Sources Of Variation

Question 1

Name two factors which can influence variation

Answer 1

Genes and the environment

Question 2

What happens in order for variation to take place within an individual ?

Answer 2

The existing genetic variation in an individual can be rearranged into different combinations by random assortment and crossing over ( recombination) during meiosis when gametes are formed.

Further variation arises due to the random fertilization of gametes during sexual reproduction.

The environment can also effect the expression of genes and the resulting phenotype.

Question 3

What is a mutation ?

Answer 3

When new genetic variation arises from the changes in the DNA of the cell.

Question 4

What are the three categories which mutations can fall into ?

Answer 4

Beneficial, neutral and harmful

Question 5

What are the main reasons for mutations occurring?

Answer 5

They can occur spontaneously due to mistakes in DNA replication.
They can be the result of environmental factors (mutagens)

Question 6

What is DNA ?

Answer 6

A double stranded molecule made up of sequence pairs of 4 chemical bases.

Question 7

What are the 4 chemical bases of DNA ?

Answer 7

Adenine (A) , Guanine (G), Cystosine (C) and Thymine (T)

Question 8

What are the 3 main sources of variation?

Answer 8

Genetic variation, Mutations and DNA