5.1 Homeostasis

5.2 The human nervous system

5.2.1 Structure and function

5.2.2 The brain (biology only)

5.2.3 The eye (biology only)

5.2.4 Control of body temperature (biology only)

5.3.1 Human endocrine system

5.3.2 Control of blood glucose concentration

5.3.3 Maintaining water and nitrogen balance in the body (biology only)

5.3.4 Hormones in human reproduction

5.3.5 Contraception

5.3.6 The use of hormones to treat infertility (HT only)

5.3.7 Negative feedback (HT only)

5.4 Plant hormones

5.4.1 Control and coordination

5.4.2 Use of plant hormones (HT only)