3.4.5 Species & Taxonomy

Question 1

(Species & Taxonomy) Describe the phylogenetic classification system. Include the names of the groups.

Answer 1

A hierarchy system places smaller groups within larger groups, with no overlap between groups.
Hierarchy consists of groups called taxa.
Taxa comprise of domain, kingdom, phylum, class, order, family, genus and species.

Question 2

(Species & Taxonomy) Describe the binomial naming system. (3)

Answer 2

1. The binomial system gives each organism two names, its genus and its species.
2. The genus name is the first word and has a capital letter, the species name comes second and has lower lowercase.
3. Both names are printed in italics, or underlined when hand-written.

Question 3

(Species & Taxonomy) Define the term ‘classification’.

Answer 3

The organisation/grouping of living organisms into groups called taxa (non-overlapping).

Question 4

(Species & Taxonomy) Define the term ‘taxonomy’.

Answer 4

The theory and practice of biologically classifying and studying these groups and their hierarchical order.

Question 5

(Species & Taxonomy) Define the term ‘phylogeny’.

Answer 5

The ‘relatedness’ of organisms, based on evolutionary links.

Question 6

(Species & Taxonomy) Define the term ‘species’.

Answer 6

Individual within a population that can interbreed and produce fertile offspring.

Question 7

(Species & Taxonomy) Explain how immunology can determine evolutionary relationships between species. (5)

Answer 7

1. Human protein injected into rabbit e.g. haemoglobin.
2. Rabbit produces antibodies in response to human protein.
3. The less related an organism is, the more different
   the gene nucleotide base sequences are…
4. …the more different the proteins are…
5. …the fewer antibody-antigen complexes (agglutination) occur between rabbit anti-human antibodies and the other species protein.

Question 8

(Species & Taxonomy) Explain the role of courtship behaviour in species recognition.

Answer 8

Courtship behaviour helps ensure reproduction is within the same species and is therefore more likely to be successful.

• Recognition of members of the same species - to ensure mating is successful and fertile offspring are produced.
• Identifying a mate that is capable of breeding.
• Forming a pair bond - more reliable reproduction and parenting of offspring.
• Synchronising mating - increased probability of sperm and egg meeting.
• Becoming ‘able to breed’ - bringing a member of the opposite sex into sexual readiness.