test

Question 1

mutation.

Answer 1

change in the base sequence or quantity of DNA
can change the sequence of amino acids

Question 2

why may the amino acid sequence not always change

Answer 2

because its degenrate

Question 3

subsitituion mutation

Answer 3

• this is when one nucleotide in the DNA sequence is replaced by another.
  A substitution may not always be harmful as the substituted nucleotide may code in that triplet for the same amino acid.

Question 4

deletion

Answer 4

when a nucleotide in the DNA sequence is lost.
eads to a frame shift, resulting in completely different amino acids being coded for.

Question 5

polypoidy

Answer 5

changes can occur in the whole set of chromosomes so that an individual has three of more sets of chromosomes instead of two.

Question 6

non disjunction

Answer 6

when chromosomes fail to separate correctly in meiosis. As a result the gametes and any zygotes formed will have one more or one less chromosome than they should.

Question 7

Meiosis

Answer 7

four daughter cells
genetically different and have half the number of chromosomes
production of haploid gametes.

Question 8

Independent assortment of chromosomes

Answer 8

various combinations of chromosome arrangement. During meiosis 1 homologous chromosomes line up in pairs, the arrangement of these pairs is random, meaning that the division into the daughter cells is also random.

Question 9

Crossing over of chromatids

Answer 9

When pairs of chromosomes line up they can exchange some of their genetic material. Crossing over occurs when one chromosome may swap places with the same part of its homologous pair leading to a different combination of alleles on the gene.

Question 10

meiosis 1

Answer 10

homologous chromosomes pair up whereby crossing over at the chiasmata may take place. The cell then divides whereby each daughter cell contains one chromosome from each homologous pair.

Question 11

meosis 2

Answer 11

the chromatids of each chromosome are separated producing 4 haploid daughter cells.

Question 12

what is genetic diversity

Answer 12

total number of different alleles in the population.

Question 12

population

Answer 12

group of individuals of the same species that live in the same place and are able to breed with one another.

Question 13

The greater the number of alleles in a population the

Answer 13

greater genetic diversity
and therefore the greater the chance that a population would survive a change in their habitat.

Question 14

niche

Answer 14

species is its role within the environment.
Species which share the same niche compete with each other. The idea that better adapted species survive is the basis of natural selection.

Question 15

Natural selection

Answer 15

fitter individuals who are betted adapted to the environment survive and pass on the advantageous genes to future generations.

Question 16

Evolution

Answer 16

the process by which the frequency of alleles in a gene pool changes over time as a result of natural selection.

Question 17

Evolution via natural selection:

Answer 17

-There’s a variety of different phenotypes within a population.
-An environmental change occurs and as a result of that the selection pressure changes.
-Some individuals possess advantageous alleles which give them a selective advantage and allow them to survive and reproduce.
-The advantageous alleles are passed on to their offspring.
- Over time, the frequency of alleles in a population changes and this leads to evolution.

Question 18

selection

Answer 18

the process by which individuals that are better adapted to their environment are more likely to survive and breed. This means that they can pass on their advantageous alleles.

Question 19

two types of selection

Answer 19

Directional Selection
Stabilising Selection

Question 20

.Directional Selection

Answer 20

when the environmental conditions change and the phenotypes best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring. Overtime the mean of the population will move in the direction of these individuals

Question 21

Stabilising Selection

Answer 21

In stabilising selection the phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection doesn’t occur due to changes in the environment. If the environment stays the same then the individuals closest to the mean are favoured because they have the alleles that have given them the survival advantage.

Question 22

Anatomical adaptations

Answer 22

either external or internal e.g. length of the Loop of Henlé - in desert mammals this is very long to produce concentrated urine and minimise water loss.

Question 23

Behavioural adaptations

Answer 23

are changes in behaviour which improve the organism’s chance of survival e.g. mating calls.

Question 24

Physiological adaptations

Answer 24

are processes inside an organism’s body that increase its chance of survival e.g. regulation of blood flow through the skin

Question 25

biodiversity

Answer 25

variety of living organisms

Question 26

what biodiversity can be measured in

Answer 26

Species diversity Genetic diversity Ecosystem diversity

Question 27

Species diversity

Answer 27

the number of different species and the number of different individuals in a community. It can be measured by simply counting the number of species present via methods such as random sampling.

Question 28

Genetic diversity

Answer 28

measure of the genetic variation found in a particular species, in other words it is the number of alleles in a gene pool.

Question 29

Ecosystem diversity

Answer 29

is the range of different habitats.

Question 30

genetic diversity within or between species can be determined by

Answer 30

comparing the frequency of measurable or observable characteristics, the base sequence of DNA, the base sequence of mRNA and the amino acid sequence of the proteins encoded by DNA and mRNA.

Question 31

observable characteristics

Answer 31

shape or size

Question 32

observable characteristics limitations

Answer 32

The characteristics could be coded for by more than one gene. - The same characteristics could have arisen separately. - The characteristics could be influenced by the environment and not the genes.

Question 33

interspecific variation.

Answer 33

The differences between species

Question 34

intraspecific variation.

Answer 34

differences between individuals of the same species

Question 35

limitations of sampling

Answer 35

may not be representative of the population due to chance and sampling bias. To eliminate sampling bias a quadrat or transect can be used by placing these on randomly generated coordinates in the sample area. To increase the reliability of the results a larger sample size is needed.