Gas Exchange questions

By Interwoven Maths

Gas Exchange question collection

Review Gas Exchange questions for Biology, with correct answers shown and coverage across breathing and ventilation; alveoli and surface area; diffusion of oxygen and carbon dioxide.

Back to Gas Exchange practice Back to Biology

Question 1

What is the main function of the human gas exchange system?
  1. Move oxygen into blood and carbon dioxide out
  2. Pump blood around the body
  3. Digest large food molecules
  4. Control blood glucose concentration

Question 2

What are the tiny air sacs in the lungs called?
  1. Alveoli
  2. Villi
  3. Nephrons
  4. Bronchi

Question 3

Which adaptation of alveoli increases the rate of diffusion?
  1. A very large surface area
  2. A thick muscular wall
  3. A waterproof outer layer
  4. A low blood supply

Question 4

Why do alveoli have walls that are one cell thick?
  1. To give a short diffusion distance
  2. To stop all gas movement
  3. To increase pressure inside each alveolus
  4. To store extra glucose

Question 5

Why is a moist lining useful in alveoli?
  1. It helps gases dissolve before diffusing
  2. It blocks oxygen from entering blood
  3. It neutralises stomach acid
  4. It prevents blood flow through capillaries

Question 6

What is the main role of capillaries around alveoli?
  1. They supply blood and maintain concentration gradients
  2. They produce mucus to trap dust
  3. They contract to move ribs
  4. They store air between breaths

Question 7

What happens to the diaphragm during inhalation?
  1. It contracts and flattens
  2. It contracts and curves upward
  3. It relaxes and flattens
  4. It relaxes and curves upward

Question 8

During inhalation, which way does the rib cage move?
  1. Up and out
  2. Down and in
  3. Up and in
  4. Down and out

Question 9

How does thoracic volume change during inhalation?
  1. It increases
  2. It decreases
  3. It stays exactly the same
  4. It drops to zero

Question 10

What happens to pressure inside the lungs during inhalation?
  1. It falls below atmospheric pressure
  2. It rises above atmospheric pressure
  3. It becomes equal to blood pressure
  4. It does not change

Question 11

What happens to the diaphragm during exhalation?
  1. It relaxes and domes upward
  2. It contracts and flattens
  3. It thickens to trap more oxygen
  4. It fills with air

Question 12

What happens to the rib cage during exhalation?
  1. It moves down and in
  2. It moves up and out
  3. It expands in all directions
  4. It locks in one position

Question 13

Which gas diffuses from alveoli into the blood?
  1. Oxygen
  2. Carbon dioxide
  3. Nitrogen
  4. Water vapour

Question 14

Which gas diffuses from blood into the alveoli to be breathed out?
  1. Carbon dioxide
  2. Oxygen
  3. Helium
  4. Hydrogen

Question 15

During exercise, why do breathing rate and depth increase?
  1. To supply more oxygen and remove more carbon dioxide
  2. To stop blood flowing to muscles
  3. To reduce glucose use in respiration
  4. To keep diaphragm movement constant

Question 16

What happens in asthma that makes breathing difficult?
  1. Airways become inflamed and narrowed
  2. Airways become wider and airflow resistance decreases
  3. Oxygen concentration in the air drops while airways stay unchanged
  4. The diaphragm contracts less but bronchioles stay normal

Question 17

Smoking damages cilia in the airways. What is a likely result?
  1. More mucus and pathogens remain in the lungs
  2. Mucus is moved towards the throat faster
  3. Pathogens are trapped before entering the nose
  4. Phagocytes stop entering lung tissue

Question 18

Why is carbon monoxide in cigarette smoke dangerous?
  1. It reduces the blood's oxygen-carrying capacity
  2. It increases oxygen binding to haemoglobin
  3. It neutralises acids in the stomach
  4. It strengthens airway cilia

Question 19

In emphysema, alveolar walls break down. What is the main effect on gas exchange?
  1. Less surface area so diffusion is less efficient
  2. More surface area so diffusion is faster
  3. No effect because capillaries do all gas exchange
  4. Digestion is affected

Question 20

What is the function of stomata in leaves?
  1. To allow gas exchange between the leaf and air
  2. To transport sugars through phloem
  3. To absorb water from soil
  4. To produce chlorophyll in roots

Question 21

What is the difference between breathing and respiration?
  1. Breathing moves air; respiration releases cellular energy
  2. Breathing releases energy; respiration moves air
  3. Breathing moves blood; respiration digests food
  4. Breathing uses glucose; respiration makes glucose

Question 22

Which tubes connect the bronchi to the alveoli?
  1. Bronchioles
  2. Trachea
  3. Capillaries
  4. Oesophagus

Question 23

How does ventilation keep alveolar diffusion fast?
  1. It refreshes air and maintains concentration gradients
  2. It thickens the alveolar walls
  3. It slows blood flow through capillaries
  4. It equalises gas concentrations on both sides

Question 24

Which substance carries oxygen in the blood?
  1. Haemoglobin
  2. Plasma glucose
  3. Platelets
  4. Antibodies

Question 25

What do the external intercostal muscles do during inhalation?
  1. Contract and lift the ribs
  2. Relax and lower the ribs
  3. Contract and lower the diaphragm
  4. Relax and narrow the trachea

Question 26

What happens to chest volume during exhalation?
  1. It decreases
  2. It increases
  3. It stays constant
  4. It doubles

Question 27

Why can smoking reduce gas exchange?
  1. It damages alveoli and reduces surface area
  2. It increases the number of alveoli
  3. It makes blood carry more oxygen
  4. It strengthens cilia

Question 28

What do cilia in airways help do?
  1. They move mucus and trapped particles towards the throat
  2. They move oxygen from the alveoli into blood
  3. They move air into the lungs during inhalation
  4. They move carbon dioxide from blood into the alveoli

Question 29

How does exercise affect gas concentration gradients at the alveoli?
  1. They become steeper
  2. They disappear
  3. They reverse direction
  4. They become equal

Question 30

What is ventilation?
  1. Movement of air into and out of the lungs
  2. Release of energy in cells
  3. Movement of blood around the body
  4. Diffusion of glucose into cells

About this topic

Review Gas Exchange questions for Biology, with correct answers shown and coverage across breathing and ventilation; alveoli and surface area; diffusion of oxygen and carbon dioxide.

This topic covers

Example question types