Transfer of Energy Flashcards

All 8 cards in this deck

Name four ways energy is lost between one trophic level and the next.

Respiration (heat), movement, excretion and egestion of undigested food.

Apart from respiration and excretion, why is not all of an organism's energy passed to the next trophic level?

Not all of the organism is eaten or digested, e.g. bones, roots and woody parts.

Why are food chains usually limited to about four or five trophic levels?

So much energy is lost at each level that there is too little left to support another level.

Why are there usually fewer organisms at higher trophic levels?

Less energy is available at each level, so it can support fewer (or smaller) organisms.

What is the formula for the percentage efficiency of energy transfer between two trophic levels?

$\text{efficiency} = \dfrac{\text{energy transferred to next level}}{\text{energy available at previous level}} \times 100$

What are the steps to calculate the energy transferred to the next trophic level from a percentage efficiency?
e.g. $200$ kJ in the plants, $10\%$ transferred

1. Divide the percentage by 100: $10 \div 100 = 0.1$.
2. Multiply by the energy available: $200 \times 0.1 = 20$.
3. Give the answer with units: $20$ kJ.

What are the steps to calculate the percentage of biomass lost at a trophic level?
e.g. $500$ kg of plants gives $50$ kg of cattle

1. Find the biomass lost: $500 - 50 = 450$ kg.
2. Divide by the starting biomass: $450 \div 500 = 0.9$.
3. Multiply by 100 and round as asked: $90\%$.

True or false? Energy lost as heat from respiration can be passed on to the next trophic level.

False. Heat energy is lost to the surroundings and cannot be used by the next trophic level.