Genetic Diversity And Adaptation

Question 1

Define mutation

Answer 1

Change to quantity or sequence of bases

Question 2

Define gene mutation

Answer 2

Change to base sequence of DNA

Question 3

When are gene mutations most likely to occur?

Answer 3

Synthesis phase

Question 4

What are the types of gene mutations?

Answer 4

Substitution

Deletion

Addition

Question 5

Describe the difference between the effects of a Deletion and substitution mutation

Answer 5

Deletion causes frame shift so all Amino acids change

Substitution changes one triplet so one Amino acid changed

Question 6

Describe how deletion can lead to a non functional protein

Answer 6

Frame shift
Diff triplets
Diff codons and anti codons
Diff Amino acids in polypeptide
Change to ionic hydrogen and disulphide bond placement
Change to tertiary structure
Change to shape and function

Question 7

Define carcinogen

Answer 7

A substance that increases the likelihood of mutations occuring

Question 8

Name carcinogens

Answer 8

UV radiation

Toxic chemicals

Question 9

Define chromosome mutation

Answer 9

Change to structure or number of chromosomes

Question 10

What are the two types of chromosome mutations

Answer 10

Change to whole set of chromosomes

Change to one pair of chromosomes

Question 11

Name the effects of change to a whole set of chromosomes and why it occurs

Answer 11

Polyploidy

Sister chromatids fail to seperate

Question 12

Name the effects of change to a one pair of chromosomes and why it occurs

Answer 12

Non-disjunction

Homologous pairs fail to seperate during meisosis

Question 13

Why is mitosis important

Answer 13

For genetic variation

Allow continuity of diploid number between generations (prevent doubling)

Allow diploid no to be restored upon fertilisation

Question 14

What occurs to chromosomes during meiosis??

Answer 14

Nuclear envelope disintegrates and chromosomes condense and pair up (crossing over) and spindle fibres develop from centrioles

Spindle fibres attach to centromeres and align pairs at equator of cell. Independent segregation.

Spindle fibres contract and pull homologous chromosomes apart to opposite poles

Spindle fibres disintegrate and nuclear envelope forms, cytokinesis

Occurs again but this time sister chromatids are. Pulled apart and centromeres divide

Question 15

When does the number of chromosomes half in meiosis (1 or 2)

Answer 15

1

Question 16

Define I dependent segregation

Answer 16

Random allocation of chromosomes to gametes

Question 17

Define crossing over/recombination

Answer 17

Chromatids on homologous pairs intertwine and pressure causes breakages and recombination or alleles.

Alleles exchanged between pairs

Question 18

What is the main source of genetic variation in meiosis

Answer 18

Crossing over and recombination

Question 19

How do you calculate the number of possible chromosome combinations in gametes due to independent segregation only?

Answer 19

2^n

n= haploid no

Question 20

How do you calculate the number of possible chromosome combinations in zygotes due to independent segregation only?

Answer 20

(2^n)^2

n=haploid no

Question 21

Why are their a variety of different organisms

Answer 21

Difference in alleles and environment

Question 22

Define genetic diversity

Answer 22

Variety of different alleles present in population

Question 23

Why does increased genetic diversity mean a more stable community

Answer 23

More chance that an individual will posses

advantageous alleles so survive and reproduce to carry on species

Question 24

Define population.

Answer 24

All organisms of a species in the same habitat at the same time

Question 25

Why does natural selection occur

Answer 25

Due to genetic diversity and selection pressures

Question 26

How does natural selection occur

Answer 26

``` Variety of alleles in gene pool Some have advantageous alleles so are more likely to survive and reproduce Pass on alleles Occurs over many generations Allele frequency increases ```

Question 27

Define selection

Answer 27

Process by which better adapted organisms are more likely to survive and reproduce

Question 28

Define polygenes

Answer 28

Describes characteristics that are controlled by multiple genes

Question 29

What are the types of selection

Answer 29

Directional and stabalising

Question 30

What's the difference between the different types of selection

Answer 30

Directional: Change in environment Change to phenotype Extremes favoured ``` Stabalising : Stable environment No change to environment Less variation Average favoured ```

Question 31

Give examples of each type of selection

Answer 31

Directional= antibiotic resistance Birth weight = Stabalising

Question 32

Describe what occurs to mean and SD/variation in directional selection

Answer 32

Mean changes SD same

Question 33

Describe what occurs to mean and SD/variation in Stabalising selection

Answer 33

Mean = same SD = smaller

Question 34

What types of adaptions may occur

Answer 34

Anatomical Physiological Behavioural

Question 35

Why might logs be used in Graphs

Answer 35

Make changes easier to see