4B Diversity classification and variation

Question 1

what are gametes

Answer 1

sperm cells in males and the egg cells in females

Question 2

when gametes join together in fertilisation what do they form

Answer 2

zygote, which divides and develops into a new organism

Question 3

what diploid number to normal body cells have

Answer 3

2n

meaning each cell has two of each chromosome one from mum and one from dad

Question 4

what is gametes haploid number

Answer 4

n

one copy of each chromosome

Question 5

what happens at fertilisation

Answer 5

a haploid sperm fuses with a haploid egg making cell with normal diploid number
half chromosomes from mum (egg) and half from dad(sperm)

Question 6

how is genetic diversity increased within species by fertilisation

Answer 6

fertilisation is random (any sperm with any egg(

so produces zygotes with different combinations of chromosomes to both parents (mixes genetic material)

Question 7

where does meiosis take place

Answer 7

reproductive organs

Question 8

how do cells start and finish via meiosis

Answer 8

start as diploid finish as haploids (have half the chromosomes)

Question 9

6 steps of meiosis

Answer 9

1) before meiosis-DNA unravels & replicates so there are two copies of each chromosomes called chromatids
2) DNA condenses forming double armed chromosomes, made from two sister chromatids - sister chromatids joined by centromere
3) meiosis I- chromosomes orange into homologous pairs
4) homologous pairs separated halting chromosome number
5) meiosis II- pairs of sister chromosatids which make up each chromosome are separated (centromere divides)
6) four haploid cells(gametes) that are genetically different are formed

Question 10

how many homologous pairs do human have

Answer 10

23

46 single chromosomes

Question 11

during meiosis I what happens which causes the chromatids to have a different combination of alleles

Answer 11

homologous pairs of chromosomes pair up together
chromatids twist around each other and parts of the chromatids swap over
now chromatids still have same genes but different combination of alleles

Question 12

how does the crossing over of chromatids during meiosis I produce cells which are genetically different

Answer 12

causes each of the four daughter cells formed have chromatids with different alleles
increases genetic variation

Question 13

how does the independent segregation of chromosomes cause cells to be produced which are genetically different

Answer 13

when homologous pairs are separated (meiosis I) its random which chromosome from the pair ends up with which daughter cell
so 4 daughter cells have different combinations of those maternal and paternal chromosomes
this shuffling causes genetic variation in potential offspring

Question 14

difference between meiosis and mitosis

Answer 14

1)mitosis produces cells w/same no. of chromosomes as parent cells
meiosis produces cells w/half chromosomes as parent cells

2)mitosis daughter cells are genetically identical to each other &parent cells
meiosis daughter cells are genetically different to each other and parent cell

3)mitosis produces two daughter cells
meiosis produces four daughter cells

Question 15

how are chromosome mutations caused generally

Answer 15

errors in cell division

Question 16

what is the chromosome mutation non-disjunction

Answer 16

failure of chromosomes to separate properly

Question 17

what does non-disjunction of chromosome 21 cause

Answer 17

downs syndrome

Question 18

detail how downs syndrome is caused

Answer 18

person having extra copy of chromosome 21

non disjunction means chromosome 21 fails to separate properly in meiosis so one cell gets an extra copy of chromosome 21 and the other cell gets none

so when the gamete with an extra chromosome fuses with another gamete at fertilisation the zygote will end up with 3 chromosomes 21

Question 19

what is another mutation

Answer 19

changes to the base sequence of DNA

deletion or substitution

Question 20

what is deletion mutation

Answer 20

one base is deleted (in DNA)

Question 21

what is substitution mutation

Answer 21

one base is substituted with another (in dna)

Question 22

how can a change in dna bases cause a mutation

Answer 22

as order of dna bases determines order of amino acids and therefore the protein which is made,
if the bases change the sequence of amino acids change and therefore a different protein is coded for

Question 23

why do not all mutations affect the order of amino acids

substitution

Answer 23

as the genetic code is degenerate and more than one dna triplet can code for an amino acid
this mean substitution does not always result in change in amino acid sequence

Question 24

why does deletion always cause change in amino acid sequence

Answer 24

as when a base is deleted it changes the number of base present - this causes a shift in all the base triplets after it

Question 25

what are mutagenic agents

Answer 25

things that increase rate of mutations

Question 26

examples of mutagenic agents

Answer 26

ultraviolet radiation ionising radiation some chemicals and viruses

Question 27

how can gentic diversity within a population be increased

Answer 27

- mutations in DNA | - different alleles introduced into population

Question 28

what is gene flow

Answer 28

when individuals from another population migrate into them and reproduce -causing genetic diversity increases

Question 29

what is a genetic bottleneck

Answer 29

an event which causes a big reduction in a population

Question 30

how do genetic bottlenecks cause reduction in genetic diversity

Answer 30

the reduction in population causes number of different alleles to reduce in the gene pool so reduces genetic diversity

Question 31

what is the founder effect

Answer 31

type of genetic bottleneck when a few organisms start new colony with only small number of alleles in gene pool a gene which is rare in initial population may be very common in new colony my lead to higher chance of genetic disease

Question 32

how does founder effect normally occur

Answer 32

result of migration leading to geographical seperation colony operates from original population for religion

Question 33

example of founder effect

Answer 33

the amish

Question 34

what is behavioural adaptations

Answer 34

ways an organism acts that increases chance of survival and reproduction

Question 35

what is physiological adaptations

Answer 35

processes inside an organisms body which increase chance of survival

Question 36

what are anatomical adaptations

Answer 36

structural features of an organisms body which increase chance of survival

Question 37

what is directional selection

Answer 37

where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce

Question 38

example of directional selection

Answer 38

bacteria evolving antibiotic resistance

Question 39

what is stabilising selection

Answer 39

where individuals with alleles for the characteristics towards the middle of the range are more likely to survive and reproduce

Question 40

what's an example of stabilising slection

Answer 40

human birth weight -larger and smaller baby less likely to survive birth

Question 41

what is phylogeny and what can it tell us

Answer 41

study of evolutionary history of groups of organisms | tells us who's related to whom and how closely they are related

Question 42

what is taxonomy

Answer 42

science of classification and names organisms organising them into groups

Question 43

what does heriachy mean

Answer 43

groups organised into largest groups at top and smallest at Bottom no overlapping groups

Question 44

what are the three domains

Answer 44

eukarya bacteria archaea

Question 45

what are the eight taxons

Answer 45

``` domain kingdom phylum class order family genus species ```

Question 46

what is a species

Answer 46

group of similar organisms able to reproduce and give fertile offspring

Question 47

what is the binomial system

Answer 47

nomenclature for classification | given one internationally accepted name in latin with two parts

Question 48

what are the fist and second parts of names in classification called

Answer 48

genus is first | species is second

Question 49

what is courtship behaviour

Answer 49

carried out by organisms to attract mate of right species

Question 50

why is courtship behaviour species specific

Answer 50

prevents interbreeding | making reproduction more successful

Question 51

explain genome sequencing

Answer 51

DNA base sequence of an organism can be compared to see how closely related they are more closely related species will have a higher percentage of similarity in there base sequence

Question 52

explain comparing amino acid sequence

Answer 52

related organisms have similar amino acid sequences in there proteins

Question 53

what is cytochrome c

Answer 53

short protein found in many organisms

Question 54

explain immunological comparisons

Answer 54

similar proteins bind to same antibodies

Question 55

what is genetic diversity

Answer 55

the number of different alleles in a population

Question 56

what can variation be caused by

Answer 56

genetic factors environment combination of genes and environment

Question 57

why are samples used to study variation

Answer 57

as its too time consuming and impossible to be able to study a whole population

Question 58

why do samples need to be random

Answer 58

make sure it accurately represents the population and makes sure it isn't biased could use random number generator

Question 59

what is biodiversity

Answer 59

the variety of living organisms in an area

Question 60

what is habitat

Answer 60

the place where an organism lives

Question 61

what is community

Answer 61

all the populations of different species in a habitat

Question 62

what local biodiversity

Answer 62

variety of species living in small habitats that's local to you

Question 63

what's global biodiversity

Answer 63

variety of species on earth | greatest at the equator

Question 64

what's species richness

Answer 64

measure of number of different species in a community

Question 65

how cam species richness/ biodiversity be worked out

Answer 65

take random samples of a community and count number of different species

Question 66

what also effects the biodiversity number

Answer 66

the population size | big and small populations should not be treated the same way

Question 67

what's index of diversity

Answer 67

another way of measuring biodiversity calculated with formula higher number + more biodiversity

Question 68

what can reduce biodiversity

Answer 68

agricultural practices

Question 69

how can woodland clearance decrease biodiversity

Answer 69

decreases number of trees and tree species destroys habitats and food resources species may be forced to migrate or die

Question 70

how can hedgerow removal decrease biodiversity

Answer 70

same reasons as woodland clearance

Question 71

how can pesticides decrease biodiversity

Answer 71

chemicals kill pests that feed on crops | also reduces food resource

Question 72

how can herbicides reduce biodiversity

Answer 72

chemicals kill unwanted plants

Question 73

how can monoculture reduce diversity

Answer 73

farmers have fields which only contain one type of plant

Question 74

what are some examples of conservation schemes which protect biodiversity

Answer 74

SSSI/ AONHb | environmental stewardship scheme