Deduce whether jellyfish or crustacea are a richer source of carbon in a food chain.

Distinguish between the transfers of energy and inorganic nutrients in ecosystems.

The diagram shows the food web for an aquatic ecosystem in which letters R–Z represent individual species.

[Source: © International Baccalaureate Organization 2019]

Which organism is a tertiary consumer?

A. Organism T

B. Organism U

C. Organism W

D. Organism Y

The image shows an example of a soil food web.

[Source: Anon., n.d. The Soil Food Web. [image online] Available at: https://www.nrcs.usda.gov/wps/portal/nrcs/
photogallery/soils/health/biology/gallery/?cid=1788&position=Promo [Accessed 11 March 2020].]

Draw a food chain from this food web, showing at least three organisms.

The trout, Oncorhynchus mykiss, that live in West Brush Creek and Cement Creek also feed on the mayflies. Fishermen come to Colorado to catch and eat trout. Draw a diagram of part of a food web for the creeks in Colorado, including mayflies, humans, trout and bats.

Draw a labelled diagram of a pyramid of energy.

Explain the movement of energy and inorganic nutrients in an ecosystem.

Outline energy flow through a community in a natural ecosystem.

Compare and contrast the effects of temperature on the biomass of autotrophs and heterotrophs with added nutrients.

Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.

Outline the criteria that should be used to assess whether a group of organisms is a species.

The diagram shows the flow of energy through an ecosystem in ${\text{kJ\hspace{0.05em}m}}^{–2}{\text{\hspace{0.05em}y}}^{–1}.$

Explain how energy enters, flows through and is lost from marine food chains.

Suggest with a reason whether having a large body mass is an advantage or disadvantage for jellyfish.

Explain the processes by which energy enters and flows through ecosystems.

Describe how energy flows through and is used by organisms in ecosystems.

State two causes of the decrease of biomass along food chains in terrestrial ecosystems.

Explain the role of decomposers in an ecosystem.

Explain the reasons for food chains rarely containing more than four or five trophic levels.

The Silver Springs feed into the Silver River in Florida. The diagram shows a pyramid of energy for the Silver Springs ecosystem. The units are kJ m^–2 y^–1.

[Source: © International Baccalaureate Organization 2019]

What do level I and level III represent in the pyramid of energy?