Unit 4: 3.4.5 Species and Taxonomy

Question 1

Complete the table to show the phylogenetic classification for these two species. (2 marks)

Answer 1

Question 2

What does the diagram suggest is the order of human migration out of Africa? (1 mark)

Answer 2

India, Europe, East Asia, Central America, South America

Question 3

The classification system used in the early 20th century grouped different species of bacteria according to the position and shape of flagella on bacterial cells and by the number of flagella per cell. These were observed using an optical microscope. Each species of bacterium has a characteristic cell shape and arrangement of flagella. These characteristics may be shared with other species within a genus. Flagella are fragile, difficult to stain and may extend from the cell at any angle. Consider the accuracy and limitations of the early classification of bacteria using the arrangement of flagella. (3 marks)

Answer 3

1. Can not identify/distinguish species;
2. (Optical) microscope resolution is low; (Ignore magnification)
3. Flagella (are fragile so) broken/damaged/missing
   OR
   Artefacts misinterpreted/mistaken for flagella;
4. (Flagella) difficult to stain so not visible; (Ignore difficult to stain unqualified)
5. (Flagella) at an angle so not visible; (Accept ‘out of plane’ for ‘at an angle’)
6. Not all bacteria have flagella;

Question 4

Suggest why several bacterial species have been renamed in recent years. (1 mark)

Answer 4

DNA/mRNA/RNA base sequencing
OR
Amino acid sequencing
OR
Use of electron microscopes with greater resolution
OR
Use of electron microscopes and improved staining/preparation;
Accept genome sequencing
Ignore detail OR magnification for resolution

Question 5

Describe how organisms are grouped in a phylogenetic classification system. (2 marks)

Answer 5

1. Hierarchy (of groups) with no overlaps
   OR
   (smaller) groups within (larger) groups with no overlaps;
2. (Grouped) according to evolutionary origins/relationships/history; (Accept ‘common ancestry’)

Question 6

In taxonomy, an organism is identified by referring to the species name and the genus name.
What term is used to describe this method of naming organisms? (1 mark)

Answer 6

Binomial;

Question 7

Although these two populations are completely separate and show genetic variation, they are both called Helianthus annuus. Explain why they are both given this name. (1 mark)

Answer 7

Same species
OR
(If mated) can produce fertile offspring
OR
(It is) genus and species name;

Question 8

Littorina littorea is a species of snail found on rocky sea shores. Name the taxon in the hierarchy of classification represented by:

1 Littorina __________________________

2 Iittorea ___________________________

Answer 8

(Littorina -) genus and

(littorea -) species;

Question 9

Define each of the following terms.
Species
Species richness

Answer 9

1. Species = (A group of) organisms that are able to produce fertile offspring;
2. Species richness = the number of (different) species in a community;
3. Accept in a habitat / ecosystem / area
4. Reject in a population
5. Ignore ‘types’ unqualified

Question 10

There is a debate about the name of one of these species of snake. Some scientists name it Liasis papuana and other scientists name it Apodora papuana.
Give the name of the taxon about which the scientists disagree.

Answer 10

Genus / genera (If the response has two answers no mark is awarded.)

Question 11

Explain what is meant by a phylogenetic group. (1 mark)

Answer 11

(Grouped according to) evolutionary links / history / relationships / common ancestry;
Ignore: closely related, factors, characteristics
Ignore: genetically similar

Question 12

Explain what is meant by a hierarchy (2 marks)

Answer 12

1. Groups within groups;
2. accept idea of larger groups at the top / smaller groups at the bottom
3. No overlap (between groups);