WJEC GCSE Biology
WJEC GCSE Biology 2.5 Response and Regulation Exam Questions
Free WJEC GCSE Biology revision for 2.5 Response and Regulation: what you need to know, common mistakes and exam-style questions with answers. Covers nervous system, reflex arc, eye structure, homeostasis, hormones, blood glucose, diabetes, temperature control, negative feedback and plant tropisms.
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About WJEC GCSE Biology 2.5 Response and Regulation
Response and regulation in Unit 2 covers how organisms detect and respond to changes. You need to describe the nervous system, the reflex arc and the structure of the eye. You must explain homeostasis, the control of blood glucose by insulin and glucagon, the causes and treatment of type 1 and type 2 diabetes, and how the skin regulates body temperature. Negative feedback runs through these mechanisms. The topic finishes with plant responses, phototropism and gravitropism, controlled by auxin. Investigating factors affecting reaction time is a specified practical. Examiners often ask for labelled reflex arcs, sweating and vasodilation explanations, and glucose control sequences.
What you need to know
- Nervous system Receptors in sense organs detect stimuli (light, sound, touch, temperature, chemicals). Impulses travel along neurones to the central nervous system (brain and spinal cord), then to effectors (muscles or glands).
- Reflexes Reflex actions are fast, automatic and often protective, e.g. withdrawing a hand from heat, blinking and changing pupil size. Reflex arc: stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response. Investigating factors affecting reaction time is a specified practical.
- Blood glucose Hormones are chemical messengers carried in the blood. When blood glucose rises, the pancreas releases insulin and the liver converts glucose to glycogen. When it falls, glucagon causes glycogen to be converted back to glucose. This is negative feedback.
- Diabetes Type 1: the pancreas does not make enough insulin; treated with insulin injections and diet. Type 2: body cells do not respond properly to insulin; linked to obesity and lack of exercise, and controlled by diet, exercise and sometimes drugs.
- Temperature control If too hot: sweating (evaporation cools the skin) and vasodilation (more blood flows near the skin surface, so more heat is lost). If too cold: shivering, no sweating and vasoconstriction. Know the labelled structure of the skin.
- Plant responses Phototropism is growth in response to light; gravitropism is growth in response to gravity. Auxin collects on the shaded side of a shoot and causes those cells to elongate, so the shoot bends towards light.
Common mistakes in 2.5 Response and Regulation
- Saying blood vessels move closer to the skin surface. Arterioles near the surface dilate so more blood flows through skin capillaries; vessels do not move.
- Confusing glucagon and glycogen. Glucagon is a hormone; glycogen is the storage carbohydrate in the liver.
- Stating that insulin converts glucose into glycogen. Insulin causes liver cells to convert glucose into glycogen; the hormone itself does not do the conversion.
- Writing that auxin makes plants grow towards light by growing faster on the lit side. Auxin builds up on the shaded side, where cells elongate more, so the shoot bends towards the light.
Try three 2.5 Response and Regulation exam-style questions
1. Describe the pathway of a reflex action when a hand touches a hot object. (4 marks)
Show the mark scheme answer
Receptor in skin detects heat; impulse travels along sensory neurone to relay neurone in spinal cord; then along motor neurone; to effector (muscle) which contracts to move hand away.
2. Explain how the body responds when blood glucose concentration rises after a meal. (3 marks)
Show the mark scheme answer
Pancreas detects rise and releases insulin; insulin carried in blood to liver; liver converts glucose into glycogen, so blood glucose falls.
3. A student's reaction times were 0.25 s, 0.21 s and 0.23 s. Calculate the mean reaction time. (2 marks)
Show the mark scheme answer
0.25 + 0.21 + 0.23 = 0.69; 0.69 / 3 = 0.23 s.
2.5 Response and Regulation FAQs
What does WJEC GCSE Biology 2.5 Response and Regulation cover?
It covers the nervous system, reflex arcs, eye structure, homeostasis, hormones, blood glucose control and diabetes, temperature regulation through the skin, negative feedback and plant tropisms controlled by auxin.
Which unit is Response and Regulation examined in?
It is examined in Unit 2: Variation, Homeostasis and Micro-organisms, a 1 hour 45 minute written paper worth 45% of the GCSE, sat at foundation or higher tier. The Unit 3 practical assessment draws on the same practical skills.
What are the key labelled diagrams for response and regulation?
Learn to label a reflex arc, the eye and a section through the skin. Practise linking each labelled part to its role, such as the iris controlling pupil size or sweat glands releasing sweat.
