Answers · Hormones

Adrenaline at work — answer key

Check meaning, not exact wording. These are teaching points, not official Cambridge marks.

1. AQ1 · Practice

Model answer. A hormone is a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.

A full answer includes

I chose the chemical made by a gland that travels in the blood and changes what certain organs do.
I did not choose the option that says it travels along nerves.

Also accept

a chemical made by a gland, carried in the blood, acting on specific target organs

Watch for

“An electrical signal made by a neurone, which travels along nerves to one muscle.” — That describes a nerve impulse. A hormone is a chemical carried in the blood.
“A chemical made by a gland, which travels along nerves and changes what every organ does.” — Two parts are wrong: a hormone travels in the blood, and it changes specific target organs only.
“A chemical taken in with food, which travels in the blood and is needed by every cell.” — That describes a vitamin or mineral. A hormone is made in the body, by a gland.

2. AQ2 · Practice

Model answer. A hormone passes into the blood flowing through the gland, and the blood carries it round the body to its target organs.

A full answer includes

I chose "in the blood".
I did not choose "along nerves": nerves carry electrical impulses, not hormones.

Also accept

in the blood

Watch for

“Along nerves.” — Nerves carry electrical impulses. Hormones are carried in the blood.
“By diffusing from cell to cell through the tissues.” — Diffusion from cell to cell would be far too slow to reach the heart or the eyes. The blood carries the hormone round the body.
“Through tubes that lead from the gland to each target organ.” — Endocrine glands have no such tubes. They release their hormones straight into the blood flowing through them.

3. AQ3 · Practice

Model answer. B. Adrenaline increases the breathing rate, the heart rate and the pupil diameter: all three increase.

A full answer includes

I chose row B.
I did not choose row A: adrenaline makes the pupils wider, not narrower.

Also accept

Watch for

“Row A: the pupil diameter decreases.” — Adrenaline makes the pupils wider. Narrower pupils in bright light are a reflex, not an effect of adrenaline.
“Row C: the breathing rate decreases.” — Adrenaline increases the breathing rate, so more oxygen is taken in.
“Row D: the heart rate decreases.” — Adrenaline increases the heart rate, so the blood carries oxygen to the muscles faster.

4. AQ4 · Practice

Model answer. The adrenal glands, one on top of each kidney, secrete adrenaline.

A full answer includes

I chose the adrenal glands.
I did not choose the kidneys: the glands sit on them but are separate organs.

Also accept

adrenal glands

Watch for

“The kidneys.” — The adrenal glands sit on top of the kidneys, but they are separate glands. The kidneys make urine.
“The pancreas.” — The pancreas secretes insulin. Adrenaline comes from two small glands, one on each kidney.
“The heart.” — The heart is a target organ of adrenaline: it beats faster. It does not secrete it.

5. AQ5 · Practice

Model answer. A target organ is an organ that responds to the hormone: its activity is altered. The blood carries the hormone to every organ, but only the target organs respond.

A full answer includes

I chose "an organ whose activity the hormone alters".
I did not choose "any organ that the blood carries the hormone to".

Also accept

an organ whose activity the hormone alters

Watch for

“Any organ that the blood carries the hormone to.” — The blood reaches every organ, but only the target organs respond to a hormone.
“The gland that produces the hormone.” — The gland makes the hormone and releases it. The target organ is where it acts.
“The organ that breaks the hormone down.” — Breaking a hormone down ends its effect. A target organ is one whose activity the hormone changes.

6. AQ7 · Practice

Model answer. The breathing rate went from 16 to 27 breaths per minute, an increase of 27 − 16 = 11 breaths per minute.

Checked automatically

Increase in breathing rate (breaths per minute): 11 (within ±0.5)
- Common wrong answer 27 : That is the value one minute later. Subtract the value before.
- Common wrong answer 43 : That adds them. Subtract: 27 − 16.

A full answer includes

I subtracted the value before from the value one minute later: 27 − 16.
I wrote 11 breaths per minute.
I did not give the breathing rate one minute later as the answer.

Also accept

11 breaths per minute

Watch for

“27 breaths per minute.” — That is the breathing rate one minute later. The increase is the difference: 27 − 16.
“43 breaths per minute.” — That adds the two values. The increase is the difference.

7. AQ8 · Practice

Model answer. Insulin is a chemical substance, produced by a gland (the pancreas), carried by the blood, and it alters the activity of a specific target organ (the liver). It fits every part of the description of a hormone.

A full answer includes

I wrote that insulin is a chemical substance.
I wrote that it is produced by a gland, the pancreas.
I wrote that it is carried by the blood.
I wrote that it alters the activity of a specific target organ, the liver.
I did not write only that it is made in the body.

Also accept

chemical; gland; blood; target organ

Watch for

“Because it is made in the body.” — Many substances are made in the body. A hormone must also be made by a gland, carried by the blood and act on target organs.
“Because it is found in the liver.” — The liver is where insulin acts. The description needs the gland that makes it, the pancreas, and the blood that carries it.

8. AQ9 · Practice

Model answer. A faster breathing rate takes more oxygen into the lungs. A faster heart rate makes the blood carry that oxygen to the leg muscles faster, so they can work hard. Wider pupils let more light into the eyes, which helps the zebra to see the lion and the ground in the dim light at dusk.

A full answer includes

Breathing: I wrote that more oxygen is taken into the lungs.
Heart: I wrote that the blood carries oxygen to the muscles faster.
Pupils: I wrote that more light enters the eyes.
Pupils: I linked the extra light to seeing better in the dim light at dusk.
I did not write that wider pupils help the eyes to focus.

Also accept

more oxygen in; oxygen carried faster; more light in at dusk

Watch for

“Wider pupils make the eyes focus better.” — Focusing is the lens's job. Wider pupils let more light into the eyes.
“A faster heart rate makes the zebra stronger.” — The heart does not add strength. It delivers oxygen to the muscles faster, so they can respire and work hard.

9. AQ10 · Practice

Model answer. A hormone alters the activity of specific target organs only. The blood carries it to both organs, so it reaches Q as well as P. P is one of its target organs and responds; Q is not a target organ, so its activity does not change.

A full answer includes

I wrote that the hormone reaches both organs in the blood.
I wrote that P is a target organ of the hormone, so it responds.
I wrote that Q is not a target organ, so its activity does not change.
I did not write that the hormone fails to reach Q.

Also accept

P is a target organ; Q is not

Watch for

“The hormone is used up before it reaches Q.” — Both organs get the same blood with the same concentration of the hormone.
“Q is too far from the gland.” — The blood carries the hormone all round the body. Distance is not the reason: Q is not one of its targets.

10. AQ11 · Practice

Model answer. The increase is 5.4 − 2.8 = 2.6 mm. The percentage increase is 2.6 ÷ 2.8 × 100 = 92.86 … %, which is 93 % to 2 significant figures. The pupils got wider.

Checked automatically

Percentage increase in pupil diameter: 93 % (2 significant figures)
- Common wrong answer 2.6 : That is the increase in mm. Divide it by 2.8 and multiply by 100.
- Common wrong answer 48 : That divides by the diameter one minute later. Divide 2.6 by the diameter before, 2.8.
- Common wrong answer 190 : That is the new diameter as a percentage of the old one. Subtract 100 % to find the increase.

A full answer includes

I found the increase: 5.4 − 2.8 = 2.6 mm.
I divided the increase by the diameter before and multiplied by 100: 2.6 ÷ 2.8 × 100.
I wrote 93 %, to 2 significant figures.
I did not divide by the diameter one minute later.

Also accept

93 %

Watch for

“2.6 %.” — 2.6 is the increase in millimetres. Divide it by the diameter before, then multiply by 100.
“48 %.” — That divides by the diameter one minute later. A percentage increase compares with the value before: 2.6 ÷ 2.8.
“190 %.” — That is 5.4 ÷ 2.8 × 100, the new diameter as a percentage of the old one. Subtract 100 % to find the increase.

11. AQ6 · Practice

Model answer. Adrenaline increases the blood glucose concentration: it makes the liver release glucose into the blood.

A full answer includes

I chose "it increases it: the liver releases glucose into the blood".
I did not choose a decrease: insulin, not adrenaline, lowers it.

Also accept

it increases it

Watch for

“It decreases it: the liver takes glucose out of the blood.” — Adrenaline raises the blood glucose concentration. Insulin is the hormone that lowers it.
“It has no effect on it: only insulin changes it.” — Insulin lowers it, but adrenaline changes it too: it raises it, ready for the muscles.
“It increases it: the stomach digests food faster.” — Adrenaline does raise it, but not through digestion. The extra glucose comes from the liver.

12. AQ12 · Practice

Model answer. It would stay close to its value before the fright. Adrenaline raises the blood glucose concentration by acting on the liver, which releases glucose into the blood. If the liver cannot respond, no extra glucose is released. The heart rate still rises, but a faster heart only moves the glucose that is already in the blood.

A full answer includes

I chose "it would stay close to its value before the fright".
I explained that adrenaline raises blood glucose by making the liver release glucose.
I explained that a liver that cannot respond releases no extra glucose.
I did not write that the faster heart rate makes the glucose.

Also accept

it would stay close to its value before

Watch for

“It would rise as usual, because the heart rate still increases.” — A faster heart delivers glucose faster, but it does not add any. The extra glucose comes from the liver.
“It would rise more than usual, because more adrenaline builds up.” — Even more adrenaline has no effect on a liver that cannot respond to it.
“It would fall to almost zero within a minute.” — Sitting still, the muscles use little glucose, and the glucose already in the blood stays there. Without the liver it simply does not rise.

13. AQ13 · Practice

Model answer. (a) The increase is 118 − 85 = 33 mg per 100 cm³ of blood. (b) Over 5 minutes, the mean rate of increase is 33 ÷ 5 = 6.6 mg per 100 cm³ per minute. The liver released this glucose in response to adrenaline.

Checked automatically

(a) Increase (mg per 100 cm³): 33 (within ±0.5)
- Common wrong answer 118 : That is the value after five minutes. Subtract the value before.
- Common wrong answer 203 : That adds them. Subtract: 118 − 85.
(b) Mean rate of increase (mg per 100 cm³ per minute): 6.6 (within ±0.05)
- Common wrong answer 33 : That is the whole increase. Divide it by the 5 minutes.
- Common wrong answer 23.6 : That divides 118 by 5. Divide the increase, 33, by 5.
- Common wrong answer 165 : That multiplies by 5. Divide the increase by 5.

A full answer includes

(a) I subtracted: 118 − 85.
(a) I wrote 33 mg per 100 cm³.
(b) I divided the increase by the time: 33 ÷ 5.
(b) I wrote 6.6 mg per 100 cm³ per minute.
I did not divide 118 by 5.

Also accept

(a) 33; (b) 6.6 per minute

Watch for

“(a) 118.” — That is the concentration after five minutes. The increase is the difference: 118 − 85.
“(b) 23.6.” — That divides the final concentration by 5. Divide the increase, 33, by 5.

14. AT1 · Apply

Model answer. In a fight or flight situation the cat's adrenal glands secrete adrenaline. Its heart rate increases, its breathing rate increases and its pupils get wider.

A full answer includes

I predicted that the heart rate increases.
I predicted that the breathing rate increases.
I predicted that the pupil diameter increases.
I stated adrenaline.
I did not predict that the pupils get smaller.

Also accept

all three increase; adrenaline

Watch for

“The pupils get smaller so the cat can focus on the dog.” — Adrenaline makes the pupils wider, letting more light in.
“The heart rate slows down so the cat can keep still.” — Adrenaline increases the heart rate, ready to fight or to run.

15. AT2 · Apply

Model answer. A human hormone is a chemical substance, produced by a gland and carried by the blood, which alters the activity of specific target organs. Auxin is a chemical that changes what other cells do, but it is made in ordinary cells of the shoot tip, not in a gland, and plants have no blood to carry it.

A full answer includes

I chose "it is not produced by a gland".
I chose "it is not carried by the blood".
I did not choose "it is not a chemical substance": auxin is a chemical.

Also accept

not produced by a gland; not carried by the blood

Watch for

“It is not a chemical substance.” — Auxin is a chemical substance. What it lacks is a gland and the blood to carry it.
“It does not alter the activity of other cells.” — It does: it makes cells in the shoot grow longer. That part of the description fits.

16. AT3 · Apply

Model answer. Adrenaline makes his liver release glucose, raising the blood glucose concentration, and increases his heart rate, so the blood delivers glucose and oxygen to his muscles faster. His muscle cells can respire faster, releasing more energy for contraction.

A full answer includes

I wrote that the liver releases glucose into the blood.
I wrote that the blood glucose concentration increases.
I wrote that the heart rate increases.
I wrote that the blood delivers glucose and oxygen to the muscles faster.
I wrote that the muscles use them in respiration, which releases energy for contraction.
I did not write that adrenaline gives the muscles energy directly.

Also accept

glucose up; heart rate up; more respiration

Watch for

“Adrenaline gives the muscles energy directly.” — Adrenaline carries no energy. It raises the blood glucose and the heart rate; the muscles release energy from glucose in respiration.
“Adrenaline makes his muscles bigger.” — Adrenaline changes metabolic activity within minutes; it does not build muscle.