Natural Selection

Question 1

natural selection:

Answer 1

Nature selects who or what survives based on if they can survive in the environment.

Question 2

selective pressure

Answer 2

Every environment has a selective pressure for organisms to survive. The frequency of beneficial alleles will increase, and frequency of non-beneficial alleles will decrease.

Question 3

natural selection requirements

Answer 3

1. variation
2. isolation
3. selection

Question 4

variation

Answer 4

if all organisms were the same, they will all either survive or all die.

Question 5

isolation

Answer 5

provides a barrier for gene flow, preventing breeding between groups of the same species. An example of this is geographically (distance).

Question 6

selection

Answer 6

those individuals who possess alleles which express characteristics suitable for survival in a particular environment tend to survive and pass on their favourable alleles to their offspring.
Those who have unfavourable alleles cannot survive in a particular environment and tend to die out and as a result their alleles are eliminated from the gene pool of that population. Therefore, the allele frequency in the gene pool is changed.

Question 7

evolution

Answer 7

a change of characteristics of a species over many generations

Question 8

species

Answer 8

A group of individuals that are alike and able to interbreed under natural conditions to produce fertile offspring.

Question 9

variation

Answer 9

Variation refers to the genetic differences between individuals within a species.

Question 10

causes of variation

Answer 10

1. mutation of the gene
2. independent assortment of genes into gamete during meiosis
3. crossing over during meiosis
4. random mating

Question 11

what does variation allow

Answer 11

Genetic variation increases biodiversity. Increased biodiversity in a species allows a greater chance to survive ecological change
eg. drought, rising sea levels, salinity, climate change

Question 12

values of biodiversity

Answer 12

1. ecosystem services
2. economic value
3. recreational value
4. cultural value
5. scientific value

Question 13

breeding

Answer 13

production of offspring (animals or plants)

Question 14

selective breeding

Answer 14

process by which humans select plants or animals to breed based on desirable traits

Question 15

example of a practical value of selective breeding

Answer 15

Plants can be reproduced to withstand adverse weather conditions, produce bigger fruits or have different flavour or colour. Selective breeding used for food production provides a variety of choice for the consumer.

Question 16

artificial selection

Answer 16

intentional reproduction of organisms that posses desirable traits, wheras, in natural selection, random forces of nature determines which individuals survive or die.
Artificial selection is similar to natural selection in that both remove some alleles from the gene pool so that certain traits become more common.

Question 17

speciation

Answer 17

the process of producing a totally different species from an existing species

Question 18

how does speciation work

Answer 18

It starts when a small fraction of a population is geographically isolated from the main population. Because of isolation, there is no gene flow between the two isolated populations. Their gene pools are separated. Over time their gene pools change as a result of natural selection and mutations. Because the exchange of genetic information (gene flow) is restricted between the two isolated groups, then the two populations will be separated into different breeding groups. In time, the populations may become so different in behaviour, physical appearance or functioning that interbreeding becomes impossible.

Question 19

Explain how interruption of the gene flow through geographical or reproductive isolation can lead to speciation. Examples include finches and tortoises of the Galapagos Islands.

Answer 19

This is referring to natural selection and how certain animals are resistant to a change in the environment such as introduction of pesticides or viruses because of their genetic variation. The coevolution of birds and flowers has to do with characteristics of bird beaks that allowed them to pollinate these types of flowers. Only these birds that have the beneficial allele to develop the correct shaped beak to pollinate these flowers, so they existed with these flowers; they depended on them for food and the flower depended on the birds to pollinate them, so they make produce seeds and survive.