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biology paper 2 > inheritance and variation > Flashcards

inheritance and variation Flashcards

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1
Q

how many chromosomes do we have

A

23 pairs

46 individual

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2
Q

which chromosome is mothers and which is father s

A

X= mum
Y = dad

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3
Q

what is stage 1 of meiosis

A

replicate its structure

line up in the middle of the cell

chromosomes get pulled apart to seperate sides of the cell (DNA IS DIFFRENT)

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4
Q

what is stage 2 of meiosis

A

they line up again in the new cells

each ARM gets pulled to opposite sides of the cell

they divide again to make 4 new gametes which are genetically unique from each other

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5
Q

summarise meiosis

A

genetic info is copied

the cell divides twice to make 4 new gametes which each a single set of chromosomes

all gametes are genetically diffrent

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6
Q

how do you genetically modify an organism

A

find an organism with a desired trait
take the gene out
transfer to another organism
modifies the organisms genome

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7
Q

what are examples of things that have been genetically modified

A

CROPS - to become bigger and better fruits and to become resistant to disease and produce more yield

BACTERIAL CELLS- to produce insulin for diabetes

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8
Q

what is gene therapy and the issues

A

treating inherited disorders by giving someone the healthy version of the gene

it’s difficult as the faulty gene would be in all cells and it’s difficult to transfer new gene to every cell

HOWEVER YOU COULD TRANSFER AT EARLY STAGE OF DEVELOPMENT INSTEAD

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9
Q

what are the pros and cons of genetic engineering

A

pros
more yield, more crops with desired characteristics and resistance to disease (more food for less money), can have plants produce special nutrients

cons
don’t know how GM plants might affect our health

can outcompete other plants and change the whole ecosystem (unlikely)

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10
Q

how do we transfer the gene to the cell

A

find the gene we want
cut out the DNA to isolate
insert DNA into virus or bacterial plasmid
organisms cells will take up the vector and the gene

it will start producing proteins

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11
Q

how does naturual selection happen

A

individual organisms have a wide range of variation

organisms which have a desired characteristic will more likely survive and therefore breed more successfully

the characteristics will be passed on to their offspring

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12
Q

why were charles darwin’s ideas not accepted

A

insufficient evidence

challenged religious beliefs that God created all life on earth

the mechanism of inheritance and variation had not been discovered

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13
Q

what is the definition of evolution

A

the change in inherited characteristics through the process of natural selection

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14
Q

reasons why species become extinct

A

loss of food
loss of habitat
new predators
competition
natural disasters
hunters
disease
environmental change

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15
Q

what did alfred russel wallace discover

A

discovered same theory as darwin but also realised that closely related species were often separated by geographical barriers

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16
Q

how do new species form

A

geographical barrier (e.g river) separates an organisms population into 2 groups

There is no interbreeding between the 2 groups

natural selection will favour diffrent alleles

any mutations can’t spread

population becomes to change

diffrent phenotypes make reproduction impossible

new species created

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17
Q

how are fossils evidence for evolution

A

can see how organisms have developed over time

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18
Q

how does an animal become a fossil

A

animal dies and falls into soft mud

mud or slit covers body

slit or mud gradually turns into rock encoding the body

hard parts replaced by minerals

soft parts do not fossilise well as they decay

earths movement causes remains to be exposed

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19
Q

give an example of a fossil

A

casts
impressions( e.g footprints

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20
Q

why were fossil records incomplete

A

many early life forms were soft bodied

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21
Q

how may fossils be formed from

A

parts of organisms that have not decayed
parts of organisms being replaced by minerals
as preserved traces of organisms

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22
Q

why can bacteria evolve

A

reproduce rapidly

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23
Q

how does resistence occur

A

random mutations cause new strains. Some strains may be resistant and therefore survive the antibiotic. They then reproduce rapidly and create a colony of that resistant strain

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24
Q

how do you reduce resistance of antibiotics

A

doctors shouldn’t prescribe antibiotics for non serious illnesses

patient complete the course of antibiotics so that all bacteria is killed and none can mutate

reduce agricultural use of antibiotics

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25
Q

why can’t we keep up with new bacteria

A

the process of developing and making a new antibiotic is long
and it’s expensive

26
Q

who discovered classification

A

carl linneas

27
Q

what are the 2 kingdoms

A

Plant and animal

28
Q

what is the hierarchy of organisms

A

kingdom
phylum
class
order
fungi
genus
species

29
Q

how do you remember it

A

King
Prawn
Curry
OR
Fat
Greasy
Sausage

30
Q

what does the binomial naming system consist of and what are the rules

A

genus and species

genus is always capitalised at the first letter
species is lower case

BOTH ARE ITALISED

31
Q

what advances in biology has made an impact on classification system

A

microscopes- can look at internal structures

three domain system

32
Q

what is the three domain system and who discovers it

A

CARL WOESE

Archaea (primitive bacteria)
bacteria (true bacteria)
eukaryotia (which includes fungi protists plants and animals

33
Q

what are gametes

A

human sex cells (sperm and egg)

34
Q

what does meiosis produce

A

gametes

35
Q

what is the definition of sexual reproduction

A

fusion of male and female gametes

36
Q

what happens as a result of sexual reproduction

A

offspring receives genetic information from both parents which provides variation for the offspring

37
Q

what does a sexual reproduction involve

A

mitosis

38
Q

what are some differences of a sexual reproduction

A

it only involves 1 parent
it dosent produce any variation in the offspring
produces genetically identical clones
dosent involve gametes
no mixing of genetic information

39
Q

what are the advantages of SEXUAL reproduction

A

produces variation in offspring
variation can increase survival chances for the offspring
Gives species survival advantage by natural selection

NATURAL SELECTION CAN BY SPED UP BY HUMANS BY SLECTIVE BREEDING TO INCREASE FOOD PRODUCTION

40
Q

ADVANTAGES OF A SEXUAL REPRODUCTION

A

Only one parent is needed
more energy efficient
quicker
indentical offspring
desirable genetics/ characteristics are passed on to the the offspring
many offspring’s can be produced if conditions are favourable

41
Q

where is dna found

A

in the chromosomes
chromosomes are found in the nucleus

42
Q

what is the structure of DNA (2 marks)

A

double helix structure
contains A G C T bases

43
Q

what is a gene

A

small section of dna on a chromosome

44
Q

what is each gene code for

A

a specific protein

45
Q

what is a genome

A

entire genetic material in an organism

46
Q

what is the benefits of understanding the human genome

A

search for genes specifically linked to a type of disease

understand and treat inherited disorders

use in human migration patterns

47
Q

what is DNA

A

Polymer made up of 2 strands

48
Q

what is dna polymer called

A

nucleotides

49
Q

what are the three main parts of nucleotides

A

circle = PHOSPHATE group
pentagon= sugar molecule
rectangle = base

50
Q

are dna strands complementary

A

yes

51
Q

what bases are always linked together in A C G T

A

A - T and vise versa
C- G and vice versa

52
Q

what are alleles

A

diffrent versions of genes

53
Q

what do genotypes tell us

A

what alleles are present

54
Q

what is homozygous

A

two of the same type of alleles (rr, RR)

55
Q

what is heterozygous

A

two diffrent alleles (Bb, bB)

56
Q

what is a phenotype

A

yells is the characteristics caused by a persons alleles

57
Q

how will a recessive allele shown

A

will only show in the phenotype if 2 copies are present

58
Q

does a dominant allele require 1 or 2 copies of the allele

A

1

59
Q

what is cystic fibrosis

A

ressesive disorder ( both parents must have the alleles)

controlled by a single gene

disorder of the cell membrane
Cc = carrier but not affected
CC= unaffected
cc= cystic fibrosis

however they are only probabilities so the real outcome can differ

60
Q

what is polydactyl

A

extra fingers or toes
caused by a dominant allele
will inherit even if only one parent carries it

Pp= will have it
PP= unaffected
pp= has it

so is more chance to get this than cystic fibrosis

61
Q

what is embryo screening and the issues around it

A

embryos are tested to see if they have a defected allele for inherited disorders
embryos which do not have the alleles will be implanted into women

FOR
stops people suffering
saving money for the government/ NHS
there are laws to stop it going to far

AGAINST
screening is expensive- people think the money should be used elsewhere
some embryos are destroyed - unethical

in the future we may be able to screen their embryos so they can pick the most desirable one - unethical

biology paper 2 (2 decks)

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