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GCSE Biology > Topic 4 - Natural Selection and Genetic Modification > Flashcards

Topic 4 - Natural Selection and Genetic Modification Flashcards

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1
Q

What is evolution?

A

The slow and continuous change of organisms from one generation to the next

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2
Q

What things act as selection pressures?

A

Predation, competition for resources and disease.

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3
Q

What do selection pressure affect?

A

An organisms chance of surviving and reproducing.

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4
Q

What do individuals with characteristics that make them better apart to selection pressure in their environment have?

A

A better chance of survival and so are more likely to breed successfully and pass on these alleles will be passed on to the next generation

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5
Q

What will happen to individuals that that are less adapted to the selection pressures?

A

They may be less able to compete and therefore less likely to survive and reproduce

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6
Q

What is bacteria becoming resistant to recently which is advantageous to them but bad for us?

A

They’re becoming resistant to antibiotics.

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7
Q

How does antibiotic resistance provide evidence for evolution?

A

It makes the bacteria better adapted to an environment in which antibiotics are present. As a result, antibiotic resistance becomes more common in the population over time.

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8
Q

What is a fossil?

A

An trace of animal that lived a long time ago

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9
Q

Where are fossils most commonly found?

A

In rocks

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10
Q

How can you tell how old a fossil in a rock is?

A

Usually the deeper in the rock it is, the older the fossil is.

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11
Q

How do fossils provide evidence for evolution?

A

By arranging fossils in chronological order, gradual changes in organisms can be observed. It shows how species have changed and developed over billions of years.

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12
Q

Who came up with the theory of evolution?

A

Charles Darwin

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13
Q

What idea did Wallace come up with?

A

The idea of natural selection

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14
Q

What was the link between the theory of evolution and the idea of natural selection?

A

Wallace’s observations provided lots of evidence to help support the theory of evolution by natural selection. For example, he realised that warning colours are used by some species to deter predators from eating them - an example of beneficial characteristics that had evolved from natural selection.

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15
Q

What does evidence from fossils suggest about what humans evolved from?

A

It suggests that humans and chimpanzees evolved from a common ancestor that existed around 6 million years ago

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16
Q

What is a hominid?

A

Human beings and their ancestors

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17
Q

What species is Ardi from?

A

Ardipithecus ramidus

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18
Q

Where was Ardi found and how old is she?

A

In Ethiopia and is 4.4 million years old

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19
Q

What were Ardi’s feet like and what does this suggest?

A

Ardi had an ape-like big toe to grasp branches suggesting she climbed trees

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20
Q

What were Ardi’s arms and legs like?

A

She had long arms and short legs (more like an ape than human)

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21
Q

What was Ardi’s brain size like?

A

Similar to a chimpanzees

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22
Q

What does the structure of Ardi’s legs suggest?

A

That she walked upright

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23
Q

What does Ardi’s hand bone structure suggest?

A

She didn’t use her hands to help her work (like apes do)

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24
Q

What species is Lucy from?

A

Australopithecus afarensis

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25
Q

How old Is Lucy?

A

3.2 million years old

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26
Q

What was Lucy’s feet like and what does this suggest?

A

Lucy had arched feet, more adapted to walking than climbing and no ape-like big toe.

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27
Q

What was Lucy’s brain like?

A

Slightly larger than Ardi’s but still similar in size to a chimp’s brain

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28
Q

What did the structure of Lucy’s leg bones and feet suggest?

A

Suggests she walked upright but more efficiently than Ardi

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29
Q

When was Homo Erectus around

A

2-0.3 million years old.

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30
Q

What were Homo Erectus’ arms and legs like in terms of length?

A

Long legs and short arms

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31
Q

What was Homo Erectus’ brain like?

A

Much larger than Lucy’s - similar to human brain size

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32
Q

What does the structure of Homo Erectus’ legs and feet suggest?

A

That he walked more upright than Lucy.

33
Q

When was Homo Habilis around?

A

2.5-1.5 million years ago

34
Q

When was Homo Neanderthalis around?

A

300,000-25,000 years ago

35
Q

When was Homo sapiens around?

A

200,000 years ago to present

36
Q

What is a pentadactyl limb?

A

A limb with five digits.

37
Q

How does a pentadactyl limb provide evidence for evolution?

A

It shows that species with a pentadactyl limb all have evolved from a common ancestor (that also had a pentadactyl limb)

38
Q

What are the groups in the five kingdom classification system and give examples for each group?

A

Animals - fish, mammals, reptiles etc.
Plants - grasses, tress etc.
Fungi - mushrooms, toadstools, yeasts etc.
Prokaryotes - all single-celled organisms without nucleus
Protists - algae etc.

39
Q

What is a protist?

A

A eukaryotic single-celled organism

40
Q

What are the kingdoms subdivided into?

A

Phylum, class, order, family, genus and species

41
Q

What classification system do we use today?

A

The three domain system

42
Q

Who came up with the three domain system?

A

Carl Woese

43
Q

What are the three groups in the three domain system?

A

Archaea
Bacteria
Eukarya

44
Q

What are archaea?

A

Organisms in this domain look similar to bacterial but are actually quite different - as differences in they DNA and RNA sequences show. They were first found in extreme places such as hot springs and salt lakes

45
Q

What does the bacteria group contain (with examples)?

A

Contains true bacteria like E.coli and Staphylococcus

46
Q

What does the eukarya group contain (with examples)?

A

Includes a broad range of organisms including fungi, plants, animals and protists.

47
Q

What is selective breeding?

A

When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population.

48
Q

Give examples of how animals, crops and plants can be selectively bred.

A

Animals that produce more meat or milk
Crops with disease resistance
Plants that produce bigger fruit

49
Q

What is the process of selective breeding?

A

1) From existing stock, select ones with desirable characteristics
2) Breed them with each other
3) Select the best of the offspring and breed then together
4) Continue this process over several generations, and the desirable trait gets stronger and stronger. Eventually all of the offspring will have the characteristic

50
Q

What is the main problem with selective breeding?

A

It reduces the gene pool - the number of alleles in a population because the “best” animals or plants are always used for breeding - and they are all closely related (inbreeding)

51
Q

What is the problem with inbreeding?

A

It can cause health problems because there’s more chance of the organisms inheriting harmful genetic defects when the gene pool is limited. This leads to ethical consideration particularly if the animals are deliberately bred to have negative characteristics for medical research.

52
Q

Why is selective breeding a problem if a new disease appears?

A

There’s not much variation in the population, so there’s less chance of resistant alleles being present. All the stock are closely related to each other, so if one is going to be killed by a new disease, the others are also likely to succumb to the disease.

53
Q

What is tissue culture?

A

Growing cells on an artificial growth medium to produce clones

54
Q

What are the benefits of tissue culture?

A

You can use tissue culture to create lines of plants with the same beneficial features e.g. pesticide resistance, tasty fruit etc.

55
Q

What are the stages of tissue culture?

A

1) First choose the plant you want to clone based on its characteristics
2) Remove several small pieces of tissue from the parent plant. You get the best results if you take tissue from fast-growing root or shoot tips
3) You grow the tissue in a growth medium containing nutrients and growth hormones. This is done under aseptic conditions to prevent the growth of microbes that could harm the plants
4) As the tissues produce shoots and roots they can be moved by potting compost to carry on growing

56
Q

What is animal tissue culture used for and why?

A

Medical research because it means you can look at the effects of a particular substance or environmental change on the cells of a single tissue, without complications from other processes in the whole organism

57
Q

What are the first two stages of animal tissue culture?

A

1) First, a sample of the tissue you want to study e.g. tissue from a pancreas, is extracted from the animal
2) The cells in the sample are separated from each other using enzymes

58
Q

What are the last three stages of animal tissue culture?

A

3) They are placed in a culture vessel and bathed in a growth medium containing all the nutrients that they need. This allows them to grow and multiply
4) After several rounds of cell division, the cells can be split up again and placed in separate vessels to encourage further growth
5) Once the tissue culture has been grown, it can be stored for future use

59
Q

What is genetic engineering?

A

Modifying an organisms genome to introduce desirable characteristics involving the use of enzymes and vectors.

60
Q

How are restrictions enzymes used in genetic engineering?

A

Restriction enzymes recognise specific sequences of DNA and cut the DNA at these points - the pieces of DNA are left with sticky ends where they have been cut

61
Q

How are ligase enzymes used in genetic engineering?

A

They are used to join two pieces of DNA together at their sticky ends

62
Q

What are two bits of DNA stuck together known as?

A

Recombinant DNA

63
Q

How is a vector used in genetic engineering?

A

It’s used to transfer DNA into a cell.

64
Q

What are the two types of vectors?

A

Plasmids and viruses

65
Q

What is a plasmid?

A

Small, circular molecules of DNA that can be transferred between bacteria.

66
Q

What is a virus?

A

They insert DNA into the organisms they infect

67
Q

What is the first step of genetic engineering?

A

1) The DNA you want to insert (e.g. the gene for human insulin) is cut out with a restriction enzyme. The plasmid DNA is then cut open using the same restriction enzyme.

68
Q

What is the second and third step of genetic engineering?

A

2) The plasmid DNA and the DNA you’re inserting are left with sticky ends. They are mixed together with ligase enzymes
3) The ligases join the pieces of DNA together to make recombinant DNA.

69
Q

What are the final stages of genetic engineering?

A

4) The recombinant DNA is inserted into other cells e.g. bacteria
5) These cells can now use the gene you inserted to make the protein you want e.g. bacteria containing the gene for human insulin can be grown in huge numbers in a fermenter to produce insulin for people with diabetes.

70
Q

How can genetic engineering be used in agriculture?

A

An example of this is that crops can be genetically modified to be resistant to herbicides which means farmers can spare their crops with it to kill the ends without affecting the crop itself. They can be also made resistant to insects pests. Both increase crop yield

71
Q

What are the concerns about growing genetically modified crops?

A

Transplanted genes may get out into the environment e.g. a herbicide resistance gene may be picked up by weeds, creating a new ‘superweed’ variety. Another concern is that genetically modified crops could adversely affect food chains - or even human health

72
Q

What are the concerns about genetic engineering of animals?

A

It can be hard to predict what effect modifying its genome will have on the organism - many genetically modified embryos don’t survive and some genetically modified animals suffer from health problems later in life.

73
Q

What is food security?

A

The global food production must increase so that we all have access to enough food that is safe for us and have the right balance of nutrition.

74
Q

How can GM crops be used to increase food production?

A

Crops that are genetically engineered to be resistant to pests or to grow better in drought conditions can help to improve crop yields. Moreover, some crops can be engineered to combat certain deficiency diseases.

75
Q

What are 3 arguments against genetically modifying crops to increase food production?

A

1) Many people argue that people go hungry because they can’t afford to buy food, not because there isn’t any food about. So they argue we need to tackle poverty first
2) There are fears that countries may become depends on companies who sell GM seeds
3) Sometimes poor soil is the main reason why crops fail, and even GM crops won’t survive

76
Q

If soil is in poor condition, what is the best way to increase yields?

A

Fertilisers as they contain minerals that are essential for plant growth - e.g. nitrates and phosphates

77
Q

What is the problem with fertilisers?

A

Excess fertilisers sometimes can cause problems in rivers and lakes through the process of eutrophication.

78
Q

How can pests be controlled without the use of GM crops of chemical pesticides?

A

Biological control

GCSE Biology (9 decks)

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