5.4 Cladistics

Question 1

Clades

Answer 1

groups of species derived from a common ancestor

Question 2

Mutations in DNA that persist and are inherited occur at a predictable rate.

Answer 2

When considering multiple changes in the base sequence of DNA. The sample size is large enough to estimate a mean rate of mutation.

Question 3

Species that have a recent common ancestor can be expected to

Answer 3

have fewer differences in base or amino acid sequence

Question 4

The rate at which mutations occur at can be used as a

Answer 4

molecular clock to calculate how long ago species diverged.

Question 5

If the DNA base sequences of two species are similar then

Answer 5

few mutations have occurred therefore the species only diverged relatively recently

Question 6

Homologous structures

Answer 6

are similar because of common ancestry
e.g. pentadactyl limbs

Question 7

Analogous structures

Answer 7

are similar because of convergent evolution
e.g. the human eye and the octopus eye

Question 8

A cladogram

Answer 8

is a tree diagram showing the similarities and differences between different species

Question 9

The branching points on cladograms are called

Answer 9

nodes

Question 10

Cladograms are mostly based on

Answer 10

DNA base sequences or the amino acid sequences in a protein.