Species And Taxonomy

Question 1

Define “species”

Answer 1

A group of similar organisms able to reproduce to give fertile offspring

Question 2

What is courtship behaviour?

Answer 2

Before animals mate the male and female have to recognise one another as being from the same species. There are many complicated rituals whereby one of the pair carries out a stereotypical action which is seen and recognised by the other which then performs its own stereotypical behaviour. Results in mating.

Done so species do not mate with the wrong species and produce no offspring

Question 3

What are the advantages of courtship behaviour?

Answer 3

1. Animals recognise and mate with adults of the opposite sex
2. Adults mate with adults of the same species
3. Healthy adults in sexual maturity
4. Species specific behaviours can be used by scientists to classify organisms. The more similar the behaviours the more closely related the species are.

Question 4

Define taxonomy

Answer 4

The study of the classification of organisms into a series of categories called taxa

Question 5

What does it mean when it says the taxa categories are hierarchy?

Answer 5

Each organism is classed into a series of smaller and smaller taxa with no overlap between the taxa

Question 6

What are the 8 parts of human classification?

Answer 6

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Rhyme to remember order:
Do Keep Penis Clean Or Face Getting Syphilis

Question 7

What is a species binomial name?

Answer 7

Genus + species

Genus has capital letter and the species has lower case

Underline name to show that it is written in italics

Question 8

The classification system is phylogenetic, what is phylogeny?

Answer 8

The study of the evolutionary history of organisms, all species have evolved from a shared common ancestor.

The more recently two species have shared a common ancestor the more closely related they are and the more taxa they share

Question 9

What are phylogenetic trees?

Answer 9

Diagrams that show relationships between species.

Eg. this diagram shows the evolutionary relationships between apes.

Question 10

How are species classified?

Answer 10

1) Physical appearance - taxonomist will look at general physical features, easy way to decide which of the higher taxa to place an organisms into.
2) Immunological comparisons - when antibodies from one animal are added to proteins from another the antibodies will bind if the proteins are similar in shape. The more closely related two organism are the more similar the shape of their proteins will be and the more likely the antibodies will be to bind. When antibodies bind the proteins usually precipitate out - the more precipitate the more similar the proteins are
3) Comparing DNA sequences/genome sequencing- process has become much more rapid and cheap. The entire genome can be sequenced in hours. Computer programmes are able to make very rapid comparisons between the sequences of 2 species. The more similar sequences are the more recently the two species shared a common ancestor with the same sequences
4) Comparing mRNA sequences - large date bases which scientist can accuse in order to make comparisons. mRNA is easier to extract from a cell than DNA because it is found in the cytoplasm and many more copies will be present
5) Comparison of amino acid sequences in proteins - closely related species have very similar DNA sequences and consequently very similar amino acid sequences