Question

(a) The blood groups of some people are recorded. Fig. 10.1 shows the results.

(i) State the total number of people who had their blood group recorded.

▶️Answer/Explanation

100 people

(ii) Describe the evidence in Fig. 10.1 that shows blood group is an example of discontinuous variation.

▶️Answer/Explanation

The graph shows distinct categories (A, AB, B, O) with no intermediate values between them. This clear separation into distinct groups with no overlap is characteristic of discontinuous variation.

(iii) Complete this sentence about discontinuous variation.
Discontinuous variation is mostly caused by …… alone.

▶️Answer/Explanation

genes

(iv) Name one example of continuous variation in humans.

▶️Answer/Explanation

Height (or other acceptable examples like weight, skin color, etc.)

(b) Blood contains four main components. The boxes on the left show the components of blood. The boxes on the right show the functions of each component. Draw lines to link each component with its function.

▶️Answer/Explanation

plasma → transport of ions, soluble nutrients and hormones
platelet → blood clotting
red blood cell → transport of oxygen
white blood cell → antibody production

Note: The correct matching is the opposite of what might be initially assumed from the question’s layout.

(c) Describe two ways the structure of a red blood cell is adapted to its function.

▶️Answer/Explanation

1. Biconcave shape – increases surface area for oxygen absorption
2. Contains hemoglobin – binds with oxygen molecules
3. No nucleus – more space for hemoglobin (any two of these)