Energy FlowCambridge IGCSE Biology: Flashcards
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What is the principal source of energy for biological systems?
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- What is the principal source of energy for biological systems?
- The Sun.
- How is light energy converted into a form organisms can use?
- Producers convert light energy into chemical energy stored in organic molecules, via photosynthesis.
- What eventually happens to energy that flows through a food chain?
- It is eventually transferred to the environment, mostly as heat lost through respiration.
- What does a pyramid of energy show?
- The amount of energy present at each trophic level in a food chain, usually over a fixed time period.
- Why are pyramids of energy always the correct pyramid shape, unlike pyramids of numbers or biomass?
- Because energy is always lost at each trophic level, so the amount of energy always decreases going up the food chain.
- Name two ways energy is lost between trophic levels.
- As heat through respiration, and in waste materials such as faeces and urine (also used in movement).
- Why do food chains usually have fewer than five trophic levels?
- Because so much energy is lost at each stage that there is not enough left to support further trophic levels.
- Why is it more energy efficient for humans to eat crop plants than livestock fed on crops?
- Eating the plant directly avoids the energy losses that occur when that energy passes through an animal first.
- What is a trophic level?
- The position of an organism in a food chain, food web, or ecological pyramid (e.g. producer, primary consumer).
- Is energy transfer between trophic levels efficient or inefficient?
- Inefficient — much energy is lost rather than passed on to the next level.