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1. GCSE combined master > B13a Variation and evolution > Flashcards

B13a Variation and evolution Flashcards

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1
Q

Give a definition of variation

A

Differences in the characteristics of individuals in a population

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2
Q

What are the causes of variation?

A

Mutations
Genes they have inherited
Environment
Combination of genes and the environment

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3
Q

What is a mutation?

A

A change in the DNA

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4
Q

When do mutations occur?

A

Continuously

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5
Q

What effect can mutations have on variation within a population?

A

Most have no effect on the phenotype
Some influence the phenotype
Very few determine the phenotype

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6
Q

Give a definition of evolution

A

A change in the inherited characteristics of a population over time through the process of natural selection.

Could result in the formation of a new species

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7
Q

Give a definition of a species

A

Individuals can interbreed and produce fertile offspring

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8
Q

What is genetic variation?

A

Variations in the genotypes of organisms of the same species

due to the presence of different alleles

Creates differences in phenotypes

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9
Q

What creates genetic variation in a species?

A

Mutation
Sexual reproduction

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10
Q

Outline the theory of natural selection

A

Wide range of variation in a population
Individuals with characteristics most suited to the environment more likely to survive and breed
beneficial characteristics are passed on to the next generation

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11
Q

How is a new species formed?

A

Two populations of one species become different in phenotype

No longer interbreed to produce fertile offspring

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12
Q

What is selective breeding?

A

Humans choose parents with desired characteristics
Breed together
Offspring with desired characteristics bred together
Continue over many generations until all offspring show desired characteristics

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13
Q

How long ago did simple life develop on Earth?

A

More than 3 billion years ago

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14
Q

Give four examples of selective breeding

A

Disease resistance in food crops
Animals which produce more meat or milk
Domestic dogs with a gentle nature
Large or unusual flowers

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15
Q

Selective breeding can lead to ‘inbreeding’.

What does this mean?

A

Closely related animals or plants are bred together

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16
Q

Why might inbreeding be a problem?

A

Some breeds are prone to disease or inherited defects

17
Q

What are the main advantages of selective breeding?

A

Creates organisms with desirable features:
Crops produce a higher yield
Cows produce a greater volume of milk
Animals produce more meat
Hens lay more eggs
Plants produce larger fruit
Domesticated animals

18
Q

Outline the disadvantages of selective breeding

A

Reduction in the variety of alleles present in the population - harmful if sudden environmental change occurs
Inbreeding results in genetic disorders
Development of physical problems eg breathing problems in bull dogs
Disease can wipe out a crop

19
Q

What is genetic engineering?

A

Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

20
Q

Give 3 examples of genetic engineering

A

Plant crops - increased resistant to disease
Plant crops - increase size of fruit
Bacteria cells - produce useful substances eg human insulin

21
Q

Outline the process of genetic engineering

A

Gene from human is cut out of the chromosome
Transferred to cells of other organisms

22
Q

Benefits of genetic engineering

A

Increased crop yield for a growing population
Useful in medicine eg making insulin to treat diabetics
GM crops produce higher concentrations of minerals and vitamins eg golden rice

23
Q

Disadvantages of genetic engineering

A

Long term effects of eating GM crops unknown
Negative environmental impacts eg reduction in biodiversity,

Impact on food chains, contamination of non-GM crops
Late onset health problems in GM animals
GM seeds are expensive. LEDCs may be unable to afford them

24
Q

Give 3 example of a genetically modified crop

A

Crops that are resistant to insect attack
Crops that are resistant to herbicides
Crops with increased yield

25
Q

Describe the main steps in the process of genetic engineering (Higher)

A

Enzymes used to isolate the required gene
Gene is inserted into ta vector (bacterial plasmid or virus)
Vector used to insert gene into the required cells
genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so they develop with desired characteristics

26
Q

What is a vector?

A

A structure that deliver the desired gene into the cells of a different species
Plasmid or virus

27
Q

State two kinds of evidence used to show evolution

A

Fossils
Antibiotic resistance in bacteria

28
Q

How are fossils formed?

A

Parts of organism that have not decayed
Part of the organism is replaced by minerals
Traces of organisms are preserved (eg burrows, footprints and rootlet traces), covered in sediment and become rock

29
Q

Why is the fossil record incomplete?

A

Very few organisms die and do not decay
Soft body parts are not fossilised

30
Q

How do fossils act as evidence for evolution?

A

Identify the age of the fossil
Show how organisms have changed over time

31
Q

What is a fossil?

A

Remains of organisms from millions of years ago which are found in rocks

32
Q

What is extinction?

A

No remaining individuals of a species still alive

33
Q

State the factors that may lead to extinction

A

New disease
Predation
Competition
Changes to the environment
Catastrophe events

34
Q

Why do bacteria evolve quickly?

A

Fast rate of reproduction

35
Q

Outline how antibiotic resistance in bacteria occurs.

A

Mutation of bacterial pathogen produce new strains
Some strains become resistant to antibiotics
These bacteria not killed by antibiotics
Antibiotic resistance strains survive and reproduce
Population of antibiotic resistant bacteria increase

36
Q

Name an antibiotic resistant bacteria

A

MRSA

37
Q

How is the rate of antibiotic resistance reduced?

A

Doctors should not prescribe antibiotics inappropriately eg treating no serious or viral infection
Patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains
Agricultural use of antibiotics should be restricted

38
Q

Why are resistance strains of bacteria dangerous?

A

People have no immunity to them
No effective treatment

39
Q

Why is it difficult to keep up with new antibiotic resistant strains?

A

Developing new antibiotics is expensive
Developing new antibiotics takes a long time

1. GCSE combined master (25 decks)

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