Question 1

Which of the following best explains why Mendel's 'hereditary factors' were initially met with skepticism by the scientific community in the 1800s?

Accepted Answer

No cellular structures had been identified that could house these factors.

Question 2

Thomas Hunt Morgan's experiments with Drosophila melanogaster provided evidence for which of the following genetic principles?

Accepted Answer

Genes are located on chromosomes.

Question 3

In Morgan's experiments, a white-eyed male Drosophila was crossed with a red-eyed female. All F1 offspring had red eyes. When F1 individuals were crossed, the F2 generation showed a 3:1 ratio of red to white eyes, but all white-eyed flies were male. What does this result demonstrate?

Accepted Answer

The gene for eye color is located on the X chromosome.

Question 4

Which of the following equations correctly represents the expected phenotypic ratio for a monohybrid cross between two heterozygous individuals (Aa x Aa) according to Mendel's laws?

Accepted Answer

$$3:1$$

Question 5

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

Accepted Answer

They will be inherited together more often than not due to genetic linkage.

Question 6

A fruit fly with genotype XwY (where Xw is the X chromosome carrying the white-eye allele and Y is the Y chromosome) is crossed with a wild-type female (X+X+). What is the expected eye color of the male offspring?

Accepted Answer

All will have red eyes.

Question 7

Which of the following best describes Mendel's Law of Independent Assortment?

Accepted Answer

Alleles of genes on nonhomologous chromosomes assort independently during gamete formation.

Question 8

In a dihybrid cross between two individuals heterozygous for both traits (AaBb x AaBb), what is the expected phenotypic ratio according to Mendel's laws?

Accepted Answer

$$9:3:3:1$$

Question 9

Which of the following scenarios would violate Mendel's Law of Independent Assortment?

Accepted Answer

Two genes are located very close together on the same chromosome.

Question 10

A scientist observes that a certain trait in plants does not follow the expected Mendelian ratios and suspects linkage. Which experiment would best test this hypothesis?

Accepted Answer

Perform a test cross and analyze the frequency of recombinant offspring.

Question 11

Which of the following statements about sex-linked traits is correct?

Accepted Answer

Males are more likely to express recessive X-linked traits because they have only one X chromosome.

Question 12

If a gene is located on the X chromosome and the allele for the trait is recessive, what is the probability that a son will express the trait if his mother is a carrier and his father is unaffected?

Accepted Answer

$$0.5$$

Question 13

Which of the following best explains why Morgan's discovery of the white-eye mutation in Drosophila was significant for genetics?

Accepted Answer

It provided the first evidence that a specific gene is located on a specific chromosome.

Question 14

During meiosis, which process ensures that each gamete receives only one allele of each gene?

Accepted Answer

Segregation

Question 15

A plant with genotype AaBb is test-crossed with aabb. If the genes are unlinked, what proportion of the offspring is expected to have the genotype AaBb?

Accepted Answer

$$0.25$$

Question 16

Which of the following is a direct consequence of the random alignment of homologous chromosomes during metaphase I of meiosis?

Accepted Answer

Genetic variation among gametes

Question 17

If a trait is determined by a gene with two alleles, one dominant (A) and one recessive (a), and two heterozygous individuals (Aa) are crossed, what is the probability that an offspring will be homozygous recessive?

Accepted Answer

$$0.25$$

Question 18

Which of the following best describes a mutant phenotype in Drosophila as discussed in Morgan's experiments?

Accepted Answer

A phenotype that differs from the wild type due to a change in the allele.

Question 19

Which of the following is NOT a reason why Mendel's laws are considered foundational to genetics?

Accepted Answer

They explain the molecular structure of DNA.

Question 20

A researcher observes that the offspring of a cross between two plants do not follow the expected Mendelian ratios. Which of the following could best explain this observation?

Accepted Answer

The genes are linked on the same chromosome.

12.1

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