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Gcse Biology > Topic 4 - Natural Selection > Flashcards

Topic 4 - Natural Selection 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

Genetic variation exists due to spontaneous mutations
Selection pressured exist
Random mutation gives an organism a selective advantage
Organism is better adapted to the environment and survives
Organism reproduces, passing on its beneficial alleles
Frequency of advantageous alleles increase

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3
Q

Why does competition between organism in a habitat exist?

A

The resources within a habitat requires for survival are limited

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4
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 mutation

Antibiotics act as a selection pressure

Mutations gives a bacterium antibiotic-resistance

If an antibiotic is administered,the bacterium is better adapted and survives, whilst other bacteria are killed

Bacterium reproduces, passing on its resistant variant

Frequency of antibiotics-resistant allele increases

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5
Q

How can the observation of fossils provide evidence for evolution?

A
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6
Q

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

A

Enables the classification of organisms into taxa

Influences modern medicine by emphasising the importance of finishing antibiotics treatments and the need for constant production of new antibiotics.

Highlights the importance of high genetic diversity in habitats, which aids conservation projects.

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7
Q

What fossils have provide evidence for human evolution?

A

“Ardi’ - 4.4 million years old
“Lucy” - 3.2 million years old
Leakey discovered 1,6 million years ago

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8
Q

What clues does “ardi” gives scientists about human evolution?

A

Female hominid fossil. She shows phenotypic traits which encompass characteristics of both humans and apes.

Ape-like characteristic e,g long arms, large big toes

Human-like characteristic - structure of her bones suggest that she walked upright

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9
Q

What clues does “Lucy” gives scientists about human evolution?

A
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10
Q

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

A
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11
Q

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

A

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

Primitive tools are older than more complex tools. Brain size has increased over time, as brain size increases , advancements in tool use were made.

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12
Q

Describe the methods used by scientists to date tools

A
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13
Q

What is a pentadactyl limb?

A

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

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14
Q

How does the pentadactyl limb provide evidence for evolution?

A

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

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15
Q

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

A

Microscopes
Biochemistry
DNA and RNA analysis

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16
Q

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

A

Organisms that are not closely related may look alike and behave similarly if they live in the same environment e,g sharks and dolphins

Some closely related species may look very different if they live in different habitats e,g queen ants, worker ants

17
Q

Describe the three domains systems

A

Organism are initially divided into an extra three groups:

Archaea, Bacteria, Eukarya

18
Q

What is selective breeding?

A

The process by which humans artificially select organisms with desirable characters and breed them to produce offspring with similar phenotypes.

19
Q

Outline the main steps involved in selective breeding

A
20
Q

What is the main advantage of selective breeding?

A

Creates organisms with desirable features

Crops produce a higher yield of grain
Cows produce a greater supply of milk
Plants produce larger fruit
Domesticated animals

21
Q

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

A

In medical research

In sports e,g horse racing

22
Q

Outline disadvantages of selective breeding

A
23
Q

How can plants be clones

A

Taking plant cuttings

Tissue cultures

24
Q

What is tissue cultures?w

A

A method of growing living tissues in a suitable medium

25
Q

Describe how plants are grown using tissue culture

A

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

26
Q

What must be ensured when preparing tissue cultures?

A

Ensure Aspetic conditions to prevents contamination by microorganisms

27
Q

What does the growth medium contain?

A

Nutrients and growth hormones

28
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 same desirable characteristics
Useful in the preservation of endangered plant species

29
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

30
Q

Why is animal tissue culturing useful?

A

Useful in the preparation of tissue samples for medical research

Enables the investigation of how different factions may affect a specific animal tissue, without harming the animal itself

31
Q

Why is animal tissue culturing useful?

A

Useful in the preparation of tissue samples of medical research
Enables the investigation of how different factors may affect a specific animal tissue, without harming the animal itself.

32
Q

Describe how animal tissue cultures are prepared

A
33
Q

What is genetic engineering

A

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

34
Q

Describe the process of genetic engineering

A

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

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

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

Recombinant DNA mixed with and “taken up’ by target cells

35
Q

Describe the benefits of genetic engineering

A
36
Q

Describe the risks of genetic engineering

A

Gcse Biology (14 decks)

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