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Date November 2019 Marks available 7 Reference code 19N.2.HL.TZ0.8
Level Higher level Paper Paper 2 Time zone TZ0 / no time zone
Command term Explain Question number 8 Adapted from N/A

Question

Draw a half-view of an animal-pollinated flower.

[4]
a.

Outline the growth of plant shoot apex.

[4]
b.

Explain the movement of energy and inorganic nutrients in an ecosystem.

[7]
c.

Markscheme

a. sepals as outermost part of flower ✔

b. petals as largest part of flower ✔

c. stamen drawn with recognizable anther and filament
OR
anther and filament shown as parts of the stamen ✔

d. carpel/pistil drawn with recognizable stigma, style and ovary
OR
stigma, style and ovary shown as parts of the carpel ✔

e. nectary at base of the ovary ✔

f. ovule inside the ovary ✔

As the question does not specify a labelled half-view, allow some marks for unlabeled structures: award one mark for any two of the six structures in the mark scheme (mpa to mpf). It must be clear what each unlabeled part is. The maximum mark is therefore 3 for an unlabeled half-view.

a.

a. growth in shoots is indeterminate/unlimited ✔

b. produces stem and leaves ✔ For mpb, both stem and leaves are needed and buds or branches should not be accepted as alternatives.

c. growth/cell growth/cell elongation controlled/affected by hormones/auxin/IAA ✔

d. new/extra cells produced by mitosis/cell division / apex is a meristem ✔

e. tropism/phototropism / grows towards the sun/light ✔

f. auxin moved away from sunny side/to shady side of shoot «apex»
OR
auxin efflux pumps set up concentration gradients ✔

b.

a. autotrophs/producers/plants obtain inorganic nutrients from the «abiotic» environment ✔

b. energy is provided «mainly» by sunlight ✔

c. light energy is converted «to chemical energy» through photosynthesis✔

d. photosynthesis/producers/autotrophs convert inorganic carbon/carbon dioxide and water into carbon/organic compounds ✔

e. carbon compounds/foods contain/are a source of «usable» energy «for life» ✔

f. carbon compounds/energy are transferred along food chains when eaten by consumers/heterotrophs ✔

g. respiration returns carbon «dioxide» to the environment ✔

h. respiration releases stored/chemical energy as heat/ATP ✔

i. energy/ATP is used to carry out life functions/synthesis/growth/movement ✔

j. energy is lost/is not recycled ✔ Both related by “or” required.

k. nutrients are recycled / example of recycled nutrient e.g. carbon ✔

l. decomposers recycle minerals/inorganic nutrients ✔

Award [5 max] if only energy is mentioned.

c.

Examiners report

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

Syllabus sections

Core » Topic 4: Ecology » 4.2 Energy flow
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