Unit 4

Question 1

What is ‘descent with modification’?

Answer 1

biological populations change over successive generations

life evolved from a common ancestor

Question 2

What are the four propositions of evolutionary theory?

Answer 2

1. More individuals are produced than can survive
2. There is competition
3. Individuals within a species show variation
4. Those with advantageous traits survive and reproduce.

Question 3

What is Natural selection?

Answer 3

a gradual, non random process by which biological traits become less or more common in a population through differential reproductive success.

Question 4

What are the other two types of Selection?

Answer 4

Sexual selection (intrasexual & intersexual)
Artificial Selection

Question 5

What is the difference between intrasexual and intersexual selection?

Answer 5

intrasexual- intimidating rivals

intersexual- attractive to opposite sex.

Question 6

What is endosymbiotic theory?

Answer 6

the theory that an ancestral prokaryote engulfed an aerobic and photosynthetic prokaryote.

Question 7

What evidence is there for Endosymbiotic theory?

Answer 7

Prokaryotes, Mitochondria and Chloroplasts each have:
1 single. circular chromosome
70S ribosomes
Similiar size
Replication via Binary Fission (1 cell splits into 2)

Question 8

What was the aim of the Miller- Urey experiment?

Answer 8

to replicate the speculated early atmosphere

Question 9

What was Miller & Urey’s theory on the creation of life?

Answer 9

Early atmosphere was composed of ammonia, methane and lots of hydrogen- these with accumulated and created amino acids.

Question 10

What is a hydrothermal vent?

Answer 10

mid oceanic ridge system where heat (energy) produces mineral rich water, reducing the oxygen environment.

Question 11

What is special about the bacteria in Hydrothermal vents?

Answer 11

due to low oxygen environment, bacteria runs a reverse Krebs cycle- generating organic material (CO2 and hydrogen), the porous rocks act like a cell membrane.

Question 12

What are prezygotic barriers of isolation? What are some examples?

Answer 12

Prezygotic- no chance to mate
Geographical location
Mechanical isolation e.g. size
Temporal isolation (active at different times of the day)
Behavioural isolation

Question 13

What is a postzygotic barrier in isolation?

What are some examples of this?

Answer 13

Postzygotic- incomplete fertilisation or hybrids not fertile
Gamete incompatibility
Hybrid infertility (F1)
Hybrid mortality

Question 14

What are the 6 features of Speciation?

Answer 14

Variation
Isolation
Decreased gene flow
Selection
Divergence
Speciation

Question 15

What is allopatric speciation?

Answer 15

seperation by geographic isolation, barriers prevent two or more populations from mating- leads to speciation

Question 16

How are extinct organisms classified?

Answer 16

Phylogenetic species concept- all possess a combination of certain defining or derived traits.
Also uses cladogenesis (branching of species using morphological species).

Question 17

How does Speciation occur on islands?

Answer 17

Founders effect- new population is created by a small amount of individuals from a larger population- leads to loss of genetic variation

Question 18

What is sympatric speciation?

Answer 18

when a new species evolves from an ancestral species whilst inhabiting the same place.

Question 19

What is the difference between Peripatric and Parapatric speciation?

Answer 19

Peripatric- formed from small isolated populations on the outskirts of a species’ range
Parapatric- reduced gene flow within the range of a species

Question 20

What is an ecological niche?

Answer 20

the role the species plays in the ecosystem e.g. includes the food, where it reproduces, relationship with other species.

Question 21

What is ‘Domestication Syndrome’?

Give examples

Answer 21

when animal is domesticated it loses specific traits

e.g. reduced size, horns are removed, coat colour varies, breeds are formed.

Question 22

What forces of evolution are involved in domestication?

Answer 22

Mutations
Genetic drift
Selection
Migration

Question 23

What is the difference between artificial and natural selection?

Answer 23

Artificial- quick, extreme performance of one trait with negative effect on the others, low genetic variation, organisms cannot adapt to changes in environment
Natural- long process, formation of balanced organisms that fit environment, high genome variation

Question 24

What is Quantitative Trait Loci?

Answer 24

Traits associated with one or more gene/chromosome location- their loci is the QTL.

Question 25

What are the genes called that control the expression of other genes?

Answer 25

Homeobox genes (Hox genes)

Question 26

What happens if a Hox gene is mutated?

Answer 26

Transform one segment of DNA into another

Can result in different morphology and anatomy

Question 27

What proteins are important for Development? What do they do? (4)

Answer 27

1. Cell adhesion proteins- control migration
2. Cell surface receptors- important in extracellular signals
3. Secreted morphogens- stimulate local cell response
4. Regulator of cell death

Question 28

Early development is _______, late development is not.

Fill in the gap. What does this mean?

Answer 28

Constrained

changes in early development may provide catastrophic results

Question 29

What are the role of genes in Development?

Answer 29

genes control rate, timing and spatial pattern of morphology

Question 30

What are Transcription factors role in development?

Answer 30

regulate gene expression and hold potential for speciation