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GM soya yield mechanisms
Glyphosate is a herbicide used in agriculture. Soya bean plants have been genetically modified (GM) to be resistant to glyphosate. A farmer can increase the yield of soya beans by:
- growing GM soya bean plants
- spraying glyphosate on the field
Explain how the use of GM soya bean plants and glyphosate can increase the yield of soya beans.
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Marking points
- 1 Explains that glyphosate kills weeds while the resistant GM soya bean plants survive.
- 2 Links weed removal to reduced competition for one or more named resources.
- 3 Develops at least one resource link into increased plant growth/biomass and therefore yield.
- 4 May link more light/water to photosynthesis and glucose production.
- 5 May link glucose to respiration or synthesis/storage products that support yield.
- 6 May develop the roles of water or named mineral ions in growth.
Full-mark answer
Glyphosate kills weeds in the field but does not kill the resistant GM soya bean plants. With fewer weeds, the soya plants face less competition for light, water, mineral ions and space. More light and water allow more photosynthesis, so more glucose is made. The glucose can be respired to release energy and used to make cellulose, proteins, starch and lipids, increasing plant growth and the mass of soya beans harvested.
Why this answer loses marks
Glyphosate makes the GM plants grow faster.
The herbicide does not directly boost growth; explain that it kills weeds, reducing competition, then link freed resources to photosynthesis and biomass.