TOPIC 3: CLASSIFICATION

Question 1

What are the stages of classification system according to the hierarchy? (Include an example)

Answer 1

1. Domain (Eukaryota)
2. Kingdom (Animalia)
3. Phylum/division (Chordata)
4. Class (Mammalia)
5. Order (Primates)
6. Family (Hominidae)
7. Genus (Homo)
8. Species (Sapiens)

Question 2

What does the binomial name tell you about the organism?

Answer 2

First part of the binomial name tells us the genus, the second part tells us the species.

Question 3

Define species.

Answer 3

A group of living organisms with similar characteristics which interbreed to produce fertile offspring.

Question 4

Ecological species model

Answer 4

Based on the ecological niche occupied by an organism.

Limitations: Niche definitions vary and many species occupy more than one niche

Question 5

Mate-recognition species model

Answer 5

Based on unique fertilisation systems, including mating behaviour

Limitations;
Many species will mate or cross-pollinate and produce fertile hybrids but be of the same species

Question 6

Genetic species model

Answer 6

Based on DNA evidence

Limitation: Some people find it hard to decide how much genetic difference makes two organisms members of different species.

Question 7

Evolutionary species model

Answer 7

Based on shared evolutionary relationships between species/organisms.

Limitations: Sometimes there is not always a clear evolutionary pathway for a particular organism

Question 8

What are the limitations of the species model?

Answer 8

1. Finding evidence – many living species have never been observed mating.
2. Plants of different but close species frequently interbreed and produce fertile hybrids
3. Many organisms do not breed sexually but asexually so definition involving reproductive behaviour is irrelevant
4. Sexual dimorphism – There is a great deal of variation between males and females of the same species

Question 9

Distinguish between analogous characteristics and homologous characteristics.

Answer 9

Analagous characteristics have a similar structures but different evolutionary origins.

Homologous characteristics are structures of a similar origin but different functions

Question 10

Outline allopatric and sympatric speciation.

Answer 10

Allopatric speciation is caused by geographical separation whereas sympatric speciation occurs within the same habitat caused by different niches (behavioral/courtship/feeding differences)

Both processes lead to the isolation of sub populations

Question 11

Define Speciation

Answer 11

Speciation is the formation of a new species by the splitting /separation of an existing species

Question 12

How can gel electrophoresis be used to distinguish between species and determine evolutionary relationships?

Answer 12

DNA AND RNA SEQUENCING

1. DNA sample + restriction enzymes
2. DNA is cut into fragments
3. DNA fragments loaded into wells in agar gel
4. DNA molecules negatively charged
5. DNA molecules move when potential difference
6. Lighter molecules move further up gel
7. Compare sample from organisms – more closely related organisms will have similar band patterns

Question 13

List the ways in which scientists check validity of investigations

Answer 13

1. Scientific journals
2. Peer review
3. Conferences

Question 14

Describe the differences between the 5 kingdoms

Answer 14

1. Prokaryotae – Bacteria and cyanobacteria, unicellular, reproduce asexually.
2. Protoctista – Eukaryotes, mostly unicellular, mainly reproduce sexually.
3. Fungi – Eukaryotes, mainly multicellular, non-motile, heterotrophic nutrition, sexual and asexual reproduction.
4. Plantae – Eukaryotes, multicellular, non-motile, autotrophic nutrition, sexual and asexual reproduction.
5. Animalia – Eukaryotes, multicellular, motile heterotrophic nutrition, mainly sexual reproduction but some reproduce asexually.

Question 15

Describe the differences between the 3 domains.

Answer 15

See image

Question 16

Define the term ecological niche.

Answer 16

How an organism feeds, where it lives and how it behaves in relation to other organisms in a habitat.

Question 17

Define Anatomical adaptions

Answer 17

form and structure of the organism e.g. thick layer of blubber on whales

Question 18

Define Physiological adaptations

Answer 18

the way the body of the organism works and differences in biochemical pathways e.g. diving mammals can drop their heart rate to conserve oxygen

Question 19

Define Behavioural adaptations

Answer 19

change to programmed or instinctive behaviour e.g. ectotherms orientate themselves to maximise sunlight keep warm

Question 20

Define the term natural selection.

Answer 20

The process by which organisms that are best adapted in a particular environment are most likely to survive and reproduce, passing on their advantageous alleles to their offspring

Question 21

Define the term evolution

Answer 21

The development of new types of living organism from pre-existing types by the accumulation of genetic differences over long periods of time

Question 22

What are selection pressures? (give some examples)

Answer 22

The pressure exerted by a changed environment or niche on individuals in a population. E.g. availability for resources, availability of a mate, predation, competition, disease

Predators
Availability of resources eg shelter and water 
Nutrient Supply eg food source 
Disease/Pathogenic spread 
Accumulation of wastes 

Phenomena eg natural disasters
Abiotic factors
Weather conditions

Question 23

What are the arguments to support natural selection and evolution?

Answer 23

1. The DNA molecule is the same in all organisms this supports darwins idea of descent from a common ancestor
2. The individuals in a species are not all identical
3. Natural selection results in offspring with favourable characteristics

Question 24

What are the isolation methods?

Answer 24

1. Geographical isolation – a physical barrier such as a river/mountains separate individuals
2. Ecological isolation – two populations inhabit the same region but develop preferences for different areas
3. Seasonal isolation – changes occur in the courtship ritual, display or mating pattern so that some animals do not recognise others as being potential mates
4. Mechanical isolation – a mutation occurs that changes the genitalia of animals, making it physically possible for them to mate successfully.

Question 25

How does isolation lead to allopatric and sympatric speciation? (please provide an example)

Answer 25

1. Allopatric speciation – When two populations are physically or geographically separated from each other by a barrier. This prevents interbreeding and mixing of their gene pools.
2. Sympatric speciation – when two populations are still able to mix freely in the same area but accumulate changes in their gene pools, which are sufficient to prevent interbreeding.

Question 26

Giving a named example, explain stabilising selection.

Answer 26

Where conditions are favourable and not changing, so pressures to change in one way are less. E.g. birth weight

Question 27

Giving a named example, explain directional selection.

Answer 27

Where environments are changing and there is a clear advantage in the population changing in one direction. E.g. antibiotic resistance

Question 28

Describe the evolutionary race between pathogens and the development of medicine.

Answer 28

1. Bacteria cause a wide range of disease
2. 1940s introduction of antibiotics
3. Signs of resistance emerged rapidly
4. New antibiotics e.g. methicillin produced to counteract evolutionary race
5. Further signs of resistance to multiple antibiotics

Question 29

What is biodiversity?

Answer 29

The variety of plant and animal life in the world or in a particular habitat

Question 30

Why is biodiversity important?

Answer 30

1. Provides genetic variation – greater variety of crops
2. Food security
3. Protection of water resources
4. Medicinal resources
5. Recovery from unpredictable events
6. Research and education

Question 31

Define species richness

Answer 31

The number of different species in an area

Question 32

What equation would you use to calculate an index of diversity?

Answer 32

D = N(N-1)/∑n(n-1)

N= Total number of Organisms of all species 
n= Total number of Organisms of each individual species

Question 33

What are the ethical and economic reason for the maintenance of biodiversity?

Answer 33

1. We are denying future generations of the opportunity to use these resources
2. Great source of pleasure for many so should be protected
3. Biodiversity is lost with extinction losing unique combinations of DNA
4. Human activities reducing biodiversity through climate change is considered unethical.

Question 34

What is ex-situ conservation and what are the limitations?

Answer 34

1. Conservation out side of the natural habitat E.g. in zoos
2. There is not enough space or sufficient resources in zoos
3. Difficult to provide the right conditions
4. Reintroduction to the wild can be unsuccessful
5. Greater problems adapting to unsupported life

Question 35

What is in-situ conservation and what are the limitations?

Answer 35

1. Conservation takes place in the natural habitat of the organisms. E.g. national parks
2. Conflicts between needs for living people and needs of animals
3. Some illegal operations occurring
4. Non always sustainable

Question 36

Define Molecular Phylogeny

Answer 36

Molecular Phylogeny is the analysis of the genetic material of organisms to establish their evolutionary relationships

Question 37

Evidence for the three domain system of classification

Answer 37

Analysis of ribosomal RNA from bacteria, Archaea and Eukarya showed the same nucleotide sequences in Archaea and Eukarya but different sequences in Bacteria

Question 38

What shows the DNA bands after going through electrophoresis

Answer 38

An Electrophoretogram