Question

Which of the following statements are true about respiration?

1. during inhalation, ribs move inward and diaphragm is raised.
2. the gaseous exchange takes place in the alveoli.
3. haemoglobin has greater affinity for carbon dioxide than oxygen.
4. alveoli increase surface area of the exchange of gases.

Options

• (i) and (iv)

• (ii) and (iii)

• (i) and (iii)

• (ii) and (iv)

Answer 1

(ii) and (iv)

Explanation:

The correct statements are (ii) and (iv). This is because the respiratory system relies on structural adaptations to maximize gas exchange, which occurs directly across the thin walls of the alveoli. Millions of these tiny, balloon-like air sacs drastically increase the available surface area within the lungs, ensuring that oxygen can diffuse rapidly into the bloodstream while carbon dioxide leaves it. Conversely, statement (i) is incorrect because inhalation requires the chest cavity to expand, meaning the ribs lift upward and outward while the diaphragm moves downward and flattens. Statement (iii) is also false because haemoglobin has a much higher affinity for oxygen than carbon dioxide, which allows it to efficiently carry oxygen from the lungs to the rest of the body.