| Date | May 2015 | Marks available | 1 | Reference code | 15M.2.SL.TZ2.3 |
| Level | Standard level | Paper | Paper 2 | Time zone | Time zone 2 |
| Command term | Deduce | Question number | 3 | Adapted from | N/A |
Question
The image shows a forest food web from North America.
Describe what is meant by a food chain.
Identify a food chain with four or more organisms from the forest food web.
Deduce the trophic level of each organism identified in your food chain from (b)(i).
State one reason that the population of mountain lions is smaller than the populations of other animals in the food web.
Markscheme
a. food chain shows feeding/trophic relationships;
b. showing which organism/animal eats which organism;
c. showing the flow of energy from producer/autotroph to top consumer/top carnivore / through trophic levels;
example from the food web with four or more organisms, given in proper sequence with arrows showing flow of energy in the correct direction and starting with a producer.
Award [0] if any organism in the food chain is not in the web diagram.
correct trophic levels
eg: raspberry bush⎯⎯→chickadee ⎯⎯→bull snake⎯⎯→mountain lion
producer primary secondary tertiary consumer
consumer consumer
Accept ECF for mistakes in previous part. Do not accept “trophic level 1” etc.
mountain lions/highest trophic level receives less energy as energy is lost at each level / mountain lions are larger than other animals and require more (smaller) individuals for food.
Examiners report
Most gained at least 1 mark for their description of a food chain.
Most students were able to pick a suitable food chain from the web given. However a significant number seemed to ignore the web given and draw one from memory. There were a few with the arrows reversed and not starting with a producer.
The naming of the trophic levels is given in 5.1.7, and these are expected.
In c most were able to give a valid reason.
