1. In plant tissue culture, cytokinin mainly promotes the formation of which structure from callus when present in a higher concentration than auxin?
A.
Roots
B.
Shoots
C.
Seeds
D.
Pollen grains
Correct Answer:
Shoots
Explanation:
A relatively high cytokinin concentration compared with auxin promotes shoot differentiation from callus.
2. A high auxin-to-cytokinin ratio in a callus culture generally favors the formation of:
A.
Roots
B.
Shoots
C.
Flowers
D.
Fruits
Correct Answer:
Roots
Explanation:
In callus differentiation, a higher proportion of auxin than cytokinin generally favors root formation.
3. What is the usual effect of a nearly balanced concentration of auxin and cytokinin on plant tissue culture cells?
A.
Callus formation and growth
B.
Immediate seed formation
C.
Pollen production
D.
Fruit ripening
Correct Answer:
Callus formation and growth
Explanation:
A relatively balanced auxin-to-cytokinin ratio commonly supports callus formation and its growth before differentiation.
4. Which plant growth regulator is commonly increased to induce shoot differentiation from callus?
A.
Cytokinin
B.
Ethylene
C.
Abscisic acid
D.
Gibberellin
Correct Answer:
Cytokinin
Explanation:
Increasing cytokinin relative to auxin in a callus culture commonly induces the development of shoots.
5. Callus is best described as:
A.
An unorganized mass of plant cells
B.
A mature plant embryo
C.
A group of pollen grains
D.
A fully developed root system
Correct Answer:
An unorganized mass of plant cells
Explanation:
Callus is an unorganized mass of cells that can later differentiate into roots or shoots under suitable hormone conditions.
6. Which hormone balance is most suitable for inducing shoot formation from callus?
A.
High cytokinin and low auxin
B.
High auxin and low cytokinin
C.
No cytokinin and no auxin
D.
High abscisic acid and low cytokinin
Correct Answer:
High cytokinin and low auxin
Explanation:
A high cytokinin-to-auxin ratio favors shoot differentiation from callus.
7. Which hormone balance is most suitable for inducing root formation from callus?
A.
High cytokinin and low auxin
B.
High auxin and low cytokinin
C.
Equal amounts of ethylene and gibberellin
D.
High cytokinin without nutrients
Correct Answer:
High auxin and low cytokinin
Explanation:
A high auxin-to-cytokinin ratio favors the differentiation of roots from callus.
8. Why are cytokinin and auxin concentrations adjusted during callus culture?
A.
To control whether roots or shoots develop
B.
To change the color of the culture vessel
C.
To prevent all cell division
D.
To produce pollen directly
Correct Answer:
To control whether roots or shoots develop
Explanation:
The relative amounts of cytokinin and auxin help control the differentiation of callus into shoots or roots.
9. If a callus culture is supplied with more cytokinin than auxin, which result is most likely?
A.
Shoot buds develop
B.
Only roots develop
C.
The callus becomes a seed
D.
The cells lose their ability to divide
Correct Answer:
Shoot buds develop
Explanation:
A cytokinin-dominant medium generally promotes the formation of shoot buds from callus.
10. The ability of callus cells to form roots or shoots under different hormone conditions is called:
A.
Differentiation
B.
Pollination
C.
Transpiration
D.
Germination
Correct Answer:
Differentiation
Explanation:
Callus differentiation is the process by which previously unorganized callus cells develop into specialized roots or shoots.
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