Question 1

Which of the following best describes the relationship between genotype and phenotype in a cell?

Accepted Answer

Genotype is the genetic makeup that determines the phenotype, which is the observable traits.

Question 2

Which of the following statements about prokaryotic and eukaryotic genomes is CORRECT?

Accepted Answer

Prokaryotic genomes are typically organized into one or a few circular chromosomes in the nucleoid region.

Question 3

Which of the following is a key structural difference between DNA and RNA?

Accepted Answer

RNA is usually single-stranded and contains ribose, while DNA is double-stranded and contains deoxyribose.

Question 4

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 5

During DNA replication, why is the lagging strand synthesized in fragments?

Accepted Answer

Because the lagging strand is made in the opposite direction of the replication fork movement, requiring discontinuous synthesis.

Question 6

Which of the following best explains the concept of the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 7

A mutation changes a codon from CGU (arginine) to UGU (serine). What type of mutation is this, and what could be the consequence?

Accepted Answer

Missense mutation; possible alteration of protein function depending on the location and properties of the amino acids.

Question 8

Which of the following is TRUE regarding plasmids in bacteria?

Accepted Answer

Plasmids are small, circular DNA molecules that replicate independently and often carry genes for antibiotic resistance.

Question 9

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

Accepted Answer

It joins Okazaki fragments together by forming phosphodiester bonds.

Question 10

A researcher exposes bacteria to a chemical and observes a significant increase in the number of colonies on a histidine-free medium in the Ames test. What does this result suggest?

Accepted Answer

The chemical is likely a mutagen and possibly a carcinogen.

Question 11

Which of the following is an example of post-transcriptional regulation in eukaryotes?

Accepted Answer

Alternative splicing of mRNA to produce different protein isoforms.

Question 12

Which process allows bacteria to acquire new genetic traits from their environment without cell division?

Accepted Answer

Transformation

Question 13

Which of the following is a feature of the genetic code that helps minimize the effects of mutations?

Accepted Answer

The code is redundant, so multiple codons can specify the same amino acid.

Question 14

Which of the following best describes an inducible operon?

Accepted Answer

It is off by default and can be activated under certain conditions, such as the presence of a specific substrate.

Question 15

Which of the following is a likely consequence of a frameshift mutation caused by the insertion of a single nucleotide?

Accepted Answer

The reading frame is shifted, resulting in a completely different and likely nonfunctional protein.

Question 16

Which of the following is a function of small noncoding RNAs (such as miRNA or siRNA) in eukaryotic cells?

Accepted Answer

They bind to mRNA and limit protein synthesis by promoting degradation or blocking translation.

Question 17

Which of the following is TRUE about conjugation in bacteria?

Accepted Answer

It requires a pilus and a fertility plasmid, and can transfer genes between different species.

Question 18

Which of the following best describes the role of DNA methylation in gene regulation?

Accepted Answer

It typically silences gene expression by preventing transcription factor binding.

Question 19

A nonsense mutation occurs in a gene. What is the most likely outcome?

Accepted Answer

The protein is truncated and likely nonfunctional.

Question 20

Which of the following is a real-world example of horizontal gene transfer with significant medical implications?

Accepted Answer

The spread of antibiotic resistance genes among pathogenic bacteria via conjugation.

Microbial Genetics: Structure, Function, and Regulation

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