Question 1

Which of the following features of Mendel's experimental design was MOST critical in allowing him to discover the basic principles of genetic transmission?

Accepted Answer

He quantified results and performed replicate, reciprocal, and test crosses.

Question 2

A cross between two pure-breeding pea plants, one with yellow seeds and one with green seeds, produces F$$_1$$ offspring. What phenotype will all F$$_1$$ offspring display, and why?

Accepted Answer

All F$$_1$$ offspring will have yellow seeds because yellow is dominant.

Question 3

In a monohybrid cross between two heterozygous pea plants (Gg x Gg), what is the expected genotypic ratio among the F$$_2$$ offspring?

Accepted Answer

1:2:1 (GG:Gg:gg)

Question 4

Which statement best describes Mendel's law of segregation?

Accepted Answer

Two alleles for a trait separate during gamete formation, and randomly unite at fertilization.

Question 5

A test cross is performed between a pea plant with the dominant phenotype and a homozygous recessive plant. If the dominant plant is heterozygous, what is the expected ratio of phenotypes in the offspring?

Accepted Answer

1:1 ratio of dominant to recessive phenotypes.

Question 6

In a dihybrid cross (RrGg x RrGg), what is the expected phenotypic ratio among the F$$_2$$ generation for round/yellow, round/green, wrinkled/yellow, and wrinkled/green seeds?

Accepted Answer

9:3:3:1

Question 7

Which probability rule should be used to calculate the likelihood of two independent genetic events occurring together?

Accepted Answer

Product rule

Question 8

A family has three children. What is the probability that exactly two of them are boys? Use the binomial expansion formula $$P = \left( \begin{array}{c} 3 \ 2 \end{array} ight) p^2$ q^1$ where p = 0.5$ (boy) and q = 0.5$ (girl).

Accepted Answer

$$P = 0.375$$

Question 9

In a cross between two Gg pea plants, what is the probability that a yellow-seeded offspring is heterozygous? (Yellow is dominant, green is recessive.)

Accepted Answer

$$\frac{2}{3}$$

Question 10

A scientist observes 5474 round and 1850 wrinkled seeds in a monohybrid cross. The expected ratio is 3:1. What is the chi-square value for this data? Use $$\$$chi^2$$ = \sum \frac{(O-E)^2$}{E}$$, where $$O is $$observed and $$E is $$expected.

Accepted Answer

$$\$$chi^2$$ = 0.263$$

Question 11

Which of the following is NOT a characteristic of autosomal dominant inheritance?

Accepted Answer

Trait typically skips generations.

Question 12

Which molecular mechanism explains the wrinkled seed phenotype in Mendel's peas?

Accepted Answer

Loss-of-function mutation in the Sbe1 gene leads to accumulation of amylose and lack of amylopectin.

Question 13

If a pedigree shows a trait appearing in both males and females, often among siblings but not in every generation, and sometimes in children of unaffected parents, what is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 14

Which of the following best describes the molecular basis for the dominant alleles in Mendel's traits?

Accepted Answer

Dominant alleles are more frequent because mutant alleles are loss-of-function and recessive.

Question 15

In a trihybrid cross (AaBbCc x AaBbCc), how many different gamete genotypes are possible?

Accepted Answer

8

Question 16

Which of the following is a correct application of the product rule in genetics?

Accepted Answer

Calculating the probability of getting a round, yellow seed in a dihybrid cross by multiplying the probability of round by the probability of yellow.

Question 17

A pea plant with genotype RrGg is crossed with a plant with genotype rrgg. What proportion of the offspring will have round, yellow seeds? (Round and yellow are dominant.)

Accepted Answer

$$\frac{1}{4}$$

Question 18

Which of the following is a key conclusion from molecular studies of Mendel’s traits?

Accepted Answer

Inheritance of alleles parallels transmission of phenotypic variants.

2. Mendelian Genetics

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