Functioning ecosystems and succession — Question 25

25

a)

$\mathrm{P}\mathrm{r}\mathrm{o}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{e}\mathrm{r}\mathrm{s}\,$

$52\,–\,16\,=\,36\,\mathrm{M}\mathrm{J}/\mathrm{m}^{2}/\mathrm{y}\mathrm{e}\mathrm{a}\mathrm{r}\,$

$\mathrm{H}\mathrm{e}\mathrm{r}\mathrm{b}\mathrm{i}\mathrm{v}\mathrm{o}\mathrm{r}\mathrm{e}\mathrm{s}\,$

$28\,–\,20\,–\,5\,=\,3\,\mathrm{M}\mathrm{J}/\mathrm{m}^{2}/\mathrm{y}\mathrm{e}\mathrm{a}\mathrm{r}\,$

• states 36 MJ/m²/year for producers [1 mark]

• states 3 MJ/m²/year for herbivores [1 mark]

Allow FT error for herbivores.

25

b)

Respiration was higher for the herbivores. Decomposition was higher for the producers.

• identifies 1 relevant difference between respiration and decomposition [1 mark]

• identifies another relevant difference between respiration and decomposition [1 mark]

OR

• determines % loss at each trophic level $24/52 = 46\% for producers$ $25/28 = 89\% for herbivores\text{[1 mark]}\,$

• identifies % loss is higher for herbivores than autotrophs [1 mark]

Differences may include any: difference in respiration (4 MJ) difference in decomposition (3 MJ) identification of respiration being higher for herbivores or other suitable response consistent with a reasonable understanding.