DP Biology (first assessment 2025)
Question 19M.2.SL.TZ2.8a
Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.2.SL.TZ2.8a |
Level | SL | Paper | 2 | Time zone | TZ2 |
Command term | Outline | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 4]
19M.2.SL.TZ2.8a
(a)
Outline energy flow through a food chain.
[4]
Markscheme
a. energy from the sun/light energy is converted to chemical energy by photosynthesis ✔
b. «chemical» energy flows through the food chains by feeding ✔
c. energy is released «from carbon compounds» by respiration
OR
energy from respiration is used by living organisms and converted to heat ✔
d. heat is not recyclable / heat is lost from food chains
OR
heat cannot be converted to other forms of energy ✔
e. energy is lost in excretion/uneaten material/egestion/feces ✔
f. energy losses between trophic levels limits the length of food chains
OR
energy transfer is only 10 % between trophic levels ✔
Examiners report
Was well answered with most students being knowledgeable about ecology.


