diversity (green) (mutations/meiosis/adaptation)

Question 1

what is a mutation?

Answer 1

change in base sequence

Question 2

what is a gene mutation?

Answer 2

• change in the base sequence of a gene
• mutations can occur naturally in dna replication.
• the frequency of a mutation is increased by mutagenic agents e.g. alcohol, ionising radiation

Question 3

what is a silent substitution mutation?

Answer 3

one base is changed to a different base

does not change the amino acid that the triplet codes for

Question 4

what is a missense subsitution?

Answer 4

one base is replaced with a different base and the amino acid that this triplet codes for is now different

Question 5

does a missense substitution affect the tertiary structure of a protein?

Answer 5

yes as the primary sequence was changed so hydrogen bonds form in different places

Question 6

what is a nonsense substitution?

Answer 6

base is replaced with a different base but this codon now codes for a stop codon instead of an amino acid

Question 7

what is an addition mutation?

Answer 7

adding a base into a base sequence

Question 8

what is a frameshift?

Answer 8

all the codons after the place of addition are changed

Question 9

what is a deletion mutation?

Answer 9

base is removed

Question 10

what mutations cause a frameshift?

Answer 10

addition and deletion

Question 11

how many divisions occur in meiosis?

Answer 11

2

Question 12

how many cells are formed at the end of meiosis?

Answer 12

4ho

Question 13

how many chromosomes does a cell have at the end of meiosis?

Answer 13

23

Question 14

why are the daughter cells of meiosis haploids?

Answer 14

to maintain the number of chromosomes after fertilisation

Question 15

what are homologous pairs?

Answer 15

chromosomes that have genes in the exact same place - same gene locus

Question 16

how do the homologous pairs of chromosomes line up for the first division?

Answer 16

on the same spindle fiber

Question 17

what happens in the first division of meiosis?

Answer 17

homologous pairs of chromosomes separate and one pair go into each daughter cell

Question 18

is there genetic variation in new cells from mitosis?

Answer 18

NO

Question 19

is there genetic variation in new cells from meiosis?

Answer 19

yes

Question 20

what are the ways genetic variation can occur in meiosis?

Answer 20

independent segregation
crossing over and recombination

Question 21

what does crossing over and recombination produce?

Answer 21

different combinations of alleles

Question 22

what does independent segregation produce?

Answer 22

different combinations of chromosomes

Question 23

describe what happens to chromosomes in meiosis

Answer 23

• chromosomes visible as they have condensed
• chroms join to the spindle fibres
• homologous pairs on the same spindle
• at the equator
• crossing over and recombination can occur
• homologous chroms separate
• independent segregation
• sister chromatids separate

Question 24

what is non disjunction?

Answer 24

mistakes in meiosis that causes a different number of chromosomes in a daughter cell

Question 25

what is meiosis1 non-disjunction?

Answer 25

the pair of homologous chromosomes failing to separate properly in the first division

Question 26

what is meiosis2 non-disjunction?

Answer 26

a pair of sister chromatids failing to separate properly in the second division

Question 27

what does non-disjunction result in?

Answer 27

one gamete having an extra chromosome and one gamete having one less chromosome

Question 28

what does a centromere do?

Answer 28

keeps the sister chromatids joined together and attatches to spindle fibre

Question 29

why do homologous chromosomes carry the same genes but arent genetically identical?

Answer 29

homologous chromosomes carry different alleles

Question 30

what is an allele?

Answer 30

different version of the same gene

Question 31

what is genetic diversity?

Answer 31

the number of different alleles of genes in a population

Question 32

what are the steps of natural selection?

Answer 32

1. random mutation
2. new alleles formed
3. differential survival
4. more successful reproduction with advantages passed to offspring
5. increase in allelic frequency of the advantageous allele

Question 33

what types of adaptation are there?

Answer 33

behavioural, physiological, anatomical

Question 34

what are antibiotics used for?

Answer 34

disease caused by bacteria

Question 35

how do antibiotics work?

Answer 35

prevent the formation of a cell wall in a bacterial cell, and then water will enter by osmosis and the cell will burst

Question 36

where is the bacterial dna stored?

Answer 36

plasmids

Question 37

what is antibiotic resistance in bacteria caused by?

Answer 37

a mutation

• eg a mutation that can cause a gene to code for an enzyme that breaks down the antibiotic so it cant kill the bacteria cell

Question 38

how do bacterial cells reproduce?

Answer 38

binary fissionw

Question 39

what is the zone where bacteria on a petri dish has been killed called?

Answer 39

inhibition zone

Question 40

what are control variables for the antibiotics on a petri dish?

Answer 40

size of the filter paper
time left on the dish for
same material used

Question 41

what are the two types of selection?

Answer 41

directional and stabilising

Question 42

what is directional selection?

Answer 42

where individuals with alleles for a certain characteristic are more likely to survive in response to an environmental change

Question 43

what is stabilising selection?

Answer 43

where individuals with alleles for a certain characteristic are more likely to survive and reproduce when there is no change to the environment
this reduces the range of possible characteristics - reduces extremes

Question 44

what occurs in independent segregation?

Answer 44

homologous pairs of chromosomes randomly separate and this can cause random combinations of chromosomes

Question 45

what occurs in crossing over and recombination?

Answer 45

parts of the chromatids swap over and this will cause different combinations of alleles

Question 46

how can genetic diversity be increased?

Answer 46

mutations in the DNA forming new alleles
different alleles being introduced into a population when individuals from another population migrate in and reproduce