Question 19M.2.SL.TZ2.3a.i
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.SL.TZ2.3a.i |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | State | Question number | a.i | Adapted from | N/A |
State two causes of the decrease of biomass along food chains in terrestrial ecosystems.
[2]
a. «cell» respiration/loss of CO2/biomass consumed to provide/as a source of energy ✔
b. loss of energy «as heat» between trophic levels means less energy available for building biomass ✔
c. waste products «other than CO2»/loss of urea/feces/egesta ✔
d. material used/CO2 released by saprotrophs ✔
e. undigested/uneaten material «teeth, bones, etc»/detritus buried/not consumed
OR
formation of peat/fossils/limestone ✔
A large proportion of students looked at this question and immediately reeled off an answer in terms of energy (as in many previous years). Few made the connection between biomass and energy, for example in respiration CO2 is lost from the food chain during respiration, or that urea has mass etc.
