Food supply, plant growth and productivity Flashcards
What is food security?
Food security is the ability of human populations to access food of sufficient quality and quantity.
How does the population affect food production?
An increase in human population and concern for food security leads to a demand for increased food production.
Describe the problems facing food production
Food production must be sustainable and not degrade the natural resources on which agriculture depends, Agricultural production depends on factors that control photosynthesis and plant growth and
The area to grow crops is limited.
What does the increase in food production depend on?
Increased food production will depend on factors that control plant growth — breeding of higher-yielding cultivars, use of fertiliser, and protecting crops from pests, diseases and competition.
What types of attributes in plants are breeders looking for?
Breeders seek to develop crops with higher nutritional values, resistance to pests and diseases, and physical characteristics suited to rearing and harvesting as well as those that can thrive in particular environmental conditions.
Name an advantage and disadvantage of livestock.
Livestock produce less food per unit area than crop plants due to loss of energy between trophic levels.
Livestock production is often possible in habitats unsuitable for growing crops.
How is light energy absorbed?
Light energy is absorbed by photosynthetic pigments to generate ATP and for photolysis. Light energy not absorbed is transmitted or reflected.
What do carotenoids do?
Carotenoids extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis.
What does the light energy that is absorbed do?
Absorbed light energy excites electrons in the pigment molecule. Transfer of these electrons through the electron transport chain releases energy to generate ATP by ATP synthase. Energy is also used for photolysis, in which water is split into oxygen, which is evolved, and hydrogen, which is transferred to the coenzyme NADP.
What happens in the Calvin cycle?
In the carbon fixation stage (Calvin cycle), the enzyme RuBisCO fixes carbon dioxide by attaching it to RuBP.The 3PG produced is phosphorylated by ATP and combined with hydrogen from NADPH to form G3P. G3P is used to regenerate RuBP and for the synthesis of glucose.
What is glucose used for?
Glucose may be used as a respiratory substrate, synthesised into starch or cellulose or passed to other biosynthetic pathways. These biosynthetic pathways can lead to the formation of a variety of metabolites such as DNA, protein and fat.
