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IB SQA Higher Biology Unit 3- Sustainability and Interdependence > Plant and Animal Breeding > Flashcards

Plant and Animal Breeding Flashcards

1
Q

Why do breeders of both plant and animal food sources need to select desirable genetic characteristics?

A

To improve the productivity of food production. Only individual plants and animals possessing a desirable genetic characteristic are selected to be included in breeding programmes.

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2
Q

Give an example of a wild species that humans have shaped into different foods by selective breeding.

A

Wild cabbage.

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3
Q

What is another name for selective breeding?

A

Artificial selection

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4
Q

Name some kinds of foods that were derived from the wild cabbage.

A

Brussel sprouts
Kale
Broccoli
Cauliflower

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5
Q

Name six desirable characteristics in plants.

A
  1. Yield Increase
  2. Increase in nutritional value
  3. Pest Resistance
  4. Disease Resistance
  5. Useful Physical Characteristics
  6. Can thrive in certain environment
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6
Q

Give an example of Yield Increase in plants.

A

Increase in mass of food produced by a wheat crop.

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7
Q

Give an example of an increase in nutritional value in plants.

A

Increase in mass of protein produced by a soya bean crop.

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8
Q

Give an example of pest resistance in plants.

A

Resistance of tomato to eel worm.

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9
Q

Give an example of disease resistance in plants.

A

Resistance of potato to the late blight

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10
Q

Give an example of useful physical characteristics in plants.

A

Growth of cereal crop to uniform height suited to mechanical harvesting.

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11
Q

Give an example of plants thriving in a certain environment.

A

Ability of maize to grow in a cold, damp climate.

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12
Q

What four desirable characteristics are livestock bred for?

A
  1. Resistance to bacterial infection.
  2. High conversion of feed to meat (Feed conversion ratio)
  3. High fertility rate.
  4. Ability to thrive in difficult environments e.g. Scottish hills in winter.
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13
Q

What is a cultivar?

A

A cultivar is a plant or animal that has been created or intentionally selected for desirable characteristics that can be maintained by cultivation.

Today almost all agriculture food crops are exclusively cultivars.

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14
Q

Give an example of a method which can be used to improve crops and livestock.

A

Genetic Modification.

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15
Q

What are field trials set up for?

A

To compare the performance of different cultivars or GM crops.

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16
Q

Why are field trials used in addition to the laboratory experiments?

A

Field trials are carefully and scientifically monitored to ensure that accurate results are obtained

and

that there are no harmful effects on the environment.

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17
Q

What is a plot in a field trial?

A

Equal sized portions of land.

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18
Q

Why are plots used in field trials?

A

They are given different treatments to compare the differences.

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19
Q

What is a treatment (in the context of field trials)? Provide an example.

A

A treatment refers to the way one plot is treated compared with the other plots.

For example, one plot given a higher concentration of herbicide and the other plot a lower concentration.

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20
Q

What three factors must be considered when designing a field trial?

A
  1. The selection of treatments used.
  2. The number of replicates.
  3. The randomisation of treatments.
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21
Q

Why is the selection of treatments important when setting up a field trial?

Give an example.

A

It is used to make it a valid investigation and ensures valid comparisons, only one treatment must be trialled at one time.

For example, the effect of fertiliser on the growth of a crop.

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22
Q

Why is the number of replicates important when setting up a field trial?

A

To take experimental error (uncontrolled variability) into account.

Three minimum replicates should be used to improve results.

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23
Q

Why is the randomisation of treatments important when setting up a field trial?

A

To prevent bias existing in the system.

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24
Q

What is inbreeding?

A

Inbreeding is the mating of two closely related individuals.

25
Q

What is heterozygotes?

A

Heterozygotes are a gene combination of one recessive gene and one dominant gene.

26
Q

What is homozygous?

A

Homozygous is a gene combination of two of the same genes i.e. two recessive or two dominant.

27
Q

How are the desired characteristics obtained by inbreeding plants or animals?

A

This happens over a long period of time and eliminates heterozygotes, therefore reducing genetic variation. This means that plants and animals become homozygous for the desired trait that is selected.

28
Q

Give an example of inbreeding to select traits.

A

When the same ram is used to mate with a flock of sheep over several generations. Eventually the ram will be mating with some of it’s own offspring.

29
Q

What is inbreeding depression?

A

The accumulation of other homozygous alleles can cause the expression of deleterious (harmful) recessive alleles caused by inbreeding.

These individuals will be less successful in surviving and therefore reproducing .

30
Q

What is the negative affect of inbreeding depression?

A

A reduction in yield and in general this leads to a decrease in the fitness of a population.

31
Q

Give 4 example of the negative effects inbreeding can have?

A

Decline in

  1. Size
  2. Vigour
  3. Fertility
  4. Yield across generations.
32
Q

What is done to prevent the harmful effects of inbreeding depression in animals? (How are new alleles brought in to an animal population?)

A

Crossbreeding

33
Q

Describe crossbreeding.

A

Crossbreeds individuals from different breeds. This can improve the characteristics of the new crossbred population.

The two parent breeds can be maintained to produce more crossbred animals that show the improved characteristics.

The F2 produced by crossbreeding show a wide variation in genotypes.

34
Q

How do the F2 generation maintain the desired characteristics?

A

Backcrossed (Testcrossed) with the parent or an individual with exactly the same genotype as the parent.

35
Q

How is backcrossing beneficial?

A

It produces individuals that have the characteristic of both parents whilst maintaining the standard of the breed.

36
Q

Give an example of a desired characteristic which come from crossbreeding.

A

Hybrid vigour in sheep (more fertile/higher lambing rate)

37
Q

What does crossbreeding in plants result in?

A

Hybridisation between two different homozygous inbred plants results in an F1 generation of hybrids that create a relatively uniform heterozygous crop.

38
Q

What characteristics do the F1 plant hybrids display?

A

Increased vigour, yield and disease resistance and fertility.

39
Q

What is hybrid vigour?

A

Superior characteristics possessed by the F1 plants over their parents.

40
Q

What are the constraints of inbreeding?

A

If F1 hybrids of animals and plants are allowed to interbreed, the F2 generation will be genetically variable and of little use for further production.

41
Q

What is genome sequencing?

A

Genome sequence is a process which allows scientist to determine the precise sequence of DNA nucelotides for a living organism.

42
Q

How is genome sequencing beneficial to farmers?

A

It can be used to identify organisms that possess the allele for desired characteristics e.g. disease resistance.

NB. These organisms can then be used within breeding programmes to try and incorporate the desired characteristic into new cultivars.

43
Q

How are plants genetically modified?

A

Single genes for desirable characteristics identified through genetic sequencing can be inserted into the genomes of crop plants creating plants with improved characteristics.

44
Q

Give an example of a breeding programme which involves crop plants that have been modified genetically using recombinant DNA technology.

A

Inserting the Bt toxin gene into plants result in better pest resistance.

45
Q

What is the glyphosate resistance gene used for?

A

This can be inserted into a plant to give it herbicide tolerance through GM.

46
Q

What is Bt toxin?

A

A soil bacterium that makes a protein that is toxic to certain plant eating insects. Many varieties exist (e.g. specific to butterflies / beetles etc)

47
Q

How does the Bt toxin improve pest resistance in plants?

A

Once consumed it binds to receptors in the insects gut, paralysing it and causing the insect to die of starvation.

48
Q

How does GM with Bt toxin gene help farmers?

A

Plants that have been genetically modified produce their own Bt toxin and do not need to be sprayed with insecticide.

49
Q

What is glyphosate?

A

Weed killer (Herbicide)

50
Q

How is glyphosate absorbed into the plant?

A

Through the leaves and then translocated throughout the plant.

51
Q

How does glyphosphate kill plants?

A

It inhibits an enzyme required for the synthesis of several amino acids.

52
Q

How does glyphosate kill plants?

A

It inhibits an enzyme required for the synthesis of several amino acids.

53
Q

What can micro-organisms do to glyphosate?

A

Breaks it down into harmless products within a few days.

54
Q

Give 3 example of plants which have been genetically modified to be resitant to glyphosate.

A
  1. Soya beans
  2. Maize
  3. Sorghum.
55
Q

Where do the resistant genes for glyphosate come from?

A

Some plants are naturally resistant to glyphosate.

56
Q

What is the desired outcome when a field is sprayed with glyphosate?

A

The weeds die leaving only the crops.

But some varieties of resistant weeds are emerging.

57
Q

Give an example of inbreeding depression.

A

A population of adders experienced inbreeding depression when farming activities in Sweden isolated them from other adder populations.

Higher proportions of stillborn and deformed offspring were born in the isolated population than in the larger populations.

When researchers introduced adders from other populations - the isolated population recovered and produced a higher proportion of viable offspring.

58
Q

How are dominant deleterious alleles eliminated?

A

Through Natural Selection

IB SQA Higher Biology Unit 3- Sustainability and Interdependence (7 decks)

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