Question 18N.2.SL.TZ0.2
| Date | November 2018 | Marks available | [Maximum mark: 7] | Reference code | 18N.2.SL.TZ0.2 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe, Explain, Label, Outline | Question number | 2 | Adapted from | N/A |
Label the area where cellulose is found in the micrograph of a plant cell.
[Source: BIOPHOTO ASSOCIATES/Getty Images]
[1]
label placed anywhere along outside perimeter/cell wall of plant cell ✔
Cellulose is the most abundant organic polymer on Earth. Describe the structure of cellulose.
[3]
a. unbranched/straight chain of glucose molecules
OR
unbranched/straight-chain polysaccharide ✔
b. formed of beta glucose;
c. formed by condensation reactions/glycosidic bonds
OR
1, 4 linkage ✔
d. hydrogen bonds form between cellulose chains
e. form microfibrils ✔
Award marks to an accurate annotated diagram
Do not allow carbohydrate
Outline one reason for humans being unable to digest cellulose.
[1]
humans lack cellulase/appropriate enzyme ✔
Explain the advantages of having both lipid and carbohydrate as energy stores in the human body.
[2]
a. lipid is long-term energy storage
OR
carbohydrate is short-term energy storage/readily available ✔
b. lipids are insoluble, so easier to store
OR
carbohydrates/sugars are soluble, so easy to transport by blood ✔
c. lipids store more energy «per gram»
OR
lipids occupy less space «per energy/kJ» ✔
OWTTE