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19.319 · Genetic Technology

Genetically Modified Organisms in Agriculture — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

5 min read 9 parts Lesson 19 of 20 2 quizzes

📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision
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Lesson summary

19.3 Genetically Modified Organisms in Agriculture — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Describe how GM crops and animals help meet food demand and evaluate their ethical and social implications.Genetic engineering — removing a gene with the desired chara…

  • Examples of GM organisms
  • Ethical implications
  • Herbicide resistance
  • Glyphosate
  • Selective breeding
  • The engineered organism contains recombinant DNA and is a GMO

Section 1 of 9Genetic engineering in agriculture

Genetic engineering
  • Genetic engineering removing a gene with the desired characteristic from one organism and transferring it, using a vector, into another where it is expressed.
The engineered organism contains recombinant DNA and is a GMO.
The main purpose of engineering plants and animals for food is to meet the global demand for food.
Crop plants have been modified to be:
  • Resistant to herbicides, raising yield.
  • Resistant to pests, raising yield.
  • Enriched in vitamins, raising nutritional value.
Farmed animals have been modified to grow faster, but this is rarer because of ethical concerns.

Section 2 of 9Genetic engineering compared with selective breeding

Organisms with the desired characteristic are produced more quickly.
All organisms contain the desired characteristic, with no chance that a recessive allele reappears.
The characteristic may come from a different species or kingdom.
Examples of GM organisms
  • Examples of GM organisms bacteria (insulin), sheep, maize (insect resistance) and rice (β-carotene).
    • (human blood protein AAT)

Section 3 of 9GM salmon

1
AquaAdventure salmon was approved by the US FDA for human consumption in 2015.
2
It grows more rapidly because growth hormone is produced all year, not just in spring and summer.
  • The producer has a product to sell in half the time.
3
Scientists combined a chinook salmon growth hormone gene with a promoter from the ocean pout, a cold-water fish.
  • The ocean pout promoter keeps the growth hormone gene expressed continuously.
4
To prevent breeding in the wild, all the salmon are female and sterile.

Section 4 of 9Herbicide resistance in soybean

1
Resistant soybeans let farmers spray herbicide after germination to kill weeds that compete for light, water and minerals.
2
The resistance gene comes from a strain of the bacterium Agrobacterium.
3
It allows an enzyme to keep making phenylalanine, tyrosine and tryptophan, needed for proteins in the growing tips.
4
The herbicide glyphosate inhibits that enzyme in plants without the gene, so they die.

Section 5 of 9Insect resistance in maize

1
Maize has been modified with the gene for Bt toxin from the bacterium Bacillus thuringiensis.
2
The plants make their own insecticide.
3
The alkaline conditions in an insect gut activate the toxin, killing the insect; it is harmless to vertebrates, whose stomachs are highly acidic.
4
Different strains make different toxins that are toxic to different insects.
5
Insect populations have developed resistance, reducing effectiveness.
  • Refuges of non-GM crop, rotation and several control methods slow resistance.

Section 6 of 9Ethical implications

Ethical implications
  • Ethical implications concern morality: whether something is right or unacceptable.
Human health:
  • Positive — may relieve hunger where yields are low and add nutrients where deficiencies are common.
  • Concern — a lack of long-term research on human health.
Environment:
  • Positive — less insecticide spraying, so less harm to non-target insects; larger yields need less land, leaving land for habitats.
  • Negative — insect resistance genes may enter wild populations and create invasive varieties, herbicides may enter food chains,
    • and targets may evolve resistance.
Informed choice:
  • Unlabelled GM food may be eaten without consent.
  • Pollen from GM crops may contaminate certified organic crops.

Section 7 of 9Social implications

Social implications
  • Social implications concern the effect on society as a whole.
Positive financial impacts:
  • GM crops may need fewer resources and be cheaper for consumers.
  • Higher yields in difficult conditions allow trade and improve the national economy.
Negative financial impacts:
  • Seeds are often made by large biotech companies and are expensive, locking out poorer farmers.
  • GM plants are often sterile, so seed must be bought every year.
Health of society:
  • Better food supply reduces starvation.
  • Fewer dietary deficiencies reduce pressure on health services.
One idea can be both social and ethical.

Section 8 of 9Key terms

TermMeaning
GMOAn organism whose genetic material has been altered by genetic engineering.
Bt toxinInsecticidal protein from Bacillus thuringiensis.
Herbicide resistanceAbility of a crop to survive a herbicide because of an introduced gene.
GlyphosateHerbicide that inhibits an enzyme needed for amino acid synthesis.
Ethical implicationA concern about morality.
Social implicationAn effect on society as a whole.
Selective breedingBreeding chosen individuals over many generations.

Section 9 of 9Exam technique

1
Mixing up ethical and social issues — ethical concerns morality, social concerns effects on society.
2
Saying Bt toxin harms humans — it needs alkaline conditions to be activated, whereas vertebrate stomachs are acidic.
3
Giving only benefits — a balanced answer includes risks such as resistance and gene flow.
4
Saying GM salmon can breed in the wild — they are female and sterile.

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