Question 21M.1A.SL.TZ2.18
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.1A.SL.TZ2.18 |
| Level | SL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 18 | Adapted from | N/A |
The diagram shows the flow of energy through an ecosystem in
[Source: “Energy flow: Figure 3,” (https://cnx.org/contents/[email protected]:fbNheNoN@8/Energy-Flow) by OpenStax College, Biology CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).]
What percentage of the energy passed from primary producers to primary consumers is lost to cellular respiration by tertiary consumers?
A. 0.001%
B. 0.08%
C. 0.2%
D. 0.4%
[1]
D
The candidates found this question difficult, possibly because the arrow coming from the primary producers shows 40 000 kJ m−2 y−1 leaving but only half of that is taken up by primary consumers, the remainder being lost to saprotrophs and detritivores. Some G2 forms suggested that the calculation was too difficult without the aid of a calculator but if the candidates had chosen the correct values from the diagram the calculation would have been straightforward ().
