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

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

Question 1

A dihybrid cross between two pea plants heterozygous for seed shape (R, round is dominant to r, wrinkled) and seed color (Y, yellow is dominant to y, green) is performed. What is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 2

In a testcross between an individual with genotype $$AaBb$$ and an individual with genotype $$aabb$$, what proportion of the offspring are expected to be $$AaBb if $$the genes are unlinked?

Accepted Answer

$$1/4$$

Question 3

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 4

If a cell with $$2n = 4$$ undergoes meiosis, how many chromosomes will each gamete contain?

Accepted Answer

$$2$$

Question 5

A fruit fly with genotype $$X^wX^w is $$crossed with a male $$X^wY. $$What proportion of the female offspring will be white-eyed?

Accepted Answer

$$100\%$$

Question 6

A plant with genotype $$PpTt is $$testcrossed with $$pptt. If $$the genes are linked and $$20\%$$ recombination occurs, what percentage of the offspring will be $$Pptt$$?

Accepted Answer

$$10\%$$

Question 7

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

Accepted Answer

autosomal dominant

Question 8

A bacterial strain that cannot grow in the absence of methionine is called:

Accepted Answer

auxotroph

Question 9

During DNA replication, which enzyme is responsible for synthesizing the RNA primer?

Accepted Answer

primase

Question 10

A woman who is a carrier for hemophilia (an X-linked recessive disorder) and a man who is unaffected have a son. What is the probability that the son will have hemophilia?

Accepted Answer

$$0.5$$

Question 11

If a gene is located 10 map units from the centromere, what is the expected frequency of recombination between the gene and the centromere?

Accepted Answer

$$10\%$$

Question 12

A testcross is performed between a plant heterozygous for two genes ($$AaBb) $$and a double recessive ($$aabb). If $$the genes are completely linked, what proportion of the offspring will be recombinant types?

Accepted Answer

$$0$$

Question 13

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

Accepted Answer

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

Question 14

Which of the following statements about DNA and RNA is correct?

Accepted Answer

DNA contains thymine, RNA contains uracil

Question 15

A man with Klinefelter syndrome has which of the following karyotypes?

Accepted Answer

$$47,XXY$$

Question 16

A bacterial cell with the F+ phenotype can:

Accepted Answer

donate the F factor during conjugation

Question 17

A woman with genotype $$IAi ($$blood type A) and a man with genotype $$IBi ($$blood type B) have a child. What is the probability that the child will have blood type O?

Accepted Answer

$$0.25$$

Question 18

Which of the following is a purine base found in DNA?

Accepted Answer

adenine

Question 19

In a three-point testcross, the following numbers of progeny were observed: 400 parental type 1, 400 parental type 2, 50 single crossover type 1, 50 single crossover type 2, and 10 double crossover. What is the recombination frequency between the two outermost genes?

Accepted Answer

$$\frac{50+50+10+10}{400+400+50+50+10+10} = \frac{120}{920} \approx 13\%$$

Question 20

Which of the following best describes antiparallel DNA strands?

Accepted Answer

The two DNA strands run in opposite directions

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