Unit 3 Topic 1 Flashcards
(28 cards)
What is food security
The ability of human populations to access food of sufficient quantity and quality
What can an increase in population do to food security?
Leads to a demand for increased food production
What must food production be?
Sustainable- must not degrade natural resources on which agriculture depends
What is food production dependent on?
Photosynthesis
What are some plant crop examples?
Cereals, potato, roots and legumes
When breeders develop crops, what do they seek to give the plant?
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
What will increased food production depend on?
factors that control plant growth - breeding of higher yielding cultivars, use of fertiliser, protecting crops from pests, disease and competition
What produces more food per unit area, crops or livestock?
Crops produce more food per unit area that livestock since livestock lose energy between tropic levels.
Is it easier to grow crops or livestock?
Livestock production is often possible in habitats unsuitable for growing crops, meaning that livestock production can happen when crop production is not possible
What is the first stage of photosynthesis called?
Light reaction
What can happen to light that hits a green leaf?
Absorbed (used for photosynthesis)
Transmitted (goes through the leaf)
Reflected (green light is reflected)
What absorbs the light energy required for photosynthesis?
Photosynthetic pigments (main one is cholorphyll A)
What does absorption spectrum mean?
The absorption spectrum is a measure of what wavelengths of light are absorbed
What does action spectrum mean?
The action spectrum is a measure of what wavelengths of light are used for photosynthesis
What do carotenoids do?
Extend the range of wavelengths absorbed and also pass the energy to chlorophyll for photosynthesis
Do all pigments absorb the same wavelengths of light?
No, all pigments absorb different wavelengths of light
What does light energy do to electrons
Excites them for the electron transport chain
What releases energy in order to generate ATP
Transfer of the excited electrons
What is the splitting of water called and what is the chemical equation?
Photolysis
H20 ———-> 1/2O2 + 2H+
What is required for photolysis to occur?
Light energy absorbed by the leaf
What happens to the oxygen after photolysis?
It is evolved / It diffuses out of the cell
What happens to the hydrogen ions after photolysis?
transferred to coenzyme NADP
What is the role of NADP in the light reaction?
attaches to hydrogen ions and carries them to them to the calvin cycle (carbon fixation stage)
What does RuBP attach to in the calvin cycle and what enzyme does this?
CO2
Rubisco
