Which of the following characteristics shows discontinuous variation in plants?

Step 1: Analyze the question The question asks which characteristic shows discontinuous variation.

Step 2: Explain the concept

• Continuous variation: Individuals show a full range of values between two extremes, with no clear-cut categories. It is controlled by many genes (polygenic) and is strongly influenced by the environment. It can be measured (length, mass, height) and gives a bell-shaped curve. Examples: height, mass, leaf size, fruit size.
• Discontinuous variation: Individuals fall into distinct categories with no intermediates. It is controlled by one or a few genes and is little affected by the environment. Examples: blood groups (A, B, AB, O), tongue rolling, sex, flower colour (e.g. red or white in certain plants).

Step 3: Test each option

• A. Colour of flower: Flowers are usually clearly red, white, yellow, and so on, with distinct categories and no gradual measurable range. This is discontinuous.
• B. Leaf size: Leaves vary gradually from small to large and are affected by light, water and nutrients. This is continuous.
• C. Height of plant: Heights vary across a whole range and depend on environment (soil, water, light). This is continuous.
• D. Fruit size: Fruits vary gradually in size, so this is continuous.

Step 4: Answer The correct option is A. Colour of flower.

Exam tip: Ask yourself, "Can I measure it with a ruler or scale?" If yes, it is usually continuous. If you can only put it into categories (colour, blood group, tongue rolling), it is discontinuous. A quick memory aid is that "Discontinuous = Distinct groups."