Lesson 8: Variation/ Evolution

Question 1

What are the 3 reasons as to why there may be variation within a population of organisms?

Answer 1

1.) The genes they have inherited are different (genetic causes.)
2.) The conditions in which they have developed in are different (environmental causes.)
3.) A combination of genes and the environment.

Question 2

What is “variation?”

Answer 2

• Variation is the differences in the characteristics of individuals in a population.

Question 3

What causes genetic variation?

Answer 3

• Mutations (changes to the bases in DNA.)

Question 4

What are the 3 effects mutations may have on a phenotype (evident characteristics caused by alleles?)

Answer 4

• Most mutations have NO effect on the phenotype.
• Some influence the phenotype (ie. alleles for tallness may lead to tallness IF coupled with good diet.)
• Some determine the phenotype (ie. eye- colour.)

Question 5

On a very rare occassion, what will a mutation lead to?

Answer 5

• On very rare ocassions, mutations will lead to a new phenotype.
• If the new phenotype is suited to an environmental change, it can lead to a rapid change in the species.

Question 6

What is “evolution?”

Answer 6

• Evolution is a change in the
  inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.

Question 7

What does The Theory of Evolution by Natural Selection state?

Answer 7

• The theory of evolution by natural selection states that all species of
  living things have evolved from simple life forms that first developed
  more than three billion years ago.

Question 8

What happens if two populations of one species become so different in phenotype (due to evolution by natural selection?)

Answer 8

• The two populations will NO LONGER be able to interbreed to produce fertile offspring - they have formed two new species.