Research Summary Practice Questions | Science for ACT PDF Download

Q1: A scientist is testing the actions of a new antibiotic. Bacterial species can be either gram-positive or gram-negative. Gram-positive bacteria turn purple when stained with crystal violet; gram-negative bacteria do not. Bacteria can also be anaerobic or aerobic. Anaerobic bacteria need an oxygen-free environment to live; aerobic bacteria need oxygen. Facultative anaerobes are bacteria that can survive in either environment.
A scientist tested the action of a new antibiotic drug, Drug A, by placing the drug in a petri dish smeared with bacteria and observing how large of an area the antibiotic can clear. The larger the radius of the cleared area, the more powerful the drug is against that particular strain of bacteria. The table below shows the effectiveness of the drug against several different bacterial strains.
In general, was this antibiotic more effective against gram-positive or gram-negative bacteria?

(a) Gram-positive, because the radius of the cleared area was larger.
(b) Gram-positive, because the radius of the cleared area was smaller.
(c) Gram-negative, because the radius of the cleared area was larger.
(d) Gram-negative, because the radius of the cleared are was smaller.

Q2: A scientist is testing the actions of a new antibiotic. Bacterial species can be either gram-positive or gram-negative. Gram-positive bacteria turn purple when stained with crystal violet; gram-negative bacteria do not. Bacteria can also be anaerobic or aerobic. Anaerobic bacteria need an oxygen-free environment to live; aerobic bacteria need oxygen. Facultative anaerobes are bacteria that can survive in either environment.
A scientist tested the action of a new antibiotic drug, Drug A, by placing the drug in a petri dish smeared with bacteria and observing how large of an area the antibiotic can clear. The larger the radius of the cleared area, the more powerful the drug is against that particular strain of bacteria. The table below shows the effectiveness of the drug against several different bacterial strains.
Consider the following four antibiotics:

• Daptomycin: used to kill gram-positive bacteria.
• Aztreonam: used to kill gram-negative bacteria.
• Metronidazole: used to kill anaerobes.
• Rifaximin: used to kill Escherichia coli.

Drug A is most likely which of these antibiotics?

(a) Daptomycin
(b) Metronidazole
(c) Aztreonam
(d) Rifaximin