The parameters of size, height, weight and colour in a population of living things are examples of

Analyze the question: Size, height, weight and colour are traits in a population. We need to identify what type of variation they represent.

Concept: Variation among individuals of a species can be grouped into two main types:

• Continuous variation: There is a full range of values between two extremes, with no clear-cut categories. It is usually controlled by many genes (polygenic) and is often influenced by the environment. Examples: height, weight, size, skin colour. When plotted, the data gives a bell-shaped curve.
• Discontinuous variation: There are distinct categories with no intermediates. It is usually controlled by one or a few genes, and the environment has little effect. Examples: blood groups (A, B, AB, O), ability to roll the tongue, sex, presence or absence of a feature.

Solution:

1. Height: people are not simply "tall" or "short". Heights range gradually, such as 150 cm, 151 cm, 152 cm, and so on. This is continuous.
2. Weight: also changes gradually across a range of values. This is continuous.
3. Size: likewise graded from small to large.
4. Colour (such as skin colour): it shows shades from light to dark with many intermediates. This is continuous.

Checking the other options:

• A. Environmental variation: This describes the cause of a difference, not the type of pattern shown. The question asks about the type of variation seen in these parameters.
• B. Non-heritable variations: These are acquired traits that cannot be passed on, such as a scar. Height and weight have a heritable component, so this does not fit.
• D. Discontinuous variations: These have distinct categories, which does not match graded traits like height and weight.

Answer: The parameters form a graded range with intermediate values, so they are continuous variations.

Exam tip: Remember "Continuous = Can measure" (with a ruler or scale: height, weight). "Discontinuous = Distinct groups" (blood group, tongue rolling). If you can measure it on a scale, it is usually continuous.