Functioning Ecosystems

Question 1

The equation that describes photosynthesis is:

Answer 1

6CO2 + 6H2O → C6H12O6 + 6O2

Question 2

The competitive exclusion principle states that:

Answer 2

two species with identical niches cannot coexist indefinitely.

Question 3

Keystone species are:

Answer 3

organisms that play a unique and crucial role in the way an ecosystem functions.

Question 4

An ecological niche is defined as:

Answer 4

the role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment.

Question 5

Explain the energy transformation from the sun to primary producers.

Explain Energy transfer from producers and consumers to decomposers.

Answer 5

Primary producers such as plants absorb ~1.3-1.6% of energy from sunlight and convert that to chemical energy during photosynthesis.

When a producer or consumer dies, the carbon and other molecules in its body are broken down by decomposers like fungi and bacteria, which releases energy that the decomposers can use.

This also happens to faeces or parts of the producer/consumer that drop off (dead skin cells, leaves) during its life.

Question 6

Contrast the efficiency of energy transfers between Herbivore A1 → Carnivore A2 to subsequent trophic energy transfers.

Answer 6

Only about 10% of the chemical energy contained in Herbivore is passed onto Carnivore .

The rest is lost, for example as heat during the lifetime of Herbivore , or because it is unable to be digested/absorbed by Carnivore

Subsequent trophic transfers are also only ~10%, which means that only about 1% of the energy captured by primary producers reaches Carnivore , and 0.1% would reach Carnivore.

Question 7

Contrast gross and net primary productivity.

Answer 7

Gross primary productivity (GPP) is the total amount of biomass produced by photoautotrophs via photosynthesis from sunlight.

In contrast, net primary productivity (NPP) is the GPP minus the biomass lost by the plants to stay alive (e.g. via metabolism, heat)

Question 8

Calculate the trophic level transfer efficiency of primary producers (16276) to decomposers in this situation (36380). State your answer as a percentage.

Answer 8

16276/ 36380 x 100

= 44.7%