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GCSE Biology- AQA > Topic 6- Inheritance,variation and evoloution > Flashcards

Topic 6- Inheritance,variation and evoloution Flashcards

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1
Q

What does DNA stand for?

A

Deoxyribonuclaic acid

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2
Q

What is DNA?

A

The chemical that all the genetic information in a cell is made from

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3
Q

What are chromosomes?

A

long structures of dna

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4
Q

How many chromosomes are there in a human?

A

46

23 pairs

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5
Q

What is the structure of DNA?

A

A double helix shape made by 2 strands coiled together

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6
Q

What is a gene

A

`a small section of DNA found on a chromosome which is responsible for a certain characteristic

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7
Q

How many amino acids are used to code thousands of different types of proteins?

A

only 20! but the order they are in matters

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8
Q

What is a Genome?

A

the entire set of genetic materiel in an organism

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9
Q

Why is understanding the human genome important?

A

it allows scientist to understand inherited diseases and identify genetic disorders

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10
Q

What is DNA made up of?

A

nucleotides

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11
Q

What are the 4 bases called?

A

A and T

C and G

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12
Q

What decides the order of amino acids in a protein?

A

the order that the basses come in

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13
Q

Where are proteins made?

A

in ribosomes

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14
Q

What s the function of mRNA?

A

it acts as a messenger, carrying code from the DNA to the ribosomes.

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15
Q

What are some of the functions of proteins?

A

enzymes- biological catalysts
hormones- carry messages around the body
structural proteins- strengthens tissues like cartilage

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16
Q

What is a mutation?

A

a change to the genetic code of an organism

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17
Q

What increases the chance of a mutation?

A

exposure to certain substances and radiation

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18
Q

Why arent mutations always bad?

A

they often have very little or no effect on the protein

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19
Q

How can mutations be bad?

A

some mutations can change the shape of an active site and make it unable to perform its function. Structural proteins could lose their shape

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20
Q

What are the 3 types of mutations?

A

insertions
deletions
substitutions

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21
Q

What is an insertion mutation?

A

a new base is inserted where it shouldn’t be

this changes the way the bases are read and can have a knock on effect further along in the sequence

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22
Q

What is a deletion mutation?

A

a random base is deleted from the sequence

this changes the way the bases are read and can have a knock on effect further along in the sequence

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23
Q

What is a substitution mutation?

A

random bases are changed to different bases.

there isn’t a knock on effect and they are general less dangerous

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24
Q

What is sexual reproduction?

A

genetic information from 2 organisms is combines to produce offspring that are genetically different to either parent

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25
Q

What is asexual reproduction?

A

a method of reproduction where there is only 1 parent so the offspring are genetically identical tot he parent

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26
Q

Does sexual reproduction use mitosis or meiosis?

A

meiosis-the mother and father produce gametes with 23 chromosomes each

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27
Q

Does asexual reproduction use mitosis or meiosis?

A

mitosis-the cell divides in 2 and makes an identical copy called a clone

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28
Q

How many cell divisions take place in meiosis?

A

2- it produces 4 gametes which are genetically different

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29
Q

What are the advantages of sexual reproduction?

A

There is variation so the chance of a species surviving in an environment change is higher
They are better adapted by natural selection
We can use selective breeding to increase food production

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30
Q

What are the advantages of asexual reproduction?

A

there only needs to be one parent so organisms dont need to find a mate. This means that it is faster.
many identical offspring can be produced in favourable conditions

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31
Q

What organisms can produce asexually and sexually?

A

malaria- asexually when in humans and sexually when in mosquitoes

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32
Q

Which chromosomes determine your sex?

A

the 23rd pair are labelled xy or xx and determine your sex

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33
Q

What is the male chromosome code?

A

XY- the Y chromosome causes male characteristics

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34
Q

What is the female chromosome code?

A

XX- the XX combination causes female characteristics

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35
Q

What do genetic diagrams show?

A

Possible gamete combinations

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36
Q

What is the probability of getting a boy or girl?

A

50:50

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37
Q

What is homozygous?

A

when 2 alleles for are particular gene are the same

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38
Q

What is hetrozygous?

A

when 2 alleles for a particular gene are different

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39
Q

When writing down genotypes, what do capital letters show?

A

capital letter- dominant allele- e.g CC Cc

lower case- recessive allele- e.g cc

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40
Q

What is a geneotype?

A

a combination of alleles you have to determine your characteristics (phenotype)

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41
Q

What is a phenotype?

A

the characteristics you have

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42
Q

What is the geneotype XX?

A

Homozygous-Dominant

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43
Q

What is the geneotype Xx?

A

Hetrozygous

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44
Q

What is the geneotype xx?

A

Homozygous- Recessive

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45
Q

What is cystic fibrosis caused by?

A

a recessive allele

46
Q

Will a man with Cc have cystic fibrosis?

A

no, but he will be a carrier

47
Q

Will a man with CC have cystic fibrosis?

A

no, it is a recessive allele that causes it

48
Q

Will a man with cc have cystic fibrosis?

A

yes, this is dangerous, he might die!!!!!!!!!!!!

49
Q

What are the symptoms of cystic fibrosis?

A

the body produces a lot of stick mucus in the air passages of the pancreas

50
Q

What is polydactyly?

A

a genetic disorder where babies are born with extra fingers or toes

51
Q

What causes polydactyly?

A

A dominent allele

52
Q

Will a man with PP have polydactyly?

A

yes, he will have extra fingers

53
Q

Will a man with Pp have polydactyly?

A

yes, it is caused by a dominent allele

54
Q

Will a man with pp have polydactyly?

A

nope, it is caused by a dominent allele

55
Q

What is the chance of a baby having polydactyly if only 1 parent has it?

A

50%

56
Q

What is the chance of a baby having polydactyly if 2 parents have it?

A

100%

57
Q

What is embryonic screening?

A

removing a cell from each embryo to test its genes and spot a genetic disorder before the baby is implanted

58
Q

What are reasons against embryonic screening?

A

it implies genetic problems are undesirable and could increase predjudice
screening is expensive
embryos could be screens to pick the most desirable one with the best characteristics like eye colour

59
Q

What are the pros of embryonic screening?

A

it will help stop people suffering
treating these disorders cost the government a lot of money
there are laws to stop it going too far

60
Q

Who was Gregor Mendel?

A

`an austrian monk who did genetic experiments with pea plants

61
Q

What did Gregor Mendel investigate?

A

how characteristics of plants were passed on to the next generation

62
Q

What 3 conclusions did Gregor Mendel make?

A
  • plant characteristics are determined by “hereditary units”
  • hereditary units are passed on to offspring with 1 unit from each parent
  • hereditary units can be dominant or recessive
63
Q

Was Gregor Mendels work accepted straight away?

A

no, it was cutting edge and took a while for people to understand. It wasn’t until the 20th century that people realised the similarities between Mendels units and chromosomes

64
Q

Are organism of the same species identical?

A

no, there are differences. sometimes these are slight like hair colour.

65
Q

What are genetic differences between a species called?

A

Variation

66
Q

What are the 2 types of variation?

A

Genetic variation

Environmental variation

67
Q

How can plant characteristics be influenced by the environment?

A

if a plant is placed in a dark room it would have yellow leaves rather than green

68
Q

Do mutations have a large effect on the genes they code?

A

no, most have a very small effect on the organism phenotype. it is very rare to see a change at all

69
Q

What does Darwin’s Theory of Evolution state?

A

All of today’s species have evolved from simple life forms that that have developed over 3 billion years

70
Q

What was Darwin’s Theory of natural selection?

A

organisms with characteristics most suited for an environment would be more likely to survive and pass on their features to the next generation

71
Q

What is speciation?

A

where natural selection causes a phenotype to change so much that it forms an entirely new species

72
Q

What is extinction?

A

when no individuals of a species remain

73
Q

Why does extinction occur?

A 
chnage of environment
new predator
new disease
catasrophic disease
competition for food
74
Q

Why were Darwins theory’s controversial?

A
  • They went against religious beliefs
  • Darwin didnt know anything about genes or mutations
  • There wasnt enough evidence to convince many scientists
75
Q

What were Lamarcks ideas ?

A

The changes an organism acquires in its lifetime will be passed on to offspring
if a characteristic was used lots it would become more developed and the offspring would inherit these developments

76
Q

Why was Lamarcks theory rejected?

A

There wasn’t evidence to support his hypothesis.

77
Q

What is selective breeding?

A

Where humans artificially select the plants or animals they want to breed and breed them to produce a desired charecteristic

78
Q

Why would we use selective breeding?

A
  • animals with more meat/milk
  • crops with disease resistance
  • dogs that are friendly
  • large wheat crops to feed more people
79
Q

Why is selective breeding bad?

A

it causes a reduced gene pool which can decrease crop resistance
there can be serious problems if a new disease appears because there is not much variation so if 1 plant dies the rest are likely to die

80
Q

What is genetic engineering?

A

transferring a gene responsible for a desired characteristic from one organisms genome into another organism so that it also had the desired charcteristic

81
Q

What items have been genetically engineered?

A

bacteria- to produce human insulin
GM crops- to improve size of crops/fruit
Sheep- to produce more milk

82
Q

Why is genetic engineering controversial?

A

it has the potential for solving many of our problems but there are worries about long term affects

83
Q

What are the pros of GM crops?

A

increased yield, making more food

gm crops could be engineered to contain nutrients that you dont get in developed countries

84
Q

What are the cons of GM crops?

A

they can reduce farmland biodiversity
they are relatively new and people arent convinced they dont carry long term effects
Transplanted genes could get into the natural environment, creating super crops that are resistant to herbicides such as super weeds

85
Q

What are the 2 ways that plants can be cloned?

A

tissue culture

cuttings

86
Q

What is tissue culture?

A

where a few plant cells are put in a growth medium with hormones and grow into new plants/clones. they can be made quickly and made all year round to preserve rare plant species in plant nurseries

87
Q

What is a cutting?

A

gardeners cut off a piece of a good plant and then plant them to produce clones. they can be produced cheaply and quickly

88
Q

What are the 2 methods of cloning animals?

A

embryo transplants

adult cell cloning

89
Q

What is the process of embryo transplants?

A

sperm cells are taken from a prize bull and egg cells are taken from a prize cow and the egg is artificially fertilised to form embryos.
these clones are then implanted into other cows where they grow into baby calves.

90
Q

What is the process of adult cell cloning?

A

taking an unfertilised egg cell and removing its nucleus. then a different nucleus is inserted into an empty egg cell
this cell is given electric shocks which makes it divide
this this then implanted in the womb of an adult sheep.

91
Q

How was dolly the sheep created?

A

Adult cell cloning

92
Q

What are fossils?

A

the remains of organisms from thousands of years ago which are found in rocks

93
Q

What are the 3 ways fossils are formed?

A

gradual replacement by minerals
casts and impressions
preservation in places where no decay happens.

94
Q

Do fossils show how life began?

A

nooooooooooooooo

there is a lack of evidence

95
Q

What is speciation?

A

the development of a new species

it often occurs when populations become so different that they can no longer interbreed

96
Q

What often leads to speciation?

A

Isolation of a species

Natural selection

97
Q

What can lead to speciation via isolation?

A

a physical barrier such as floods or earthquakes can geographically isolate species. conditions on each side of the barrier are slightly different so different characteristics develop

98
Q

How do you know a new species is formed in speciation?

A

eventually, the individuals will have changed so much that they wont be able to breed with each other to reproduce fertile offspring

99
Q

What are the 3 stages of speciation?

A

physical barrier seperates population
populations adapt to new environments
they change so much that they can no longer interbreed

100
Q

Who was Alfred Russel Wallace?

A

a scientist who studied beetles
he worked around Darwins time
he independently came up with the idea of natural selection

101
Q

Why was Alfred Russel Wallace important?

A

he prompted Darwin to publish origin of species in 1859

he provided evidence for natural selection as he travelled the world

102
Q

Why can bacteria become resistant?

A

random mutations can lead to bacteria being less effected by a certain antibiotic

103
Q

Why are antibiotic bacteria a problem?

A

there is no treatment so the infection easily spreads between people

104
Q

Why is it important to take a full course of bacteria?

A

taking the full course ensures that all bacteria are destroyed so there are none left to mutate into resistant strains

105
Q

Why is antibiotic resistance becoming more common?

A

doctors are prescribing them for non serious conditions and viruses and he more often they are used, the bigger the problem is

106
Q

What is the linnaean system?

A

a classification system that classifies organisms based on characteristics and structures

107
Q

How do you spell Linnaean

A

lin-na-e-an

108
Q

What is the order of the linnaean system?

A 
kingdom
phylum
class
order
family
genus
species
109
Q

What happened to the classification system as microscopes improved?

A

it changed from the Linnaean system to the three domain system

110
Q

What is the 3 domian system?

A

organisms are first split into 3 domains then the linnaean smaller groups are applied

111
Q

What is the genus of castor fiber?

A

castor

112
Q

On an evolutionary tree, what do closer branches represent?

A

closely related species

GCSE Biology- AQA (7 decks)

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