Question

reading
antibiotic resistance occurs when bacteria evolve mechanisms to survive drugs designed to kill them. when antibiotics are overused, only the strongest bacteria survive and reproduce, passing their resistance genes to future generations. scientists have observed this phenomenon in staphylococcus aureus (mrsa), a dangerous antibiotic - resistant pathogen.
data table: percentage of bacteria resistant to penicillin over time
year % resistant bacteria
1950 5%
1960 10%
1970 25%
1980 45%
1990 60%
2000 75%
2010 90%
multiple - choice questions:

1. what trend does the data show?

a) resistance is decreasing over time
b) resistance is increasing over time
c) there is no clear trend
d) resistance peaked in the 1960s and declined

1. what is the most likely explanation for the increase in antibiotic resistance?

a) increased bacterial mutations due to natural selection
b) people becoming immune to antibiotics
c) scientists improving antibiotic effectiveness
d) bacteria learning to avoid antibiotics

Explanation:

1. Looking at the data table, the percentage of bacteria resistant to penicillin increases from 5% in 1950 to 90% in 2010, so resistance is increasing over time.
2. Antibiotic - resistance in bacteria occurs mainly due to natural selection. When antibiotics are over - used, bacteria with resistance mutations survive and reproduce, passing on their resistance genes. People do not become immune to antibiotics (they are for killing bacteria, not for human immunity), scientists improving antibiotic effectiveness would decrease resistance rather than increase it, and bacteria do not "learn" in the cognitive sense but evolve through genetic changes.

Answer:

1. b) Resistance is increasing over time
2. a) Increased bacterial mutations due to natural selection