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AQA Biology [Paper 2] > B13- variation 🐶 > Flashcards

B13- variation 🐶 Flashcards

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1
Q

What does variation mean ?

Hint: characteristics

A
  • variation, is differences in the characteristics of individuals in a population
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2
Q

What are the three main causes of variation ?

A
  • genetic causes- alleles a person may have inherited
  • the conditions in which a person has developed [environmental causes]- for example in plants, the colour of flowers can depend on the pH of the soil
  • and, a combination of genes and the environment [e.g- height]
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3
Q

How can height, be a genetic and environmental cause of variation ?

Hint: bones

A
  • some people may have alleles, making them likely to grow taller
  • ; their diet must also include enough calcium, for their bones to fully develop.
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4
Q
  • Fill in the gaps: in any population of a species, there is an extensive amount of genetic variation due to _________.
A
  • in any population of a species, there is an extensive amount of genetic variation due to mutations
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5
Q

TRUE OR FALSE: most mutations that take place, have an effect on the phenotype

A
  • FALSE- instead, most mutations that take place don’t have an affect on the phenotype [the observable characteristics of an organism]
  • [; some mutations may influence the phenotype, and very few determine the phenotype]
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6
Q

Can mutation lead to a new phenotype ?

A
  • yes; mutation can rarely lead to a new phenotype.
  • but sometimes, the new phenotype can be beneficial if the environment changes [which then leads to a relatively rapid change in the species]
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7
Q

What is evolution ?

Hint: change

A
  • evolution, is a change in the inherited characteristics of a population over time, through a process of natural selection which may result in the formation of a new species
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8
Q

What is natural selection ?

Hint: leads organisms

A
  • natural selection, is a process that leads organisms to be more adapted to their surroundings, in order for them to survive longer and reproduce more
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9
Q

Why can two populations of a species no longer interbreed, to produce fertile offspring ?

Hint: formed

A
  • if two populations of a species become so different in phenotype, they can no longer interbreed to fertile offspring because they have formed two new species
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10
Q

What is selective breeding ?

Hint: particular

A
  • selective breeding [artificial selection], is the process by which humans breed plants and animals for particular gene characteristics
  • [and these characteristics may be chosen for usefulness or appearance]
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11
Q

Name the four desired characteristics of selective breeding

Hint: crops

A
  • disease resistance in food crops
  • animals which produce more meat or milk [e.g- in cows]
  • domestic dogs with a gentle nature
  • and, certain plants are selectively bred to produce large or unusual flowers
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12
Q

What is the process of selective breeding?

A
  • parents are chosen with the desired characteristics from a mixed population
  • the parents are then bred together, and from the offspring those with the desired characteristics are bred together
  • this then continues over many generations, until all the offspring show the desired characteristic
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13
Q

What are two risks of selective breeding ?

A
  • inbreeding
  • a population dying out
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14
Q

Why can selective breeding cause a population to die out ?

Hint: prone

A
  • if closely related animals or plants are bred together, selective breeding can lead to inbreeding
  • inbreeding can cause some breeds of animals, to be prone to disease or inherited defects
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15
Q

Why can selective breeding, cause a population to die out ?

A
  • selective breeding greatly reduces the number of alleles in the population because, only individuals with the chosen alleles are allowed to breed.
  • this reduces the variation between individuals; selective breeding also reduces the variation in alleles for a given characteristic
  • this means that when conditions are unstable [e.g- a new disease emerges], the population can die out, as the lack of variation means none of the plants or animals in this population can cope with the change
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16
Q

What is genetic engineering ?

Hint: introducing

A
  • genetic engineering, is a process which involves modifying the genome of an organism, by introducing a gene from another organism, to give a desired characteristic
17
Q

What are two potential benefits of genetic engineering in agriculture ?

A
  • GM crops typically show an increased yield.
  • GM crops can be made to be resistant to disease, or resistant to insect attack
18
Q

Give two other potential benefits of genetic engineering in agriculture ?

Hint: nutritional value

A
  • GM crops can produce bigger or better fruits [with a greater nutritional value] so farmers can profit more
  • GM crops can be made resistant to herbicides, so farmers can spray their fields to kill weeds, without harming the GM crop
19
Q

[Easy] How can GM crops be produced ?

A
  • genes can be transferred into plants to produce genetically modified [GM] crops
20
Q

What are the potential risks of genetic engineering in agriculture ?

A
  • some GM crops can lead to health risks because, they could contain chemicals that cause allergy or toxins
  • there are also ethical hazards associated with genetic engineering for agricultural purposes because, some people may have religious beliefs and argue it is not ethically fair to modify organisms and make newer life forms
21
Q

What’s an example of genetic engineering ? 💉

A
  • the production of insulin
  • bacteria have then been genetically modified to contain the human insulin gene
  • and, these bacteria can now produce human insulin in a fermenter, which can be purified, collected and used for type one diabetes
22
Q
  • Fill in the gaps: in genetic engineering, the gene can be transferred into a small ______ of DNA [a plasmid], or a virus can be used
A
  • in genetic engineering, the gene can be transferred into a small circle of DNA [a plasmid], or a virus can be used
23
Q

How are there unknowns about genetic engineering ?

A
  • there are also unknowns involved with GM crops
  • the long-term effects of genetic engineering are unknown and some worry they could lead to a huge effect on the ecology of organisms
  • this could then lead to negative effects on the populations of wild organism and flowers
24
Q

How do restriction enzymes isolate genes?

A
  • restriction endonuclease cut DNA, to cut the genome of the human cell and remove the required gene
25
Q

What are restriction endonuclease ?

A
  • restriction endonuclease, are a group of enzymes that can recognise and cut specific sequences of DNA into fragments with sticky end
26
Q

What restriction endonuclease is used, to cut the vector and gene ?

Hint: allows

A
  • the same restriction endonuclease is also used to cut the vector [bacterial plasmid or virus] in a unique pattern, that allows both ends to be joined together by DNA ligase [an enzyme]
27
Q
  • Fill in the gaps: natural selection brings the evolution of new _______ of animals and plants
A
  • natural selection brings the evolution of new species of animals and plants

AQA Biology [Paper 2] (30 decks)

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