Question 1: Discuss Excellence

Tulips flower in spring and are pollinated by the wind or by animals. Decades of study have shown how they respond to their abiotic surroundings: they show geotropic responses and both thermonasty and photonasty, and even when cut and standing in a vase they still show geotropism and phototropism.

Discuss how these responses help to ensure the success of the tulip.

The 2023 paper, page 2 ↗ Marking schedule, page 2 ↗

Work it out

Try it on paper first. Stuck? Take one hint at a time.

1 Start from the explain answer: how do the two tropisms work together?
Negative geotropism lifts the stem and phototropism turns it to the light, so the flower stands high, warm and in full view, and the leaves are lit for photosynthesis: the best conditions for growth.
2 How do the two nastic responses work together?
The flower opens only when it is both warm and light: on sunny days, when pollinators are active and the air is moving. The rest of the time it is closed, so it spends no energy staying open and loses no pollen to weather or night visitors.
3 So what do all four achieve in sync?
An upright, sunlit flower that is open just when pollinators fly or the wind blows, and shut otherwise. Pollen moves from tulip to tulip far more often.
4 What does more pollination lead to?
More fertilisation and more seed, which increases reproductive success. Pollen carried between plants also increases variation in the species, and more seed means the population can grow.

Answer The tropisms and nastic responses work in sync. Negative geotropism lifts the stem and positive phototropism turns it to the light, so the flower stands high, warm and visible and the leaves are lit for photosynthesis. Thermonasty and photonasty open the flower only when it is both warm and light, on sunny days when pollinators are active and the air is moving, and keep it shut otherwise, saving energy and protecting the pollen from weather and night visitors. So the flower is open, upright and in view at exactly the times pollen is most likely to be carried from tulip to tulip. More pollination means more fertilisation and seed, which increases reproductive success, increases variation in the species, and lets the population grow.

What the marker wanted

Achieved The describe points: the two definitions, the four named responses and what they gain, and warmth for pollinators.
Merit Those advantages explained, with thermonasty and photonasty defined and tied to the flower opening for pollination.
Excellence Discusses two things. First, how the named responses benefit the tulip, the nastic and tropic ones working in sync so the plant grows well and is pollinated, open on warm, sunny or windy days when pollen moves. Second, what more pollination leads to: greater reproductive success, and so more variation in the species and a larger population. One gives E7, both E8.

One answer, N0 to E8. Excellence points come last: one gives E7, both give E8.

In our words, from NZQA’s 2023 marking schedule.

Common mistake

Explaining the advantage of each tropism and nastic response separately, without linking them together or to reproductive success. NZQA’s 2023 report says that is where Merit answers stopped.

How did it go?

Got it moves it further out. Review brings it back tomorrow.