Unit 3 Flashcards
What is food security? Give def.
The ability of human population to access food of sufficient quality and and quantity.
Human food are mostly sourced from what crops?
- Cereals
- Potato
- Roots
- Legumes
What factors affect plant growth?
- Light availability
- Nutrients available
- Water in soil
- competition with other plants (space)
What happens to light energy in photosynthesis? (Fates of light striking a leaf)
Light is:
- Absorbed
- reflected
- transmitted (passed through the leaf)
What happens when light becomes absorbed? (Stage one)
- electrons become excited and energy goes to electron transport system
- rest of energy used for photolysis (splitting water into hydrogen and oxygen)
What happens to the hydrogen and oxygen in stage one of photosynthesis?
Oxygen - released as a by-product.
Hydrogen - bonds with coenzyme NADP to form NAPH which goes to the Calvin cycle.
Does the Calvin cycle require light?
The carbon fixation stage does not require light.
What happens in the Calvin cycle? Break into 3 steps.
CO2 enters the cycle and becomes attached to RuBP (ribulose biphosphate) to produce 3-phosphoglycerate (3PG)
3-phosphoglycerate is phosphorylated by ATP and combined with hydrogen from NADPH to form G3P (glyceraldehyde-3-phosphate)
G3P is used to regenerate RuBP or can be used to synthesise sugars.
What do the synthesised sugars do?
Sugars can be made into starch or cellulose, or passed through pathways to form metabolites.
What does RuBP stand for?
Ribulose biphosphate.
How is the CO2 attached to the RuBP?
By enzyme RuBisCO.
What does 3PG stand for?
3-phosphoglycerate.
What does G3P stand for?
Glyceraldehyde-3-phosphate.
What are the types of characteristics scientists would look for in GM plants?
- higher crop yield.
- higher nutritional value.
- resistance to pests and disease.
- ability to thrive in certain environment.
What are plant field trials?
Field trials are to investigate a range of different characteristics by plots. (equally divided space)
What is inbreeding?
The breeding of two closely related species to breed a desired characteristic. This process is done to eliminate heterozygotes.
Why is inbreeding rarely carried out?
There can be negative results, such as:
- decline in size
- decline in yield
- poor vigour
What is crossbreeding?
The breeding of two different breeds.
What are annual weeds?
Weeds that grow yearly.
What are perennial weeds?
Weeds that live for several years. (Jeez.)