Section 7 - Variation and Evolution

Question 1

Why are organisms of the same species similar?

Answer 1

They all have the same genes

Question 2

Why do organisms of the same species vary? (2)

Answer 2

• They have different versions of the same genes (called alleles)
• The environment also causes organisms of the same species to vary

Question 3

What is an adaptation?

Answer 3

An adaptation is a characteristic that helps an organism to survive and reproduce, e.g. polar bears have thick, white fur to stay warm and camouflaged in the snow.

Question 4

What is evolution?

Answer 4

Evolution is the gradual change in the characteristics of a population from one generation to the next. The theory of evolution is that all organisms evolved from simple life forms over millions of years

Question 5

Describe how variation leads to natural selection

Answer 5

Organisms from the same population all vary (e.g. different length of fur). Organisms compete with each other for food, shelter, water, etc. Those with better adaptations (caused by different alleles) are more likely to find food, shelter, water, etc. survive and have offspring. So they pass on the alleles for their better adaptations. Over time, the number of organisms with the better adaptations (alleles) increases. The whole population of organisms evolves to have the better adaptations (alleles).