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All the following contribute to an increase in girth of dicots and gymnosperms except:
\(
\begin{array}{|l|l|}
\hline \text { 1. Apical meristem } & \text { 2. Lateral meristems } \\
\hline \text { 3. Vascular cambium } & \text { 4. Cork-cambium } \\
\hline
\end{array}
\)
(a)
The shape of the growth curve characteristic of a living organism growing in natural environment is:
(b)
Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called:
(b)
Identify the plant growth regulator that, though is largely an inhibitor but, can be placed in both plant growth promoter and plant growth inhibitor groups?
(d)
Callus from internodal segments of tobacco stem gets proliferated only if in addition to one of the following – extracts of vascular tissues, yeast extract, coconut milk or DNA, the nutrient medium also contains:
(a)
\(
\begin{aligned}
& \text { Auxin was first isolated from: }\\
&\begin{array}{|l|l|}
\hline \text { 1. Coconut milk } & \text { 2. Barley endosperm } \\
\hline \text { 3. Oat coleoptiles } & \text { 4. Human urine } \\
\hline
\end{array}
\end{aligned}
\)
(d)
Auxin does not:
(b)
Ethylene is the hormone that promotes the formation of female flowers in cucumbers.
To extend their market period, fruits can be left on trees longer by the application of:
(b)
\(
\begin{aligned}
& \text { Kinetin was first discovered from: }\\
&\begin{array}{|l|l|}
\hline \text { 1. Herring sperm DNA } & \text { 2. Coconut milk } \\
\hline \text { 3. Yeast extract } & \text { 4. Corn kernels } \\
\hline
\end{array}
\end{aligned}
\)
(a)
Cytokinins do not help in:
(d)
Cytokinins help in delay of leaf senescence because they:
(d)
Normally, when the seeds are mature, ethylene production increases and builds-up within the fruit, resulting in a climactic event that means:
(c)
Which PGR is used to initiate flowering and for synchronizing fruit set in pineapple?
(c)
How does pruning help in making the hedge dense?
(b)
Which of the following is not an inhibitory substance governing seed dormancy?
(d)
Which PGR stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stress?
(d)
Cell elongation in internodal regions of the green plants takes place due to :-
(b)
Cytokinins
a. Stimulate lateral shoot growth
b. Help in mobilization of nutrients
c. Inhibit cell division
d. Delay senescence
(b)
Inhibit cell division ❌
(This is incorrect — cytokinins actually promote cell division.)
In most situations, which PGR acts as an antagonist to GAs?
(b)
To promote stem elongation, gibberellins act in concert with:
(a)
The given figure shows the effects of increasing concentration of a certain PGR on the growth of seven-day-old dark-grown pea seedlings. The effects include a decrease in epicotyl elongation, a thickening of the shoot and a change in orientation of growth from vertical to horizontal. Which PGR would be responsible for these effects?
(d)
All the following statements regarding cytokinins are true except:
(c)
Statement 3: Kinetin occurs widely in almost all plants.
❌ Incorrect. While kinetin was initially considered a synthetic compound, subsequent studies have detected its presence in various organisms, including plants. However, its occurrence is not widespread across all plant species, and it is not as prevalent as other natural cytokinins like zeatin.
Which gaseous PGR is synthesised in large amounts by tissues undergoing senescence and ripening fruits?
(c)
Which of the following is not a function of the PGR ethylene?
(a)
Horizontal growth of seedlings not vertical
Ethylene does not:
(c)
Ethylene actually promotes abscission (the shedding) of flowers and fruits in cotton, cherry, and walnut
PGR causing the closure of stomata in response to water stress is:
(a)
When compared to their normal sized counterparts, the dwarf mutant varieties of a plant generally produce less:
(d)
Dwarf mutant varieties of plants often have a genetic defect that results in:
Reduced synthesis of gibberellins or
Impaired response to gibberellins.
Gibberellins (GAs) are essential plant hormones that promote:
Stem elongation,
Seed germination,
Flowering, and
Fruit development.
When gibberellins are deficient or not perceived properly, the plant exhibits dwarfism due to inhibited cell elongation and division
Plant growth is generally indeterminate because of:
(c)
One of the synthetic auxin is:
(a)
Parthenocarpy in tomato plants can be induced by:
Select the odd one out w.r.t. developmental heterophylly.
(d)
The ‘bakanae’ (foolish seedling) disease of rice
seedlings led to the discovery of which of the following
plant growth regulators?
(b)
In the equation of arithmetic growth \(
L_t=L_0+r t,{ }^{\prime} r \text { ‘ }
\)
represents
(c)
Abscisic acid is also called:
(d)
Hormones which are essential in tissue culture for promoting root and shoot development respectively in callus are:-
(d)
Which of the following statements is incorrect ?
(c)
Abscisic acid (ABA) is often called a “stress hormone” because it plays a role in responses to adverse conditions like drought, cold, and high salt. It slows down or inhibits growth, promotes stomatal closure to conserve water, and initiates bud dormancy. While some growth may be slowed down under stressful conditions, ABA’s primary function is not to promote overall growth.
By the application of which plant hormone, stem elongation can be induced in “rossette plants”?
(c)
Who has discovered and confirmed that release of a volatile substance from ripened oranges hastened the ripening of unripe banana kept with it ?
(c)
Read the given statements and choose the correct option regarding plant growth.
A. Increased vacuolation, cell enlargement and new cell wall deposition are characteristics of cells
in elongation phase.
B. Cells of maturation zone attain maximal size in terms of wall thickening and protoplasmic
modifications.
(c)
Which of the following PGRs is known as fruit ripening hormone ?
(b)
Which of the following is correct w.r.t. auxins?
(b)
Auxins and cytokinins act antagonistically w.r.t.
(a)
Which of the following plant growth regulators is mainly involved in growth inhibiting activities ?
(d)
Which among the following is not the characteristic of cells in meristematic phase of growth ?
(b)
Ethylene can be used in all, except
(d)
Precursor of auxins is
(a)
Identify the following statements and state true (T)
or false (F) and choose the correct option.
A. Single maize root apical meristem can give rise
to more than 17,500 new cells per hour.
B. Cells in a watermelon may increase in size of
the cell by upto 3,50,000 times.
(c)
Which of the following pair of hormones promote flowering in pineapple
(c)
Hormone responsible for Climacteric effect is —
(a)
Which phytohormone is synthesized by the tissues of senescing organs?
(b)
The correct answer is: (B) Ethylene
Ethylene is a gaseous phytohormone that is synthesized in large amounts by senescing tissues and ripening fruits. It plays a crucial role in:
Promoting senescence (aging) of leaves and flowers
Accelerating fruit ripening
Inducing abscission (shedding of leaves, flowers, and fruits)
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