5. Classification of Biodiversity

Question 1

What is ‘classification’ in biology?

Answer 1

the process of putting species of living organisms into groups

Question 2

Why is ‘classification’ an essential process in biology?

Answer 2

there are so many species and without a classification system it would be very hard to store and access information about them

Question 3

What are biologists that specialise in classification called?

Answer 3

taxonomists

Question 4

How many ways of classifying organisms are there?

Answer 4

‘many possible ways’

Question 5

What is an artificial classification? Give an example of an artificial classification.

Answer 5

when animals are not similar enough to be grouped together in other ways:

e. g. those that have wings and those that do not:
- that would encompass insects, birds and bats
- but even their wing structure is not homologous and has evolved separately

Question 6

What is the opposite of artificial classification?

Answer 6

natural classification

Question 7

What is natural classification? What will species that have been classified through natural classification all have in common?

Answer 7

classification in which the species in a group have evolved from one common ancestral species
- one common ancestral species: therefore they will share many characteristics that they have inherited from the ancestral species

Question 8

What does natural classification allow taxonomists to do? What does it also help with?

Answer 8

• allows the prediction of characteristics shared by species within a group
• help in identification of species

Question 9

Is natural classification obvious? Why?

Answer 9

• no

- not always clear what the pattern of evolution was in a group of species

Question 10

When might taxonomists reclassify a species?

Answer 10

when new evidence shows that a previous taxon contains species that have evolved from different ancestral species

Question 11

Give an example of taxonomists reclassifying a species.

Answer 11

‘five kingdoms system’ developed in second half of the 20th century:

• all prokaryotes in one kingdom
• eukaryotes in four kingdoms

HOWEVER,

when the base sequence of nucleic acids was compared, two very different groups of prokaryotes were identified

SO

a higher grade of taxonomic group was needed to reflect this, now called a ‘domain’

Question 12

All current organisms are currently classified into how many domains? Name all of them.

Answer 12

3 domains:

• Archea (referred to as archaeans)
• Eubacteria (referred to as bacteria)
• Eukaryota (referred to as eukaryotes)

Question 13

What is the original evidence that obliged scientists to classify all organisms within the current three domains? What does this evidence suggest?

Answer 13

base sequences of ribosomal RNA:
- found in all organisms and evolves slowly
- so it is suitable for studying the earliest evolutionary
events

suggests that prokaryotes diverged into Eubacteria and Archaea early in the evolution of life, so it is not appropriate to classify them together in one kingdom

Question 14

Where are viruses classified? Why?

Answer 14

• not classified into any domains nor are they classified into a domain of their own
• not considered by biologists to be living organisms

Question 15

Define ‘taxon’.

Answer 15

a group of organisms, such as a species or a genus

Question 16

What is a ‘taxa’.

Answer 16

• plural of taxon

- a series of taxons (you’ll see an example in later cards in this deck or on page68)

Question 17

What is the ‘hierarchy of taxa’.

Answer 17

a series of taxa, each of which includes a wider range of species than the previous one

Question 18

How are similar species grouped?

Answer 18

into a genus

Question 19

How are similar genera grouped?

Answer 19

into a family

Question 20

How are similar families grouped?

Answer 20

into an order

Question 21

How are similar orders grouped?

Answer 21

into a class

Question 22

How are similar classes grouped?

Answer 22

into a phylum

Question 23

How are similar phula grouped?

Answer 23

into a kingdom

Question 24

How are similar kingdoms grouped?

Answer 24

into a domain

Question 25

You don’t need to learn this!

Here is the hierarchy of taxa for a blue whale:

Answer 25

Animal: Balaenoptera musculus
Genus: Balaenoptera
Family: Balaenopteridae
Order: Cetacea
Class: Mammalia
Phylum: Chordata
Kingdom: Animalia
Domain: Eukaryota