IGCSE Biology Coordination & drugs topical questions

Name each part of the reflex pathway described.

1. (a)The structure that detects the stimulus.[1]
2. (b)The neurone carrying the impulse towards the CNS.[1]
3. (c)The neurone carrying the impulse away from the CNS.[1]
4. (d)The muscle or gland that carries out the response.[1]

Match each eye structure to its function.

1. (a)Refracts light entering the eye.[1]
2. (b)Focuses light on to the retina.[1]
3. (c)Contains light receptors.[1]
4. (d)Carries impulses to the brain.[1]

State the hormone secreted by each gland.

1. (a)Adrenal glands[1]
2. (b)Pancreas[1]
3. (c)Testes[1]
4. (d)Ovaries[1]

A hand touches a hot pan and is pulled away instantly.

1. (a)Name this type of action and state two of its characteristics.[2]
2. (b)Describe the pathway of the impulse from the skin to the muscle that pulls the hand away.[3]

Describe and explain what happens in the eye when a person walks from a dark cinema into bright daylight.

1. (a)State what happens to the pupil. (Core)[1]
2. (b)Explain why this change is useful. (Core)[1]
3. (c)Describe the role of the iris muscles. (Extended)[3]

Compare nervous and hormonal control.

1. (a)State two differences in speed and duration.[2]
2. (b)Explain why hormonal effects can reach the whole body.[1]
3. (c)Give one example of a hormone and its target effect.[1]

A synapse joins the end of one neurone to the next neurone in a reflex arc. (Supplement)

1. (a)Describe the structures found at a synapse.[2]
2. (b)Describe the events that pass an impulse across the synapse.[3]
3. (c)Explain why impulses can cross a synapse in only one direction.[1]

A germinating seedling is grown in a horizontal position in a dark cupboard, while another identical seedling grows upright beside a window with light coming from one side only.

1. (a)Name the response of the seedling’s shoot towards the window light.[1]
2. (b)State how the root of the horizontal seedling in the dark will grow.[1]
3. (c)Explain how auxin produces the shoot’s response to light. (Supplement)[3]

A person with Type 1 diabetes injects insulin before meals, eats regular balanced meals and monitors the effect of exercise.

1. (a)Explain why the person needs these insulin injections.[2]
2. (b)Explain why the insulin is injected rather than swallowed.[2]
3. (c)Adrenaline also raises blood glucose. State two effects of adrenaline on the body and explain how each prepares it for action.[2]

A healthy person drinks a glucose solution and their blood glucose concentration rises, then returns to normal within two hours. (Extended)

1. (a)Name the hormone released in response to the rise, the organ that releases it, and the organ that carries out the correction.[3]
2. (b)Explain this return to normal as an example of negative feedback.[3]

A doctor refuses to prescribe antibiotics for a patient’s flu, and warns a second patient to finish her whole course for a bacterial infection. (Extended)

1. (a)Explain why antibiotics were not prescribed for the flu.[1]
2. (b)Explain how incomplete courses of antibiotics can lead to resistance.[3]
3. (c)Explain why using antibiotics only when essential limits resistant strains such as MRSA.[3]

A runner finishes a race on a hot day; an hour later she sits in a cold, air-conditioned room. (Supplement)

1. (a)Describe two changes in her skin that cool her body on the hot day, and explain how each works.[4]
2. (b)Describe how her skin helps to warm her body in the cold room.[2]

A student switches from reading a book 25 cm away to looking at a mountain far in the distance. (Supplement)

1. (a)Describe what happens to the ciliary muscles, suspensory ligaments and lens as she focuses on the distant mountain.[3]
2. (b)Name this process.[1]
3. (c)State the difference in distribution and function of rods and cones in the retina.[2]

A healthy person’s blood glucose concentration was measured after drinking a glucose solution. (Supplement)

1. (a)State the normal (set point) value shown by the data.[1]
2. (b)Name the hormone released as the level rose, and the organ that responds to it.[2]
3. (c)Explain the fall in blood glucose between 30 and 120 minutes.[2]
4. (d)State which hormone would be released if the level fell below the set point, and state its effect.[1]
5. (e)Name the type of control system shown by these changes.[1]