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GCSE - biology > B4 - natural selection and genetic modification > Flashcards

B4 - natural selection and genetic modification Flashcards

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1
Q

Define evolution

A

A gradual change in the characteristics of a species over time

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2
Q

What is the genus of a binomial name

A

Capital letter
Eg. Homo (in Homo sapiens)

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3
Q

What is the species in a binomial name

A

Lowercase letter
Eg. sapien (in Homo sapiens)

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4
Q

Why can’t scientists be certain species evolved from one another

A

Gaps in fossil records

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5
Q

How are stone tools dated from their environment?

A

Scientist date, the layers of sediment where the stone tool was found

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6
Q

Ardi (Ardipithecus ramidus)

A
  • 4.4 million years ago
  • 1.2m tall, 50kg
  • leg bones suggest upright walking
  • long arms and long big toes suggest tree climbing
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7
Q

Lucy (Australopithecus afarensis)

A
  • 3.2 million years ago
  • arched feet (walking not climbing)
  • toes more curved than modern arrangement
  • leg bones and feet suggest walked more efficiently than Ardi
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8
Q

Handyman (Homo habilis)

A
  • 2.4-1.4 million years ago
  • short height, long arms, walked upright
  • smaller face and teeth than Lucy
  • thought to be the first makers of stone tools
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9
Q

Homo Erectus

A
  • 1.6 million years ago
  • tall and strongly built
  • short arms and long legs (more human like)
  • walk upright
  • developed and used stone tools
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10
Q

Homo sapiens

A
  • 195,000 years ago - present
  • evolved from Africa
  • lighter build skeleton
  • less heavy jaws and smaller teeth
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11
Q

What are humans and ancestors called

A

Hominids

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12
Q

How have stone tools created by human-like species developed over time

A

They have increased in complexity

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13
Q

Why might stone tools have become more complex over time

A
  • changes in hunting techniques
  • increased intelligence and dexterity (supported due to increasing brain sizes)
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14
Q

Causes of genetic variation

A

Sexual reproduction and mutations

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15
Q

What is evolutionary fitness

A

Ability to reproduce and survive in an environment

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16
Q

How do adaptations allow species to survive

A

Animals with characteristics that make them better adapted to selection pressures in their environment have a better chance of survival and so are more likely to breed successfully

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17
Q

What is a selection pressure, give eg

A

Factors that affect an organisms chance of survival and reproduction
Eg. Predation, competition and disease

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18
Q

How can natural selection lead to the evolution of new species

A
  • organisms with advantageous characteristics breed, and pass on the useful alleles
  • This process causes species change over time
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19
Q

Which scientist had theory of natural selection and evolution?

A

Charles Darwin

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20
Q

How does the development of resistance in organisms support Darwin’s theory?

A
  • Random mutations in the DNA of bacteria, cause antibiotic resistance
  • When the host gets treated with antibiotics are non-resistant bacteria, die out, leaving a population of mostly resistant bacteria
  • The resistant bacteria reproduce passing on the resistant allele, which becomes more common in the population over time
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21
Q

How were organisms originally classified?

A

According to similarities and differences in their observable characteristics
- As technology improved, this came to include cell structure
Then they are subdivided into smaller groups of common features and DNA

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22
Q

order of the five kingdom classification system

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

King prawn curry or fat greasy sausages

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23
Q

What are the five kingdoms?

A
  • Animals
  • Plants
  • Fungi
  • Prokaryotes
  • Protists
24
Q

Characteristics of animals

A
  • multicellular
  • Cells have nuclei
  • No cell walls
25
Q

Characteristics of plants

A
  • multicellular
  • chloroplasts for photosynthesis
  • Cells have nuclei
  • Cellulose cell walls
26
Q

Characteristics of fungi

A
  • multicellular (apart from yeasts)
  • Cells have nuclei
  • Cell walls contain Chintin not cellulose
27
Q

Characteristics of protists

A
  • Mostly unicellular
  • Cells have nuclei
  • Some have cell walls (not made of chintin)
    -Some have chloroplasts
28
Q

Characteristics of prokaryotes

A
  • unicellular
  • Cells don’t have nuclei
  • Flexible cell walls
29
Q

What is genetic analysis?

A

Determining and comparing the sequences of DNA bases in organisms

30
Q

Why are organisms now classified into three domains?

A

It was found that some organisms in the prokaryote kingdom weren’t is closely related as originally thought

31
Q

What are the three domains?

A
  • Eukarya
  • Bacteria
  • Archaea
32
Q

Characteristics of eukarya

A

Cells with a nucleus and genes with a unused sections of DNA

33
Q

Characteristics of bacteria

A

A cell without a nucleus, and no unused sections of DNA

34
Q

Characteristics of archaea

A

A cell without a nucleus and genes with unused sections of DNA

35
Q

Why are new breeds and varieties selectively bred?

A
  • disease tolerance
  • Greater crop yield
  • Size
  • Pet characteristics (dogs)
  • Fertility (sheep)
36
Q

What is a genetically modified organism (GMO)?

A

modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic

37
Q

How is selective breeding carried out?

A
  • Select organisms possess the desired characteristics
  • breed them with each other
  • Select the best offspring and breed them together
  • Continue this process over several generations, so the desirable trait get stronger and eventually all offspring will have the characteristic
38
Q

Risks of selective breeding

A
  • Gene pool is reduced (animals are closely related: inbreeding)
  • Health problems due to increase chance of inheriting genetic defects
  • Lack of variation, if a new disease appears less chance of resistant alleles, if one organism dies, the others are likely to as well (closely related)
39
Q

What is the restriction enzyme?

A

Enzymes that recognise specific sequences of DNA, cut the DNA at these points, leaving the DNA with sticky ends

40
Q

What are ligase enzymes?

A

Enzymes are used to join two pieces of DNA together at the sticky ends

41
Q

What is recombinant DNA?

A

Two different bits of DNA stuck together

42
Q

What is a vector?

A

Something that is used to transfer DNA into a cell (a carrier of something)

43
Q

Examples of vectors in genetic engineering

A

Plasmids and viruses

44
Q

What are plasmids?

A

Small molecules of DNA that can be transferred between bacteria

45
Q

Why can viruses be used as vectors?

A

Insert DNA into organisms, they infect

46
Q

The stages of genetic engineering of bacteria

A
  • gene wanted for insertion is cut open by restriction enzyme left with sticky ends
  • vector DNA is cut open with same restriction enzyme left with sticky ends
  • Ligase enzymes are used to join these pieces of DNA, making recombinant DNA
  • recombinant, DNA inserted into bacterial cells, which replicate the gene as they can reproduce quickly
47
Q

How are bacteria used to make insulin?

A

Genetic engineering process
Bacteria containing the gene for human insulin can be grown in large numbers in a fermenter

48
Q

What happens at sticky ends?

A
  • Restriction enzymes leave single strands of DNA with unpaired bases
  • Ligase enzymes match bases with complementary bases on the other sticky end
49
Q

Advantages of GM, golden rice

A

Greater quantity of vitamin A helps eyesight

50
Q

Disadvantages of GM, golden rice

A

Worries that it may damage, food chains or human health

51
Q

Advantages of GM, herbicide resistant plants

A

Increases crop yield as weeds are killed, but the plants can survive

52
Q

Disadvantages of GM herbicide resistant plants

A

The gene may be picked up by weeds, creating a new ‘super-weed’ variety

53
Q

Advantages of GM insulin

A

Can be produced in large amounts to meet demand

54
Q

Disadvantages of GM insulin

A

Can’t be used by all diabetics, as it is not the same as insulin from mammals

55
Q

Disadvantages of selective breeding

A
  • Takes much longer than genetic engineering
  • Animals might not necessarily pick up desired characteristic (chance)
56
Q

Benefits of genetically, modifying over selective breeding

A
  • genes are changed directly
  • Much quicker
  • Organisms are more likely to gain the desired characteristic

GCSE - biology (9 decks)

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