Question 1

Which of the following best describes the outcome of a complementation test when two Drosophila mutants with the same recessive phenotype are crossed and the offspring are wild type?

Accepted Answer

The mutations are in different genes, and complementation occurs.

Question 2

In a complementation test, two Drosophila flies with mutations in the same gene are crossed. What is the expected phenotype of their offspring?

Accepted Answer

All offspring will be mutant and not develop wings.

Question 3

If two flies with the genotypes $$m^1$$/+; $$+/m^2$$ and $$+/m^1$$; $$m^2$$/+$$ are crossed, and the resulting offspring are wild type, what does this indicate about the mutations?

Accepted Answer

The mutations are in different genes.

Question 4

Which statement about complementation is correct?

Accepted Answer

Complementation occurs when two mutations in different genes restore the wild-type phenotype.

Question 5

A researcher crosses two Drosophila mutants, each with a recessive mutation causing winglessness. All F1 offspring have wings. What is the most likely explanation?

Accepted Answer

The mutations are in different genes and complement each other.

Question 6

If two flies with mutations in different genes are crossed and the F1 generation is wild type, what is the genotype of the F1 flies?

Accepted Answer

$$m^1$$/+; $$+/m^2$$

Question 7

In a complementation test, what does it mean if the F1 offspring are mutant?

Accepted Answer

The mutations are in the same gene and do not complement.

Question 8

Which of the following is a correct interpretation of the result: two mutant flies are crossed, and all offspring are mutant?

Accepted Answer

The mutations are allelic (in the same gene).

Question 9

Why do flies with genotype $$m^1$$/+; $$+/m^2$$ develop wings, while flies with $$m^1/m^2$ do not?

Accepted Answer

Each gene has one functional copy in $$m^1$$/+; $$+/m^2$$, but both copies are mutant in $$m^1/m^2$.

Question 10

Which scenario would NOT result in complementation in a Drosophila cross?

Accepted Answer

Both parents have mutations in the same gene.

Genetics Exam 1 Study Guide: Core Concepts and Applications

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