Question 1

Which of the following best explains why Pasteur’s swan-neck flask experiment disproved the theory of spontaneous generation?

Accepted Answer

It demonstrated that microorganisms grew only when exposed to pre-existing microbes from the environment.

Question 2

Which of the following statements correctly distinguishes between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus surrounded by a nuclear envelope, whereas prokaryotic cells lack a true nucleus.

Question 3

A patient presents with a fungal infection caused by Candida albicans. Which of the following characteristics is most likely associated with this organism?

Accepted Answer

It is a yeast that reproduces primarily by budding.

Question 4

Which of the following best describes the difference between Gram-positive and Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Question 5

Which of the following is a correct sequence of steps in Koch’s postulates for linking a microbe to a specific disease?

Accepted Answer

Observe the microbe in all cases of the disease, isolate and grow it in pure culture, introduce it into a healthy host to reproduce the disease, and re-isolate the same microbe.

Question 6

Which of the following structures is found in both prokaryotic and eukaryotic cells and is responsible for protein synthesis?

Accepted Answer

Ribosomes

Question 7

A bacterium is observed to move toward a chemical attractant. Which structure is primarily responsible for this movement, and what is the process called?

Accepted Answer

Flagella; chemotaxis

Question 8

Which of the following statements about viral structure is correct?

Accepted Answer

Viral envelopes are derived from the host cell membrane and may contain viral spikes.

Question 9

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

In the lytic cycle, the host cell is lysed to release new phages, while in the lysogenic cycle, the phage DNA is incorporated into the host genome and can remain dormant.

Question 10

Which of the following is a medically important protozoan that causes malaria, and how is it transmitted?

Accepted Answer

Plasmodium; transmitted by Anopheles mosquitoes

Question 11

Which of the following statements about endospores is correct?

Accepted Answer

Endospores are highly resistant structures formed by certain bacteria to survive harsh environments.

Question 12

Which of the following best explains why antibiotics that target peptidoglycan synthesis are generally ineffective against fungi?

Accepted Answer

Fungal cell walls are composed of chitin, not peptidoglycan.

Question 13

Which of the following is a correct example of a persistent viral infection?

Accepted Answer

Hepatitis B virus remaining in the liver and producing low levels of virus over many years

Question 14

Which of the following best describes the role of normal microbiota in human health?

Accepted Answer

They compete with pathogens for nutrients and help prevent infections.

Question 15

Which of the following is a distinguishing feature of eukaryotic ribosomes compared to prokaryotic ribosomes?

Accepted Answer

Eukaryotic ribosomes are 80S, while prokaryotic ribosomes are 70S.

Question 16

Which of the following best describes the function of the Golgi complex in eukaryotic cells?

Accepted Answer

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 17

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack nucleic acids.

Question 18

Which of the following best explains why arthropods are important in the transmission of infectious diseases?

Accepted Answer

They act as vectors, transmitting pathogens between hosts.

Question 19

Which of the following statements about active and passive transport across the plasma membrane is correct?

Accepted Answer

Active transport requires energy input, while passive transport does not.

Question 20

A patient is diagnosed with a tapeworm infection. To which group of helminths does this organism belong, and what is a key feature of its life cycle?

Accepted Answer

Platyhelminthes; often involves intermediate hosts and complex life cycles

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