Question 1

A genetic cross between F1 plants heterozygous for a given allele produces a 3:1 phenotypic ratio in the F2 generation. What is the name for this type of cross?

Accepted Answer

monohybrid cross

Question 2

Given a cell is diploid during the G1 phase of the cell cycle and is set to undergo meiosis, how many different types of gametes (with respect to chromosome combinations) can it produce if it is heterozygous at 4 loci?

Accepted Answer

$$2^4 = 16$

Question 3

Commercial potatoes are not diploid, but tetraploid. All somatic cells have four copies of the genome instead of two. If a potato plant undergoes meiosis, how many copies of the genome will one pollen grain have?

Accepted Answer

2

Question 4

Bananas are triploid and almost never have seeds. If a banana plant were to undergo meiosis, what would be the most likely outcome for the resulting gametes?

Accepted Answer

Most of the meiotic products will be aneuploid and fail to be viable.

Question 5

A human gene, T, contributes to the development of the muscles in the tongue. Individuals homozygous for one allele can roll their tongues, while individuals homozygous for the other allele cannot. If both parents can roll their tongues, but their child cannot, what can be said about the model of inheritance?

Accepted Answer

Both parents were heterozygous (Tt).

Question 6

A woman is heterozygous for all four genes (AaBbCcDd). How many different types of gametes can she produce?

Accepted Answer

$$2^4 = 16$

Question 7

Individuals that harbor a defective form of the BRCA1 'tumor suppressor' gene are at high risk for developing breast or ovarian cancer. However, not all carriers of defective BRCA1 develop cancer. The defective BRCA1 allele shows:

Accepted Answer

incomplete penetrance

Question 8

Men who have the mutated BRCA1 allele have a smaller, but still elevated cancer risk compared to women. This is an example of:

Accepted Answer

sex-limited inheritance

Question 9

A female fly heterozygous for short bristles (s/s+) and ebony body (e/e+) is testcrossed to a male homozygous for the corresponding recessive alleles. The following progeny are observed: 537 long bristles, ebony color; 542 short bristles, normal color; 466 short bristles, ebony color; 75 long bristles, normal color. Are these two genes linked?

Accepted Answer

Yes

Question 10

In a cross between two plants, the following F2 phenotypic ratio is observed: 9:3:3:1. Which genetic principle does this illustrate?

Accepted Answer

Independent assortment

Question 11

A tomato plant with genotype D/d, J/j, T/j is crossed with a plant of genotype d/d, j/j, t/t. Assuming the genes are not linked, what is the probability of having an offspring of phenotype D, J, and T?

Accepted Answer

$$\frac{1}{8}$$

Question 12

The mutation leading to Huntington's disease is an example of which type of unusual mutation?

Accepted Answer

trinucleotide repeat expansion

Question 13

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

Accepted Answer

Hemophilia factor X and red-green color blindness

Question 14

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 15

The relationship between relative fitness $$(w)$$ and selection $$(s) is as $$follows:

Accepted Answer

$$s = 1 - w$$

Question 16

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

Accepted Answer

Sickle cell disease

Question 17

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

Accepted Answer

0.05

Question 18

In a small population, changes in allele frequency can occur just by chance. This effect is called:

Accepted Answer

Genetic drift

Question 19

A woman is a carrier for an X-linked recessive disorder. She has a child with a man who does not have the disorder. What is the probability that their son will be affected?

Accepted Answer

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

Question 20

Which of the following best describes linkage disequilibrium?

Accepted Answer

Non-random association of alleles at different loci

Genetics Practice Exam Study Guide: Core Concepts, Linkage, Pedigrees, and Population Genetics

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