IMO Practice Test — Chemical Coordination and Integration
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
After a sugary meal, insulin lowers blood glucose mainly by causing cells to:
Take up glucose from the blood
Release glucose into the blood
Stop using glucose
Make more sugar
Explanation: Insulin signals liver and muscle cells to absorb glucose, lowering its level in the blood.
Question 2 of 6
A frightened person's heart races because of a sudden release of:
Adrenaline
Insulin
Thyroxine
Oestrogen
Explanation: Adrenaline triggers the fight-or-flight response, speeding the heart.
Question 3 of 6
Adding iodine to table salt helps prevent goitre because iodine is needed to make:
Thyroxine
Insulin
Adrenaline
Growth hormone
Explanation: The thyroid needs iodine to make thyroxine; iodised salt supplies it and prevents goitre.
Question 4 of 6
Although hormones circulate everywhere, a hormone acts on just one organ because only that organ's cells have the right:
Receptors
Ducts
Blood vessels
Nerves
Explanation: Specific receptors (lock-and-key) ensure only target cells respond.
Question 5 of 6
Damage to the pituitary could disturb many body functions because it:
Controls several other endocrine glands
Makes blood
Digests food
Filters urine
Explanation: As the master gland, the pituitary regulates other glands, so its damage has wide effects.
Question 6 of 6
Both the nervous and endocrine systems are needed because together they provide:
Fast short-term and slow long-term coordination
Only fast control
Only digestion
Only movement
Explanation: Nerves give rapid brief responses and hormones give slower lasting control — together they fully coordinate the body.