CLEP CLEP Biology Microbiology and Immunology 3

Question 1

Which bacteria form root nodules on legumes and fix atmospheric nitrogen into usable ammonia?

Accepted Answer

Rhizobium species

Answer

Rhizobium species form symbiotic relationships within legume root nodules, using nitrogenase to convert atmospheric N₂ into ammonia available to plants.

Question 2

Disease transmission involving an intermediate host organism such as a mosquito is called:

Accepted Answer

Vector-borne transmission

Answer

Vector-borne transmission occurs when an intermediate organism (vector) such as a mosquito carries a pathogen and transfers it to a new host.

Question 3

Penicillin kills bacteria by which mechanism?

Accepted Answer

Inhibiting cell wall (peptidoglycan) synthesis

Answer

Penicillin inhibits transpeptidase enzymes that cross-link peptidoglycan in bacterial cell walls, causing osmotic lysis of growing bacteria.

Question 4

Which category of bacteria absolutely requires oxygen for growth and cannot survive without it?

Accepted Answer

Obligate aerobes

Answer

Obligate aerobes require oxygen as the final electron acceptor in aerobic respiration and cannot survive in anaerobic environments.

Question 5

Koch's postulates were developed to:

Accepted Answer

Establish a causal link between a specific microorganism and a specific disease

Answer

Koch's postulates provide a rigorous set of criteria — isolation, culture, reinoculation, and re-isolation — to prove that a specific microorganism causes a specific disease.

CLEP Practice Test

CLEP Practice Test

CLEP CLEP Biology Microbiology and Immunology 3