Question 23M.3.HL.TZ1.15
| Date | May 2023 | Marks available | [Maximum mark: 6] | Reference code | 23M.3.HL.TZ1.15 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Explain, Identify, Outline | Question number | 15 | 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;
Most were able to get the mark for correctly identifying the trophic level of sea lions from the food web given.
Outline the additional information that would be required to convert the food web into a pyramid of energy.
[2]
- energy content in biomass/all organisms of each trophic level;
- size of study area included;
- over period of time / per year;
Very few had any understanding of what was needed to convert a food web into a pyramid of energy.
Outline a reason that the orca whale would be difficult to represent in a pyramid of energy.
[1]
orca is in different trophic levels depending on its food source;
Some candidates could get a mark for seeing that an orca could be in several different trophic levels and thus difficult to represent in a pyramid of energy.
Explain reasons for the feed conversion ratio in fish being lower than in cattle.
[2]
- the efficiency by which an organism uses food is the feed conversion ratio/FCR
OR
FCR = mass of food taken in/production of biomass; - fish have low respiration rate/body temperature so need less food/lose less energy;
This question on food conversion ratio was poorly answered by almost all candidates, with very few receiving any marks. Many incorrectly tried to relate this to the food web or to size differences between fish and cattle.