Question 1:

Bronchioles are the small, branching air passages inside the lungs that connect the bronchi (larger airways) to the alveoli (tiny air sacs where gas exchange occurs).

These are shown by label C in the diagram.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 2:

Explanation:
When breathing out (exhalation), air flows out of the lungs and exits the body. The reverse path of inhalation:

• Air starts in the alveoli (air sacs where gas exchange occurs)

• Then moves into the bronchioles (small airways)

• Then into the bronchi (larger airways) — specifically one bronchus (singular)

• Then into the trachea (windpipe)

• Finally out through the nose/mouth

Thus, the order is: alveoli → bronchioles → bronchus → trachea → matches option C.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 3:

The correct answer is A. Diaphragm contracts, External intercostal muscles contract.

Explanation:
When we breathe in (inhalation):

• The diaphragm contracts (flattens and moves downward).

• The external intercostal muscles contract (pulling the rib cage upward and outward).

Both actions increase the volume of the thoracic cavity, which decreases pressure inside the lungs relative to the atmosphere, causing air to flow into the lungs.

• B – Diaphragm contracts, external intercostals relax → This would not lift the rib cage properly; not correct for inhalation.

• C – Diaphragm relaxes, external intercostals contract → Diaphragm relaxation happens during exhalation.

• D – Diaphragm relaxes, external intercostals relax → This describes passive exhalation, not inhalation.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 4:

The correct answer is D. lined with cilia.

Explanation:

• Bronchioles (especially the larger ones) are lined with cilia and mucus-producing cells. Cilia sweep mucus and trapped particles upward toward the trachea to keep the airways clean.

• Alveoli are not lined with cilia; they are composed of a single layer of squamous epithelial cells for gas exchange.

Checking the options:

• A. large surface area – True for alveoli (enormous surface area for gas exchange), but bronchioles also contribute somewhat to surface area; however, large surface area is a defining feature of alveoli, not bronchioles.

• B. very good blood supply – True for both, but alveoli have an especially dense capillary network for gas exchange.

• C. walls are one cell thick – True for alveoli (for efficient diffusion), but bronchioles have thicker walls (ciliated columnar or cuboidal epithelium, smooth muscle).

• D. lined with cilia – True for bronchioles, not for alveoli ✅.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 5:

The correct answer is B. 4%.

Explanation:
Oxygen makes up 20% of inhaled air and 16% of exhaled air.
The difference is:

• A. 0.04% – This is the percentage of carbon dioxide in inhaled air, not the oxygen difference.

• C. 0% – Incorrect; oxygen concentration does change.

• D. 16% – This is the oxygen percentage in exhaled air, not the difference.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 6:

The correct answer is greater than.

Complete sentence:
To breathe out, the air pressure in our lungs must be greater than the air pressure outside our body.

Explanation:
During exhalation:

• The diaphragm relaxes and the rib cage moves downward and inward.

• This decreases the volume of the thoracic cavity, which increases the pressure inside the lungs.

• When the pressure in the lungs becomes greater than atmospheric pressure outside the body, air flows out down the pressure gradient.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 7:

The correct answer is B. It causes cancer.

Explanation:
Tar in cigarette smoke is a sticky, brown substance that contains many known carcinogens (cancer-causing chemicals). When inhaled, it settles on the lining of the airways and lungs, damaging cells and leading to lung cancer, as well as other cancers of the mouth, throat, and esophagus.

• A. It causes addiction – This is caused by nicotine, not tar.

• C. It makes platelets stick together – This is also related to nicotine and other chemicals, which increase the risk of blood clots, not primarily tar.

• D. It sticks to blood vessel walls – While tar does deposit in the lungs, sticking to blood vessel walls is more associated with other substances like nicotine and carbon monoxide contributing to atherosclerosis. The well-known, primary danger of tar is cancer.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 8:

When smoking damages goblet cells (which produce mucus) and cilia (which normally sweep mucus upward), mucus accumulates and blocks the bronchioles (airways), not the alveoli directly. However, blocked bronchioles prevent fresh air from reaching the alveoli.

This means:

• Oxygen concentration in the alveolar air falls because fresh air cannot fully replace the stale air.

• Carbon dioxide concentration in the alveolar air rises because it cannot be removed efficiently.

• As a result, the diffusion gradient for oxygen (high in alveoli → low in blood) is reduced, and the gradient for carbon dioxide (high in blood → low in alveoli) is also reduced.

• Reduced gradient = slower diffusion = reduced gas exchange.

Now checking the other options:

• A. The surface area of the alveoli is reduced – Smoking can eventually destroy alveolar walls (emphysema), but the immediate mechanism described (blocked bronchioles from mucus) does not directly reduce alveolar surface area.

• B. There is less blood supply to the alveoli – Not caused by blocked bronchioles; blood supply is a separate issue.

• C. The thickness of the bronchiole walls have increased – Not mentioned in the stem; even if true, bronchiole wall thickness doesn’t directly affect alveolar gas exchange as much as the concentration gradient does.

Therefore, D is correct: the blocked bronchioles reduce the renewal of air in the alveoli, decreasing the concentration gradient.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 9:

• 2 minutes after exercise → 25 breaths per minute

• 4 minutes after exercise → 16 breaths per minute

Difference = 25−16=9 25 − 16 = 9 breaths per minute.

Correct answer: C. 9 breaths per minute

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.

Question 10:

The correct answer is A. Her muscle cells needed to get rid of the carbon dioxide.

Explanation:
After exercise, the body continues to have elevated levels of carbon dioxide (CO₂) in the blood because the muscles produced extra CO₂ during increased respiration. The breathing rate stays high to expel this excess CO₂ and also to continue supplying oxygen to help repay oxygen debt (related to lactic acid removal), but the immediate reason in terms of gas balance is to remove CO₂.

• B. Her muscle cells needed to get rid of oxygen – False; cells need oxygen, they don’t need to get rid of it.

• C. Her muscle cells needed more carbon dioxide – False; CO₂ is a waste product, not something cells need more of.

• D. She was sweating – Sweating cools the body but is not the direct cause of high breathing rate.

*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret.
Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.