Key Area 3.1 Food Supply Flashcards
What is the definition of food security?
The ability of a human population to access food of sufficient quality and quantity.
What is sustainable food production?
Food production which does not degrade the natural resources which agricultural depends.
What 2 processes affect food production?
Photosynthesis
Plant growth.
What factors affect food production?
Light intensity Water Carbon dioxide concentration Soil nutrients Temperature Competition.
What happens to the light energy that is not absorbed by photosynthetic pigments?
Transmitted
Reflected.
What are the three photosynthetic pigments?
Chlorophyll A
Chlorophyll B
Carotenoids.
Where does chlorophyll A and B absorb light energy?
In the blue and red wavelength regions.
What is the purpose of carotenoids?
To broaden the absorption spectrum which increases energy available for photosynthesis.
What does the action spectrum show?
It shows how effective each wave length of light is at photosynthesis.
How many stages are there in photosynthesis?
2.
What is stage one of photosynthesis called?
Light-dependant stage.
What is stage 2 of photosynthesis called?
The Calvin cycle (carbon fixations).
What happens in stage one of photosynthesis?
Absorbed energy excites electrons in the pigment molecule.
These high energy electrons transfer through the electron transport chain and releases energy to generate ATP by ATP synthase.
Energy also splits water into oxygen, which is released, and hydrogen, which is transferred to the coenzyme NADP which because NADPH and goes to the next stage.
What is stage 2 of photosynthesis called?
The Calvin Cycle
In stage 2 what does carbon dioxide attach to?
Ribulose biphosphate.
What is formed when carbon dioxide attaches to ribulose biphosphate in stage 2 of photosynthesis?
3-phosphoglycerate.
What enzyme catalyses the reaction between carbon dioxide and ribulose biphosphate during stage 2 of photosynthesis?
RuBisCo.
What happens to NADPH in stage 2 of photosynthesis?
Carries the hydrogen from stage one to stage 2.
Why is ATP needed in the Calvin Cycle?
It brakes down into ADP + Pi and the phosphate is used to phosphorylate the 3-phosphoglycerate.
What is formed when the 3-phosphoglycerate is phosphoralated and is combined with hydrogen?
Glyceraldehyde-3-phosphate.
What is Glyceraldehyde-3-phosphate used for?
To regenerate Ribulose biphosphate and for the synthesis of glucose.
What is glucose used for once it has been produced?
- Used as a respiratory substrate
- Synthesised into starch (storage)
- Synthesised into cellulose (structural)
- Used in other metabolic pathways to form a variety of metabolites.
Why is it important that ribulose biphosphate is regenerated?
To allow the cycle to continue.
