1. What is apical dominance?
A.
Inhibition of lateral bud growth by the apical bud
B.
Growth of roots toward water
C.
Opening of flowers in sunlight
D.
Formation of seeds without fertilization
Correct Answer:
Inhibition of lateral bud growth by the apical bud
Explanation:
Apical dominance is the condition in which the apical bud suppresses the growth of lateral buds.
2. Which plant part mainly causes apical dominance?
A.
Root cap
B.
Apical bud
C.
Mature fruit
D.
Root hair
Correct Answer:
Apical bud
Explanation:
The apical bud produces auxin, which helps suppress the growth of lateral buds.
3. Which hormone is mainly associated with apical dominance?
A.
Auxin
B.
Ethylene
C.
Abscisic acid
D.
Gibberellin
Correct Answer:
Auxin
Explanation:
Auxin produced in the shoot apex moves downward and contributes to the inhibition of lateral bud growth.
4. What usually happens to lateral buds when the shoot tip is present?
A.
They are strongly stimulated to grow
B.
Their growth is inhibited
C.
They immediately form roots
D.
They change into flowers
Correct Answer:
Their growth is inhibited
Explanation:
The active shoot tip maintains apical dominance, so lateral buds generally remain dormant or grow slowly.
5. What is a common result of removing the shoot apex from a plant?
A.
Increased growth of lateral branches
B.
Complete stoppage of root growth
C.
Immediate loss of all leaves
D.
Inhibition of seed germination
Correct Answer:
Increased growth of lateral branches
Explanation:
Removing the shoot apex reduces the source of auxin responsible for apical dominance, allowing lateral buds to grow.
6. Why is the shoot tip often removed during pruning?
A.
To promote branching
B.
To prevent root formation
C.
To stop photosynthesis permanently
D.
To increase apical dominance
Correct Answer:
To promote branching
Explanation:
Pruning removes the apical bud and weakens apical dominance, encouraging the growth of lateral branches.
7. A plant with strong apical dominance is most likely to have which growth form?
A.
A tall main shoot with fewer lateral branches
B.
A short plant with many side branches
C.
Only underground stems
D.
No growing shoot
Correct Answer:
A tall main shoot with fewer lateral branches
Explanation:
Strong apical dominance suppresses lateral buds and favors the continued growth of the main shoot.
8. Which practice reduces apical dominance in garden plants?
A.
Pinching off the shoot tip
B.
Protecting the shoot tip from removal
C.
Removing all lateral buds
D.
Increasing the height of the main stem
Correct Answer:
Pinching off the shoot tip
Explanation:
Pinching removes the apical bud, reducing auxin-mediated suppression of lateral buds and promoting branching.
9. If the apical bud of a young plant is removed, which buds are most likely to begin growing?
A.
Lateral buds
B.
Root cap cells
C.
Seed coat cells
D.
Pollen grains
Correct Answer:
Lateral buds
Explanation:
Without the apical bud, the inhibitory effect of apical dominance is reduced, so lateral buds can develop.
10. What is the main horticultural benefit of controlling apical dominance?
A.
Managing the number and arrangement of branches
B.
Preventing all plant growth
C.
Stopping water absorption by roots
D.
Eliminating the need for sunlight
Correct Answer:
Managing the number and arrangement of branches
Explanation:
Controlling apical dominance through pruning or pinching helps gardeners encourage branching and shape plants.
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