Question

A maximum of 10% of the energy present in any trophic level is passed on to the next level when an organism from the lower level is consumed by an organism from the higher level.  Imagine that an acre of land produces 50 pounds of plant biomass per week.  Calculate how many acres of land would be required to support a tertiary consumer (some type of carnivore) that consumes 10 pounds of prey per week.

1 acre
		10,000 acres
		1,000 acres
		200 acres
		0.2 acres

Answer 1

As per question, A maximum of 10% of the energy present in any trophic level is passed on to the next level when an organism from the lower level is consumed by an organism from the higher level.

Here the tertiary consumers consume 10 pounds of prey, which is means there must be 10 pounds of secondary consumers per week*.

Note:- * 10 % thing won't be allowed because it is written that tertiary consumers consume 10 pounds of prey, which means they get 1 pound equivalent energy per week.

Now to have 10 pounds of secondary consumer we must have 100 pound of primary consumer as per 10 % rule. Similarly, to have 100 pound per week of primary consumer we must have 1000 pounds of biomass per week.

As 50 pounds per week is produced in 1 acre, then total acre required to have 1000 pounds per week = 1000/50 = 20 acres

But if your options are 1 acre, 10000 acre, 1000 acre, 200 acre, 0.2 acre

Then select option 200 acre as answer and follow the solution below.

In this case they might have considered that tertiary consumers consume 10 pounds of energy from their prey. Then as per 10% rule secondary consumers must have energy of 100, then primary must have 1000 and biomass must be 10000 pounds per week.

So total acres required = 10000/50 =200 acres

But consuming 10 pounds of prey never means transfer of that much energy equivalent. So choose your answer wisely as question is bit unclear. Thank you.