Question 1

Which of the following best explains why a child with blood type AB cannot have a biological father with blood type O?

Accepted Answer

Blood type O individuals have two O alleles and cannot contribute an A or B allele required for AB blood type.

Question 2

A true-breeding pea plant with genotype GGTT (green pods, tall) is crossed with a true-breeding ggtt (yellow pods, dwarf). If the two genes are on different chromosomes, what is the expected phenotypic ratio in the F2 generation after crossing two F1 individuals?

Accepted Answer

9:3:3:1

Question 3

Which of the following best describes pleiotropy?

Accepted Answer

A single gene affects multiple, seemingly unrelated phenotypic traits.

Question 4

In Morgan’s experiments with white-eyed flies, why did his results support the chromosomal theory of inheritance proposed by Sutton and Boveri?

Accepted Answer

The white-eye trait showed a sex-linked pattern, supporting the idea that genes are located on chromosomes.

Question 5

A man with normal vision and a woman who is a carrier for red/green color blindness have a son who is color blind. What is the genotype of the son?

Accepted Answer

$$X^cY$$

Question 6

In birds, sex is determined by a ZW chromosome scheme. If a male pigeon heterozygous for a recessive lethal allele on the Z chromosome is crossed with a normal female, what is the expected sex ratio among surviving offspring?

Accepted Answer

2:1 male to female

Question 7

Which of the following best defines aneuploidy?

Accepted Answer

A condition in which an organism has one or more extra or missing chromosomes.

Question 8

A woman with Favism (an X-linked recessive disorder) and a normal man have a son and a daughter. What is the probability that their son will have Favism?

Accepted Answer

$$100\%$$

Question 9

Which of the following statements about Barr bodies is correct?

Accepted Answer

A Barr body is an inactivated X chromosome found in female somatic cells, ensuring dosage compensation.

Question 10

A frequency of recombination of $$50\%$$ between two genes indicates:

Accepted Answer

The genes are likely located on different chromosomes or far apart on the same chromosome.

Question 11

Which of the following best explains why two hydrangea plants that are genetic clones can produce different colored flowers?

Accepted Answer

Environmental factors such as soil pH affect flower color expression.

Question 12

Which of the following is the only viable monosomy in humans?

Accepted Answer

Monosomy X (Turner Syndrome)

Question 13

A child is born with trisomy 21 (Down syndrome). Which of the following best explains how this can occur?

Accepted Answer

Nondisjunction during meiosis leads to an egg with two copies of chromosome 21.

Question 14

Which of the following best describes the difference between pericentric and paracentric inversions?

Accepted Answer

Pericentric inversions include the centromere; paracentric inversions do not.

Question 15

Why are male humans more often affected by X-linked recessive traits than female humans?

Accepted Answer

Males are hemizygous for the X chromosome.

Question 16

Which of the following scenarios could result in a child with the genotype XXY?

Accepted Answer

Nondisjunction during meiosis in either the egg or sperm, resulting in a gamete with both X and Y chromosomes or two X chromosomes.

Question 17

Which of the following best explains why duplication of a gene can potentially cause a disease phenotype?

Accepted Answer

Increased gene dosage can disrupt normal cellular function by producing too much of a protein.

Question 18

In some insect species, males are haploid. Which process do these males use to produce gametes?

Accepted Answer

Mitosis

Question 19

The Philadelphia chromosome is an example of which chromosomal abnormality, and why does it lead to cancer?

Accepted Answer

Reciprocal translocation; it juxtaposes the BCR and ABL genes, creating a fusion protein with abnormal kinase activity.

Question 20

Which of the following is NOT a possible genotype in a gamete from an organism with genotype HhTt (genes on separate chromosomes, no errors in meiosis)?

Accepted Answer

Hh

Genetics and Chromosomal Inheritance: Step-by-Step Study Guidance

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