4. genetics, variation and interdependence

Question 1

degrees of freedom

Answer 1

no. of categories -1

Question 2

benefits of genetic variation

Answer 2

higher chance of survival
allows for natural selection
ability to adapt and change

Question 3

natural selection

Answer 3

random mutation
beneficial alleles - higher chance of survival
pass on alleles via reproduction
new allele increases in frequency

Question 4

bottleneck effect

Answer 4

previously large population is reduced in numbers significantly
reduces genetic diversity

Question 5

stabilising selection

Answer 5

selection pressures which favour the middle characteristic

Question 6

directional selection

Answer 6

selection pressures which favour an extreme characteristic

Question 7

why is courtship important

Answer 7

allows organisms to identify other organisms of the same species of the opposite sex
to allow for successful reproduction

Question 8

species richness

Answer 8

number of species in a community
higher species richness = more stable

Question 9

importance of biodiversity

Answer 9

moral
more stability
provides nutrients/essentials
economic
looks nice
rescue from catastrophe

Question 10

index of diversity

Answer 10

(no. of one species)(no. of one species - 1)

divided by

(total no. of organisms)(total no. of organisms -1)

Question 11

use of index of diversity

Answer 11

measureless of eveness of species richness

Question 12

causes of genetic variation (4)

Answer 12

mutation
crossing over
independent assortment
random fertilisation

Question 13

why can bacteria use human DNA sequence to make the same proteins

Answer 13

universal code
mechanism for transcription/translation universal

Question 14

why might bacteria struggle to make the same protein as humans

Answer 14

no Golgi body to process/package
cannot splice so can’t remove introns
do not have transcription factors

Question 15

mutagenic agents

Answer 15

UV light
toxic chemicals
ionisation radiation

Question 16

crossing over

Answer 16

non sister chromosomes exchange alleles
form a chiasmata

Question 17

mitochondrial/chloroplastal DNA

Answer 17

matrix of mitochondria/stroma
short
circular
not protein assosiated

Question 18

genome

Answer 18

complete set of genes present in a cell

Question 19

define triplet

Answer 19

sequence of three DNA bases that codes for a specific amino acid

Question 20

define codon

Answer 20

sequence of three mRNA bases that codes for a specific amino acid

Question 21

degenerate

Answer 21

Multiple mRNA codons can encode the same amino acid

Question 22

non-overlapping

Answer 22

Each base is only read once in the codon it is part of

Question 23

silent mutation

Answer 23

the mutation does not alter the amino acid sequence

Question 24

missense mutation

Answer 24

the mutation alters a single amino acid in the polypeptide chain

Question 25

nonsense mutation

Answer 25

the mutation creates a premature stop codon

Question 26

non-disjunction

Answer 26

when chromosomes dont separate during meiosis

Question 27

independent assortment

Answer 27

alleles for different genes get separated into different gametes independently and randomly

Question 28

stages of meiosis

Answer 28

interphase, prophase 1, metaphase 1, anaphase 1, telophase 1, cytokenesis, prophase 2, metaphase 2, anaphase 2, telophase 2, cytokinesis

Question 29

when does crossing over occur

Answer 29

prohase 1

Question 30

when do chromosomes condense in meoisis

Answer 30

prophase 1 and prophase 2

Question 31

founder effect

Answer 31

small group of large population start new population smaller gene pool

Question 32

genetic drift

Answer 32

very small population chance determines which allies get passed on

Question 33

bottleneck effect

Answer 33

incident leads to dramatic effect on population size