Page 26 - Biology_Form_3

Coordination in plants
15. You are a plant biologist analyzing
experimental data on plant
movements. During a study, you
observe two phenomena:
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(a) A shy plant (Mimosa pudica)
folds its leaflets when touched,
but the same plant also opens/
closes its leaves daily without
visible external triggers.
(b) A sunflower seedling bends
toward a light source, while
a Venus flytrap (Dionaea
muscipula) snaps shut when prey
touches its trigger hairs.
Explain the biological concepts
behind your observation.
16. You are a plant physiologist
investigating how gravitational
forces influence hormonal regulation
during seed germination. You design
an experiment where germinating
pea seeds (Pisum sativum) are
placed in a clinostat device that
rotates seeds to neutralize the effects
of unidirectional gravity. After 72
hours, you observe that the roots
and shoots grow in atypical patterns
compared to stationary controls.
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BIOLOGY FORM 3 FINAL EDITED 16.09.2025.indd 19
BIOLOGY FORM 3 FINAL EDITED 16.09.2025.indd 19 KAMISHNA
KAMISHNA
(a) How would you analyse the role
of auxin redistribution and other
hormonal interactions in explaining
the altered growth patterns observed
in the clinostat-treated seeds?
(b) Explain the significance of this
response to the plant growth and
survival.
17. Evaluate the following statements:
(a) You are a horticulturist tasked with
optimizing the growth of a bushy
plant species, for a nursery. A
colleague suggests that pruning the
plant will enhance its growth rate
compared to leaving it unpruned.
(b) Ethylene is inevitably produced by
the plant in soil compared to the
emerged plant.
18. Explain how paratonic movements
(e.g. phototropism, thigmotropism,
or nyctinasty) could address the
farmer’s challenges by enhancing
plant survival, resource acquisition,
or pest resistance.
19. How would you design an experiment
using a clinostat to demonstrate
phototropism, and what steps would
you take to ensure accurate results?
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23/10/2025 11:52:31