Biology- Evolution and Natural Selection

Question 1

What factors are needed for evolution to occur?

Answer 1

• Selective Pressure

- Mutations

Question 2

Define Mutation

Answer 2

A change in the DNA code

Question 3

Define selective pressures

Answer 3

Factors affecting the survival in a population

Question 4

What causes selective pressures?

Answer 4

• Predation
• Habitat destruction
• Competition
• Geographical boundaries
• Environmental changes (eg. climate change)
• Disease

Question 5

What is a positive mutation?

Answer 5

Where a different amino acid is formed which ultimately codes for a different functioning protein.

Question 6

What is a negative mutation?

Answer 6

Where a different amino acid is formed which ultimately codes for a non-functioning protein due to a different folding structure or no folding at all.

Question 7

What is a neutral/silent mutation?

Answer 7

Due to degenerative nature of DNA, then the amino acid formed may still code for a functioning protein just with a different code of amino acids.

Question 8

What is continuous variation?

Answer 8

Variation that has no limit on the value that can occur within a population

Question 9

What is discontinuous variation?

Answer 9

Variation where individuals fall into a number of distinct classes or categories.
Based on features that can not be measured across a complete range.

Question 10

What are the 3 types of selection?

Answer 10

Directional
Disruptive
Stabilising

Question 11

Define Gene pool

Answer 11

All alleles in a population

Question 12

Define selection

Answer 12

When an allele frequency changes

Question 13

Define differential reproductive success.

Answer 13

Some individuals in a population are more successful at breeding over others due to their phenotype being more advantageous since the variation in allele frequencies and selective pressure causes natural selection to occur.

Question 14

What is disruptive selection?

Answer 14

Selection pressures towards the extremes creating 2 modal values.
Selection against mean population so the 2 extremes of allele population increases.

Question 15

What is stabilising selection?

Answer 15

Selection keeping the allele distribution similar. (often goes against extremes).
Selection pressure towards centre.

Question 16

What is directional selection?

Answer 16

An extreme allele trait moving the mean and normal distribution towards the extreme trait.
Selection pressure towards one extreme.

Question 17

What are the types of speciation?

Answer 17

Allopatric- Speciation by geographical isolation.

Sympatric- Speciation in the same habitat but by factors such as zonation/mutation/behavioural.

Question 18

What are some geographical isolation barriers?

Answer 18

• Mountain range
• Rivers/oceans/reefs
• Earthquakes/volcanoes
• Landslides/rock falls
• Human intervention

Question 19

What are some causes for sympatric isolation?

Answer 19

• Ecological isolation (zonation)
• Behavioural isolation (courtship)
• Temporal (different breeding seasons)
• Mechanical Isolation (gametes cannot fuse)
• Genetic isolation –> don’t have a homologous pair.
• Hybrid sterility.

Question 20

What are the main key points in speciation?

Answer 20

• Mutation in gene pool
• Isolation barriers (Allo/sympatric)
• Natural selection (selection pressures)
• Allele frequency changes
• Overtime 2 species arise as cannot breed and produce fertile offspring.

Question 21

Define bottlenecking

Answer 21

A portion of the population is randomly eliminated resulting in a population that reflects the genetics of the survivors.

Question 22

Define The Founder Effect.

Answer 22

The genetics of a population reflect those of the initial members.

Question 23

Define genetic drift.

Answer 23

The random drift between phenotypes that occur in a population.