Question 1 Medium
Name the airways that lead from the windpipe to the lungs.
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Answer: bronchi
- The windpipe divides in two.
- The branches are the bronchi.
Exchange surfaces and gas exchange in the lungs: GCSE Combined Science Biology practice questions
A second set of questions on exchange surfaces and gas exchange in the lungs. 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
Is the wall of an alveolus one cell thick or many cells thick?
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Answer: one cell thick
- A thin wall gives a short diffusion distance.
- It is one cell thick.
Question 3 Hard
A cube has a side of 4 cm. Calculate its surface area to volume ratio, in the form n : 1.
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Answer: 1.5 : 1
- Surface area = 6 × 4 × 4 = 96 cm². Volume = 4 × 4 × 4 = 64 cm³.
- 96 ÷ 64 = 1.5, so 1.5 : 1.
Question 4 Hard
Why does the surface area to volume ratio of an animal fall as it grows?
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Answer: volume increases faster than surface area
- Doubling the side of a cube makes the volume 8 times bigger.
- The surface area only gets 4 times bigger.
Question 5 Hard
What does a rich blood supply do to the concentration of oxygen in the capillaries next to the alveoli?
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Answer: keeps it low
- Blood carries oxygen away.
- So the oxygen concentration stays low, giving a steep gradient.
Question 6 Hard
Name one feature of the villi that makes absorption efficient.
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Answer: large surface area
- Villi are adapted for diffusion.
- They give a large surface area.
Question 7 Hard
In which type of organism are gills used for gas exchange?
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Answer: fish
- Gills take oxygen from water.
- They are found in fish.
Question 8 Hard
What do root hair cells absorb from the soil?
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Answer: water and mineral ions
- Roots take in what the plant needs from the soil.
- They absorb water and mineral ions.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
Why do big organisms need exchange surfaces?
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They have a small surface area to volume ratio, so diffusion across the skin is not enough.
Check 2
Why do multicellular organisms need a transport system?
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Substances must be carried to every cell, which are too far away for diffusion.
Check 3
Name six substances transported into and out of organisms.
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Oxygen, carbon dioxide, water, dissolved food molecules, mineral ions and urea.
Check 4
What is surface area to volume ratio?
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Surface area divided by volume.
Check 5
What happens to the ratio as an organism gets bigger?
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It decreases.
Check 6
What is the ratio for a 1 cm cube?
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6 : 1.
Check 7
What is the ratio for a 2 cm cube?
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3 : 1.
Check 8
What is the ratio for a 3 cm cube?
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2 : 1.
Check 9
What are alveoli?
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Tiny air sacs in the lungs where gases are exchanged.
Check 10
Which gas diffuses into the blood in the alveoli?
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Oxygen.
Check 11
Which gas diffuses out of the blood in the alveoli?
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Carbon dioxide.
Check 12
Why is there a large surface area in the lungs?
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There are millions of alveoli.
Check 13
Why are the walls of alveoli thin?
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To make the diffusion distance short.
Check 14
Why is a good blood supply important for the alveoli?
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It carries oxygen away and brings carbon dioxide, keeping a steep concentration gradient.
Check 15
Why is ventilation important?
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It brings fresh air with a high concentration of oxygen to the alveoli.
Check 16
How does oxygen travel in the blood?
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Joined to haemoglobin in red blood cells.
Check 17
What are villi?
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Finger-like projections in the small intestine that give a large surface area.
Check 18
How are gills adapted for gas exchange?
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Many thin filaments give a large surface area, thin walls and a good blood supply.
Check 19
How are root hair cells adapted?
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A long projection gives a large surface area to take up water and mineral ions.
Check 20
How is a leaf adapted for gas exchange?
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Flat and thin, with air spaces and stomata for carbon dioxide to diffuse in.
Check 21
What is the name for the tubes from the windpipe to the lungs?
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Bronchi.
Check 22
What is diffusion?
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The net movement of particles from a higher concentration to a lower concentration.
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