Question 23M.3.SL.TZ1.14
| Date | May 2023 | Marks available | [Maximum mark: 5] | Reference code | 23M.3.SL.TZ1.14 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe, Identify, Outline | Question number | 14 | Adapted from | N/A |
The diagram shows a simplified marine food web in an area of the North Pacific Ocean.
Identify the
trophic level of sea lions.
[1]
secondary consumer / third trophic level/ trophic level 3 / 3;
The term secondary consumer is preferred here, but many candidates were credited for trophic level 3.
type of interspecific relationship between orca whales and sea otters.
[1]
predation/predator-prey;
Do not accept whale eats otter
Many answers referred to the orca feeding on sea otters, without giving the correct interspecific relationship term of predation or predator-prey.
Ex situ conservation measures are being introduced due to a rapid decline in sea otter populations. Describe the advantages of ex situ conservation.
[2]
- protecting species outside their natural habitats in zoos/aquariums/botanical gardens;
- essential requirements can be managed/monitored;
- allows breeding programmes;
- useful when there is a serious decline/destruction of natural habitats
OR
when there is a threat to individuals in the wild;
This was quite well answered but some candidates did not understand the term ex situ and discussed effects on the natural food web.
A pyramid of energy can be constructed to show energy flows in this food web. Outline one limitation of these pyramids.
[1]
do not show seasonal variations in energy transfers
OR
difficult to assign species to a specific trophic level
OR
do not show energy transfer to decomposers;
Do not accept does not show food web
There were some vague answers referring to food webs or chains without mentioning feeding at more than one trophic level.