Tpic 7: evolution and speciation

Question 1

Within a population of a species, there can be a wide range of phenotypes. State the two overall causes of this:

Answer 1

1) Genetic factors
2) Environmental factors

Question 2

Name 3 selection pressures that can drive natural selection.

Answer 2

1) Predation
2) Disease
3) Competition

Question 3

Define evolution

Answer 3

The change in the allele frequency over many generations in a given population.

Question 4

What are the three types of selection that occur?

Answer 4

1) Stabilising
2) Directional
3) Disruptive

Question 5

Define genetic drift

Answer 5

The change in the allele frequency within a population between generations.

Question 6

Does genetic drift have a bigger impact on smaller or larger populations and explain your answer?

Answer 6

The smaller a population, the greater the proportional impact changes in allele frequencies will have. This is why evolution often occurs more rapidly in smaller populations.

Question 7

define speciation

Answer 7

Speciation is the process that results in the creation of new species.

Question 8

What is the difference between sympatric and allopatric speciation?

Answer 8

Allopatric speciation is when a population can become reproductively isolated due to geographical barriers, whereas sympatric is when changes in reproductive mechanisms cause isolation.

Question 9

Different species of palm tree, all located on the same island, flower at different times of the year. All these palm trees have a common ancestor. Describe how new species of palm trees would have arisen
(5 marks)

Answer 9

1.Occurs in the same habitat / environment / population;
2.Mutation/s cause different flowering times; 3.Reproductive separation / isolation or no gene
flow
4.Different allele/s passed on / selected OR change
in frequency of allele/s
5.Disruptive (natural) selection;
6.Eventually different species cannot (inter)breed
to produce fertile offspring;

Question 10

Define population

Answer 10

group of organisms of the same species living in the same habitat

Question 11

Define habitat

Answer 11

part of an ecosystem in which particular organisms live

Question 12

Define community

Answer 12

all the populations of different species in the same area at the same time

Question 13

Write hardy-weinburg principle

Answer 13

p+q=1

p2 + 2pq +q2 = 1