1. Explain what a pyramid of biomass is.
Answer
A graphical way of representing the relative amount of biomass in each level of a food chain. (Trophic level 1 is at the bottom of the pyramid.)
2. What are primary consumers ?
Answer
Herbivores that eat plants or algae.
3. What are carnivores ?
Answer
Animals that eat herbivores or other carnivores.
4. What are apex predators and where are they found in a food chain ?
Answer
Carnivores with no predators that are the final organism in a food chain.
5. Describe some ways that biomass can be lost between trophic levels.
Answer
Not all ingested material is absorbed; some is egested as faeces. Some of the absorbed material is lost as waste, such as carbon dioxide and water during respiration, or water and urea in urine.
6. Describe how decomposers break down dead matter.
Answer
Decomposers are microorganisms including bacteria and fungi. They secrete enzymes to digest dead matter and break it down into small, soluble food molecules which can then diffuse into the microorganism.
7. Sardines have a greater biomass than tuna. Explain why a greater proportion of biomass is passed to humans if they eat sardines rather than tuna.
Answer
Eating sardines would mean that there are fewer trophic levels and so less biomass would be lost in faeces, urine or carbon dioxide. Large amounts of glucose are used in respiration, so there would be less respiratory losses.
8. Why do plants and algae transfer only about 1% of the energy from light into glucose during photosynthesis ?
Answer
Some light is reflected by the leaf, not absorbed by chlorophyll, or transmitted through the leaf.