9700 · 15.1
Common exam mistakes on 9700 Control and coordination in mammals. Learn what loses marks, then practise the topic with Examiner’s Ink.
When describing the action potential, always mention the specific ion movements (Na+ in, K+ out) and the opening/closing of voltage-gated channels. Don't just say 'ions move'; specify which ones and in what direction. For myelinated neurones, explicitly state 'nodes of Ranvier' and 'saltatory conduction' for full marks.
When explaining negative feedback, always clearly state: 1. The stimulus (deviation from set point). 2. The sensor/control centre. 3. The effector(s) and their action. 4. The response (return to set point) and how it reduces the initial stimulus. Use blood glucose as your go-to example.
Control and coordination in mammals (Syllabus 9700, Topic 15.1) refers to how the body regulates its internal environment (homeostasis) and responds to external stimuli. It primarily involves the nervous system (fast electrical signals) and the endocrine system (slower chemical hormones) working together. You can master this topic with our free revision lessons and extensive past paper practice for Cambridge A Level Biology.
The nervous system uses rapid, short-lived electrical impulses and neurotransmitters for precise, localised control (e.g., muscle contraction). The endocrine system uses hormones, which are transported via the bloodstream for slower, widespread, and longer-lasting effects (e.g., growth or metabolism). Both are vital for homeostasis, often interacting, such as the hypothalamus influencing hormone release. Our platform offers detailed explanations and practice questions on these distinctions.
Negative feedback is a crucial regulatory mechanism where a change in a physiological variable (e.g., blood glucose level) triggers a response that counteracts the initial change, bringing the variable back to its normal range. For example, high blood glucose stimulates insulin release, which lowers glucose, thus 'feeding back negatively' to reduce the stimulus. Learn more about this and other hormonal controls with our comprehensive A Level Biology resources, including past papers and expert mark scheme guidance.