Q: If a triple heterozygote is testcrossed and 1,000 progeny are counted, how many are expected to result from double crossovers if interference $$= 0.5$$ and the expected double crossover frequency is $$0.10$$?

$$0.10 \times 0.5 \times 1000 = 50$$

Q: In a population, the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

In a dihybrid cross AaBb x AaBb, what is the expected phenotypic ratio in the F2 generation, assuming independent assortment and complete dominance?

Accepted Answer

$$9:3:3:1$$

Question 2

A woman with blood type O has a child with blood type O. Which of the following men could NOT be the father?

Accepted Answer

A man with blood type AB

Question 3

If two genes are linked and 20% of the gametes are recombinant, what is the map distance between the genes?

Accepted Answer

$$20$$ map units

Question 4

A fruit fly with genotype AaBb is testcrossed to aabb. What is the probability that the first three offspring are all dihybrid females?

Accepted Answer

$$(1/8)^3 = 0.00195$

Question 5

In a bacterial conjugation experiment, gene a first appears at 7 minutes, and gene b first appears at 12 minutes. What is the order of transfer?

Accepted Answer

$$a, b$$

Question 6

A plant with genotype TtRr is self-fertilized. What is the probability that an offspring will have the dominant phenotype at both loci?

Accepted Answer

$$9/16$$

Question 7

A male fruit fly is heterozygous for detached wings (dw). What is the probability that the first three offspring are all females with detached wings?

Accepted Answer

$$(1/4)^3 = 1/64$

Question 8

In a pedigree, if all daughters but none of the sons have a genetic disease, how is the trait most likely inherited?

Accepted Answer

X-linked dominant

Question 9

A bacterial cell with the phenotype $$F^-$$ can:

Accepted Answer

receive the F factor during conjugation

Question 10

If a triple heterozygote is testcrossed and 1,000 progeny are counted, how many are expected to result from double crossovers if interference $$= 0.5$$ and the expected double crossover frequency is $$0.10$$?

Accepted Answer

$$0.10 	imes 0.5 	imes 1000 = 50$$

Question 11

Which of the following is a purine?

Accepted Answer

adenine

Question 12

A woman is a carrier for hemophilia (X-linked recessive). If she has a son, what is the probability that he will have hemophilia?

Accepted Answer

$$1/2$$

Question 13

In a testcross between AaBb and aabb, if the genes are linked and 10% of the offspring are recombinants, what is the map distance between the genes?

Accepted Answer

$$10$$ map units

Question 14

Which process is responsible for the transfer of bacterial DNA via a pilus?

Accepted Answer

conjugation

Question 15

If a fruit fly is aneuploid for its autosomes but has one X and one Y chromosome, what is its sex?

Accepted Answer

male

Question 16

A bacterial strain that requires methionine for growth is named:

Accepted Answer

auxotroph

Question 17

In a cross AaBb x aabb, what is the expected genotypic ratio if the genes assort independently?

Accepted Answer

$$1:1:1:1$$

Question 18

Which of the following statements about antiparallel DNA strands is correct?

Accepted Answer

DNA strands run in opposite directions

Question 19

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

autosomal dominant

Question 20

In a population, the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Genetics Exam Study Guide: Mendelian Inheritance, Linkage, Chromosome Behavior, and Bacterial Genetics

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