U3 KA1 Food Supply, Plant Growth and Productivity Flashcards
What is food security?
The ability for human populations to access food of sufficient quality and quantity.
Why is there a growing demand for increased food production?
Due to the increase in human population and concern for food security.
What must food production be to meet future demands?
Sustainable and not degrade natural resources essential for agriculture.
What factors does agricultural production depend on?
Factors that control photosynthesis and plant growth.
Why is crop-growing area limited?
Because available land is finite and cannot be endlessly expanded.
What are key methods to increase food production?
Breeding high-yield cultivars, using fertilisers, and protecting crops from pests, diseases, and competition.
Why do livestock produce less food per unit area than crops?
Because of energy loss between trophic levels.
(Only 10% energy passes per level)
When is livestock production more appropriate than crop production?
In habitats unsuitable for growing crops.
What is the role of photosynthetic pigments?
To absorb light energy for ATP generation and photolysis. (Light dependent stage).
What do absorption spectra show?
The wavelengths of light absorbed by chlorophyll a, chlorophyll b, and carotenoids.
What do carotenoids do in photosynthesis?
Extend the range of light wavelengths absorbed and transfer energy to chlorophyll. (These will be more present in shaded plants).
What happens to electrons in pigment molecules when light is absorbed?
Electrons become excited and transfer energy through the electron transport chain.
What is the function of ATP synthase and the electron transport chain in photosynthesis?
High energy electrons release their energy to protein pumps that pump H+ ions through the membrane. The H+ ions flow back through ATP synthase releasing energy and ATP synthase generates ATP.
What is photolysis?
The splitting of water into oxygen, hydrogen ions, and electrons using light energy.
What happens during carbon fixation in the Calvin cycle?
RuBisCO enzyme attaches carbon dioxide to RuBP to form 3-phosphoglycerate (3PG).
How is glyceraldehyde-3-phosphate (G3P) formed in the Calvin cycle?
3PG is phosphorylated by ATP and combined with hydrogen from NADPH.
What is G3P used for?
To regenerate RuBP and to synthesize glucose.
What can glucose be used for after photosynthesis?
As a respiratory substrate (glucose), or to form starch, cellulose, or other biosynthetic products.
