3.1 Food Supply, Plant Growth and Productivity Flashcards
What is food security?
The ability of human populations to access food of sufficient quality and quantity
What leads to a demand in increased food production?
An increase in human population and concern for food security
What are the standards of food production?
It must be sustainable and not degrade the natural resources on which agriculture depends
What is food production dependant on?
Photosynthesis
What limits agricultural production?
When the area to grow crops is limited
What factors control plant growth?
Breeding of higher yielding cultivars, use of fertiliser, protecting crops from pests, diseases and competition
What do breeders seek to develop?
Crops with higher nutritional values, resistance to pests and diseases, physical characteristics suited to rearing and harvesting as well as those that can thrive in particular environmental conditions
Why do livestock produce less food per unit area than crop plants
Due to the loss of energy between trophic levels
How is light energy absorbed?
By photosynthetic pigments to generate ATP and for photolysis
What are the three fates of light?
Absorption, transmission and reflection
What is the absorption spectra?
The levels of absorption of chlorophyll an and b and carotenoids at different wavelengths of light. Each pigment absorbs a different range of wavelengths of light
What is the action spectra?
The rate of photosynthesis at each wavelength of light
What do carotenoids do?
Extend the range of wavelengths absorbed and passes the energy to chlorophyll for photosynthesis
What happens to the absorbed light energy?
It excites the electrons in the pigment molecule.
What happens to the transfer of electrons through the electron transport chain?
It releases energy to generate ATP by ATP synthase
What is the energy produced by the electron transport chain used for?
Photolysis
What is photolysis?
Where water is split into oxygen, which is released, and hydrogen ions, which are transferred to the coenzyme NADP to make NADPH
What happens in the carbon fixation stage? (Calvin cycle)
The enzyme RuBisCO fixes carbon dioxide by attaching it to ribulose bisphosphate (RuBP)
The 3 phosphoglycerate (3PG) produced is phosphorylated by ATP and combined with hydrogen ions from NADPH to form glyceraldehyde 3 phosphate (G3P). G3P is used to regenerate RuBP and for the synthesis of glucose
What are the fates of the glucose produced from carbon fixation? (Calvin cycle)
May be used as a respiratory substrate, synthesised into starch or cellulose or passed to other biosynthetic pathways
