Which of the following traits is not a morphological variation in humans?

Analyze the question: The question asks which trait is not a morphological variation. Morphology refers to the visible external form and structure of an organism, such as its shape, size, and colour.

Explain the concept: Variation among humans can be grouped into two types:

• Morphological (structural) variation: differences you can see or measure physically, such as height, body size, skin colour, fingerprints, and hair type.
• Physiological (functional) variation: differences in how the body functions, such as blood group, ability to taste PTC (phenylthiocarbamide), sickle-cell status, and the ability to roll the tongue.

Solution, option by option:

• A. Ability to taste PTC: This is a chemical or functional response. A person tastes the substance as bitter or tastes nothing. It is determined by a gene and involves taste receptors, but it cannot be seen from the body's form. This is physiological variation.
• B. Colour: Skin, eye, or hair colour is visible, so it is morphological.
• C. Fingerprints: These are visible patterns of ridges on the fingertips, so they are morphological.
• D. Size: Height and body size are physical and measurable, so they are morphological.

Answer: The only trait that is not morphological is the ability to taste PTC, which is option A.

Exam tip: Ask yourself, "Can I see or measure this just by looking at the body?" If yes, it is morphological. If it needs a test, such as a chemical taste test, a blood test, or a function check, it is physiological. Remember PTC tasting and blood group as the common physiological examples in WASSCE and JAMB.