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CCEA GCSE Biology > Variation & Natural Selection > Flashcards

Variation & Natural Selection Flashcards

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1
Q

Antibiotics 


2 marks

A

Substance that controls the spread of bacteria in the body by killing them or stopping them reproducing.

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2
Q

Gene 


2 marks

A

A short length of DNA that codes for a particular characteristic.

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3
Q

Histogram

(1 mark)


A

A graphical representation of the distribution of numerical data.

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4
Q

Mutation 


(3 marks) 


A

Random + spontaneous change in the structure of a gene, chromosome or number of chromosomes.

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5
Q

Species

3 marks

A

Type of organism that is the basic unit of classification.

Individuals of different species are not able to interbreed successfully.

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6
Q

Continuous variation

3 marks

A

This is a gradual change in a characteristic across a population, e.g human height, mass + shoe size.

  • it is represented as a histogram.
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7
Q

Histogram should show

2 marks

A

Normal distribution, with most individuals around the average value + a few at the extremes.

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8
Q

Discontinuous variation

4 marks

A

Individuals will fit into a group – there are no intermediates.

e. g ability to roll your tongue, blood group + hand dominance
- it is represented as a bar chart.

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9
Q

How is Discontinuous Variation represented?

1 mark

A

Bar chart

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10
Q

Main Blood Groups

4 marks

A

A, B, AB, O

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11
Q

All Blood Groups

8 marks

A

A-, A+, B-, B+, O-, O+, AB-, AB+

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12
Q

Causes of Genetic Variations

7 marks

A

Changes to chromosomes or genes (DNA);

  • Mutations are random changes in the number of chromosomes or the structure of a gene.
  • Independent assortment during meiosis increases variation because it results in genetically different gametes.
  • The random nature of sexual reproduction also gives rise to variation.
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13
Q

Mutations are random changes in

4 marks

A

The number of chromosomes (e.g. Down syndrome)

or the structure of a gene (e.g. cystic fibrosis).

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14
Q

The random nature of sexual reproduction also gives rise to

1 mark

A

Genetic variation

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15
Q

Independent assortment during meiosis increases variation because

(1 mark)

A

It results in genetically different gametes.

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16
Q

Example of environmental variation

2 marks

A

Human height is genetically controlled but actual height reached will depend on the nutrition available.

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17
Q

Causes of Variation

2 marks

A

Genetic + Environmental factors

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18
Q

How is Continuous variation represented?

1 mark

A

As a histogram.

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19
Q

Natural selection

1 mark

A

Living organisms are adapted to their environments in order to survive.

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20
Q

Thorny devil

4 marks

A
  • Lizard native to the Australian Outback.
  • In between its scales; microscopic channels that catch + carry water.
  • Drink through their scales (like sipping through straws); by opening/ closing mouth
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21
Q

Fennec fox

4 marks

A
  • Has huge, bat-like ears to pinpoint their prey, even when buried under the shifting sands.
  • Ears also lined with blood vessels; help regulate + cool body temp.
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22
Q

Cuttlefish

3 marks

A
  • Can change colour + texture of their skin; disguise themselves as clumps of floating seaweed - as they stalk their prey or hide from predators.
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23
Q

Atlantic Bluefin tuna

3 marks

A
  • Has an internal heating sytem; special blood vessel structure allows them to maintain a body temp higher than the cold surrounding water.
24
Q

Competition makes adaptations for survival

1 mark

A

Very important - only the best adapted will survive.

25
Q

The theory of natural selection – Charles Darwin

4 marks

A

There is variation among the phenotypes of individuals in a population.

  • Competition (food etc) causes a struggle for existence.
26
Q

Differential survival

2 marks

A

The best-adapted individuals survive

+ the less well-adapted individuals do not survive.

27
Q

The Surviving Phenotype

2 marks

A

(The fittest) is able to reproduce;

- passes it’s beneficial gene to the next generation.

28
Q

Natural selection: antibiotic resistance

2 marks

A

There is variation within bacterial phenotypes.

Some are resistant to antibiotics and some are not.

29
Q

Resistant individuals survive + non-resistant individuals do not survive

(1 mark)

A

Differential survival.

30
Q

The Resistant Bacteria

3 marks

A

Increase in number - able to reproduce; pass on the resistance gene to the next generation.

31
Q

Resistant individuals

1 mark

A

Survive

32
Q

Non-resistant individuals

1 mark

A

Do not survive.

33
Q

Gene for antibiotic resistance

2 marks

A

Usually caused by a beneficial mutation in the bacterial cells.

34
Q

Bacterial phenotypes

2 marks

A

Some are resistant to antibiotics + some are not.

35
Q

Treating Bacteria with Antibiotics

1 mark

A

Provides competition.

36
Q

Evolution

3 marks

A

A continuing process of natural selection - leads to the gradual change of an organism over time.

  • May result in the formation of a new species.
37
Q

Darwin used the theory of natural selection to

1 mark

A

Explain the process of evolution.

38
Q

Fossils

2 marks

A

Remains of living organisms that have been preserved in rock for millions of years.

39
Q

Fossils provide

4 marks

A

Evidence for evolution by showing how an organism looked millions of years ago + how it has changed over time.

  • They have provided us with info on some extinct species.
40
Q

Extinction

1 mark

A

Species are extinct if there are no living examples left.

41
Q

Cause of Extinction

2 marks

A

Species fails to adapt to changes in its environment.

42
Q

Examples of Extinct Species

2 marks

A

Dinosaurs + dodos.

43
Q

Cause of the Extinction of Dinosaurs

1 mark

A

Meteor strike.

44
Q

Cause of the Extinction of Dodos

1 mark

A

Hunted by humans.

45
Q

Endangered species

1 mark

A

Species that are at risk of becoming extinct.

46
Q

Cause of the Extinction of a Species

8 marks

A
  • Climate change.
  • Natural disaster.
  • Hunted by humans.
  • Hunted by non-native animals (introduced by humans).
  • Disease.
  • Loss of habitat (e.g. deforestation).
47
Q

Extinction can be avoided by:

8 marks

A
  • Legislation; preventing hunting
  • International agreements; limit climate change.
  • Special programmes; Nature reserves.
  • Education; encourages people to do their part.
48
Q

How can Legislation help prevent the extinction of a Species

(1 mark)

A

Preventing the hunting of endangered species.

49
Q

How International agreements can help prevent the Extinction of a Species

(1 mark)

A

Agreements that plan to limit climate change.

50
Q

What Special programmes can help prevent the Extinction of a Species?

(2 marks)

A

Nature reserves to protect habitats.

51
Q

How can Education help prevent the Extinction of a Species?

1 mark

A

Encouraging people to do their part in protecting the environment.

52
Q

Selective Breeding/Artificial Selection

4 marks

A

Manipulating natural selection by selecting desirable characteristics in crop plants/domesticated animals that are of use to humans.

53
Q

Selective Breeding/Artificial Selection Process

4 marks

A

Humans select individual plants/animals with desirable characteristics (e.g increased crop yield, disease resistance + longer shelf life).

  • Are then bred to produce offspring.
54
Q

Repeated Selection + Breeding Over Many Generations

1 mark

A

Results in all offspring containing the desirable characteristic.

55
Q

Wheat has been bred over many years to produce these characteristics:

(5 marks)

A
  • Shorter stalk length less likely to suffer wind damage;
  • Uniform size that’s easier to harvest;
  • Larger yield.
56
Q

Benefits of Shorter Stalk Length in Wheat

(1 marks

A

Less likely to suffer wind damage.

57
Q

Benefit of Uniform Size Wheat

1 mark

A

Easier to harvest.

CCEA GCSE Biology (33 decks)

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