Question 1

Which experiment provided the most direct evidence that DNA, and not protein, is the genetic material in cells?

Accepted Answer

Hershey-Chase blender experiment using bacteriophages labeled with $$^{32}P $$and $$^{35}S$$

Question 2

During DNA replication in eukaryotes, which enzyme is responsible for replacing RNA primers with DNA nucleotides?

Accepted Answer

DNA polymerase I

Question 3

A mutation changes a codon from UAU to UAA in the coding region of a gene. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; results in premature termination

Question 4

Which of the following best explains why telomerase activity is important in germ cells but not in most somatic cells?

Accepted Answer

Germ cells must maintain chromosome length for future generations

Question 5

In the lac operon of E. coli, what happens when both glucose and lactose are present in the environment?

Accepted Answer

The operon is repressed because glucose inhibits CAP-cAMP binding

Question 6

Which of the following is a postzygotic reproductive barrier?

Accepted Answer

Reduced hybrid fertility

Question 7

A population of beetles experiences a sudden flood that drastically reduces its size. The surviving beetles have different allele frequencies than the original population. Which evolutionary mechanism is illustrated?

Accepted Answer

Bottleneck effect (a form of genetic drift)

Question 8

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is less condensed and transcriptionally active; heterochromatin is highly condensed and inactive

Question 9

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Accepted Answer

Small population size

Question 10

A scientist observes that a certain gene can produce several different proteins in human cells. Which process most directly explains this observation?

Accepted Answer

Alternative splicing of pre-mRNA

Question 11

Which of the following best explains why viruses are considered obligate intracellular parasites?

Accepted Answer

They require host cell machinery to replicate their nucleic acids and proteins

Question 12

Which of the following is a real-world example of gene flow?

Accepted Answer

A population of birds migrates to a new island and interbreeds with the local population

Question 13

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

Information flows from DNA to RNA to protein

Question 14

A patient is diagnosed with a neurodegenerative disease caused by prions. Which of the following best describes prions?

Accepted Answer

Infectious proteins that induce misfolding of normal proteins

Question 15

Which of the following equations represents the Hardy-Weinberg equilibrium for allele frequencies?

Accepted Answer

$$p + q = 1$$

Question 16

Which of the following is a key difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotes have linear chromosomes and telomeres; prokaryotes have circular chromosomes and no telomeres

Question 17

Which of the following scenarios best illustrates allopatric speciation?

Accepted Answer

A population of squirrels is separated by the formation of a canyon, leading to divergence

Question 18

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

Accepted Answer

It is repressible and turned off when tryptophan is abundant

Question 19

Which of the following is a direct result of differential gene expression in multicellular organisms?

Accepted Answer

Cells become specialized for different functions

Question 20

Which of the following is the correct sequence of events during eukaryotic transcription?

Accepted Answer

Initiation → Elongation → Termination

Molecular Basis of Inheritance, Gene Expression, Regulation, Viruses, and Evolution

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