Question

9. A class discussion turns to why not all family members with a mutation develop coronary artery disease. Some students think this proves mutations don’t really matter, while others argue that only single-gene disorders are linked to disease. The teacher reminds them of polygenic traits and environmental factors.

Which ideas reflect accurate scientific understanding?
(Select all that apply).

Responses

A. Not all traits are controlled by a single gene; many traits involve multiple genes.
A. Not all traits are controlled by a single gene; many traits involve multiple genes.

B. If a family member carries a mutation, every relative will develop the same disease.
B. If a family member carries a mutation, every relative will develop the same disease.

C. A person with a mutation is always guaranteed to develop coronary artery disease.
C. A person with a mutation is always guaranteed to develop coronary artery disease.

D. All mutations have a harmful effect.
D. All mutations have a harmful effect.

E. Environmental factors, such as diet and exercise, can interact with genetics to affect disease risk.

Answer 1

Correct answers: A and E.

- A is true: many traits (including coronary artery disease risk) are polygenic — influenced by multiple genes.
- E is true: environment (diet, exercise, smoking, etc.) interacts with genetics to change disease risk.

B, C, and D are incorrect:
- B and C are false because carrying a mutation does not guarantee that all relatives (or the carrier) will develop the disease — penetrance and expression vary and many diseases are influenced by multiple genes and environment.
- D is false because mutations can be harmful, neutral, or sometimes beneficial.