Chapter 9 - Genetic diversity and adaptation

Question 1

What is genetic diversity

Answer 1

Variation in alleles of genes
Variation in chromosome numbers/structures
Forms the basis of selection

Question 2

What are the sources of genetic diversity

Answer 2

Mutations (9.1)
Meiosis (9.2)
Mate selection
Random fertilisation

Question 3

what is gene mutation

Answer 3

Change in the base sequence of an allele or chromosome

Arise spontaneously/randomly

Occur during DNA replication during Interphase

Can be harmful, neutral or beneficial

Rate of mutation can be increased by mutagenic agents e.g. ionising radiation, x rays, UV light, carcinogens (cigarette smoke)

Question 4

What are the two types of mutation

Answer 4

Base deletion and base substitution

Question 5

what is base deletion

Answer 5

When a nucleotide and therefore a base is lost from DNA

All bases after the deletion then shift to the left so all subsequent triplets are read differently (frame shift)

Leads to a change in amino acid sequence (primary structure) so a change in H bonds/ionic bonds and tertiary structure and a non-functioning protein

The position of the deletion on the gene determines the impact. If the base is deleted at the start of a gene then the effect will be more drastic than if the base is deleted near the end.

Question 6

example of base deletion

Answer 6

Question 7

What is base substitution

Answer 7

When a nucleotide is replaced and therefore a base is altered

Question 8

example of base substitution

Answer 8

Question 9

what are the characteristics of base substitution

Answer 9

only affects one triplet

due to the genetic code being degenerate not all substitutions change the amino acid produced

can lead to non-functioning proteins

can be a problem is start or stop codons are affected

Question 10

amino acid name table

Answer 10

Question 11

what is a chromosome mutation

Answer 11

when the structure or number of chromosomes are altered

Question 12

what is non-dysjunction

Answer 12

occurs during meiosis when chromosomes fail to separate

Question 13

what is meiosis

Answer 13

genetic replication what produces 4 haploid daughter cells that are genetically different from each other

Replication followed by two nuclear divisions

(genetic material is halved)

Question 14

what is the importance of meiosis

Answer 14

It produces haploid gametes so diploid number can be restored at fertilisation
It introduces genetic variation

Question 15

diagram of meiosis

Answer 15

Question 16

differences between meiosis and mitosis

Answer 16

Question 17

how does genetic diversity arise from meiosis

Answer 17

due to the random arrangement of chromosomes along the equator during metaphase 1

Question 18

what are the steps in crossing over between homologous chromosomes

Answer 18

Homologous chromosomes form a bivalent
Chiasmata form
Exchange of alleles between non-sister chromatids
Producing new combinations of alleles

Question 19

diagram of crossing over between homologous chromosomes

Answer 19

Question 20

how does genetic diversity arise from sexual reproduction

Answer 20

Mate selection – which 2 organisms mate together.
Random fertilisation – which two gametes fuse.

number of combinations is shown by the equation 2n^2

Question 21

life cycle of a plant

Answer 21

Question 22

life cycle of an animal

Answer 22

Question 23

What is genetic diversity

Answer 23

the number of different alleles of genes in a population

Question 24

what is the definition for population

Answer 24

group of individuals of the same species living in the same place at the same time
Each species has the same genes

Question 25

What is the gene pool

Answer 25

all of the alleles in a population The greater the number of alleles for a gene, the greater the genetic diversity The greater the genetic diversity, the more likely individuals (and therefore a species) will survive environmental change

Question 26

what is evolution

Answer 26

the change in allele frequency in a population or species over time

Question 27

what are the steps in natural selection

Answer 27

1. Random mutations can result in new alleles of a gene 2. Some mutations are harmful but some are advantageous in certain environments (selection pressure) 3. The advantageous mutation leads to increased reproductive success 4. Advantageous allele is inherited by members of the next generation 5. Over many generations, the new allele increases in frequency in the population

Question 28

example of natural s election in giraffes

Answer 28

Question 29

what are the 3 types of adaptation

Answer 29

Anatomical Physiological Behavioural

Question 30

what is anatomical adaptation with an example

Answer 30

Anatomical - physical features Shorter ears and thicker fur for arctic foxes compared to warmer climates

Question 31

what is physiological adaptation

Answer 31

Physiological - Internal body processes oxidising of fat rather than carbohydrates to produce additional water for kangaroo rats in a warm environment

Question 32

What is behavioural adaptation

Answer 32

Behavioural - Things organisms do autumn migration of swallows.

Question 33

what are the two types of selection

Answer 33

directional selection stabilising selection

Question 34

what is the graph that show variation in a population called

Answer 34

a normal distribution curve

Question 35

what is directional selection

Answer 35

directional selection results in phenotypes at one extreme of the population being selected for and those at the other end of the extreme being selected against.

Question 36

what is stabilising selection

Answer 36

If the environmental conditions remain stable the individuals with the phenotype closest to the mean are favoured and therefore these individuals are most likely to pass on their alleles to the next generation

Question 37

graph displaying directional selection

Answer 37

Question 38

graph displaying stabilising selection

Answer 38