Question 1

Which of the following best explains why Mendel chose pea plants as his model organism for studying inheritance?

Accepted Answer

Pea plants have a short generation time and produce many offspring, allowing for statistical analysis.

Question 2

In a monohybrid cross between two heterozygous pea plants (Tt x Tt), what is the expected phenotypic ratio in the F$$_2$$ generation?

Accepted Answer

$$3:1$$

Question 3

Which of Mendel's postulates is directly supported by the observation that the F$$_1$$ generation of a monohybrid cross always shows only one of the parental traits?

Accepted Answer

Dominance/Recessiveness

Question 4

A testcross is performed between a plant with an unknown genotype showing a dominant phenotype and a homozygous recessive plant. If the unknown plant is heterozygous, what will be the expected ratio of phenotypes in the offspring?

Accepted Answer

$$1:1$$

Question 5

In a dihybrid cross (YyRr x YyRr), where Y = yellow, y = green, R = round, r = wrinkled, what is the probability of obtaining an offspring with yellow and wrinkled seeds?

Accepted Answer

$$3/16$$

Question 6

Which law allows you to calculate the probability of two independent genetic events occurring together?

Accepted Answer

Product law

Question 7

A trihybrid cross involves three pairs of contrasting traits. What is the total number of different phenotypes expected in the F$$_2$$ generation if all genes assort independently and show complete dominance?

Accepted Answer

$$8$$

Question 8

Which of the following statements about the chromosomal theory of inheritance is correct?

Accepted Answer

Genes are located on chromosomes, and their segregation during meiosis explains Mendel's laws.

Question 9

If 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 10

A geneticist is analyzing the results of a monohybrid cross and wants to determine if the observed data fit the expected 3:1 ratio. Which statistical test should be used?

Accepted Answer

Chi-square ($$\$$chi^2$$) test

Question 11

In a chi-square analysis, how do you calculate the degrees of freedom ($$df) $$for a genetic cross with four possible phenotypic categories?

Accepted Answer

$$df = 4 - 1 = 3$$

Question 12

Which of the following best describes the molecular basis of Tay-Sachs disease?

Accepted Answer

A recessive mutation resulting in the absence of Hexosaminidase A, leading to accumulation of GM2 ganglioside in neurons.

Question 13

If two heterozygous individuals (Aa) are crossed, what is the probability that their first two children will both show the dominant phenotype?

Accepted Answer

$$9/16$$

Question 14

Which of the following is NOT a criterion for classifying two chromosomes as homologous pairs?

Accepted Answer

They must both be inherited from the same parent.

Question 15

A plant with genotype AaBb is self-fertilized. What is the probability of obtaining an offspring with genotype aabb?

Accepted Answer

$$1/16$$

Question 16

Which of the following best explains the concept of independent assortment?

Accepted Answer

Alleles of different genes assort independently during gamete formation.

Question 17

In a real-world scenario, a couple has a child with Tay-Sachs disease, but neither parent is affected. What is the most likely explanation?

Accepted Answer

Both parents are heterozygous carriers of the recessive allele.

Question 18

Which of the following is an example of a reciprocal cross?

Accepted Answer

Crossing a tall plant (male) with a dwarf plant (female), and then crossing a dwarf plant (male) with a tall plant (female).

Question 19

Which of the following best describes a phenotype?

Accepted Answer

The physical expression of a trait.

Question 20

A pedigree shows a trait that skips generations and appears only when both parents are unaffected carriers. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Mendelian Genetics: Principles, Experiments, and Applications

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