A cyclist sees a hazard. The muscles in the cyclist's hands and arms tighten the brake levers almost immediately. This initial movement lasts less than one second.
Which system coordinates the initial movement, and why?
The endocrine system, because blood carries hormones to the arm muscles almost immediately
The nervous system, because electrical impulses have very fast, short-lived effects
The nervous system, because only nerve impulses can reach more than one muscle at once
The endocrine system, because coordinating several muscles requires a hormone to be released
85 exam-style questions on AQA GCSE Biology 5.3 Hormonal coordination in humans, covering 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, 5.3.4 Hormones in human reproduction, 5.3.5 Contraception, 5.3.6 The use of hormones to treat infertility (HT only), and 5.3.7 Negative feedback (HT only). Each one has a worked solution and a mark scheme showing where the marks go.