Question 1

Which of the following best explains why liver cells and skin cells in the same individual can have very different structures and functions, despite containing the same DNA?

Accepted Answer

They express different sets of genes due to differential gene expression.

Question 2

In the lac operon of E. coli, which combination of nutrient conditions will result in the highest level of transcription?

Accepted Answer

High lactose, low glucose

Question 3

Which of the following modifications to chromatin is most likely to increase transcription of a gene in eukaryotes?

Accepted Answer

Histone acetylation near the gene

Question 4

A mutation prevents the addition of a 5' cap to a eukaryotic pre-mRNA. Which of the following is a likely consequence?

Accepted Answer

The mRNA will be rapidly degraded and poorly exported from the nucleus.

Question 5

Which statement correctly distinguishes between the lac operon and the trp operon?

Accepted Answer

The lac operon is induced by allolactose, while the trp operon is repressed by tryptophan.

Question 6

Which of the following best describes the role of alternative splicing in eukaryotic gene expression?

Accepted Answer

It allows a single gene to produce multiple protein variants.

Question 7

A scientist observes that a certain protein is present in low amounts in a cell, even though its mRNA is abundant. Which regulatory mechanism could best explain this observation?

Accepted Answer

Rapid degradation of the protein by ubiquitin tagging and proteasomes

Question 8

Which of the following is NOT a stage in cell signaling?

Accepted Answer

Replication

Question 9

Which evidence most directly supports the idea of descent with modification from a common ancestor?

Accepted Answer

Similarities in DNA and protein sequences among different species

Question 10

Which of the following best defines 'fitness' in the context of natural selection?

Accepted Answer

The relative reproductive success of an individual in a particular environment

Question 11

A population of insects is exposed to a new pesticide. After several generations, most individuals are resistant. Which process best explains this outcome?

Accepted Answer

Natural selection acting on heritable variation in pesticide resistance

Question 12

Which of the following is an example of a homologous structure?

Accepted Answer

The wings of a bat and the arms of a human

Question 13

Which taxonomic rank is immediately larger than genus in the hierarchy of biological classification?

Accepted Answer

Family

Question 14

In a phylogenetic tree, what does a branch point (node) represent?

Accepted Answer

The most recent common ancestor of the descendant lineages

Question 15

Which group contains a common ancestor and all its descendants?

Accepted Answer

Clade (monophyletic group)

Question 16

Why is similarity alone not sufficient to establish close evolutionary relatedness between two species?

Accepted Answer

Similarities can result from convergent evolution, producing analogous traits.

Question 17

Which of the following best describes the difference between prokaryotic and eukaryotic gene regulation?

Accepted Answer

Prokaryotes use operons and can couple transcription and translation; eukaryotes regulate gene expression at multiple levels, including chromatin structure and RNA processing.

Question 18

A researcher finds that a gene is highly methylated at its promoter region in a certain cell type. What is the most likely effect on this gene's expression?

Accepted Answer

Decreased transcription

Question 19

Which of the following best explains why the traditional kingdom Protista is not considered a single clade?

Accepted Answer

It does not include all descendants of a common ancestor.

Question 20

Which process allows a single eukaryotic gene to produce multiple proteins with different functions?

Accepted Answer

Alternative splicing

Gene Expression, Evolution, and Phylogeny: Study Notes for General Biology

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