genetic and environmental causes of variation and weigh its advantages and disadvantages; distinguish continuous from discontinuous variation and use the t-test to compare samples; explain natural selection and its types and the methods of artificial selection; and use allele frequencies, genetic drift, the founder effect and the Hardy-Weinberg principle to analyse gene pools.

12

Evolution and Speciation

Compare hypotheses on the origin of life and outline how multicellular organisms evolved; evaluate the theories of evolution and their causes; interpret fossil, anatomical, embryological and molecular evidence, including evolution happening today; and explain how isolation, natural selection and artificial selection lead to new species.

Units