Control and Coordination — Practice

Question 1

What is the junction between two neurons called?

Accepted Answer

Step 1 — The gap where one neuron passes a signal to the next is the synapse.

✦ Answer: synapse.

Question 2

Which part of the brain maintains posture and balance?

Accepted Answer

Step 1 — The cerebellum controls balance and coordination of movement.

✦ Answer: cerebellum.

Question 3

Which hormone regulates blood sugar, and which gland secretes it?

Accepted Answer

Step 1 — Insulin regulates blood sugar; secreted by the pancreas.

✦ Answer: insulin, from the pancreas.

Question 4

Define reflex action and name the components of a reflex arc in order.

Accepted Answer

Step 1 — A reflex action is a rapid, automatic response to a stimulus.

Step 2 — Arc: receptor → sensory neuron → spinal cord → motor neuron → effector.

✦ Answer: automatic response; arc as above.

Question 5

Give two differences between nervous and hormonal control.

Accepted Answer

Step 1 — Nervous: fast, short-lived, along nerves to a specific part.

Step 2 — Hormonal: slow, long-lasting, via blood to widespread targets.

✦ Answer: speed and duration/spread differ as above.

Question 6

Why is iodine necessary in our diet?

Accepted Answer

Step 1 — Iodine is needed by the thyroid gland to make thyroxine.

Step 2 — Thyroxine regulates metabolism; iodine deficiency causes goitre.

✦ Answer: to produce thyroxine and prevent goitre.

Question 7

Explain phototropism and how auxin causes a shoot to bend towards light.

Accepted Answer

Step 1 — Phototropism is directional growth in response to light (shoots grow towards it).

Step 2 — Auxin accumulates on the shaded side and promotes cell elongation there.

Step 3 — The shaded side grows faster, bending the shoot towards the light.

✦ Answer: unequal auxin causes faster growth on the dark side, bending the shoot to light.

Question 8

How is the timing and amount of hormone secretion regulated? Give an example.

Accepted Answer

Step 1 — Secretion is controlled by feedback based on the level of the substance regulated.

Step 2 — If blood sugar rises, the pancreas secretes more insulin; as sugar falls, insulin release decreases.

✦ Answer: feedback control, e.g. insulin secretion tracking blood sugar.

Question 9

State the main functions of the cerebrum, cerebellum and medulla.

Accepted Answer

Step 1 — Cerebrum: thinking, memory, voluntary actions and sensations.

Step 2 — Cerebellum: balance, posture and precision of movement.

Step 3 — Medulla: involuntary actions such as heartbeat, breathing and blood pressure.

✦ Answer: as listed for the three parts.

Question 10

How does the response of a Mimosa (touch-me-not) leaf differ from the bending of a shoot towards light?

Accepted Answer

Step 1 — Mimosa folds by rapid turgor (water) change — a nastic movement, no growth, quick and reversible.

Step 2 — Shoot bending is a growth movement (tropism), slow and directional.

✦ Answer: turgor-driven nastic movement vs growth-driven tropism.

Practice — Control and Coordination

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