Question
HLPaper 2
1.[4]
Draw a half-view of an animal-pollinated flower.
Verified
Solution
- Sepals as outermost part of flower;
1 mark - Petals as largest part of flower;
1 mark - Stamen drawn with recognizable anther and filament
OR
Anther and filament shown as parts of the stamen;1 mark - Carpel/pistil drawn with recognizable stigma, style, and ovary
OR
Stigma, style, and ovary shown as parts of the carpel;1 mark - Nectary at base of the ovary;
1 mark - Ovule inside the ovary;
1 mark
Since 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.
[Max 4 Marks]
2.[4]
Outline the growth of plant shoot apex.
Verified
Solution
- Growth in shoots is indeterminate/unlimited;
1 mark - Produces stem and leaves;
1 mark
(For mpb, both stem and leaves are needed and buds or branches should not be accepted as alternatives.) - Growth/cell growth/cell elongation controlled/affected by hormones/auxin/IAA;
1 mark - New/extra cells produced by mitosis/cell division / apex is a meristem;
1 mark - Tropism/phototropism / grows towards the sun/light;
1 mark - Auxin moved away from sunny side/to shady side of shoot «apex»
OR
Auxin efflux pumps set up concentration gradients;1 mark
[Max 4 Marks]
3.[7]
Explain the movement of energy and inorganic nutrients in an ecosystem.
Verified
Solution
- Autotrophs/producers/plants obtain inorganic nutrients from the «abiotic» environment;
1 mark - Energy is provided «mainly» by sunlight;
1 mark - Light energy is converted «to chemical energy» through photosynthesis;
1 mark - Photosynthesis/producers/autotrophs convert inorganic carbon/carbon dioxide and water into carbon/organic compounds;
1 mark - Organic compounds/glucose are used as a source of chemical energy «through respiration»;
1 mark - Organic compounds/glucose are used to synthesize other organic compounds;
1 mark - Organic compounds/glucose are used to synthesize ATP;
1 mark - Organic compounds/glucose are used for growth/repair/reproduction;
1 mark - Organic compounds/glucose are stored as starch/lipids;
1 mark - Organic compounds/glucose are passed on to other organisms in food chains;
1 mark
Award [5 max] if only energy is mentioned.
[Max 7 Marks]
