Question 1 Medium
When the body is too hot, do the blood vessels near the skin dilate or constrict?
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Answer: dilate
- More blood near the surface loses heat.
- They dilate.
Water balance, kidneys and temperature control: GCSE Combined Science Biology practice questions
A second set of questions on water balance, kidneys and temperature control. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
More questions
Question 2 Medium
What process cools the body when sweat dries on the skin?
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Answer: evaporation
- Evaporation takes energy from the skin.
- It is evaporation.
Question 3 Medium
When the body is too cold, do the blood vessels near the skin dilate or constrict?
Show answer
Answer: constrict
- Less heat must be lost.
- So the vessels constrict.
Question 4 Medium
Name one type of large molecule that stays in the blood and is not filtered out by the kidney.
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Answer: protein
- Large molecules cannot be filtered.
- Proteins stay in the blood.
Question 5 Hard
When more ADH is released, is the urine more concentrated or more dilute?
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Answer: more concentrated
- More water is reabsorbed.
- So the urine is more concentrated.
Question 6 Hard
Which part of the brain monitors the temperature of the blood?
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Answer: thermoregulatory centre
- It coordinates temperature control.
- It is the thermoregulatory centre.
Question 7 Hard
Why may a kidney transplant patient need drugs that suppress the immune system?
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Answer: to prevent rejection
- The immune system treats the kidney as foreign.
- So drugs prevent rejection.
Question 8 Hard
In dialysis, which substance diffuses out of the blood into the dialysis fluid? Give one.
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Answer: urea
- It is at a higher concentration in the blood.
- Urea diffuses out.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
Where is urea made?
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In the liver, from excess amino acids.
Check 2
How is urea carried to the kidneys?
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In the blood plasma.
Check 3
What does the kidney filter out of the blood?
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Water, urea, glucose and ions.
Check 4
What is reabsorbed by the kidney?
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All the glucose, some ions and the water the body needs.
Check 5
What is urine?
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A solution of urea, excess water and ions.
Check 6
Where is urine stored?
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In the bladder.
Check 7
What is ADH?
Show answer
A hormone from the pituitary gland that controls water reabsorption in the kidney.
Check 8
What does more ADH do?
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The kidney reabsorbs more water, so less, more concentrated urine is made.
Check 9
When is more ADH released?
Show answer
When the blood is too concentrated.
Check 10
What does dialysis do?
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Removes urea and excess ions from the blood of a patient whose kidneys fail.
Check 11
Why is dialysis fluid the same glucose concentration as blood?
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So glucose does not diffuse out of the blood.
Check 12
Name two problems of kidney transplants.
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Not enough donors and the risk of rejection.
Check 13
Which part of the brain monitors body temperature?
Show answer
The thermoregulatory centre.
Check 14
Why does sweating cool the body?
Show answer
Evaporation of sweat takes energy from the skin.
Check 15
What is vasodilation?
Show answer
Blood vessels near the skin widen, so more heat is lost.
Check 16
What is vasoconstriction?
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Blood vessels near the skin narrow, so less heat is lost.
Check 17
What is excretion?
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Removing waste substances from the body.
Check 18
Which waste leaves the body through the lungs?
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Carbon dioxide.
Check 19
Why do proteins and blood cells stay in the blood?
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They are too large to be filtered out.
Check 20
What is negative feedback?
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A change triggers a response that reverses the change.
Check 21
What is reabsorption in the kidney?
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Useful substances are taken back into the blood.
Check 22
What happens to urea if the kidneys fail?
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It builds up in the blood.
Check 23
What is the normal body temperature?
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About 37 °C.
Check 24
Why do kidney transplant patients take drugs to suppress the immune system?
Show answer
To stop the body rejecting the new kidney.
Check 25
What happens to the vessels near the skin when too cold?
Show answer
They narrow, so less heat is lost.
Check 26
What happens to sweating when the body is too cold?
Show answer
Sweating stops.
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