Question 1

Which of the following best describes the difference between incomplete dominance and codominance in genetic inheritance?

Accepted Answer

Incomplete dominance results in a phenotype that is a blend of the two alleles, while codominance results in both alleles being fully expressed in the phenotype.

Question 2

A woman who is heterozygous for a recessive X-linked disorder marries a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

$$\frac{1}{2}$$

Question 3

Which of the following best explains why a frameshift mutation is often more severe than a point mutation?

Accepted Answer

A frameshift mutation changes the reading frame, potentially altering every amino acid downstream, while a point mutation usually affects only one amino acid.

Question 4

In a dihybrid cross between two heterozygous individuals (AaBb x AaBb), what is the expected phenotypic ratio of the offspring, assuming independent assortment?

Accepted Answer

$$9:3:3:1$$

Question 5

A patient is diagnosed with sickle cell anemia, which is caused by a single nucleotide substitution in the beta-globin gene. What type of mutation is this?

Accepted Answer

Missense mutation

Question 6

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It allows the bacteria to metabolize lactose only when glucose is absent and lactose is present.

Question 7

A woman with blood type AB and a man with blood type O have a child. What are the possible blood types of their child?

Accepted Answer

A or B

Question 8

Which of the following best explains why males are more likely to express X-linked recessive disorders than females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will result in the disorder.

Question 9

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to the growing chain?

Accepted Answer

DNA polymerase

Question 10

A geneticist is studying a trait that shows a 3:1 ratio in the F2 generation of a monohybrid cross. What does this suggest about the inheritance of the trait?

Accepted Answer

The trait is controlled by a single gene with two alleles, one dominant and one recessive.

Question 11

Which of the following best describes the process of crossing over during meiosis?

Accepted Answer

Exchange of genetic material between homologous chromosomes, increasing genetic diversity.

Question 12

A child is born with Down syndrome, which is caused by trisomy 21. Which of the following best explains how this condition arises?

Accepted Answer

Nondisjunction during meiosis leads to an extra copy of chromosome 21.

Question 13

Which of the following statements about PCR (Polymerase Chain Reaction) is correct?

Accepted Answer

PCR amplifies specific DNA sequences using repeated cycles of heating and cooling.

Question 14

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 15

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon.

Question 16

A woman who is a carrier for hemophilia (an X-linked recessive disorder) and a man without hemophilia have a daughter. What is the probability that the daughter will have hemophilia?

Accepted Answer

The daughter can only be a carrier, not affected, unless the father also has hemophilia.

Question 17

Which of the following best explains why mitochondrial DNA is inherited only from the mother?

Accepted Answer

The mitochondria in the sperm are typically destroyed after fertilization, so only the mother's mitochondria are passed on.

Question 18

Which of the following best describes the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand.

Question 19

A genetic counselor is analyzing a pedigree for a rare autosomal dominant disorder. Which of the following patterns would you expect to see?

Accepted Answer

The disorder appears in every generation and affected individuals have at least one affected parent.

Question 20

Which of the following best explains the significance of crossing over during meiosis for evolution?

Accepted Answer

It increases genetic variation, which provides raw material for natural selection.

Genetics, Molecular Biology, and Developmental Biology: Study Guide Notes

Guida di studio - Domande di pratica

Study guide - Flashcard