variation and evolution

Question 1

what is variation

Answer 1

differences in characteristics of individuals

Question 2

what is evolution

Answer 2

gradual change in inherited characteristics of a population over time

Question 3

natural selection occurs because

Answer 3

• due to differences in genes, individuals may show variation in their phenotypes
• individuals with characteristics best suited to environment are more likely to survive
• they then breed and pass the desirable characteristics to their offspring

Question 4

when two populations from one species become so different, what happens

Answer 4

they can no longer interbreed to produce fertile offspring

Question 5

there are gaps in the fossil record, because:

Answer 5

• many early life forms were soft bodied, so they have very few traces left
• what traces there were may have been destroyed by geographical activity

Question 6

the development of antibiotic-resistant strains of bacteria can be explained using the theory of natural selection:

Answer 6

• bacteria can evolve rapidly because they reproduce at a fast rate
• when they reproduce, mutations occur
• some mutated bacteria might be resistant to antibiotics and are not killed
• these bacteria survive and reproduce so a resistant strain develops