B6 Classification

Question 1

What is classification?

Answer 1

Organising living organisms into groups.

Question 2

How were organisms traditionally classified?

Answer 2

According to similarities and differences, eg how many legs something has.

Question 3

What are the five groups called that living things are first divided into called?

Answer 3

Kingdoms

Question 4

List the groups that kingdoms are subdivided into 6

Answer 4

Phylum
Class
Order
Family
Genus
Species

Question 5

Although the kingdom system is still used, why is it now a bit out of date?

Answer 5

Technology has developed further and our understanding of things like biochemical processes and genetics have increased.

This has resulted in new discoveries being made and the relationships between organisms being clarified.

Question 6

How does DNA analysis help scientists with classification?

Answer 6

Allows scientists to find out the difference between organisms, even if the organisms are physically very similar.

Question 7

What can scientists compare from only a small tissue sample?

Answer 7

Using DNA sequencing they can compare particular genes or entire genomes of different organisms.

Question 8

What is an organisms genome?

Answer 8

All of its genetic material

Question 9

How does DNA sequencing help scientists classify organisms?

Answer 9

The more similar the DNA sequence between species, the more closely related they are and the more likely it is that they’ll be classified in the same group.

Question 10

What is the percentage in similarity between human and chimpanzee DNA? And what does this mean?

Answer 10

94%

So humans and chimpanzees are closely related to each other

Question 11

How can scientists estimate how long ago two species separated from each other?

Answer 11

By using DNA sequencing.

Because genetic variants arise by mutation, scientists have estimates for how frequently these mutations can happen.

By finding the number of different genetic variants between two species, scientist can estimate when speciation occurred

Question 12

What is speciation?

Answer 12

The emergence of a new species

Question 13

What do evolutionary trees show?

Answer 13

How species are related to each other

Question 14

See p91 for evolutionary tree diagram

Answer 14

.

Question 15

Suggest one limitation of classifying organisms based only on their physical characteristics. (1 mark)

Answer 15

Organisms may be very similar physically but have many genetic differences/belong to a different species (1 mark)