Q: A coding DNA sequence is 5'-ATG GAA TGC-3'. What is the corresponding mRNA sequence produced during transcription?

$$5'\text{-}AUG\ GAA\ UGC\text{-}3'$$

Question 1

A bacterial cell is exposed to free DNA fragments from a lysed cell in its environment and incorporates a gene for antibiotic resistance. Which genetic process is responsible for this change?

Accepted Answer

Transformation

Question 2

Which enzyme is responsible for synthesizing a new DNA strand by adding nucleotides to a pre-existing chain during DNA replication?

Accepted Answer

DNA polymerase

Question 3

A coding DNA sequence is 5'-ATG GAA TGC-3'. What is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{-}AUG\ GAA\ UGC	ext{-}3'$$

Question 4

Which of the following best describes the function of the operator region in an inducible operon?

Accepted Answer

It is the DNA sequence where the repressor binds to regulate transcription.

Question 5

A patient is diagnosed with botulism after eating contaminated canned food. Which route of transmission is most likely responsible for this infection?

Accepted Answer

Foodborne

Question 6

Which of the following statements about viruses is correct?

Accepted Answer

Viruses require host cell machinery for replication.

Question 7

During the lytic cycle of a bacteriophage, which event occurs immediately after biosynthesis?

Accepted Answer

Assembly (maturation)

Question 8

Which immune cell is primarily responsible for rapid phagocytosis of bacteria during the early stages of infection?

Accepted Answer

Neutrophil

Question 9

A patient with a deep puncture wound develops a severe infection. Which innate immune defense is most critical in this scenario?

Accepted Answer

Phagocytic cells such as macrophages and neutrophils

Question 10

Which of the following best explains why vaccination can lead to herd immunity in a population?

Accepted Answer

Vaccination reduces the number of susceptible hosts, decreasing overall transmission.

Question 11

A patient is exposed to the influenza virus and later receives a flu vaccine. Which type of immunity is produced by the vaccine?

Accepted Answer

Artificially acquired active immunity

Question 12

Which immunoglobulin class is most abundant in serum and is important in secondary immune responses?

Accepted Answer

IgG

Question 13

A helper T cell (CD4+) is activated by an antigen-presenting cell. Which of the following is a primary function of this activated helper T cell?

Accepted Answer

Releasing cytokines to stimulate other immune cells

Question 14

Which of the following best describes the role of Toll-like receptors (TLRs) in innate immunity?

Accepted Answer

They recognize pathogen-associated molecular patterns (PAMPs) and activate immune responses.

Question 15

A patient’s antibody titer is measured after initial exposure to an antigen and again after a booster shot. Which graph best represents the expected antibody response?

Accepted Answer

A rapid, high-level response after the booster compared to the primary response

Question 16

Which of the following is a correct sequence of events in the classical complement pathway?

Accepted Answer

Antigen–antibody complex formation $$\rightarrow$$ complement activation $$\rightarrow$$ opsonization $$\rightarrow$$ membrane attack complex formation

Question 17

A virus with a segmented genome infects a host cell already infected by a different strain of the same virus. What is the most likely outcome of this co-infection?

Accepted Answer

Genetic reassortment may occur, leading to antigenic shift.

Question 18

Which of the following best describes the difference between lysogeny and latency?

Accepted Answer

Lysogeny involves integration of viral DNA into bacterial DNA, while latency refers to dormant viral infection in eukaryotic cells.

Question 19

A patient is found to have high levels of IgM but low levels of IgG specific to a pathogen. What does this most likely indicate?

Accepted Answer

The patient is in the early stages of a primary immune response.

Question 20

Which of the following scenarios best illustrates generalized transduction in bacteria?

Accepted Answer

A bacteriophage accidentally packages host bacterial DNA and transfers it to another bacterium.

Microbiology Exam 2 Study Guide: Genetics, Viruses, Disease, and Immunity

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