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Date November 2017 Marks available 4 Reference code 17N.2.SL.TZ0.07
Level Standard level Paper Paper 2 Time zone TZ0 / no time zone
Command term Describe Question number 07 Adapted from N/A

Question

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.

Explain the process of photosynthesis.

[8]
b.

Describe the process of peat formation.

[4]
c.

Markscheme

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]

a.

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]

 

b.

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]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Core » Topic 4: Ecology » 4.3 Carbon cycling
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