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GCSE Biology - Paper 1 > SB4 - Natural Selection and Genetic Modifications > Flashcards

SB4 - Natural Selection and Genetic Modifications Flashcards

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1
Q

What is evolution?

A

Slow and continuous change of organisms’ inherited characteristics from one generation to another

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2
Q

Name the process that drives evolution

A

Natural selection

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3
Q

Name the scientist that came up with the theory of evolution

A

Charles Darwin

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4
Q

Explain the theory of evolution by natural selection

A

Genetic variation in a population gives some organisms a survival advantage over others when faced with certain selection pressures. The better suited organisms are more likely to survive, reproduce and pass on their beneficial alleles to their offspring

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5
Q

Whilst travelling, what did Darwin notice about individuals in a species?

A

There was variation in their characteristics

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6
Q

What did Darwin notice about each of the characteristics of the species he observed?

A

They were the characteristics that were best suited for that environment

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7
Q

Name the other scientist who also came up with the idea of natural selection

A

Alfred Russel Wallace

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8
Q

Explain why classification of living organisms is a result of evolution. All living things have a common ancestor

A

Organisms are classified according to how related they are

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9
Q

What is ‘selection pressure’?

A

The things that affect an organism’s chance of surviving and reproducing

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10
Q

Name two examples of selection pressures

A

Predation, competition for food, competition for water, competition for mates, disease

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11
Q

Explain how antibiotic resistance develops in bacteria

A

Some bacteria are more resistant to antibiotics than others. The more resistant bacteria survive longer when a person takes antibiotics. If people do not finish the antibiotic course, some of the most resistant bacteria will survive. They will then replicate and pass on antibiotic resistance to other bacteria

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12
Q

Why is antibiotic resistance in bacteria evidence for evolution?

A

It is an example of natural selection taking place that we can observe

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13
Q

What is a fossil?

A

A trace of an organism that lived a very long time ago - usually millions of years ago

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14
Q

Why are fossils important evidence to show how life has developed?

A

Fossils can be arranged in chronological order to show the gradual changes in the organism to show how species have changes and developed over billions of years

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15
Q

Why are there gaps in fossil records?

A

Most dead organisms are not turned into fossils - they decompose and therefore do not leave a trace

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16
Q

What are hominids?

A

Human beings and their ancestors

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17
Q

How did the skulls of hominids change over the past six million years?

A

Older skulls are smaller and more ape-like

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18
Q

What is Ardi’s species name?

A

Ardipithecus ramidus

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19
Q

How old is ‘Ardi’?

A

4.4 million years old

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20
Q

Describe the structure of Ardi’s feet and suggest what this says about her movement

A

She had ape-like big toe to grasp branches which suggested Ardi climbed trees

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21
Q

What does the structure of Ardi’s legs and arms suggest about her movement?

A

She had short legs and walked upright. She had long arms but didn’t use her hands to help her walk

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22
Q

What is Lucy’s species name?

A

Australopithecus afarensis

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23
Q

When did Lucy walk the planet?

A

3.2 million years ago

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24
Q

Who is closer related to humans: Lucy or Ardi?

A

Lucy

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25
Q

Describe Lucy’s feet that showed that she was more adapted to walking than climbing

A

Lucy had arched feet and no ape-like big toe

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26
Q

Where was a fossil of ‘Homo Erectus’ named ‘Turkana boy’ found in 1984?

A

Kenya

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27
Q

How old is the Turkana boy fossil?

A

1.6 million years old

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28
Q

How does the record of stone tools provide evidence for different ‘Homo’ species evolution?

A

Stone tools were very simple at first. At time passed the tools become more complex. Human brains must have been getting larger

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29
Q

Describe how the fossil of ‘Homo Erectus’ is different to Lucy

A

His short arms and long legs were more human-like in proportions, his brain size was larger than Lucy’s and more human-like, he was more adapted to walking upright compared to Lucy

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30
Q

When did ‘Homo Habilis’ live?

A

Between 2.5 and 1.5 million years ago

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31
Q

Describe the simple stone tools and how they were used by ‘Homo Habilis’

A

Simple tools called ‘pebble tools’ made by hitting rocks together to make sharp flakes that were then used to scrape meat from bones, to skin animals, and to crack bones open

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32
Q

When was ‘Homo Erectus’ walking the planet?

A

Between 2 and 0.3 million years ago

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33
Q

How were stone tools made by ‘Homo Erectus’ different to ‘Homo Habilis’?

A

Sculpting rocks into complex shapes allowed specialised tools to be developed, (e.g. simple hand-axes). Tools could be used for hunting, digging, copping and scraping meat from bones

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34
Q

When did ‘Homo Neanderthalensis’ live?

A

Between 300,000 and 25,000 years ago

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35
Q

Describe some of the more complex tools that ‘Homo Neanderthalensis’ used

A

Flint tools with sharp, pointed edges and wooden spears

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36
Q

When did the first ‘Homo Sapiens’ appear?

A

Around 200,000 years ago

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37
Q

Name some of the more specialised pointed tools that ‘Homo Sapiens’ were using from around 50,000 years ago

A

Fish hooks, needles and arrowheads

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38
Q

What is stratigraphy?

A

The study of rock layers

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39
Q

How do scientists use stratigraphy to date tools and fossils?

A

A tool or fossil must have been present at the time the layer of rock was formed. Older rock layers are usually found below newer layers of rock. Tools or fossils found lower down in deeper layers are usually older

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40
Q

If carbon is found in a fossil or tool, how can it be used to date the item?

A

Use Carbon-14 dating

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41
Q

Describe how the dating technique that uses carbon works

A

All carbon-based material contains a small amount of 14C which decreases over time. The amount of 14C is measured and can be used to date the object

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42
Q

How can rocks be dated using a radio metric dating?

A

Measuring the content of other radioactive compounds in the rock (e.g. potassium-argon and uranium-lead dating)

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43
Q

What is a pentadactyl limb?

A

A limb with five digits

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44
Q

How is the pentadactyl limb evidence for evolution?

A

The similarity of bone structure shows that species with a pentadactyl limb have evolved from a common ancestor

45
Q

Name the five kingdoms used in classification

A

Animals, Plants, Fungi, Prokaryotes, Protists

46
Q

Name the seven subdivisions of the five-kingdom classification method

A

Kingdom, Phylum, Class, Order, Family, Genus, Species [King Philip Came Over From Germany Swimming]

47
Q

Name the subdivisions of the Three Domain classification system

A

Eukaryotes, Archaea, Bacteria

48
Q

Explain why the three-domain classification system is more accurate than the five-kingdom classification method

A

Over time, technology has developed and DNA sequencing shows more detail about the interrelatedness of species

49
Q

Explain why Carl Woese decided that the Prokaryote kingdom should be split into two groups

A

The DNA and RNA sequences of organisms in the Archae domain is different to the Bacteria domain

50
Q

What is selective breeding?

A

When humans artificially select the organisms they are going to breed so that the genes for particular characteristics remain in the population

51
Q

Why are organisms selectively bred?

A

To develop features that are useful or attractive to humans

52
Q

Suggest two characteristics that cattle breeders would select for

A

Animals that produce more milk or more meat, or better tasting meat

53
Q

Suggest two characteristics that crop farmers would select for

A

Plants with more disease resistance, more resistance to pests, increase size of crop, more drought resistance, more vitamins in crop, bigger fruit

54
Q

List the four steps of the basic process of selective breeding

A
  1. Select individuals that have the desired characteristics
  2. Breed the selected individuals with each other
  3. Select the best of the offspring and breed them together
  4. Repeat the process over several generations to make the desirable trait stronger and stronger until all offspring have the desired characteristic
55
Q

What can selective breeding be used for in agriculture?

A

Improve yields

56
Q

Describe how selective breeding can be used in medical research into alcoholism

A

Researchers bred rats with either a strong preference for alcohol or a weak preference for alcohol. Researchers can compare the differences between the two different types of rats to help improve our understanding and possible treatment pathways

57
Q

What is the main problem with selective breeding?

A

It reduces the gene pool - the number of different alleles in a population

58
Q

The wild mustard plant has been selectively bred to produce a wide variety of vegetables. What characteristic was selected for to produce cauliflowers?

A

Clusters of flowers

59
Q

What characteristic was selected for to produce Brussel sprouts?

A

Side buds on the stem

60
Q

What characteristic was selected for to produce kohlrabi?

A

Swollen stem

61
Q

What characteristic was selected for to produce cabbage?

A

A big bud at the top of the plant

62
Q

What characteristic was selected for to produce broccoli?

A

Stems and flowers

63
Q

What is ‘inbreeding’?

A

When people keep breeding from the ‘best’ animals or plants they end up breeding with closely related individuals

64
Q

What can inbreeding cause?

A

Health problems - more likely to inherit harmful genetic defects when the gene pool is limited

65
Q

Why is inbreeding a problem if a new disease appears?

A

The lack of variation in the population means that there is less chance of resistance alleles being present in the population

66
Q

What is tissue culture?

A

When cells are grown on or in an artificial growth medium

67
Q

Can tissue culture be used to produce whole plants from the cells of a single individual?

A

Yes

68
Q

Can tissue culture be used to produce whole animals from the cells of a single individual?

A

No

69
Q

Can tissue culture be used to produce animal cells and tissues from the cells of a single individual?

A

Yes

70
Q

Give three advantages of plant tissue culture

A

Plants can be grown quickly, in very little space and grown all year around, clones will have the same beneficial features (e.g. pest resistance)

71
Q

The plants produced via tissue culture are clones. What does this mean?

A

Genetically identical organisms

72
Q

List the four steps to culture plant tissue

A
  1. Choose plant to clone based on its beneficial characteristics
  2. Remove several small pieces of tissue from the parent plant - fast-growing root and shoot tips are best
  3. Grown the tissue on a growth medium under aseptic conditions
  4. As the tissues produce shoots and roots, they can be removed and placed in potting compost to carry on growing
73
Q

What are ‘aseptic conditions’?

A

Sterile conditions

74
Q

Explain why aseptic conditions are important

A

To prevent growth of microbes that could harm the plants

75
Q

Explain why animal tissue culture is often used in medical research

A

Scientists can carry out investigations on tissues in isolation to look at the effects of different changes on the cells of a single tissue. No animals are harmed during this process, reducing the number of animals needed for medical research

76
Q

List the five steps to tissue culture animal cells

A
  1. Take a sample of the tissue to be studied from an animal
  2. Separate the cells in the sample using enzymes
  3. Individual cells are placed into a culture vessel containing growth medium
  4. After several rounds of cell division, the cells can be split up again and placed into separate vessels to encourage more growth
  5. Tissue culture can be stored to be used in the future
77
Q

A scientist trying to save the rare plant species Wood Calamint from extinction decides to use tissue culture to grow more plants. Describe a method of tissue culture that the scientist would use

A

Take small pieces of tissue from the root and shoot ups of one of the remaining Wood Calamint plants. Grow the tissue samples under aseptic conditions in a growth medium that contains nutrients and growth hormones. Once shoots and roots start growing from the tissues, move them to potting compost to continue growing

78
Q

Suggest one reason why the scientist chose to use tissue culture to save the Wood Calamint

A

New Wood Calamint plants can be grown quickly, in very little space, throughout the year, lots of plants can be grown from one parent plant, there are too few Wood Calamint plants for normal breeding methods

79
Q

When viruses infect animal cells, they replicate inside them. To develop new vaccines against viruses, scientists need lots of animal cells. Explain why scientists use tissue culture to produce these cells

A

Scientists want to be able to study the effects of the vaccines on animal cells in isolation, they want lots of identical cells to test the vaccines on, to ensure a fair test

80
Q

What is genetic engineering?

A

When a gene from one species genome is transferred into another organism’s genome in order to introduce a desirable characteristic

81
Q

The genes for which characteristic has been inserted into a bacteria genome in order to help people with diabetes?

A

Genes to make the protein insulin

82
Q

What is used to cut out the gene that is to be transferred during genetic engineering?

A

A restriction enzyme

83
Q

How do restriction enzymes cut DNA at specific points?

A

Restriction enzymes recognise specific sequences of DNA and only cut the DNA at those points

84
Q

What is a ‘sticky end’ produced during genetic engineering?

A

The end of the DNA strand that has unpaired bases

85
Q

What is vector DNA?

A

Something used to transfer DNA into a cell

86
Q

Give an example of a vector DNA

A

Plasmids (small, circular molecule of DNA)

87
Q

What type of restriction enzyme is used to cut open the vector DNA?

A

The same restriction enzyme used to cut the gene from the original DNA strand

88
Q

Explain why the same restriction enzyme used to cut the gene from the original DNA strand is so important

A

To ensure the vector DNA and the DNA being inserted have complementary sticky ends (complementary sticky ends)

89
Q

Name the enzyme used to join the sticky ends of the gene and vector DNA together

A

Ligase enzymes

90
Q

What do we call the two different bits of DNA once they are joined together?

A

Recombinant DNA

91
Q

Once the gene and plasmids are joined together, what happens next during the process of genetic modification?

A

The recombinant plasmids are inserted into bacteria which are then grown in big vats of culture medium

92
Q

Give an ethical concern about the genetic engineering of animals

A

It can be hard to predict what effect modifying a genome will have on an animal

93
Q

Give a practical concern about growing genetically modified crops

A

Transplanted genes may get out into the environment, genetically modified crops might adversely affect food chains

94
Q

Why could GM crops be a benefit as the world’s population is rising very quickly?

A

GM crops can increase the amount of food that a crop provides, some GM crops are able to grow better in drought conditions, GM crops could be engineered to contain certain nutrients, combatting deficiency diseases

95
Q

What is ‘Golden rice’ and what can it prevent?

A

Rice that has been engineered to produce a chemical that the body converts into vitamin A, to prevent vitamin A deficiency which can lead to blindness

96
Q

State a concern about genetically modified crops

A

Fears that countries could become dependent upon companies who sell GM seeds, even GM crops cannot survive in cortina areas where cops fail because the soil is so poor, worries about possibility of long term effects of exposure to GM crops

97
Q

What does Bt stand for?

A

Bt stands for Bacillus thuringiensis which is a type of bacteria that produces a toxin that kills many insect larvae that harm crops

98
Q

Describe how genetic engineers are using the gene for the Bt toxin

A

The Bt gene can be inserted into the genome of crops which then produce the toxin in their stems and laves. This makes them more resistant to insect pests

99
Q

Explain how Bt crops can improve yield

A

Insects that usually eat the crops are killed by the toxin. Less plant gets eaten so it can photosynthesise more and grow faster

100
Q

Explain how Bt crops reduce the need for chemical pesticides and why this is a benefit

A

Chemical pesticides can be harmful to good insects and the environment. Bt crops require less pesticide use because insects are killed by the Bt toxin

101
Q

Give one concern about the use of Bt crops on the insects that feed on them

A

There is a danger that the insects will develop resilience to the Bt toxin

102
Q

What can be added to poor soil to help plants grow?

A

Fertilisers

103
Q

What do fertilisers contain?

A

Minerals like nitrates, phosphates and potassium

104
Q

What problem can be caused by the excessive use of fertilisers?

A

Eutrophication

105
Q

What can eutrophication cause?

A

Algal blooms and the death of aquatic organisms due to the absence of oxygen in the water

106
Q

What are ‘biological control methods’?

A

Using other organisms (e.g. predators and parasites) to reduce the pest numbers

107
Q

Which animal species was introduced to Australia to control beetles that were damaging sugarcane crops?

A

Cane toads

108
Q

Which animal species can be used to control aphid populations?

A

Ladybirds and parasitic wasps

109
Q

Explain why the animal species introduced to Australia is now a pest species itself

A

No native Australian predator species can eat the toads because they are poisonous

GCSE Biology - Paper 1 (5 decks)

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