What is a hormone?
A chemical substance produced by an endocrine gland and carried in the blood to one or more specific target organs, where it alters their activity.
Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) · 14.3
Revise Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028) specification point 14.3, Hormones, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What is a hormone?
A chemical substance produced by an endocrine gland and carried in the blood to one or more specific target organs, where it alters their activity.
Where are the adrenal glands located?
Above the kidneys.
Which hormone do the adrenal glands secrete?
Adrenaline.
Where is the pancreas located?
In the upper abdomen.
Which hormone does the pancreas secrete?
Insulin.
Where are the testes located?
In the scrotum.
Which hormone do the testes secrete?
Testosterone.
Where are the ovaries located?
On either side of the uterus.
Which hormone do the ovaries secrete?
Oestrogen.
Which glands secrete adrenaline?
The adrenal glands.
In what situations is adrenaline secreted?
In fight-or-flight situations, when a situation is threatening or stressful.
How does adrenaline affect breathing rate during fight-or-flight?
It increases breathing rate.
How does adrenaline affect heart rate during fight-or-flight?
It increases heart rate.
How does adrenaline affect pupil diameter during fight-or-flight?
It increases pupil diameter.
How do signals travel in nervous control compared with hormonal control?
How does the speed of action differ between nervous and hormonal control?
Nervous control acts rapidly; hormonal control generally acts more slowly.
How does the duration of effects differ between nervous and hormonal control?
Nervous effects are generally short-lived; hormonal effects are generally longer-lasting.
Which organ secretes both glucagon and insulin?
The pancreas.
How are glucagon and insulin transported after secretion?
They are carried in the blood.
Is glucagon another name for insulin?
No. Glucagon and insulin are distinct hormones—different chemical signals.
How does adrenaline affect blood glucose concentration during a fight-or-flight response to threat or stress?
It increases blood glucose concentration, making more glucose available in the blood.
What effect does adrenaline have on heart rate?
It increases heart rate, separately from its effect on blood glucose.