Genetic Technology in Agriculture (Chapter 19)

Question 1

What proteins for use in medicine are produced from GM plants?

Answer 1

• Vaccines, albumin, proteins in breast milk for infants

- Avoids problems of contamination by animal proteins

Question 2

What are most GM plants?

Answer 2

• Crop plants modified to be herbicide or insect resistant to increase crop yield
• Some provide improved nutrition

Question 3

What is oil seed rape?

Answer 3

A source of of vegetable oil used as biodiesel fuel, as a lubricant and in human/animal foods

Question 4

How has oil seed rape been modified to make it more desirable?

Answer 4

• Natural oil seed rape contains substance (erucic acid and glucosinolates) which are undesirable in oil used in human/ animal foods
• Hybrid called canola produces a low conc of these substances

Question 5

How has gene tech modified oil seed rape to improve its yield?

Answer 5

• Gene tech has been used to produce herbicide resistant strains of oil seed rape resistant to glyphosate or glufosinate
• This allows fields to be sprayed with herbicide after the crop has germinated, killing any weeds that would compete with the crop for space, light, water or ions

Question 6

What are the two common herbicides?

Answer 6

Glyphosate and glufosinate

Question 7

How does glyphosate work?

Answer 7

1) it inhibits an enzyme involved in the synthesis of 3 amino acids: phenylalanine, tyrosine and tryptophan
2) it is absorbed by the plant’s leaves and transported to the growing tips
3) the amino acids are needed for producing essential proteins ∴ the plant dies

Question 8

How can microorganisms be used to genetically engineer herbicide resistant crops?

Answer 8

• Some microorganisms e.g. Agrobacterium have versions of the enzyme that are not affected by glyphosate
• ∴ the gene for this enzyme can be transferred into crop plants

Question 9

What two herbicides has tobacco been made resistant to?

Answer 9

Sulfenylurea and dinitroaniline by taking genes from another species of plant

Question 10

What are the possible negative environmental effects of growing herbicide-resistant crops?

Answer 10

1) GM plant will become an agricultural weed
2) pollen will transfer the gene to wild relatives, producing hybrid offspring that are invasive weeds
3) herbicide-resistant weeds will evolve bc so much of the same herbicide is used

Question 11

Is GM oil seed rape more or less invasive than unmodified versions?

Answer 11

Slightly less invasive

Question 12

How is the risk of pollen transfer shown in oil seed rape and how can this be prevented?

Answer 12

• Oil seed rape interbreeds easily with 2 related species (wild radish/turnip)
• Flowers can be pollinated by wind
• it has been shown that resistance can be passed down through hybrid offspring (only in labs)
• ∴ safe planting distances are needed to allow organic farming to remain GM-free

Question 13

Discuss the risk of herbicide resistant weeds arising

Answer 13

• Near where glyphosate has been much use, herbicide resistant mutant plants of various species have been found
• However, herbicide is not only used on resistant crop species
• Also, GM is not directly responsible as resistance may evolve in the absence of any GM crop

Question 14

Give two examples of how crops made insect-resistant have increased the yield of the crops

Answer 14

1) maize is protected against the corn borer, which eats the leaves of the plants and burrows into the stalk, eating its way upwards until the plant cannot support the ear
2) cotton is protected against pests e.g. boll weevil

Question 15

What insect is GM tobacco (not yet grown commercially) protected against?

Answer 15

Tobacco bud worm

Question 16

What are the 4 possible negative environmental effects of growing insect-resistant crops?

Answer 16

1) evolution of resistance by insect pests
2) damaging effect on other species of insect
3) transfer of the added gene to other species of plant
4) where lots of GM crop is grown, there is a danger of losing biodiversity

Question 17

How are negative environmental effects minimised when growing insect-resistant crops?

Answer 17

• Less pesticide is used ∴ reducing the risk of spray carrying to and affecting non-target species of insects in other areas
• Only insects that eat the crops are affected

Question 18

Describe how Bt toxin has been used to make GM insect-resistant crops e.g. Bt maize

Answer 18

• A gene for Bt toxin, which is lethal to insects that eat it but harmless to other animals has been taken from the bacterium Bacillus thuringiensis
• Different strains of the bacterium produce different toxins that can be used against different insect species
• Crop plants containing the Bt toxin ∴ produce their own insecticide

Question 19

What is the risk of using Bt toxin to GM plants?

Answer 19

• Insect populations can evolve resistance to toxins
• Large numbers of crop plants containing the Bt toxin genes may accelerate the evolution of resistance to it
• e.g. many populations of corn borers in USA are resistant to Bt toxin (but resistance = recessive allele)

Question 20

Discuss the potential environmental risks of using the Bt toxin

Answer 20

1) pollen of Bt maize expresses the gene and can disperse at least 60m by wind, transferring to milkweed, a source of food for caterpillars of the monarch butterfly (reduces survival rate of caterpillars to 56% in lab) - however doesn’t reflect real world bc caterpillars are not normally present when pollen is shed
2) leaves from GM Bt plants can end up in streams and be eaten by aquatic insect larvae e.g. caddis larvae, reducing the growth of the larvae
3) if Bt maize is grown in Mexico, could pollinate teosinte (wild parent species), transferring genes to it - but maize pollen not viable after 2 hours of being released from anthers and exposed to air ∴ need 2 hour wind drift distance
4) some evidence of reduced populations of microorganisms in soil where Bt maize has been growing

Question 21

What is a social disadvantage of growing GM crop?

Answer 21

GM crop seed is expensive and have to buy new seed each season ∴ cost may outweigh the advantage of herbicide of insect resistance

Question 22

Why is vitamin A (VA) deficiency a problem?

Answer 22

• Can cause blindness (WHO estimate: 500,000 children go blind every year as a result of VA deficiency)
• Can cause immunodeficiency syndrome, which is a significant cause of mortality esp in children in certain parts of the world

Question 23

Where is VA deficiency a problem?

Answer 23

Where people are poor and rice forms a major part of their diet

Question 24

What is vitamin A?

Answer 24

A fat soluble vitamin found in oil fish and animal products (eggs, milk, cheese) and made from carotene, found in carrots

Question 25

Where are pro-VA carotenoids found in rice?

Answer 25

In the aleurone layer of rice grains, but not in the endosperm which is what humans eat

Question 26

Why is white rice produced instead of brown rice?

Answer 26

Bc it no longer contains the aleurone layer (unlike brown rice), which goes rancid if stored for any length of time

Question 27

Why can it be difficult for poor families to avoid VA-deficiency?

Answer 27

Due to the lack of animal products and not enough carotenoid containing vegetables

Question 28

How is Golden Rice produced?

Answer 28

1) genes for the production of carotene are extracted from maize and the bacterium Pantonoea ananatis
2) these genes and promoters are inserted into plasmids, which are inserted into bacteria (Agrobacterium tumefaciens) - these bacteria naturally infect plants ∴ can introduce the GM plasmids into rice cells
3) the bacteria are mixed with rice embryos in petri dishes, some of which were infected by the bacteria containing the carotene genes
4) the rice embryos containing the carotene genes were grown into adult plants, producing seeds containing carotene in their endosperm

Question 29

Why is Golden rice called so?

Answer 29

Because of the high conc of carotene, an orange pigment

Question 30

How is Golden rice used?

Answer 30

• It is being bred into other varieties of rice which grow well in different conditions with the same yield, pest resistance and eating qualities as the original e.g. in Bangladesh
• It may be as useful as VA containing capsules, milk or eggs to overcome VA deficiency in rice-consuming populations

Question 31

What is the controversy over Golden rice?

Answer 31

• Several NGOs opposed to GM crops say that Golden rice is the wrong way to solve the problem of people eating VA-lacking diets
• Reason for VA-lacking diets is poverty ∴ way to solve problem is to help them out of poverty so that they have access to a more varied diet
• However, this cannot be quickly achieved

Question 32

What is a social advantage of Golden rice?

Answer 32

It will be made available in LEDCs at no greater cost than white rice seeds

Question 33

Conclude about Golden rice

Answer 33

• Need to solve root cause of poor diets including numerous political, cultural and economic issues
• But in the mean time, pro-VA enhanced rice could help millions of people to avoid blindness or death

Question 34

Describe the example of a GM animal (GM Atlantic salmon in USA and Canada)

Answer 34

1) insertion of growth-hormone regulating gene and promoter from other fish species into fertilised egg of Atlantic salmon allowed them to produce growth hormone and ∴ grow all throughout the year, not just in spring and summer
2) as a result, fish reach market size in roughly 18 months instead of 3 years as with the unmodified fish
3) characteristics of GM salmon reduce their ability to compete with wild salmon in a natural environment
4) ∴ the FDA has declared then as unlikely to have a significant effect on the environment and safe to eat
5) but have not yet been given permission to enter the human food chain

Question 35

What are the 4 environmental concerns about GM crops (insect and herbicide resistant crops)?

Answer 35

1) GM crop plants may become agricultural weeds or invade natural habitats
2) the introduced gene(s) may be transferred by pollen to wild relative whose hybrid offspring may become more invasive or to unmodified plants growing on a farm with organic certification
3) the herbicide that can now be used on the crop will leave toxic residues on the crop
4) in parts of the world where a lot of GM crops are grown, there is a danger of losing traditional varieties with their desirable background genes for particular localities and their possibly unknown traits that might be useful in a world where the climate is changing - this requires a programme of growing and harvesting traditional varieties and setting up a seed bank to preserve them

Question 36

What are the 3 social concerns about GM crops?

Answer 36

1) the modified plants may be a direct hazard to humans, domestic animals or other beneficial animals by being toxic or producing allergies
2) GM seeds and herbicide are expensive and their cost may remove any advantage of growing a resistant crop
3) growers mostly need to buy seed each season, keeping costs high, unlike for traditional varieties, where the grower keeps seeds from one crop to sow for the next

Question 37

What evidence is there to refute some of the negative environmental effects?

Answer 37

1) little evidence of genes ‘escaping’ into the wild
2) no ‘superweed’ has appeared to reduce crop growth
3) no examples of foods produced from GMOs unexpectedly turning out to be toxic or allergenic

Question 38

Conclude about GMOs

Answer 38

• Unless the known effects of GMOs become much greater than have so far been measured, the effect on human societies may be said to be small, but positive
• Although, there are possible effects that cannot yet be measured e.g. the future consequences of any loss of biodiversity from growing GM crops

Question 39

What does ILGBHBB mean?

Answer 39

I love getting banged hard by bae.