Plant Growth and Development
Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which plant hormone is known as the 'stress hormone'?

Auxin
Gibberellin
Abscisic acid
Cytokinin
3

Abscisic acid (ABA) is called the stress hormone as it helps plants respond to environmental stress and induces stomatal closure.

Which phase of growth is characterized by maximum cell enlargement and thickening of cell walls?

Meristematic phase
Elongation phase
Maturation phase
Lag phase
3

During the maturation phase, cells attain their final size with thickened walls and protoplasmic modifications.

Who discovered the plant hormone responsible for phototropism?

E. Kurosawa
Charles Darwin
F.W. Went
H.H. Cousins
2

Charles Darwin and his son Francis observed that coleoptiles of canary grass bend towards light, demonstrating phototropism.

Which plant hormone is used for thinning of cotton, cherries, and walnuts?

Gibberellin
Cytokinin
Ethylene
Auxin
3

Ethylene, released from ethephon, is used for thinning flowers and fruits in crops like cotton, cherry, and walnut.

What happens if cytokinin is not added to a plant tissue culture medium?

Root formation is inhibited
Shoot formation is inhibited
Flowering is delayed
Leaf abscission increases
2

Cytokinin promotes shoot formation; without it, shoot growth is inhibited in tissue culture.

Which of the following statements about auxins is incorrect?

Auxins promote apical dominance.
Auxins induce parthenocarpy.
2,4-D is a synthetic auxin.
Auxins are produced mainly in roots.
4

Auxins are primarily produced in the shoot apical meristem and young leaves, not in roots.

Which of the following about differentiation and dedifferentiation is correct?

Dedifferentiation is when cells lose their ability to divide.
Differentiation produces specialized cells.
Dedifferentiated cells cannot redifferentiate.
Differentiation is a reversible process.
2

Differentiation is the process by which cells become specialized. Dedifferentiation allows cells to regain division ability, which can lead to redifferentiation.

Which of the following about plant growth measurement is incorrect?

Growth can be measured by an increase in dry weight.
Growth can be measured by an increase in cell number.
Surface area increase is not a measure of growth.
Fresh weight is used to measure growth.
3

Surface area increase, such as in leaves, is a valid measure of growth. Growth can also be measured by dry weight, fresh weight, or cell number.

Which parameter is commonly used to measure growth in a dorsiventral leaf?

Volume
Cell number
Surface area
Dry weight
3

In a dorsiventral leaf, growth is typically measured in terms of the increase in surface area.

Which type of growth pattern produces a sigmoid curve?

Arithmetic growth
Geometric growth
Linear growth
Exponential growth
2

Geometric growth results in a sigmoid (S-shaped) curve, with lag, log, and stationary phases.

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