Question 1

Which of the following best explains why Mendel chose garden peas as his model organism for genetic experiments?

Accepted Answer

Garden peas produce large numbers of seeds, have a short generation time, and allow for controlled matings.

Question 2

In Mendel’s monohybrid crosses, the F2 generation consistently showed a phenotypic ratio close to 3:1. What does this ratio represent?

Accepted Answer

Three dominant phenotypes for every one recessive phenotype.

Question 3

Which of the following statements about alleles is correct?

Accepted Answer

Alleles are different forms of a gene found at the same locus on homologous chromosomes.

Question 4

A testcross is performed between a pea plant with an unknown genotype for seed shape (dominant phenotype) and a homozygous recessive plant. If all offspring have round seeds, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant ($$RR)$$

Question 5

Which principle is illustrated by the observation that alleles for seed shape and seed color in peas are inherited independently?

Accepted Answer

Principle of Independent Assortment

Question 6

In a dihybrid cross between two heterozygous pea plants ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 7

Which of the following best describes codominance?

Accepted Answer

Both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits distinctly.

Question 8

A cross between a pure-line red-flowered plant ($$RR) $$and a pure-line white-flowered plant ($$rr) $$produces all pink-flowered offspring ($$Rr). $$What type of inheritance is this?

Accepted Answer

Incomplete dominance

Question 9

Which of the following scenarios would most likely result in a quantitative trait with a bell-shaped distribution in a population?

Accepted Answer

A trait influenced by many genes, each contributing a small effect.

Question 10

If two genes are located close together on the same chromosome, which of the following is most likely true?

Accepted Answer

They are likely to be inherited together due to genetic linkage.

Question 11

A woman with blood type AB ($$I^A I^B) $$and a man with blood type O ($$ii) $$have children. What are the possible blood types of their children?

Accepted Answer

A or B

Question 12

Which of the following best explains why environmental factors can influence phenotype?

Accepted Answer

Phenotype results from the interaction between genotype and environment.

Question 13

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 14

Which of the following is true about the principle of segregation?

Accepted Answer

Alleles of a gene separate into different gametes during meiosis.

Question 15

A male with an X-linked recessive disorder and a female who is a carrier have a child. What is the probability that their son will have the disorder?

Accepted Answer

$$0.5$$

Question 16

Which of the following best describes a pure line in Mendelian genetics?

Accepted Answer

Individuals that are homozygous and produce offspring with the same phenotype when crossed.

Question 17

If the frequency of recombinant offspring between two genes is 10%, what does this suggest about the genes’ locations?

Accepted Answer

The genes are relatively close together on the same chromosome.

Question 18

Which of the following is an example of a polymorphic trait?

Accepted Answer

Flower color in pea plants, which can be purple or white.

Question 19

A cross between two heterozygous tall pea plants ($$Tt 	imes Tt) $$results in what genotypic ratio among the offspring?

Accepted Answer

$$1:2:1 (TT$$:Tt:tt)

Question 20

Which of the following is NOT a characteristic of an autosomal recessive trait as seen in a pedigree?

Accepted Answer

Trait appears in every generation.

Mendel and the Gene: Foundations of Classical Genetics

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