Outline how these results indicate that blackberry distribution is limited by light intensity.

Distinguish between the transfer of matter and energy in closed ecosystems.

A pyramid of energy represents the amount of energy taken in by each trophic level per unit time and per unit area. Discuss the advantages and disadvantages of the use of pyramids of energy as models of energy flow in an ecosystem.

a. as light level changes so does the percentage cover «of blackberry» ✔

b. distribution is higher at intermediate/moderate light intensities ✔ Accept appropriate numerical values

c. little growth at low light intensities
OR
little growth at high light intensities ✔ Accept appropriate numerical values

d. distribution is bell shaped ✔

only energy can be lost/gained/exchanged/transferred «with the exterior»
OR
only matter is constant/recycled ✔

Advantages:
a. can show the energy loss/transfer between trophic levels ✔

b. permits a ‹quantitative› comparison between ecosystems ✔

c. shows change over time ✔

Disadvantages:
d. are difficult to produce accurately ✔

e. require destructive methods to obtain the data ✔

f. do not show all the interactions/food chains/feeding relationships «between different members of the community» ✔

g. cannot represent organisms that feed at different trophic levels ✔

Award [3 max] if only one side of the argument is given.