(a)[2]
Complete the sentence on ecosystems. An ecosystem is a unit made up of the [BLANK] of organisms and their [BLANK], all interacting together.
(b(i))[1]
State how many secondary consumers are shown in Fig. 6.2.
(b(ii))[1]
State the name of a species in Fig. 6.2 that feeds at more than one trophic level.
(b(iii))[1]
State how many different organisms are in the shortest food chain in Fig. 6.2.
(b(iv))[1]
State the evidence from the food web in Fig. 6.2 that shows phytoplankton are producers.
(b(v))[3]
Explain what restricts the number of trophic levels in food webs.
(c)[3]
Discuss the threats to aquatic ecosystems apart from climate change.