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Unit 3 Biology

Booklet 3

What is food security? The ability of a human population to access food in sufficient quantity and quality. This maintains a healthy population and helps avoid malnutrition and starvation
What does an increasing human population and concern for food lead to? there is a continuing demand for increased food production.
What is meant by sustainable food production? it does not degrade the natural resources on which agriculture depends.
What is Availability? Existence of food in sufficient quantities and of appropriate quality over time.
What is Sustainability? Degree to which food security can be guaranteed over extended periods of time and not degrade the natural resources on which agriculture depends.
What is Accessibility? Sufficient economic and infrastructure resources to get available food resources.
What are the main producers of human food? Only a small number of green plant species such as sugar cane, cereals (wheat and maize, rice and legumes)
Plant breeders manipulate heredity and are seeking to develop crops with? Higher nutritional values. Higher yields. Resistance to pests and diseases. Physical characteristics for harvesting and rearing (large fruit). Ability to thrive in particular environmental conditions.
How does energy loss in food chains explain why livestock produce less food per unit area than plant crops? Due to loss of energy between trophic levels - (the shorter the food chain, the greater the quantity of energy held in food)
Why has there been a major increase in concern about food security in recent years? The growing population requires food - we will be unable to provide enough/
What is a trophic level? The next level in a food chain.
What do plants convert in photosynthesis? Light energy --> Chemical energy
What is Net assimilation? Mass increase due to photosynthesis (-) loss in respiration.
Why is net assimilation measured by the (increase in dry mass) per unit leaf area. Because the water content of a living organism (especially plants) can vary greatly over a short period of time.
Why is net assimilation measured by the increase in dry mass (per unit leaf area.) to measure the rate of production. Allows comparison of different species.
What is biological yield? The total plant biomass produced (dry mass)
What does biological yield demonstrate? The productivity in the ecosystem.
What is economic yield? The mass of desired product produced (dry mass)
What does the economic yield demonstrate? The productivity for market
What is harvest index? (dry mass of economic yield) / (dry mass of biological yield)
What does harvest index useful for? to show efficiency of production (conversion allows comparison of efficiency between different crops e.g maize and barely)
What are the 3 fates of light? Absorbed, Reflected, Transmitted.
Why are chloroplasts green? The green light is not absorbed, but it is reflected and transmitted
Created by: StudyMore6outof7