Science (086) — AI-generated practice question

A gene is a segment of DNA that controls the production of a specific protein, which in turn determines a physical trait.

In pea plants, the gene for height exists in two forms (alleles): T (tall) and t (short). The allele T directs the production of a protein (enzyme) that promotes normal growth, making the plant tall. Allele t does not produce this functional protein, so the plant remains short.

Since T is dominant, even one copy (Tt) makes the plant tall. Both copies must be tt for the plant to be short. Thus, the gene controls the characteristic by determining which protein is made.

Source: Chapter 8, Section 8.2.2

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• Examiners expect three clear points for 3 marks: (1) what a gene does (controls protein production), (2) how the specific alleles T and t work, and (3) the dominant/recessive relationship explaining the final trait.
• Avoid writing a full essay — keep it tight and use the terms dominant, recessive, allele for full credit.
• The phrase "protein that promotes growth" is key — it links the gene directly to the physical characteristic, which is what the question asks.