Genetic Diversity

Question 1

Genetic diversity

Answer 1

Total number of alleles in a population

Caused by gene mutation, chromosome mutation, random factors with meiosis, fertilisation

Question 2

Why is genetic diversity important

Answer 2

Disease, environmental factors will affect more people

Wider range of characteristics, more likely 1 will be advantageous to change

Question 3

Gene mutation definition

Answer 3

Change in DNA base sequence of gene

Question 4

Mutagenic agents

Answer 4

Environmental factors, increase rate of mutation above normal low rate
Mechanisms in cell identify, repair damaged DNA
Eg, toxic chemicals, ionising and high energy radiation in somatic cells

Question 5

Chromosome mutations

Answer 5

Polyploidy in plants, while set of chromosomes changes

Non disjunction in meiosis, fail to separate, trisomy, Down’s syndrome

Question 6

Substitution

Answer 6

1 nucleotide in DNA molecule replaced by another with diff base
Codon changed, forms diff amino acid, small change to protein formed
Silent mutation, degenerate codons

Question 7

Deletion

Answer 7

Section of DNA lost, shift whole codon sequence by 1 base

Frameshift

Question 8

Duplication

Answer 8

1 or more bases repeated

From shift

Question 9

Inversion

Answer 9

Group of bases become separated from DNA sequence, rejoin at the same position but in reverse order
Changes amino acid formed

Question 10

Addition

Answer 10

Extra base inserted into sequence

Frame shift

Question 11

Translocation

Answer 11

Nucleotide groups separated from DNA sequence from DNA sequence on 1 chromosome, inserted into DNA sequence on different chromosome
Cancer, reduced fertility

Question 12

Neutral mutation

Answer 12

Results in alleles that code for different sequence of amino acid in protein, do not affect function

Question 13

Harmful mutation

Answer 13

Changes amino acid sequence, damages protein function

Question 14

Beneficial mutation

Answer 14

Advantageous allele, survive, pass on allele, frequency of the allele will increase
Basis of evolution by natural selection

Question 15

Antibiotic resistance

Answer 15

Bacteria have variation in gene pool, some more resistant
Exposed to antibiotic, kills majority
Resistant not killed, no competition for resources
Survive, reproduce, pass on allele/plasmid for antibiotic resistant to next gen
Frequency of antibiotic resistant allele/plasmid increases

Question 16

Peppered moth

Answer 16

Peppered moths, silver allele
Live on silver birch, IR, sooty trees
Some had dark allele, advantage, camouflage
Dark moths, less likely to be eaten, survive, reproduce successfully, pass on dark winged allele
Population mostly dark
IR ends, silver trees, dark disadvantage
Silver less likely to be eaten, survive, successfully reproduce, pass on silver allele

Question 17

Cystic fibrosis

Answer 17

Mucus too thick, can block lungs, other organs
Deletion mutation, faulty protein affects movement of chloride ions in water in and out of cells
No cure, can thin mucus with meds

Question 18

Sickle cell anaemia

Answer 18

Affects people who live in areas with malaria
Cannot carry as much oxygen as normal erythrocytes leading to anaemia
Gene substitution, makes haemoglobin less soluble
Haemoglobin stick together, distort RBC
Block blood vessels, risk of heart failure

Question 19

Natural selection

Answer 19

Representative of standard distribution of trait in organism

Question 20

Directional selection pressure

Answer 20

Extra of trait experience selection against in it

Results in population trait distribution shifts towards other extremes

Question 21

Stabilising selection pressure

Answer 21

Non extreme trait favoured instead of 2 extreme traits

Mean not shifted