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Separate Biology Edexcel GCSE > 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

A gradual change in the inherited traits within a population over time

Occurs due to natural selection

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2
Q

Outline the theory of natural selection

A
  1. Genetic variation exists due to spontaneous mutations
  2. Selection pressures ( competition , disease) exists
  3. Random mutation gives an organism a selective advantage
  4. Organism is better adapted to the environment and survives
  5. Organisms reproduces, passing on it’s beneficial alleles
  6. Frequency of advantageous alleles increase
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3
Q

Why does competition between organisms in a habitat exist?

A

The resources within a habitat required for survival are limited

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4
Q

Give some examples of competition between organisms within a habitat

A

Competition between animals for food, shelter , Mayes

Competition between plants for light, water , minerals

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5
Q

Describe how antibiotic resistance in bacteria can be used as an example to illustrate the process of evolution

A
  1. Genetic variation exists due to spontaneous mutation
  2. Antibiotics act as a selection pressure
  3. Mutations give a bacterium antibiotic resistance
  4. If an antibiotic is administered, the bacterium is better adapted and survives whilst other bacteria are killed
  5. Bacterium reproduces, passing on its resistant variant
  6. Frequency of antibiotic resistance allele increases
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6
Q

Why is the development of antibiotic resistance in bacteria a good study for evolution?

A

Bacteria reproduce very rapidly, allowing the first hand observation of evolution

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7
Q

How can the observation of fossils provide evidence for evolution?

A

Older fossils ( found in rocks deeper in the ground) contain simpler organisms. Newer fossils ( found closer to the surface) contain more complex organisms. Comparisons of fossils show that simple organisms evolved into more complex life forms.

Fossils can be organised into chronological order, allowing the changes in organisms over time to be observed

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8
Q

Describe the role of Darwin in the development of the theory of evolution by natural selection

A
  • studied a variety of organisms whilst travelling around the world on the HMS Beagle
  • noted traits that can be passed from parents to offspring
  • proposed idea of survival of the fittest
  • established theory of natural selection and published his ideas in ‘On the origin of species”
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9
Q

Describe the role of Wallace in the development of the theory of evolution by natural selection

A
  • he proposed a theory of natural selection that was similar to Darwin’s although the mechanisms were different
  • he gathered greater evidence ( studying warning colouration in butterflies) to support the theory
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10
Q

How has the theory of evolution by natural selection impacted modern biology ?

A
  • enables the classification of organisms into taxa
  • influences modern medicine by emphasising the importance of finsineinf antibiotic treatment and the need for the constant production of new antibiotics
  • highlights the importance of high genetic diversity in habitats which aids conservation projects
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11
Q

What fossils have provided evidence for human evolution?

A
  • Ardi - 4.4 million years old
  • Lucy - 3.2 million years old
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12
Q

What clues does Ardi give scientists about human evolution ?

A

Female fossil. Show phenotype traits which encompass characteristics of both human and apes

  • ape like characteristics- long arms large big toes
  • human like characteristics- structure of her bones suggests she walked upright
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13
Q

What clues does Lucy give scientists about human evolution?

A

Female fossil - more human than Ardi

More adapted to walking than climbing
Brain size like an ape

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14
Q

How did Leakey’s findings provide evidence for human evolution?

A

He discovered many hominid fossils

The 1.6 million year fossil showed traits comparable to modern day humans

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15
Q

How has the development of stone tools provided evidence for evolution

A

Correlation between the development of more complex tools and an increase in brain size

Primitive tools are older than more complex tools. Brain size has increased over time. As brain size increased advancements in tools use was made

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16
Q

Describe methods used by scientists to date tools

A

Carbon 14 dating- estimating the age of carbon containing material that is found in tools or alongside tools

Stratigraphy- using the age of the layers of sediment surrounding the tool as an indicator of the age of the tool

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17
Q

What is a pentadactyl limb?

A

A limb with five digits present in animals , birds, reptiles, and amphibians

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18
Q

How does the pentadactyl limb provide evidence for evolution?

A

The presence of the pentadactyl limb suggests that all species which posses it have descended from a common ancestor

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19
Q

What is classification?

A

The organisation of organisms into groups

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20
Q

What is taxonomy?

A

The classification of organisms into a taxa: kingdom, phylum, class, order, family, genus, species

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21
Q

Name the five kingdoms

A

Animals
Plants
Fungi
Protists
Prokaryotes

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22
Q

What happens to the number of organisms in each taxon as you move down the hierarchy?

A

The number of organisms in each taxon group decreases

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23
Q

Traditionally, organisms were grouped based on similarities and differences in their anatomy and behaviour. What is the problem with this?

A

Organisms that are not closely re,aged may look alike and behave similarly if they live in the same environment

Some closely related species look very different if they live in different habitat

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24
Q

What advancements in science have led scientists to reconsider the five kingdoms classification system?

A

Microscopy
Biochemistry
DNA and RNA analysis

25
Q

Describe the three domains system of class

A

Organisms are initially dived into an extra three groups - archaea , bacteria , eukarya

26
Q

Which domain do eukaryotic organisms belong to?

A

Eukarya

27
Q

Which domain to prokaryotic organisms belong to?

A

Archea and bacteria

28
Q

Describe the domain bacteria

A

Consists of true bacteria - ecoli

29
Q

Describe the domain archea

A

Consists of primitive microorganisms

Contains extramophiles - adapted to live in extreme conditions

30
Q

What is selective breeding?

A

The process by which humans artificially select organs is with desirable characteristics and breed them to produce offspring with similar phenotypes

31
Q

Outline the main steps involved in selective breeding?

A
  1. Identify a desired characteristic- disease resistance
  2. Select a parent organisms that show the desired traits and breed them together
  3. Select offspring with the desired traits and breed them together
  4. Process repeated until all offspring have the desired traits
32
Q

What is the main advantage of selective breeding?

A

Creates organisms with a desirable features
- crops produce a higher yield of grain
- cows produce a greater supply of milk
- plants produce larger fruit
- domesticated animals

33
Q

Other than in agriculture, where else is selective breeding useful?

A

In medical, research
In sports - horse racing

34
Q

Outline the disadvantages of selective breeding

A
  • reduction in the gene pool ( which becomes especially harmful if sudden environmental changes occurs )

Inbreeding results in genetic disorders

Development of other physical problems - respiratory problems in bulldogs

Potential to unknowingly select harmful recessive alleles

35
Q

How can plants be cloned?

A

Taking plant cuttings

Tissue culture

36
Q

What is tissue culture?

A

A method of growing living tissue in a suitable medium

37
Q

Describe how plants are grown using tissue culture

A
  1. Select a plant that shows desired characteristics
  2. Cut multiple small sample pieces from meristem tissue
  3. Grow in a Petri dish contain g growth medium
  4. Transfer to compost for further growth
38
Q

What must be ensured when preparing tissue cultures

A

Ensure aseptic conditions to prevent contamination by microorganisms

39
Q

What does growth medium contain ?

A

Nutrients and growth hormones

40
Q

What are the advantages of growing plants by tissue culture?

A

-Fast and simple process
-Requires little space
-Enables the growth of many plant clones with the same desirable characteristics
- useful in the preservation of endangered plant species

41
Q

What are the disadvantages of growing plants by tissue culture?

A

Reduction in the gene pool
Plant clones often have a low survival rate
Could unknowingly increase the presence of harmful recessive alleles

42
Q

Why is animal tissue culturing useful?

A

Useful in the preparation of tissue samples for medical research

Enables the investigation of how different factors may affect specific animal tissue without harming the animal itself

43
Q

Describe how animal tissue cultures are prepared

A
  1. Extract a sample of tissue from an animal
  2. Use enzymes to separate cells within the sample
  3. Grow in a culture vessel containing growth medium
  4. Once grown, store the sample
44
Q

What is genetic engineering?

A

The modification of the genome of an organism by the insertion of a desired gene from another organisms

Enables the formation of an organism with beneficial characteristics

45
Q

Describe the process of genetic engineering

A
  1. DNA is cut at specific base sequences by restriction enzymes to create sticky ends
  2. Vector DNA cut using the same restriction enzymes to create complementary sticky ends
  3. Ligaments enzymes join the sticky ends of the DNA and vector DNA forming recombinant DNA
  4. Recombinant DNA mixed with and taken up by target cells
46
Q

What is a vector ?

A

A structure that delivers the desired gene into the recipient cell - plasmid a , viruses

47
Q

Describe the benefits of genetic engineering

A
  • increased crop yields for growing population - herbicide resistance , disease resistance
  • useful in medicine e.g insulin producing bacteria, antthrombin in goats,milk
  • GM crops produce scarce resources
48
Q

Describe the risks of genetic engineering

A

Long term effects of consumption of GM crops unknown

Negative environmental impacts e.g reduction in biodiversity, impact on food chain, contamination of non GM crops forming super weeds

Late onset health problems in Gm animals

GM seeds are expensive

49
Q

What is Bacillus thuringiensis ( Bt) ?

A

Insect larvae are harmful to crops
Bt is a bacterium which secrets a toxin that kills insect larvae

50
Q

How is genetic engineering used to protect crops against insects

A
  • the gene for toxin production in Bt can be isolated and inserted into the DNA of crops
  • Bt crops now secret the toxin which kills any insect larvae that feed on it
51
Q

What are the benefits of Bt crops?

A

Increase crop yield ( fewer crops damaged )
Lessens need for artificial insecticides
Bt toxin is specific to certain insect insect larvae so is not harmful to other organisms that ingest it

52
Q

What are the risks of Bt crops?

A

Long term effects of consumption of Bt crops unknown
Insect larvae may become resistant
Killing insect larvae reduces biodiversity

53
Q

Outline the agricultural methods of increasing food production

A

Intensive farming methods - battery farming and fertilisers and insecticides

Biological control

54
Q

What is the main advantage of intensive farming?

A

Increases crop yields

55
Q

What are the disadvantages of intensive farming methods?

A

Fertilisers can wash into nearby water sources and cause eutrophication

The use of herbicides and insecticide reduces biodiversity

Battery farming is often seen as unethical

56
Q

What is biological control?

A

When a new organism is introduced into an eco system to control a pest of pathogen

57
Q

What are the advantages of using biological control to increase food production?

A

The results of biological control generally last for a long period of time

The effects on wildlife are less sever

58
Q

What is the risk of using biological control?

A

Risk of the control organism becoming a pest

Separate Biology Edexcel GCSE (5 decks)

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