Question
Some strains of the pathogenic bacterium Staphylococcus aureus have developed mechanisms that protect them against foreign DNA. What effect does this have on the evolution of antibiotic resistance in these strains of S. aureus?
A. Slower evolution, as bacteria with the antibiotic resistance gene will not reproduce
B. Slower evolution, as the antibiotic resistance gene from other species will not be accepted
C. Faster evolution, as mutations within a population are less likely to occur
D. Faster evolution, as antibiotic resistance genes can only be passed to individuals of the same species
▶️Answer/Explanation
Ans:B
Question
In 1940, Florey and Chain tested penicillin on bacterial infections in eight mice, before treating a sick patient. Currently, what is the correct order for testing the effectiveness of an antibiotic or other drug?
A. Affected patients, animals, healthy people
B. Animals, healthy people, affected patients
C. Healthy people, animals, affected patients
D. Animals, affected patients, healthy people
▶️Answer/Explanation
Ans:B
Question
Many blood-feeding insects inject an anticoagulant into their host in order to prevent blood from clotting. Female mosquitoes of the genus Anopheles inject the anticoagulant anophelin, which inhibits the action of the enzyme thrombin. Which statement explains how anophelin prevents blood clotting?
A. Platelets are no longer produced.
B. Platelets cannot produce fibrin.
C. Fibrinogen is not converted to fibrin.
D. Prothrombin is not converted to thrombin.
▶️Answer/Explanation
Ans:C