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CBSE Questions for Class 11 Medical Biology Plant Growth And Development Quiz 16 - MCQExams.com
CBSE
Class 11 Medical Biology
Plant Growth And Development
Quiz 16
Induction of cell division and delay in senescence is caused by
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Cytokinin
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IAA
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Gibberellins
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NAA
Explanation
Cytokinins are the plant growth hormones that play a major role in the cell division and also in the plant development. Leaf senescence is a final stage of the leaf development as all the nutrients will be distributed to other parts and is also defines as the decline in leaf cytokinin. If there is an endogenous application of cytokinin there will be increase in the cytokinin content and delay senescence. Hence, the option A is correct.
Indole acetic acid and napthalene acetic acid are the auxins that promotes rooting.
Gibberlins are the plant growth hormones that are responsible fro the flowering and bolting.
Therefore, the correct answer is option A.
The Avena curvature is used for bioassay of
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ABA
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$${ GA }_{ 3 }$$
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IAA
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Ethylene
Explanation
The Avena geo-curvature test is a bioassay for auxin-type growth regulators. Etiolated oat coleoptiles are used and the test is conducted in special perspex trays under diffuse daylight. The coleoptiles, with the primary leaves intact, are arranged in grooves on the trays in 4 series of 6 coleoptiles each, and cut to a size of 10 mm. The test substance is applied on an agar strip covering only the lower halves of the apical cut surfaces of each series. After a 4-hour stay in the dark in moist Petri dishes the coleoptile cylinders are shadow graphed on a 35-mm photographic film. The curvatures are measured from an enlarged projection (10 times natural size) of the shadow graphs. The lowest IAA concentration which can be determined is around 30 to 60 μg/l IAA. The concentration response curves follow a logarithmic course up to 1,000 μg/l.
Two different plants associated with the discovery of two different phytohormones having common biosynthetic precursor exhibit one of the following character each.
I- Versatile anthers
II- Compound spadix
III- Pentalocular ovary
IV- Trifoliate compound leaves
The correct answer is:
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II and III
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I and III
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II and IV
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I and IV
Explanation
Auxin was discovered from the grass
Phalaris
belonging to family-Poaceae. It is characterized by versatile anthers. Abscisic acid was discovered from cotton (Malvaceae). Cotton contains trifoliate compound leaves. The mevalonic acid in involved is the synthesis of both.
Thus, the correct answer is the option (D).
To test the effect of an auxin on plant growth, the auxin was dissolved in a gelatin block. Several plant seedlings were prepared and growth was measured every five days.
Plant
Growth after 5 days
Growth after 10 days
1
15 mm
29 mm
2
4 mm
9 mm
3
5 mm
10 mm
4
14 mm
31 mm
5
8 mm
20 mm
Which of the following plants in the experiment acted as a control?
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Plant 1
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Plants 2 and 3
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Plant 5
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Plant 1, 2 and 3
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Plant 4 and 5
Explanation
Plant 1 is intact plant and no external material is applied on it. It is serving as control. Plant 2 has only tip removed but nothing is applied. The experiment is about effect of auxin on growth of plant. Plant 2 will serve as control for the experimental plant on which auxin is applied on cut edge. Plant 3, 4 5 exhibit some exogenous application of auxin/gelatin or both. However, plant 3 will serve as control to show if the effect is due to auxin only or auxin + gelatin. Therefore, the correct answer is option D.
To test the effect of an auxin on plant growth, the auxin was dissolved in a gelatin block. Several plant seedlings were prepared and growth was measured every five days.
Plant
Growth after 5 days
Growth after 10 days
1
15 mm
29 mm
2
4 mm
9 mm
3
5 mm
10 mm
4
14 mm
31 mm
5
8 mm
20 mm
What proves that auxin is necessary for plant growth?
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Plant 1 grew faster than Plants 2 or 3.
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Plant 4 grew faster than Plants 2 or 3.
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Plant 5 grew faster than Plant 1.
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Plant 3 grew faster than Plant 2.
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Plant 5 grew faster than Plant 4.
Explanation
Growth rate in intact plant 1 is 3 mm per day which is reduced in plant 2 upon removal of tip to 1 mm per day. The growth rate is resumed to 3 mm per day upon application of auxin as in plant 4. This means plant tip contain auxin and removal of tip resulted in truncated growth. Also, comparing the growth rates, plant 4 exhibit 3.1 mm growth rate after auxin application while plants 2 and 3 (plants with removed tip) showed only 0.9 mm and 1 mm growth rate per day. This proves that auxin is necessary for plant growth.
Therefore, the correct answer is option B.
Ethylene gas is a plant hormone that regulates plant growth, development and response to environmental stress. It is produced from leaves, roots, stems, flowers and fruits, and it plays a major role in fruit ripening, flowering and abscission (the natural shedding of leaves, flowers and fruits). The biosynthesis of ethylene in plant cells occurs in a two-step biochemical pathway illustrated in figure below:
Figure : Ethylene biosynthesis starts when S-adenosyl-L-methionine (SAM) is converted to 1-aminocyclopropane-1-carboxylic acid (ACC) by the enzyme ACC synthase (ACS). ACC is then converted to ethylene by the enzyme ACC oxidase (ACO). The ACS and ACO genes are expressed in response to internal developmental cues and environmental stresses, such as wounding, flooding, drought, and pathogen attack.
Atta-Aly, Brecht and Huber (2000) researched ethylene feedback mechanisms in tomato and strawberry fruit tissues. Their studies revealed that immature fruit had a reduced concentration of ACC when exposed to ethylene gas, but ethylene application on mature fruit increased ACC oxidase (ACO) activity.
Which statement best explains how different plant tissues respond to ethylene gas?
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Ethylene gas serves as a positive feedback signal in immature fruit and a negative feedback signal in mature fruit.
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Exposure to ethylene gas results in a negative feedback loop in both immature and mature fruit.
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Ethylene gas serves as a negative feedback signal in immature fruit and a positive feedback signal in mature fruit.
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Exposure to ethylene gas results in a positive feedback loop in both immature and mature fruit.
Explanation
Atta-Aly, Brecht and Huber (2000) researched revealed that immature fruit had a reduced concentration of ACC when exposed to ethylene gas, but ethylene application on mature fruit increased ACC oxidase (ACO) activity.
So the correct option is 'Ethylene gas serves as a positive feedback signal in immature fruit and a negative feedback signal in mature fruit.'
Cell division is initiated by
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Cytokinin
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Auxin
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Gibberellin
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ABA
Explanation
The cytokinin hormones promote cell division and tissue growth, and depend upon the presence of auxins to determine the extent of their activity. When the ratio of cytokinins to auxins is relatively high, stem and leaf growth is stimulated.
So the correct option is 'Cytokinin'.
Bakane disease is connected with discovery of
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GA
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IAA
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ABA
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2, 4-D
Explanation
In 1930s Gibberellin (GA) was first isolated in Japan from a fungus that causes a serious disease in rice, called “foolish seedling disease” (bakanae-byo) by Japanese farmers.
So the correct option is 'GA'.
What conclusion can be drawn from the comparison of treatments I and II?
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Growth is promoted by cutting off the tip
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The tip is the site of sensing light
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The tip is the site of auxin synthesis
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The tip is necessary for the response to light
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There is a range of response to a single treatment
Explanation
As can be seen from the experiments, when the tip of the coleoptile is cut off, the growth towards the light is prevented while the intact coleoptile responds to the light. This shows that the tip is necessary for the response to light.
First chemical identification of auxin, indole 3-acetic acid, was carried out by
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Went
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Thimann
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Darwin
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Paal
Explanation
F. W. Went found that when the tip of Avena coleoptile is cut, its elongation ceases. However, when auxin was added externally, its growth renewed. He suggested that experiments suggested that
auxin is synthesized in the coloptile tip and is translocated downwards towards the gravity. It moves from illuminated side to shaded side. More auxin is present on the shaded side than on illuminated side.
Due to this, the plant to grow more on the shaded side and bend in the direction of the light source. It shows positive phototropism where faster cell elongation is seen on the shaded side and less on the illuminated side.
Thus, the correct answer is option A.
Upright growth of lodged (horizontal) stem is due to
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Activity of lateral meristem
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Accumulation of more auxin on the lower side
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Accumulation of more auxin on upper side
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Greater cell enlargement on upper side
Explanation
Auxin is a plant hormone that plays important role in the growth of stem and roots
to gravity. Root shows positive
gravitropism
and shoot shows negative gravitropism.
In stems, auxin accumulates towards the lower side. It results in increase in cell expansion and results in the shoot growing upright.
Thus, the correct answer is option B.
Ethylene gas is a plant hormone that regulates plant growth, development and response to environmental stress. It is produced from leaves, roots, stems, flowers and fruits, and it plays a major role in fruit ripening, flowering and abscission (the natural shedding of leaves, flowers and fruits). Like all hormones, ethylene functions via an intracellular signal transduction pathway, which is illustrated in Figure 1 above.
Figure 1.
Signal transduction pathway of ethylene in plant cells. Key:Ethylene GasPlasma MembraneReceptor ProteinEndoplasmic ReticulumConstitutive Triple Response Protein Kinase 1 (CTR1)Ethylene Insensitive 2 protein (EIN2)Ethylene Insensitive 3 protein (EIN3)DNAmRNAEnzyme production
What is the MOST direct evidence that the ethylene gas signaling mechanism functions to mediate gene expression?
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The reception of ethylene gas (1) occurs on the endoplasmic reticulum (4), resulting in the release of EIN2 (6) by CTR1 (5). Binding of EIN2 on the nuclear membrane allows EIN3 (7) to bind to a regulatory gene resulting in the transcription and translation of enzymes involved in plant cell growth and regulation.
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The reception of ethylene gas (1) occurs on the plasma membrane (2), which triggers the release of EIN2 (6) by CTR1 (5). EIN2 binds to the nuclear membrane which activates EIN3 (7) to function as a transcription factor in the transcription and translation of enzymes involved in plant growth and regulation.
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Ethylene (1) binds to a receptor on the endoplasmic reticulum (4), resulting in the release of EIN2 (6) by CTR1 (5). EIN 2 binds to the nuclear membrane which triggers the transcription and translation plant proteins necessary for plant growth and regulation.
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Ethylene (1) binds to a receptor on the endoplasmic reticulum (4), resulting in the release of EIN3 (7), which functions as a transcription factor in the expression of enzymes involved in plant growth and regulation.
Explanation
The reception of ethylene gas occurs on the endoplasmic reticulum which triggers Constitutive Triple Response Protein Kinase 1 (CTR1) to release EIN2 and EIN2 binds on the nuclear membrane allows EIN3, EIN3 will initiate to transcription and translation of enzymes involved in plant growth and regulation.
So the correct option is 'The reception of ethylene gas (1) occurs on the endoplasmic reticulum (4), resulting in the release of EIN2 (6) by CTR1 (5). Binding of EIN2 on the nuclear membrane allows EIN3 (7) to bind to a regulatory gene resulting in the transcription and translation of enzymes involved in plant cell growth and regulation.'
Test Group 1
Test Group 2
Test Group 3
Pair of ripe apples
One ripe apple, one unripe apple
Pair of unripe apples
Presence of ethylene gas causes fruits to ripen. As fruit ripens, it produces increasing amounts of ethylene. An investigator placed fruit samples sealed containers as shown in the image, and left them for three days. At the end of the time period, the investigator used iodine to test for the presence of starch.
List these in order from highest to lowest starch content.
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Group 1, Group 2, Group 3
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Group 3, Group 2, Group 1
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Group 1, Group 3, Group 2
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Group 3, Group 1, Group 2
Explanation
The iodine test is used to test Starch content. The solution of iodine contains, an aqueous solution of 1.8% iodine and 3.0% potassium iodide, binds with starch, producing a dark color. The fruits which show more stain the fruit shows, the more starch it contains and the less ripe it is.
So the correct option is 'Group 3, Group 2, Group 1.'
The process of changing the form in order to carry out a specialized function
is called _________.
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Differentiation
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Growth
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Cell division
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Cell elongation
The aleurone synthesizes and secretes digestive enzymes that hydrolyze nutrients stored in the endosperm, in the presence of
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Auxin
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Gibberellin
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Cytokinin
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Ethylene
Explanation
The aleurone layer is the outermost layer of the endosperm. It synthesizes and secretes digestive enzymes that hydrolyze nutrients stored in the endosperm in presence of enzyme gibberellin. Gibberellin is released by the embryo.
The digestive enzymes hydrolyze the components stored in the endosperm to support the early growth of the embryo.
Thus, the correct answer is option B.
Bakanae disease is caused by
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Fungus
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Alga
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Bacterium
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Virus
Explanation
Bakanae disease is also called as foolish seedling disease. It affects the rice plant through the roots or crowns. It is caused by the fungus
Gibberella fujikuroi.
Affected seedlings show abnormal elongation and in severe cases may lead to death.
Thus, the correct answer is option A.
Compare the statements I and II and choose correct option.
Statement (I) Auxin promotes apical dominance by suppressing the activity of lateral buds.
Statement (II) In moriculture, periodic prunning of shoot tips is done to make mulberry plants bushy.
Choose the correct options.
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I is false, but II is true
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II is false, but I is true
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Both I and II are true
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Both I and II are false
Explanation
Auxin is a plant growth hormone. This hormone is responsible for the growth and elongation of the shoot.
There is apical dominance observed in the presence of auxin. This results in the growth of the central stem which is dominant and suppresses the growth of the lateral buds.
The auxins are produced at the tips. The pruning of the tips is done where the branches are cut periodically in moriculture.
This allows the lateral buds to grow and form branches. This helps to make the plant bushy.
Thus, the correct answer is option C.
According to statolith theory, a plant distinguishes up from down by means of
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Phytochrome
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Amyloplasts
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Auxin distribution
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Ascent of sap
Explanation
Statoliths are dense amyloplasts organelles that are involved in the gravitropism or graviperception. According to statolith theory, a plant distinguishes up from down by means of amyloplast. The statoliths sediment in response to the gravity. In shoots, it is present in starch sheath cells or endodermis cells. It is present in the root tip. Their sedimentation transmit signal for the auxin reorientation and redistribution which ultimately results in upwards growth of stem and downward growth of root.
So, the correct answer is '
Amyloplasts'
$$2,4-D$$ causes
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Delay in senescence
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Bolting
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Increase in branches
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Increased growth of all parts
Explanation
A 2, 4-D is a type of auxin, plant hormone. It is a weedicide. It kills the weeds by causing uncontrolled growth in stem. It mimics the action of auxin hormone. It stimulates increased uncontrolled growth of all parts of plants which ultimately results in death of plant.
Thus, the correct answer is option D.
Bending of stem/coleoptile towards light or shoot of potted plant placed near a window is due to
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Greater oxygen availability to the tip
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More auxin content on the shaded side
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Greater light availability to tip
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Availability of necessary warmth to the tip
Explanation
Auxin is a plant hormone that plays important role in phototropism, growth movement in response to light. It promotes cell elongation. It is unequally distributed in the plant cells. It is transported towards the shady side and thus present in higher concentration. However, less auxin is transported towards the illuminated side. Due to this, the plant to grow more on the shaded side and bend in the direction of the light source. It shows phototropic response where faster cell elongation is seen on the shaded side than on the illuminated side.
Thus, the correct answer is option B.
Bioassay for gibberellin is
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Avena curvature test
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Seed dormancy test
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Dwarf maize test
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Green leaf test
Explanation
There are various bioassay for gibberellin such as dwarf maize test, hypocotyl test, barely endosperm test, etc. Dwarf maize test is based on the principle that gibberellin causes elongation of the internodes. In maize, it also increases the length of the leaf sheaths surrounding the internodes. Length of the leaf sheath is directly proportional to the gibberellin concentration. Avena curvature test is a bioassay for auxin.
Thus, the correct answer is option C.
The hormone capable of replacing the requirement of long photoperiods for flowering is
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Ethylene
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Auxin
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Gibberellin
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Cytokinin
Explanation
Gibberellin is a plant hormone which helps in growth of stem.
The rapid induction of flowering is called bolting.
It requires either long photoperiods or cold treatment.
However, it can be induced artificially by the application of gibberellin under normal conditions. Hence, it replaces the long photoperiods required for flowering.
Thus, the correct answer is option C.
Growth of both stem and root is mediated by auxin. However, stem grows into air while root grows into soil. The reason is
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Differential reaction of root and stem to auxin
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Only the stem tip produces auxin
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Only the root tip produces cytokinin
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Only the root cap can perceive gravity
Explanation
Auxin is a plant hormone that plays important role in the growth of stem and roots
to gravity. Root shows positive
gravitropism
and shoot shows negative gravitropism. This exactly opposite response of stem and root is due to changes in concentration of the auxin. Roots bend towards gravity due to regulated movement of the auxin known as polar auxin transport. Stem and root cells require differential optimum concentration for elongation. In roots, auxin accumulates towards the gravity that results in the inhibition of cell expansion on the lower side and the curvature of the roots towards gravity. In stems, auxin accumulates towards the gravity. However, it results in increase in cell expansion and results in the shoot curving up.
Thus, the correct answer is option A.
Antigibberellin is
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Cycocel
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Plastoquinone
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IAA
0%
Ubiquinone
Explanation
Cycocel is a chemical which act as anti-gibberellin. It results in the growth of thick and short stem. It is also called as dwarfing agent. It reduces growth in plant unlike gibberellin.
Thus, the correct answer is 'Cycocel'.
Parthenocarpic fruit cannot be produced by application of
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IAA
0%
2, 4-D
0%
ABA
0%
IBA
Explanation
Parthenocarpy is the process of producing seedless fruits without fertilization. Various phytohormones are used to produce parthenocarpic fruit. Auxin hormone like
IAA, IBA, 2, 4 -D are
most widely used to induce parthenocarpy. It can also be induced by application of gibberellin hormone.
Thus, the correct answer is option C.
Avena coleoptile auxin is
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IBA
0%
Indole 3-lactic acid
0%
Indole 2-acetic acid
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Indole 3-acetic acid
Explanation
Bioassay is a sensitive and specific test that determines the biological activity of hormones by measuring its effect on a specific part of plant material. There are various bioassays to determine the concentration of auxin hormone in plant such as avena coleoptile test, split pea stem curvature test, cress root inhibition test. The Avena coleoptile test is a bioassay for IAA (indole-3-acetic acid) that measures the angle of curvature of a decapitated coleoptile after placing an agar block containing auxin on one side.
Thus, the correct answer is option D.
Synthetic auxins are employed for
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Ripening of fruits
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Increasing size of fruits
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Killing weeds
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Preventing elongation of internodes
Explanation
Synthetic auxins like 2, 4-D and 2, 4, 5-T are used as herbicide. A 2,4-D stands for 2,4-Dichlorophenoxyacetic acid. It is a plant growth regulator. It is used as weedicide. It kills the broadleaf weeds that harm the plants by causing uncontrolled growth in them.
Thus, the correct answer is option C.
Gibberellin is a
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Sterol
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Vitamin
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Sugar
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Protein
Explanation
Gibberellin is a plant hormone. It is diterpenoids chemically. There are two pathways for the synthesis of gibberellin, mevalonic acid-dependent and mevaloni acid-independent cycle. Mevalonic acid-dependent pathway also involves synthesis of sterol. Second pathway involves synthesis of carotenoids. Farnesyl pyrophosphate in MVA pathway either forms triterpenes and sterols or forms diterpenes and gibberellin.
Thus, the correct answer is a 'Sterol'.
Growth substance that stimulates nodule formation in leguminous plants is
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NAA
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IAA
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IBA
0%
ABA
Explanation
Indoleacetic acid (IAA) is a type of auxin, plant hormone. It shows various effects on development of plants. It stimulates cell elongation and cell division. It also induces nodule formation in leguminous plants.
Thus, the correct answer is option B.
Antiauxin used in picking cotton bolls is
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2, 4-D
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TIBA
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NAA
0%
Both A and B
Explanation
Triidobenzoic Acid (TIBA) is a chemical which act as antiauxin. It is used in picking cotton balls. It is sprayed on the cotton plants to defoliate. This will help in machine picking of cotton balls.
Thus, the correct answer is option B.
Common inhibitor of germination is
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GA
0%
ABA
0%
Pantothenic acid
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Tartaric acid
Explanation
Abscisic acid is a phytohormone which act as plant growth inhibitor. It is used to maintain the dormancy of seed. It inhibits the germination of seeds in adverse condition and ensures seed germination in favourable condition only.
Thus, the correct answer is option B.
Pruning of plants promotes branching due to sensitisation of axillary buds by
Report Question
0%
IAA
0%
Ethylene
0%
Gibberellin
0%
Cytokinin
Explanation
Pruning is the method of selectively removing plant parts like branches, buds, leaves, roots. When apical bud is removed, it results in branching due to sensitisation of axillary buds by IAA, a type of auxin. Pruning of any part of plant will give lower axillary buds a chance to pour their auxin into the stem. This makes plant bushy.
Thus, the correct answer is 'IAA'.
Hormone that breaks dormancy of seeds/potato tuber is
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IAA
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ABA
0%
Zeatin
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Gibberellin
Explanation
Gibberellin is a plant hormone that is involved in various physiological processes. It breaks dormancy of seeds and potato tuber and induces germination of seeds. It causes elongation of stem in plants.
Thus, the correct answer is option D.
Match the columns:
Column I
Column II
1.
Human urine
a
Cytokinin
2.
Gibberella fujikuroi
b
Auxin
3.
Herring fish DNA
c
Ethylene
4.
Ripening fruits
d
Abscisic acid
5.
Aged leaves of plants
e
Gibberellin
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1- b, 2- e, 3- a, 4- c, 5- d
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1- b, 2- c, 3- d, 4- e, 5- a
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1- a, 2- e, 3- b, 4- d, 5- c
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1- e, 2- d, 3- c, 4- b, 5- a
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1- c, 2- b, 3- a, 4- e, 5- d
Explanation
Auxin is a plant hormone which was originally purified from human urine byKogl and Haagen-Smit 1931. Gibberellin is a plant hormone which was isolated from fungus
Gibberella fujikuroi
. It causes Bakanae disease.
Miller and Skoog first isolated kinetin, a type of cytokinin hormone from autoclaved herring fish sperm DNA.
Ethylene is a plant hormone. It is also called as ripening hormone as it is responsible for ripening of fruits. Abscisic acid is a plant hormone found in high concentration in aged leaves of plants and is responsible for abscission of leaves.
Thus, the correct answer is '1- b, 2- e, 3- a, 4- c, 5- d'.
Pineapple can be made to produce fruits throughout the year by application of
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IAA, IBA
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NAA, 2, 4-D
0%
Phenyl acetic acid
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Cytokinins
Explanation
Auxin is a plant hormone. It usually inhibits flowering. However, it promotes flowering in pineapple. IAA (indoleacetic acid) and IBA (indolebutyric acid) are naturally occurring type of auxin hormone. These hormones promote fruit production in pineapple throughout the year. It is also used for synchronizing fruit set.
Thus, the correct answer is 'IAA, IBA'.
Phytohormone which induces triple response is
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IAA
0%
ABA
0%
$${GA}_{3}$$
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$${C}_{2}{H}_{4}$$
Explanation
Ethylene is a phytohormone which induces triple response in plant. During mechanical stress on the stem, ethylene is produced. It induces seedling to produce triple response and stem grows sidewise. This triple response allows stem to go around an object above.
Thus, the correct answer is option D.
Find the correct statements.
Causal organism of foolish seedling disease is source of gibberellin
Ascorbic acid is growth promoter
Ratio of auxin to cytokinin controls differentiation
Bolting of cabbage can be induced by treatment with IAA
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1, 2, 3 correct
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1, 2 correct
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2, 4 correct
0%
1, 3 correct
Explanation
Foolish seedling disease affects the rice plant through the roots or crowns. It is caused by the fungus
Gibberella fujikuroi.
Hence, it is source of gibberellin hormone. Ascorbic acid acts as growth promoter in plants. Ratio of auxin to cytokinin controls differentiation. High ratio of auxin to cytokinin induces shoot regeneration and low ratio induces root regeneration. Bolting is the process of premature flowering. It is induced artificially in cabbage by treatment of gibberellin under normal condition.
Thus, the correct answer is option A.
6-furfuryl amino purine, 2, 4-dichlorophenoxy acetic acid and indole 3-acetic acid are
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Synthetic auxin, kinetin and natural auxin
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Gibberellin, natural auxin and kinetin
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Natural auxin, kinetin and synthetic auxin
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Kinetin, synthetic auxin and natural auxin
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Natural auxin, gibberellin and kinetin
Explanation
Kinetin is also called as 6-furfuryl amino purine. It is a type of cytokinin hormone. A 2,4-dichlorophenoxyacetic acid is also called as 2,4-D. It is a synthetic auxin hormone which acts as weedicide. Indole-3-acetic acid is also called as IAA. It is a most common naturally found auxin hormone in plants.
Thus, the correct answer is option D.
Auxin develops at the tip of the stem. Its movement is largely
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Acropetal
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Centropetal
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Basipetal
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Acropetal and basipetal
Explanation
Auxin is a plant hormone that is involved in various physiological processes. It promotes cell elongation. Hence, it is mostly produced in the meristematic region of the stem. It is also present on the tip of roots and buds. In stems, the movement of auxin is basipetal, that is movement is from apex towards the base. In roots the auxin transport is acropetal.
Thus, the correct answer is option C.
Natural plant hormone isolated from corn kernels and coconut milk is
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Florigen
0%
$${GA}_{3}$$
0%
Free auxins
0%
Zeatin
0%
IAA
Explanation
Kinetin is a type of cytokinin which is a plant hormone. It promotes cell division. The first known cytokinin hormone was found in coconut milk. It stimulates the embryo to grow when it is supplied with food. Zeatin is the most common type of cytokinin hormone isolated from corn kernels.
Thus, the correct answer is 'Zeatin'.
Common biosynthetic inhibitor of GA is
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CCC
0%
Jasmonic acid
0%
Citric acid
0%
Lactic acid
Explanation
Gibberelic acid (GA) is a plant hormone that is involved in various physiological processes. It helps in stem elongation, flowering, germination. CCC (2-chloroethyltrimethylammonium chloride) Is a common biosynthetic inhibitor of GA. It inhibits growth in plants and induces early seedset.
Thus, the correct answer is option 'CCC'.
During which phase of growth, cell increases in volume
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Exponential
0%
Cell division
0%
Differentiation
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Enlargement
Explanation
In plants, the growth is divided into three main phases, namely phase of cell division, cell enlargement and cell maturation. The phase of cell division is called as formative phase. The second phase is phase of enlargement. In this, cell enlargement and cell differentiation takes place. During this phase, cell increases in volume as cell size increases but cell number remains the same. The last phase is maturation phase. In this, cell differentiate into distinct type of cells and tissues.
Thus, the correct answer is option D
Natural hormone isolated from coconut milk and corn kernels is
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Florigen
0%
$${GA}_{3}$$
0%
Auxins
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Zeatin
Explanation
Zeatin is a type of cytokinin, a plant hormone. It stimulates cell division. It is present in coconut milk. It was first isolated from Zea maize (corn kernels).
It stimulates growth in plants.
Thus, the correct answer is option D.
Find the correct combination.
(A) DCMU...........Herbicide...........Inhibitor of non-cyclic electron transport
(B) PMA..........Fungicide...............Reduces transpiration
(C) Colchicine...........Alkaloid..............Causes male sterility
(D) Solnite-Sodium alginate..........Encapsulation of somatic embryos.
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$$a, b$$
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$$a, c$$
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$$b, c$$
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$$b, d$$
Explanation
DCMU (dichlorophenyl)-1,1-dimethylurea) is a herbicide which kills algae and hence inhibits photosynthesis. It acts by inhibiting non-cyclic electron transport system. It has no effect on cyclic electron transport system. PMA (Phenylmercuric acetate) is a fungicide. It acts as antitranspirants by closing the stomata. It reduces transpiration rate. Colchicine is an alkaloid. It causes male infertility and not sterility. Encapsulation of somatic embryos is done by using sodium alginate and calcium chloride.
Thus, the correct answer is 'a,b'.
Discovery of gibberellin is related to
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Blast disease of Rice
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Early blight of Potato
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Bakane disease of Rice
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Rust of Wheat
Explanation
Bakanae disease is also called as foolish seedling disease. It affects the rice plant through the roots or crowns. It is caused by the fungus
Gibberella fujikuroi.
Affected seedlings show abnormal elongation and in severe cases may lead to death.
Thus, the correct answer is option C.
Rosette habit of cabbage can be changed by the application of
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ABA
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IAA
0%
GA
0%
Ethephon
Explanation
Cabbage is a rosette plant.
The rosette habit of cabbage can be changed drastically by the application of gibberellic acid. GA is a plant hormone which helps in longitudinal growth of the stem. The rapid stem elongation of rosette plant is called bolting. Bolting needs either long days or cold treatment. However, bolting can be induced artificially by the application of gibberellic acid under normal conditions.
Thus, the correct answer is option C.
Growth hormone that speeds up malting in brewery industry is
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Kinetin
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Gibberellic acid
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Auxin
0%
Ethylene
Explanation
Gibberellic acid is a plant hormone that is involved in various physiological processes of plants. It stimulates stem elongation, germination, flowering. It also causes fruit elongation and delays senescence. Hence, in brewery industry, it is used to speed up malting process.
Thus, the correct answer is option B.
Which one is derivative of a carotenoid?
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IAA
0%
ABA
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IBA
0%
GA
Explanation
Abscisic acid is plant hormone. It is terpenoid chemically, that is derivative of carotenoid. It stimulates seed dormancy in plants. Carotenoids are also called as tetraterpenoids.
Thus, the correct answer is option B.
Which of the following plant function is not controlled by auxins?
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Apical dominance
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Photosynthesis
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Photoperiodism
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Growth
Explanation
Auxin is a plant hormone which is involved in various physiological processes of plants. It induces growth in plants. It also regulates apical dominance as it promotes stem elongation and inhibits growth of lateral buds. It is produced at the tip of stem and is involved in process of phototropism. Photoperiodism is the physiological reaction like flowering in plants that depends on the length of day and night.
Thus, the correct answer is option C.
Cytokinins which have specific effect in cytokinesis are modified forms of
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Cytosine
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Adenine
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Guanine
0%
Thiamine
Explanation
Cytokinin is a plant hormone. It has the specific effect in cytokinesis in plants. It is modified form of adenine. Kinetin, zeatin, and 6-benzylaminopurine are adenine type cytokinins. It is adenine molecule that is modified by the addition of 5-carbon sidechains off the 6 position.
Thus, the correct answer is option B.
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Practice Class 11 Medical Biology Quiz Questions and Answers
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