Q: In a population, the frequency of the sickle cell allele (HbS) is 0.3. What is the expected frequency of heterozygotes (HbA/HbS) under Hardy-Weinberg equilibrium?

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

Q: A population of 1000 individuals has the following genotype frequencies for a gene: $$AA = 700$$, $$Aa = 200$$, $$aa = 100. $$What is the frequency of allele $$A$$?

$$p = \frac{2 \times 700 + 200}{2 \times 1000} = 0.8$$

Question 1

In a genetic cross between F1 plants heterozygous for a given allele, what is the expected phenotypic ratio in the F2 generation if the trait follows Mendelian inheritance for a single gene with complete dominance?

Accepted Answer

3:1

Question 2

A diploid cell undergoes meiosis. How many different types of gametes can it produce if it is heterozygous at three independent loci (AaBbCc)?

Accepted Answer

$$2^3 = 8$

Question 3

Commercial potatoes are tetraploid (4n). If a potato plant undergoes meiosis, how many copies of each gene will be present in the resulting gametes?

Accepted Answer

2

Question 4

Bananas are triploid and typically do not produce seeds. If a triploid banana plant were to undergo meiosis, what would be the expected outcome for the gametes?

Accepted Answer

Gametes would have a random assortment of chromosomes, leading to sterility.

Question 5

A human is heterozygous for four genes (AaBbCcDd). How many different types of gametes can this individual produce?

Accepted Answer

$$2^4 = 16$

Question 6

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

Accepted Answer

Autosomal dominant

Question 7

A woman is a carrier for an X-linked recessive disorder. If she has a child with a man who does not have the disorder, what is the probability that her son will be affected?

Accepted Answer

$$\frac{1}{2}$$

Question 8

In a dihybrid cross (AaBb x AaBb), what is the expected phenotypic ratio in the F2 generation if both genes assort independently and show complete dominance?

Accepted Answer

9:3:3:1

Question 9

A male fly heterozygous for short bristles (s+/s) and ebony body (e+/e) is testcrossed to a female homozygous for the recessive alleles. If the observed progeny numbers are: long bristles, ebony body = 537; short bristles, normal color = 542; long bristles, normal color = 46; short bristles, ebony body = 75. Are the two genes linked?

Accepted Answer

Yes

Question 10

In a population, the frequency of the sickle cell allele (HbS) is 0.3. What is the expected frequency of heterozygotes (HbA/HbS) under Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 11

A woman is heterozygous for the Huntington's disease allele (autosomal dominant). What is the probability that her child will inherit the disease allele?

Accepted Answer

$$\frac{1}{2}$$

Question 12

Which of the following is an example of a trinucleotide repeat expansion mutation?

Accepted Answer

Huntington's disease

Question 13

In a population of 10,000 Hopi, 25 are phenotypic albinos. What is the frequency of the albino allele ($$q) $$under Hardy-Weinberg equilibrium?

Accepted Answer

$$q = \sqrt{\frac{25}{10000}} = 0.05$$

Question 14

Which two conditions are inherited as X-linked recessive in humans?

Accepted Answer

Hemophilia factor X and red-green color blindness

Question 15

A population is in Hardy-Weinberg equilibrium. If the frequency of allele $$A is$$ $$p = 0.6$$, what is the expected frequency of genotype $$AA$$?

Accepted Answer

$$p^2 = 0.36$

Question 16

In a pedigree, a rare trait appears only in males and is passed from father to son. What is the most likely mode of inheritance?

Accepted Answer

Y-linked

Question 17

Which of the following best describes genetic drift?

Accepted Answer

Random fluctuation of allele frequencies over time independent of natural selection

Question 18

A well-known disease allele in humans where heterozygotes have a large fitness advantage is:

Accepted Answer

Sickle cell disease

Question 19

In eukaryotes, the units for map distances on the genetic map are in ________, while the units for physical map distances are in ________.

Accepted Answer

centiMorgan; basepair

Question 20

A population of 1000 individuals has the following genotype frequencies for a gene: $$AA = 700$$, $$Aa = 200$$, $$aa = 100. $$What is the frequency of allele $$A$$?

Accepted Answer

$$p = \frac{2 	imes 700 + 200}{2 	imes 1000} = 0.8$$

Comprehensive Genetics Study Guide: Principles, Linkage, Pedigrees, and Population Genetics

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