Classification

Question 1

What is phylogeny?

Answer 1

The study of evolutionary history of organisms

Question 2

What have all organisms evolved from?

Answer 2

Common ancestors

Question 3

What is taxonomy?

Answer 3

The science of classification

Question 4

There are 8 levels to classification starting with domain. What are the others (called taxa)?

Answer 4

Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 5

What is a hierarchy?

Answer 5

When all the taxonomic groups are arranged with the biggest at the top, in order, with NO overlap

Question 6

If Homo sapiens is man, what does each part represent?

Answer 6

Genus Homo

Species sapiens

Question 7

What is a species?

Answer 7

A group of similar organisms who can reproduce to give fertile offspring

Question 8

Why is courtship behaviour important?

Answer 8

To attract the right species

Question 9

Dopey King Prawns Can’t Order Fried Green Sausages can help you with what?

Answer 9

Helping you to remember….Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 10

How can DNA technology help with classification?

Answer 10

You can look for similarities in genome, amino acid sequencing and immunological comparisons

Question 11

Give some reasons for courtship….

Answer 11

Acts as (sign) stimulus for mating behaviour /courtship signal;
Assists species recognition;
Identify members of the opposite sex recognition;
Identify members of the same species; as only they can have fertile offspring
Identify members of the species that are sexually mature;
Synchronises mating behaviour;
Reduces aggression and allows animals to approach each other
Forms a pair bond
Indicates fittest / healthy male;

Question 12

How is DNA Hybridisation carried out to look at how similar DNA/ genes of different species are?

Answer 12

• The DNA of the species to be compared is separated by heating, breaks H bonds.
• The DNA is mixed and cooled; this allows H-bonds to reform between specific base pairs. The result will be a mixture of species A, B and the desired hybrid DNA.
• Hybrids are isolated and then heated to break the H-bonds. The temperature required to break the H-bonds is recorded.
• A high temperature suggests a high degree of H bonds; this could only have happened if there were many complementary base pairs, indicating the DNA is similar. A low temperature suggests few H-bonds and thus the base sequence must have been different.

Question 13

Protein and base sequencing is done as follows…..

Answer 13

Here the same protein is used. With proteins the amino acid sequence is determined. The greater the differences in the amino acid sequence then this would indicate a greater difference in the base/gene sequence that coded for it. Suggesting a more distant evolutionary relationship, where more time has passed to allow mutations to change the base sequence. Sequencing the bases is a better approach, due to the degeneracy of the genetic code where the same protein could be coded for by a different codon, so although the proteins are the same the actual bases/codons could be entirely different.

Question 14

How do you carry out an immunological comparison of species?

Answer 14

The same proteins form different species are compared. The process relies upon the specificity of antibodies for antigens
Serum albumin from A is injected into B.
B produces antibodies specific c to all the antigen sites on the albumin from species A.
Serum is extracted from B; containing antibodies specific to the antigens on the albumin from A.
Serum from species B is mixed with serum from the blood of a third species C.
The antibodies respond to their corresponding antigens on the albumin in the serum of species C.
The response is the formation of a precipitate.
The greater the number of similar antigens, the more precipitate is formed and the more closely the species are related. The fewer the number of similar antigens, the less precipitate is formed and the more distantly the species are related.

Question 15

Explain the principles which biologists use to classify organisms into groups. (3)

Answer 15

large groups are divided into smaller groups; (not just ‘hierarchical’)
members of a group have features in common; based on anatomy/fossils/embryology/DNA/specific aspect of cell biology or homologous structures, reflecting evolutionary history; phylogeny. Process starts with species grouped into genus then grouped into family, order, class, phylum. As the groups get larger there is a more distant common ancestry

Question 16

How does a phylogenic system differ to a simple hierarchy? 3 max

Answer 16

Hierarchical classification, large groups are divided into smaller groups with no overlap
Process starts with species grouped into genus then grouped into family, order, class, phylum. As the groups get larger there is a more distant common ancestory
Initially this was based on shared easily observable characteristics
(phylogenetic) based on evolutionary history;
shows ancestry of groups / points of divergence;
members of a group have features in common; based on anatomy/fossils/embryology/DNA/specific aspect of cell biology or homologous structures, reflecting evolutionary history; phylogeny.

Question 17

Describe the principles on which the system of classification of living organisms is based. (4)

Answer 17

hierarchy / groups within groups / KPCOFGS;
no overlap;
common structures / similar characteristics;
reflecting evolutionary history;
binominal nomenclature / example;
definition of a species;