Question 17N.2.SL.TZ0.07
| Date | November 2017 | Marks available | [Maximum mark: 15] | Reference code | 17N.2.SL.TZ0.07 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Describe, Draw, Explain | Question number | 07 | Adapted from | N/A |
Plants have widespread influences, from food chains to climate change.
Draw a diagram of a palisade mesophyll cell labelling only the structures that would not be present in a pancreatic cell.
[3]
a. cell wall
Must be shown as a double line
b. large vacuole
Labelled either inside or on the membrane
c. chloroplast/plastid
d. starch grain
e. tonoplast
Allow [2 max] if any features common to both plant cells and animal cells are labelled
[Max 3 Marks]
Explain the process of photosynthesis.
[8]
a. autotrophs perform photosynthesis
b. carbon dioxide and water are the reactants/raw materials required for «photosynthesis»
c. light splits water molecules/causes photolysis
d. «photolysis» releases oxygen as a «waste» product
e. light energy is converted into chemical energy
f. «photosynthesis» produces organic compounds/glucose/carbohydrates
g. photosynthesis occurs in chloroplasts
h. chlorophyll «photosynthetic pigment» absorbs light
i. different pigments absorb different wavelengths «of light»
j. chlorophyll absorbs red and blue light/ends of the spectrum
k. carbon dioxide concentration/temperature/light intensity are limiting factors
Award only [1] for correct display of equation unless further annotated or explained
Allow up to [2] for correct use of understandings specified as AHL topic 8
[Max 8 Marks]
Describe the process of peat formation.
[4]
a. formed from dead plant material/leaves/mosses/Sphagnum
b. formed in waterlogged sites/bogs/mires/swamps
c. where bacteria/fungi/saprotrophs are not active/are inhibited
d. organic matter not fully decomposed
e. «occurs» in acidic conditions
f. «occurs» in anaerobic conditions
Reject anaerobic respiration
g. «very» slow process/takes a long time
[Max 4 Marks]
