Home / iGCSE Biology (0610)-11.1 Gas exchange in humans – iGCSE Style Questions Paper 1

iGCSE Biology (0610)-11.1 Gas exchange in humans – iGCSE Style Questions Paper 1

IGCSE Biology (0610) Practice Questions Paper 1 - All Chapters

Question

The diagram shows part of the gas exchange system in humans.

Which row identifies the structures in the diagram?

▶️ Answer/Explanation
To identify the correct row, we must match the labels to the anatomical structures of the respiratory system. Label T points to the bone structure of the chest wall, which is the rib. Label U points to the tissue located between the ribs, identifying the intercostal muscle. Label V points to the large, dome-shaped muscular sheet at the base of the thorax, which is the diaphragm. Finally, label W points to the tiny air sacs at the end of the bronchioles where gas exchange occurs, known as the alveoli. Comparing these identifications with the table, row A is the only option that correctly matches all four structures.
✅ Answer: (A)

Question

A student investigates the effect of physical activity on their breathing rate.
They record their breathing rate at different times.
Which row shows the change in the breathing rate of the student?

▶️ Answer/Explanation
Correct Answer: C

During physical activity, breathing rate increases significantly to supply more oxygen to muscles and remove carbon dioxide. Row C correctly illustrates this peak during exercise ($15 \rightarrow 34$). Immediately after activity stops, the rate begins to decrease ($34 \rightarrow 28$) as the body starts to recover. Within five minutes, the breathing rate should return to near-resting levels ($16$). Row D is incorrect because the rate cannot continue to rise after exercise stops, while Rows A and B show insufficient increases for physical exertion.

Question

Which substance is produced during anaerobic respiration in yeast?
A alcohol
B glucose
C lactic acid
D water
▶️ Answer/Explanation
Detailed solution

The correct answer is A.

Explanation:
In yeast, anaerobic respiration is also known as alcoholic fermentation. During this process, glucose is broken down in the absence of oxygen to produce ethanol (a type of alcohol) and carbon dioxide. Unlike aerobic respiration, water is not produced, and unlike anaerobic respiration in muscles, lactic acid is not formed. This process is essential in brewing and baking, where the ethanol and $CO_2$ are the desired primary products.

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