Question 23M.2.HL.TZ2.3
| Date | May 2023 | Marks available | [Maximum mark: 5] | Reference code | 23M.2.HL.TZ2.3 |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Outline, State, Suggest | Question number | 3 | Adapted from | N/A |
The drawing shows a flower of red valerian, Centranthus ruber.
State the name and function of structures I and II.
Structure I name and function:
Structure II name and function:
[2]
- I is the stigma which receives the pollen/where pollen lands/is captured (during pollination);
- II is the anther and produces/contains/releases pollen;
Both name and function must be included in each marking point.
The role in pollination should be stated. Do not accept “pollination” on its own.
Many candidates confused the stigma and the anther. In many cases, even if the structures were correctly identified, a function was not stated (as requested by the question).
Structure III is the ovary. Outline the processes that occur in the ovary.
[2]
- female gamete/ovule is produced/meiosis to produce ovules/ovule develops;
- Fertilisation occurs
OR
fusion/union of male and female gametes/nuclei; - development of seed (from fertilised ovule);
- development of fruit (from the whole ovary);
Mpb: Do not accept union of pollen and ovule (Too vague).
Do not accept carpel/pistil as equivalent of ovary
Even though many candidates were able to identify that fertilization takes place in the ovary, it was common to observe lack of precision in the terms used. In many cases the terms ovule, ovum and ovary were confused. Few students were accurate with the concept of the union of the male and female gamete (or nuclei). Some candidates were able to indicate that the ovary is where ovules are produced and develop. A limited number of responses mentioned that seeds and fruits develop, however, the ideas were rather vaguely stated.
Structure IV contains a gland that secretes a sugary liquid. Suggest a benefit to the plant of secreting this liquid.
[1]
- attracts an insect/animal/which pollinates the flower;
- attracts a pollinator;
Mpa: Both parts of the sentence are needed to award the point.
Most candidates were able to associate the role of nectar to attracting pollinators such as insects which would aid in pollination. Some vague answers were sometimes observed referring to the sugary liquid being used to provide energy.
