Practice Questions

1.Describe what could happen if a person does not produce enough thyroxine.

If a person does not produce enough thyroxine, their basal metabolic rate decreases, so their body uses less energy. This can cause tiredness, weight gain, and feeling cold, and in children, slowed growth and delayed development.

The pituitary gland responds by releasing more TSH to stimulate the thyroid, showing how negative feedback works to try to restore thyroxine to normal levels.

2.Explain why negative feedback is important in the body.

Negative feedback is important in the body because it keeps conditions stable.
If a level of a substance (like a hormone, temperature, or blood glucose) becomes too high, negative feedback reduces it. If the level becomes too low, negative feedback increases it. This ensures the body’s internal environment remains within safe limits, allowing cells and organs to function properly.

3.Describe two effects adrenaline has on the body.

Increases heart rate – this boosts blood flow, delivering more oxygen and glucose to muscles and the brain.

Increases delivery of oxygen and glucose to muscles and brain – this prepares the body for rapid action, the “fight or flight” response.