Q: Which of the following best describes the central dogma of molecular biology?

$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$

Question 1

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

Accepted Answer

Genotype is the set of genes an organism carries, and phenotype is the observable traits resulting from gene expression.

Question 2

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

Accepted Answer

Prokaryotic cells usually have a single circular chromosome in the nucleoid, while eukaryotic cells have multiple linear chromosomes in the nucleus.

Question 3

Which of the following is a correct pairing of nitrogenous bases in DNA?

Accepted Answer

Adenine pairs with thymine

Question 4

What is the main difference between DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil.

Question 5

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

Accepted Answer

Helicase

Question 6

During DNA replication, why is the lagging strand synthesized discontinuously?

Accepted Answer

Because DNA polymerase can only add nucleotides to the 3’ end, and the lagging strand runs antiparallel to the leading strand.

Question 7

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$

Question 8

Which type of mutation results in a premature stop codon, leading to an incomplete protein?

Accepted Answer

Nonsense mutation

Question 9

A bacterial cell is exposed to ultraviolet (UV) light, which causes thymine dimers in its DNA. Which repair mechanism is most likely to fix this damage?

Accepted Answer

Excision repair

Question 10

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids are extrachromosomal, circular DNA molecules that often carry genes for antibiotic resistance.

Question 11

Which process allows bacteria to take up naked DNA from their environment and incorporate it into their genome?

Accepted Answer

Transformation

Question 12

What is the role of tRNA during translation?

Accepted Answer

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

Question 13

Which of the following is an example of horizontal gene transfer?

Accepted Answer

A bacterium acquiring a plasmid from another bacterium via conjugation.

Question 14

Which of the following best explains why the genetic code is described as 'redundant'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 15

A scientist uses the Ames test to evaluate a chemical. If the chemical is a mutagen, what result should she expect?

Accepted Answer

More colonies on the experimental plate than on the control plate.

Question 16

Which of the following is true about inducible operons such as the lac operon?

Accepted Answer

Their default state is OFF, and they are activated only when their gene products are needed.

Question 17

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of bases not in multiples of three, altering the reading frame.

Question 18

Which of the following is a post-transcriptional regulatory mechanism in eukaryotes?

Accepted Answer

Alternative mRNA splicing

Question 19

Which of the following statements about reverse transcription is correct?

Accepted Answer

It is the process by which RNA is used as a template to make DNA, as seen in retroviruses.

Question 20

Which of the following is a function of small noncoding RNAs in post-transcriptional regulation?

Accepted Answer

They bind to mRNA to prevent translation or tag it for destruction.

Microbial Genetics: Structure, Function, and Variation

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