Topic 4: Species And Taxonomy

Question 1

What is a species?

Answer 1

A group of organisms that can interbreed and produce fertile offspring
They have similar genes so are physically and biochemically similar but different from members of other species

Question 2

What is classification?

Answer 2

The term to describe the grouping of organisms

Question 3

3 features of a natural classification system

Answer 3

It is based on evolutionary relationships between organisms and their ancestors
Classifies features into groups using shared features derived from their ancestors
Arranges the groups into a hierarchy where groups are contained withing larger groups with no overlap between them

Question 4

What are relationships between species in classification based on?

Answer 4

Homologous structures
They have similar evolutionary origins regardless of functions
E.g. wing of bird,human arm and horse front leg
They all have the same basic structure because they are all evolved from a common ancestor so are described as homologous

Question 5

What is taxonomy?

Answer 5

It studies the classification groups and their positions in a hierarchical order where they are known as taxonomic ranks

Question 6

6 key points about taxonomic hierarchy

Answer 6

1.organisms classified into groups called taxons, larger groups split into smaller
2. There is no overlap between taxonomic groups
3. Organisms are classified on the basis of similar or shared features
4. The more similar features individuals have, the more closely related they are
5. The fossil records can be used to determine similarities and differences in physical features
6. Hierarchy describes how different groups are arranged according to the size of the groups

Question 7

What does it mean that there is no overlap between taxonomic groups?

Answer 7

An organisms must be a bird or a reptile it cant be halfway in between

Question 8

Taxonomic groups in order

Answer 8

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 9

Largest taxonomic rank

Answer 9

Domain

Question 10

Smallest taxonomic group

Answer 10

Species

Question 11

mnemonic to remember taxonomic groups

Answer 11

Do Keep Ponds Clean Or Frogs Get Sick

Question 12

What are the 3 domains?

Answer 12

Bacteria
Eukarya
Archaea (group of prokaryotes)

Question 13

How are species named? What is the name of this system?

Answer 13

Binomial system
The first name describes the genus an organism belongs to
The second name is to describe the species an organism belongs to

Question 14

What is phylogeny

Answer 14

It describes the evolutionary relationships between different groups of organisms
It comes from the word ‘phylum’ which is a group of similar or related organisms

Question 15

What are phylogenetic trees?

Answer 15

The phylogenetic relationships of different species represented by a tree like diagram

Question 16

How are species represented in phylogenetic trees?

Answer 16

Oldest species at the base/start
Most recent ones are at the ends of branches

Question 17

2 key points about phylogenetic trees

Answer 17

The more distantly related species has an earlier common ancestor
The more closely related species have a more recent common ancestor

Question 18

Summarise the main features of natural classification

Answer 18

The evolutionary relationships between organisms and ancestors are studied
The phylogenetic groups are based on patterns of evolutionary history
Species are classified into groups based on shared characteristics
Groups are arranged in hierarchy, where large groups divide into smaller ones, there is no overlap between groups

Question 19

What is the difference between a phylogenetic system and and a hierarchy?

Answer 19

Phylogenetic system is based on evolutionary history and shows the ancestry of groups, and points of divergence
Hierarchy is based on shared characteristics

Question 20

Why is courtship behaviour needed?

Answer 20

1.to recognise members of their own species
2. To identify a mate capable of breeding
3. They form a pair bond
4. To synchronise mating

Question 21

What difficulties might there be in identifying species?

Answer 21

Species aren’t fixed, they evolve over time
There can be significant variation among individuals in a species e,g, dogs
Many species are extinct and left no fossil records
Members of different groups of same species may be isolated so never meet or interbreed

Question 22

Why are mules infertile?

Answer 22

When a horse and donkey gametes are fused they produce offspring with 63 chromosomes
A mule cannot produce gametes because of the odd number so is infertile