CCRI MICRO TEST PAPER 2025/2026 QUESTIONS AND
ANSWERS RATED A+
✔✔The spectrophotometer is used in microbiology to - ✔✔indirectly measure microbial
growth
✔✔Pyrimidine dimers are formed in DNA when DNA - ✔✔absorbs UV radiation
✔✔These microorganisms are anaerobic but can live in the presence of oxygen even
though they do not actually use the oxygen - ✔✔aerotolerant
✔✔Which statement is true concerning penicillin? - ✔✔it destroys the cell wall of
bacteria by breaking down peptidoglycan
✔✔A type of antibiotic that injures the plasma membranes is - ✔✔polymyxin B
✔✔This type of bacteria is most likely to spoil refrigerated food - ✔✔psychrotrophs
✔✔Cultures of a bacterial species were incubated on the shelf of a refrigerator, out on a
lab bench top, on the shelf of a 37° C incubator and on the shelf of a 50° C incubator.
After incubation, there was no growth at 37° C and 50° C, slight growth out on the
bench top, and abundant growth at refrigeration. What term could be used for this
species? - ✔✔psychrotroph
✔✔Most human diseases are caused these microorganisms - ✔✔mesophiles
✔✔A microorganism that does not have the enzymes catalase or superoxide dismutase
would find it difficult to live in an environment with - ✔✔oxygen
✔✔Which antibiotic binds to the 50s portion of the ribosome and inhibits the formation
of the peptide bond? - ✔✔chloramphenicol
✔✔Microorganisms living around deep sea hydrothermal vents are classified as -
✔✔hyperthermophiles
✔✔Sulfanilamides inhibit - ✔✔enzyme function
✔✔Mesophiles grow best - ✔✔body temperature
✔✔Fungi are not affected by penicillin because they lack - ✔✔peptidoglycan in their cell
walls
, ✔✔Competitive inhibitors stop enzyme action by binding to - ✔✔the active site of the
enzyme
✔✔Microorganisms that can live in the Dead Sea are classified as - ✔✔extreme
halophiles
✔✔When bacteria are placed in a hypotonic solution, what physiological process
occurs? - ✔✔osmotic lysis
✔✔Microorganisms that live in hot springs are - ✔✔hyperthermophiles
✔✔Microorganisms that use oxygen in lesser amounts than obligate aerobes are -
✔✔microaerophiles
✔✔If the bacterial membrane is destroyed by an antibiotic, which of the below would be
responsible? - ✔✔polymixin B
✔✔If 1 mL of bacteria from an original culture is transferred from a stock culture to 9 mL
of sterile broth, then 1mL of the broth culture is transferred to 9 mL of a second broth
culture, how much has the original culture been diluted? - ✔✔1:100
✔✔A body of water with a pH of 4.0 had microbes living there. These microbes must be
- ✔✔acidophiles
✔✔ADP can gain energy and a phosphate group to become - ✔✔ATP
✔✔Catalase functions to - ✔✔convert hydrogen peroxide to oxygen and water
✔✔Pyrimidine dimers generally form between which two bases? - ✔✔T and T
✔✔The active site of an enzyme recognizes the - ✔✔substrate in an enzymatic reaction
✔✔A catabolic reaction is - ✔✔respiration
✔✔One NADH indirectly makes how many ATPs during electron transport? - ✔✔three
✔✔All are connected to ethyl alcohol production except - ✔✔36 ATP made
✔✔All enzymes - ✔✔work at an optimum temperature
✔✔An apoenzyme is - ✔✔an enzyme not combined with its coenzyme
✔✔What is the net gain of ATP in glycolysis? - ✔✔two
ANSWERS RATED A+
✔✔The spectrophotometer is used in microbiology to - ✔✔indirectly measure microbial
growth
✔✔Pyrimidine dimers are formed in DNA when DNA - ✔✔absorbs UV radiation
✔✔These microorganisms are anaerobic but can live in the presence of oxygen even
though they do not actually use the oxygen - ✔✔aerotolerant
✔✔Which statement is true concerning penicillin? - ✔✔it destroys the cell wall of
bacteria by breaking down peptidoglycan
✔✔A type of antibiotic that injures the plasma membranes is - ✔✔polymyxin B
✔✔This type of bacteria is most likely to spoil refrigerated food - ✔✔psychrotrophs
✔✔Cultures of a bacterial species were incubated on the shelf of a refrigerator, out on a
lab bench top, on the shelf of a 37° C incubator and on the shelf of a 50° C incubator.
After incubation, there was no growth at 37° C and 50° C, slight growth out on the
bench top, and abundant growth at refrigeration. What term could be used for this
species? - ✔✔psychrotroph
✔✔Most human diseases are caused these microorganisms - ✔✔mesophiles
✔✔A microorganism that does not have the enzymes catalase or superoxide dismutase
would find it difficult to live in an environment with - ✔✔oxygen
✔✔Which antibiotic binds to the 50s portion of the ribosome and inhibits the formation
of the peptide bond? - ✔✔chloramphenicol
✔✔Microorganisms living around deep sea hydrothermal vents are classified as -
✔✔hyperthermophiles
✔✔Sulfanilamides inhibit - ✔✔enzyme function
✔✔Mesophiles grow best - ✔✔body temperature
✔✔Fungi are not affected by penicillin because they lack - ✔✔peptidoglycan in their cell
walls
, ✔✔Competitive inhibitors stop enzyme action by binding to - ✔✔the active site of the
enzyme
✔✔Microorganisms that can live in the Dead Sea are classified as - ✔✔extreme
halophiles
✔✔When bacteria are placed in a hypotonic solution, what physiological process
occurs? - ✔✔osmotic lysis
✔✔Microorganisms that live in hot springs are - ✔✔hyperthermophiles
✔✔Microorganisms that use oxygen in lesser amounts than obligate aerobes are -
✔✔microaerophiles
✔✔If the bacterial membrane is destroyed by an antibiotic, which of the below would be
responsible? - ✔✔polymixin B
✔✔If 1 mL of bacteria from an original culture is transferred from a stock culture to 9 mL
of sterile broth, then 1mL of the broth culture is transferred to 9 mL of a second broth
culture, how much has the original culture been diluted? - ✔✔1:100
✔✔A body of water with a pH of 4.0 had microbes living there. These microbes must be
- ✔✔acidophiles
✔✔ADP can gain energy and a phosphate group to become - ✔✔ATP
✔✔Catalase functions to - ✔✔convert hydrogen peroxide to oxygen and water
✔✔Pyrimidine dimers generally form between which two bases? - ✔✔T and T
✔✔The active site of an enzyme recognizes the - ✔✔substrate in an enzymatic reaction
✔✔A catabolic reaction is - ✔✔respiration
✔✔One NADH indirectly makes how many ATPs during electron transport? - ✔✔three
✔✔All are connected to ethyl alcohol production except - ✔✔36 ATP made
✔✔All enzymes - ✔✔work at an optimum temperature
✔✔An apoenzyme is - ✔✔an enzyme not combined with its coenzyme
✔✔What is the net gain of ATP in glycolysis? - ✔✔two
