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

Topic 4 - Natural Selection And Genetic Modification Flashcards

1
Q

What is evolution?

A

Gradual change in inherited traits within population over time

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2
Q

How does evolution occur?

A

Natural selection

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3
Q

Outline the theory of natural selection

A

Genetic variation exists due to mutations
Selection pressures exist
Random mutation gives selective advantage
Organism better adapted and survives
Organism reproduces passing on alleles
Frequency of advantageous alleles increases.

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4
Q

Why does competition between organisms in a habitat exist?

A

Resources within a habitat required for survival are limited

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5
Q

Give some examples of competition between organisms within a habitat

A

Animals - food, shelter, mates…

Plants - lights, water, minerals…

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6
Q

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

A

Genetic variation exists due to spontaneous mutations.
Antibiotics act as selection pressure.
Mutations give bacterium antibiotic resistance.
Bacterium better adapted survive.
Reproduces passing on resistant gene.

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7
Q

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

A

Bacteria reproduce rapidly, allowing fist hand observation of evolution

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8
Q

How can the observation of fossils provide evidence for evolution?

A

Older fossils contain simpler organisms.
Newer fossils contain more complex organisms.
Can be organised in chronological order, observe changes in time.

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9
Q

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

A

Studied variety of organisms whilst travelling around world on HMS beagle.
Noted that traits can be passed from parents to offspring.
Proposed idea of ‘survival of fittest’

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10
Q

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

A

Similar to Darwin’s.

Gathered more evidence.

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11
Q

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

A

Enables classification of organisms

Influences modern medicine - importance of finishing antibiotic treatments

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12
Q

What fossils have provided evidence for human evolution?

A

Ardi - 4.4 million years old
Lucy - 3.2 million years old
Leakey discovered 1.6 million year old fossils

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13
Q

What clues does Ardi give scientists about human evolution?

A

Female hominid fossil shows phenotypic traits which encompass characteristics of humans and apes.
Ape: long arms, large toes
Human: bone structure suggests upright walking

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14
Q

What clues does Lucy give scientists about human evolution?

A

Female hominid fossil shows phenotypic traits more human like than Ardi
Structure of bones and feet more adapted to walking
Brain size close to ape

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15
Q

How did Leakeys findings provide evidence for human evolution?

A

Discovered many hominid fossils.

1.6 million year old fossil Turkana Boy showed traits comparable to that of modern day humans

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16
Q

How has the development of stone tools provided evidence for evolution?

A

Correlation between development of complex tools and increased brain size.
Older tools = more basic

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17
Q

Describe methods used by scientists to date tools

A

Carbon 14 dating - estimating age of carbon containing material found in tools/alongside tools.
Stratigraphy - using age of layers of sediment around tool as indictor

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18
Q

What’s a pentadactyl limb?

A

Limb with 5 digits present in animals, birds, reptiles and amphibians

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19
Q

How does the pentadactyl limb provide evidence for evolution?

A

Presence of pentadactyl limb suggests all species which posses it have descended from common ancestor.

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20
Q

What is classification?

A

Organisation of organisms into groups

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21
Q

What is taxonomy?

A

Classification of organisms into taxa

22
Q

What are the taxas ?

A

Kingdom, phylum, class, order, family, genus, species.

23
Q

Name the 5 kingdoms.

A 
Animals
Protists
Plants
Fungi
Prokaryotes
24
Q

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

A

Decreases

25
Q

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

A

Organisms not closely related may look/act similar if live in same environment.
Closely related species may look different if live in diff habitats

26
Q

What advancements in science have led scientists to reconsider the 5 kingdoms classification system?

A

Microscopes
Biochemistry
DNA and RNA analysis

27
Q

Describe the 3 domains system of classification

A

Organisms are initially divided into an extra 3 groups: archaea, bacteria & eukarya.

28
Q

Which domain do eukaryotic organisms belong to?

A

Eukarya

29
Q

Which domains do prokaryotic organisms belong to?

A

Archaea and bacteria

30
Q

Describe the domain bacteria

A

Consists of true bacteria (eg e.coli)

31
Q

Describe the domain archaea

A

Consists of primitive microorganisms.

Contains extremophiles - adapted to live in extreme conditions

32
Q

What is selective breeding?

A

Artificially selecting organisms with desirable characteristics and breeding them to produce offspring with similar phenotypes

33
Q

Outline the main steps involved in selective breeding

A

Identify desired characteristic
Select parent organisms showing traits and breed them
Select offspring with desired traits and breed them
Process repeated

34
Q

Main advantage of selective breeding?

A

Creates organisms with desirable features.

35
Q

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

A

Medical research

Sports eg horse racing

36
Q

Outline disadvantages of selective breeding

A

Reduction in gene pool (harmful if environmental change occurs)
Inbreeding = genetic disorders
Development of other physical problems
Potential to unknowingly select harmful recessive alleles

37
Q

How can plants be cloned?

A

Taking plant cuttings

Tissue culture

38
Q

What is tissue culture?

A

Method of growing living tissue in a suitable medium

39
Q

Describe how plants are grown using tissue culture

A

Select a plant that shows desired characteristics
Cut multiple sample pieces from meristem tissue
Grow in Petri dish containing growth medium
Transfer to compost for further growth

40
Q

What must be ensured when preparing tissue cultures?

A

Ensure aseptic conditions to prevent contamination by microorganisms

41
Q

What does the growth medium contain?

A

Nutrients and growth hormones

42
Q

What are the advantages of growing plants by tissue culture?

A

Fast and simple process
Requires little space
Enables growth of many plant clones w same characteristics
Useful in preservation of endangered plant species

43
Q

What are the disadvantages of growing plants by tissue culture?

A

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

44
Q

Why is animal tissue culturing useful?

A

Useful in preparation of tissue samples for medical research

Enables investigation of how different factors may affect a specific animal tissue, without harming animal

45
Q

Describe how animal tissue cultures are prepared

A

Extract sample of tissue from animal
Use enzymes to separate cells in sample
Grow in culture vessel containing growth medium
Store sample

46
Q

What is genetic engineering?

A

Modification of genome of organism by insert action of desired gene

47
Q

Describe 1 step of genetic engineering

A

DNA cut at specific base sequences by restriction enzymes to create sticky ends

48
Q

2 step of genetic engineering

A

Vector DNA cut using same restriction enzymes to create complementary sticky ends

49
Q

3 step of genetic engineering

A

Ligase enzymes join sticky ends of DNA and vector DNA forming recombinant DNA

50
Q

4 step of genetic engineering

A

Recombinant DNA mixed with and taken up by target cells

51
Q

What is a vector

A

Structure that delivers desired gene into recipient cell (eg plasmids)

GCSE - Biology (7 decks)

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