Biology 9700 · AS & A Level · Cells as the basic units of living organisms

Cells as the basic units of living organisms — practice question

Within a mangrove ecosystem, leaves shed by grey mangrove plants drop into the water and settle in the mud beneath. Bacteria and fungi then decompose them. Invertebrates such as crabs, prawns, and molluscs live in the mud and consume the dead leaves. The bullseye fish feeds on the invertebrates. Humans eat prawns, crabs and fish. Herons and other wading birds live and reproduce in the mangroves. These birds feed on invertebrates and fish. Which statement about this ecosystem is correct?

  • ABacteria, fungi, crabs, prawns and molluscs form the community in the mud.
  • BBullseye fish are at the second trophic level in the food web.
  • CFungi in the water are the main producers in the ecosystem.
  • DGrey mangroves are the ecological niche of herons.

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