Pleiotropy - Unsolved Practice Set
Chapter: Principles of Inheritance and Variation | Topic: Pleiotropy
PLEIOTROPY - UNSOLVED PRACTICE SET
Topic: Pleiotropy
Multiple Choice Questions
Q1. Pleiotropy refers to a situation where:
- A single gene influences multiple, seemingly unrelated phenotypic traits
- Multiple genes control a single trait
- A trait is controlled by environmental factors only
- Two alleles blend to form an intermediate phenotype
Q2. Which of the following human genetic disorders is commonly cited as an example of pleiotropy?
- Colour blindness
- Phenylketonuria (PKU)
- Down syndrome
- Turner syndrome
Q3. In pea plants, the gene affecting starch grain synthesis studied by Mendel is also known to influence:
- Flower colour and seed shape
- Plant height only
- Number of seeds per pod
- Nothing else
Q4. Pleiotropy is best distinguished from polygenic inheritance because pleiotropy involves:
- One gene affecting many traits, unlike polygenic inheritance where many genes affect one trait
- Many genes affecting many traits
- Codominant alleles only
- Sex-linked genes only
Q5. A pleiotropic gene mutation is generally more likely to cause a condition with:
- A single isolated symptom
- Multiple, seemingly unconnected symptoms across the body
- No symptoms at all
- Only cosmetic changes
Short Answer Questions
Q6. Define pleiotropy, in your own words.
Q7. Give one human genetic disorder that is a classic example of pleiotropy, and briefly mention two of its effects.
Q8. How is pleiotropy different from a gene simply showing variable expression in different individuals?
Q9. Why might a single mutated gene affect organs that seem completely unrelated to each other?
Long Answer Questions
Q10. Explain the concept of pleiotropy with reference to phenylketonuria (PKU), describing how a single defective gene leads to multiple, seemingly unconnected symptoms.
Q11. Discuss why pleiotropy is an important concept in understanding the complexity of gene function, and how it differs from polygenic inheritance.
APPLICATION / ANALYSIS
Q12. A child is diagnosed with a genetic disorder that affects both their skin pigmentation and their nervous system development. A doctor explains that both symptoms trace back to a single faulty gene. Using your understanding of pleiotropy, explain how one gene defect can cause such seemingly unrelated symptoms.
Q13. Researchers studying a particular gene in mice find that when it is knocked out (disabled), the mice show changes not just in one organ but in their fur colour, behaviour, and heart function. Explain, using the concept of pleiotropy, why disabling a single gene could cause effects across so many different body systems.