Natural Selection

Question 1

What do differences in DNA lead to?

Answer 1

genetic diversity

Question 2

How is genetic diversity measured?

Answer 2

by the number of different alleles in the population

Question 3

fill in the gaps:

the …… the population, the larger the variety of alleles, the ……..the genetic diversity will be.

Answer 3

the larger the population, the larger the variety of alleles, the greater the genetic diversity will be.

Question 4

What can cause an increase in alleles of a gene pool?

Answer 4

death, predation, poaching, disease, natural disaster, lack of food, competition, emigration (move out of area)

Question 5

What can cause a decrease in alleles of a gene pool?

Answer 5

survive and reproduce, immigration (move into the area)

Question 6

name four causes of variation and explain

Answer 6

gene mutation- sudden changes to genes and chromosomes that produce new alleles. Meiosis- independent assortment of homologous chromosomes and crossing over of block of genes between chromosomes result in new combinations of alleles. Random fertilisation- gametes are genetically unique and which gamete fuses with which at fertilisation is a random event thus offspring are different to both of their parents. Environmental factors

Question 7

What does beneficial adaptation do?

Answer 7

increase the chance of survival so individuals can reproduce and ass on their favourable alleles to their offspring

Question 8

give 2 examples of behavioural adaptations

Answer 8

1. ) possums ‘play dead’- if they’re being threatened by a predator they play dead to escape attack
2. ) scorpions dance before mating- ensures they attract a mate of the same species

Question 9

give an example of physiological adaptation

Answer 9

brown bears hibernate as it lowers their rate of chemical reactions (metabolism) over winter, conserving energy, so that they don’t need to look for food in the months when it is scarce.

Question 10

give 2 examples of anatomical adaptations

Answer 10

1. ) otters have a streamlined shape- making it easier to glide through the water. This makes it easier for them to catch prey and avoid predators.
2. ) whales have a thick layer of fat which keeps them warm in the cold sea

Question 11

What does natural selection do?

Answer 11

Changes the allele frequency of a population

Question 12

give the 2 types of natural selection

Answer 12

directional and stabilising selection

Question 13

what is directional selection

Answer 13

this is the selection of alleles for extreme characteristics when there is a change in environmental conditions. Individuals with extreme characteristics are more likely to survive, reproduce and pass on their alleles to their offspring.

Question 14

what is stabilising selection?

Answer 14

this is the selection for alleles for the middle of the range characteristics. this occurs when there is no change in environmental conditions. it reduces the range/ variety of characteristics.