Eduqas GCSE Biology 4 Coordination and Control Exam Questions

About Eduqas GCSE Biology 4 Coordination and Control

Coordination and control is a large Eduqas GCSE Biology topic with four parts: nervous coordination, hormonal coordination, homeostasis in humans and plant hormones. You need the reflex arc, the structure of the eye and brain, endocrine glands and named hormones, negative feedback including thyroxine, the menstrual cycle and contraception. Homeostasis covers blood glucose and diabetes, temperature control and the kidney, including the nephron and ADH. The topic finishes with auxins, gibberellins and ethene. It links to cell transport and respiration. Examiners regularly ask for reflex arc sequences, negative feedback explanations and nephron functions, and there are specified practicals on reaction time and kidney dissection.

What you need to know

• 4.1 Reflexes A reflex is a fast, automatic response that protects the body, such as withdrawing a hand or the pupil reflex. Reflex arc: receptor, sensory neurone, relay neurone in the spinal cord, motor neurone, effector. Impulses cross synapses by chemical transmitters. SP4.1: factors affecting reaction times.
• 4.1 Eye and brain Learn the cornea, iris, pupil, lens, retina, choroid, sclera, blind spot and optic nerve. Short and long sight and cataracts are eye defects. The cerebral hemispheres, cerebellum and medulla have different functions; MRI and electrical stimulation are used to study the brain, and damage to the nervous system (Parkinson's disease, multiple sclerosis) is hard to treat.
• 4.2 Hormones and negative feedback Hormones are chemical messengers released by glands (pituitary, thyroid, adrenal, pancreas, ovaries, testes) into the blood. Thyroxine is controlled by negative feedback via TRH and TSH. Adrenaline increases heart and breathing rate to prepare the body for action.
• 4.2 Menstrual cycle and fertility FSH causes an egg to mature and stimulates oestrogen; oestrogen builds the uterus lining; LH triggers ovulation; progesterone maintains the lining. Hormonal contraceptives and non-hormonal methods (such as condoms) have advantages and disadvantages. FSH and LH are used in fertility treatment.
• 4.3 Blood glucose and temperature When blood glucose rises, the pancreas releases insulin, which causes the liver to convert glucose into glycogen; glucagon has the opposite effect. Type 1 diabetes is treated with insulin, type 2 with diet and exercise. Temperature is controlled by sweating, vasodilation, vasoconstriction, shivering and hair erector muscles.
• 4.3 The kidney The nephron filters blood under pressure in the Bowman's capsule, then selectively reabsorbs glucose, some salts and water in the tubule. ADH from the pituitary makes the collecting duct reabsorb more water, producing concentrated urine when the body is short of water. SP4.3: dissection of a mammalian kidney.
• 4.4 Plant hormones Auxins cause phototropism (shoots grow towards light) and gravitropism by unequal distribution and cell elongation. Gibberellins and ethene also control growth, such as germination and fruit ripening, and are used commercially.

Common mistakes in 4 Coordination and Control

• Writing that the brain is always involved in a reflex. Simple reflexes pass through a relay neurone in the spinal cord, without conscious thought.
• Confusing glucagon and glycogen. Glucagon is the hormone; glycogen is the storage carbohydrate in the liver and muscles.
• Saying blood vessels move closer to the skin surface in hot conditions. Arterioles near the skin dilate (vasodilation), so more blood flows near the surface.
• Stating that glucose is filtered and then lost in urine in a healthy person. All glucose is filtered, but all of it is selectively reabsorbed.
• Saying auxin moves towards the light. Auxin collects on the shaded side, causing those cells to elongate more so the shoot bends towards the light.

Try three 4 Coordination and Control exam-style questions