Gas Exchange questions

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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.

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Question 1

What is the main function of the human gas exchange system?
  1. To move oxygen into blood and carbon dioxide out of blood
  2. To pump blood around the body
  3. To digest large food molecules
  4. To control blood glucose directly

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 bring blood for gas exchange 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 relaxes and domes upward
  3. It tears to increase chest volume
  4. It stays still while ribs move

Question 8

What happens to the rib cage during inhalation?
  1. It moves up and out
  2. It moves down and in
  3. It becomes fixed and cannot move
  4. It moves only downward

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. Only 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. Alveoli gain extra surface area
  3. Oxygen becomes easier to dissolve
  4. The rib cage becomes more flexible

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. Only 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

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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.

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