Question

Frequency of recombination between linked genes in Drosophila is affected by
A. Distance between genes
B. Sex of heterozygotes for linked genes
C. Age of female
D. Temperature
Choose the correct answer from the options given below:

• A. A, B and D only
• B. A, B and C only
• C. A, B, C and D
• D. B, C and D only

Hint:

While distance is the primary determinant of recombination frequency, remember that it's a biological process, not a fixed physical constant. Therefore, other factors like genetics (sex), physiology (age), and environment (temperature) can modulate the rate of crossing over. The lack of recombination in male Drosophila is a classic exam topic.

Answer 1

The Correct Option is C

Step 1: Concept Overview:
Genetic recombination, or crossing over, generates new allele combinations on a chromosome. The frequency of recombination between linked genes varies and is influenced by genetic and environmental factors, particularly in Drosophila.
Step 2: Factor Analysis:
Examining each factor's effect:


A. Gene Distance: The primary factor. Sturtevant's principle states recombination frequency is proportional to the physical distance between genes. Correct.

B. Sex of Heterozygote: Significant in Drosophila melanogaster. Recombination is absent in males. The heterozygous parent's sex significantly impacts the result. Correct.

C. Female Age: Drosophila studies indicate recombination rate changes with female age, generally decreasing. Correct.

D. Temperature: An environmental factor influencing recombination. Non-optimal temperatures alter crossing over frequency in flies. Correct.

Step 3: Conclusion:
Distance, sex, age, and temperature all influence recombination frequency in Drosophila.