Topic 5.2: Natural Selection

Question 1

Describe the theory of natural selection

Answer 1

The theory of natural selection was posited by Charles Darwin (and also Alfred Wallace) who described it as ‘survival of the fittest’

According to this theory, it is not necessarily the strongest or most intelligent that survives, but the ones most responsive to change

Question 2

Define adaptive radiation

Answer 2

Adaptive radiation describes the rapid evolutionary diversification of a single ancestral line

Question 3

Define antibiotics

Answer 3

Antibiotics are chemicals produced by microbes that either kill (bactericidal) or inhibit the growth (bacteriostatic) of bacteria

Question 4

Describe antibiotic resistance

Answer 4

When treated with antibiotics, the resistant bacteria will survive and reproduce by binary fission (asexual reproduction)
The antibiotic resistant bacteria will flourish in the absence of competition from other strains of bacteria (killed by antibiotic)
Antibiotic resistant bacteria may also confer resistance to susceptible strains by transferring plasmids via bacterial conjugation
The introduction of antibiotic (selection pressure) has caused the antibiotic resistance gene to become more frequent (evolution)