Variation which exhibits a wide range from one extreme to the other is

Analyze the question: It asks for the type of variation that shows a wide range from one extreme to the other, with many intermediate forms in between.

Explain the concept:

• Continuous variation: The trait shows a full range of values between two extremes, with no distinct categories. Examples are height, weight, skin colour, and finger length. These traits are usually controlled by many genes (polygenic) and are also influenced by the environment. A graph of the data gives a bell-shaped curve.
• Discontinuous variation: The trait falls into a few distinct groups, with no intermediates. Examples are blood group (A, B, AB, O), tongue rolling, and sex. These traits are usually controlled by one or two genes, and the environment has little effect on them.
• Phenotypic variation: This is any observable difference in appearance or characteristics. It can be continuous or discontinuous, so it is too general to be the answer.
• Genotypic variation: This is a difference in genetic makeup. It is not a description of a range of observable traits.

Solution:

1. The question stresses a "wide range from one extreme to the other", which means there are many gradual intermediate values.
2. Discontinuous variation has distinct categories, so it does not fit.
3. Phenotypic and genotypic variation describe the source or type of difference, not the pattern of a range.
4. Continuous variation is the one that shows a gradual range between extremes.

Answer: C. continuous variation

Exam tip: Think "continuous = a continuous line of values, like height." Think "discontinuous = distinct boxes, like blood groups." If the question mentions a range or intermediates, choose continuous.