Evidence for evolution

Question 1

What does fossil evidence currently suggest?

Answer 1

Current species compared to the fossil records indicate that there have been significant changes over a long period of time (evolution).

Question 2

How did circular DNA become linear?

Answer 2

As the chromosomes became larger, they broke up into multiple linear double strands. DNA itself become bigger due to an increase in complexity, particularly with the inclusion of introns.

Question 3

State the methods of genetic variation in sexually reproducing species.

Answer 3

• Crossing over (prophase I)
• Independent assortment (metaphase I)
• Fertilisation (fusion of gametes from different parents)
• Mutation

Question 4

State the methods of genetic variation in asexually reproducing species.

Answer 4

Only mutation.

Question 5

What is comparative genomics?

Answer 5

This involves comparing the genomes of species to determine their evolutionary relationships. DNA and amino acid sequences show greater similarity between closely related species than between distantly related species. As time passes, a greater number of mutations occur and accumulate, which leads to greater difference in the DNA sequences of the two species.

Question 6

What are comparative anatomy studies?

Answer 6

Establishing evolutionary relationships on the basis of similarities in characteristics.

Question 7

What are homologous structures?

Answer 7

Similar anatomical features found in different species that are inherited from a common ancestor.

Question 8

What is the purpose of a phylogenetic tree?

Answer 8

It is used to show the evolutionary relationship between species. Where a line branches, those two groups of organisms no longer interbreed, and are considered to be different species. They subsequently follow separate lines on the tree.

Question 9

What is DNA hybridisation?

Answer 9

A method used to compare the DNA of different species.