Gibberellins Questions in English

(A) During the germination of barley seeds,the embryo releases gibberellins.
These gibberellins move to the aleurone layer of the seed.
In the aleurone layer,they induce the synthesis of the enzyme $\alpha$-amylase.
This $\alpha$-amylase then hydrolyzes the stored starch in the endosperm into simple sugars,which provide energy for the growing embryo.

(D) $1$. Passive transport of nutrients does not require $ATP$ as it occurs along the concentration gradient.
$2$. Apoplast is the system of adjacent cell walls that is continuous throughout the plant,excluding the cytoplasm. $Plasmodesmata$ are involved in the symplastic pathway.
$3$. Potassium is an actively mobile element in plants,not immobile.
$4$. Bakane (foolish seedling) disease in rice is caused by the fungus $Gibberella fujikuroi$ (anamorph: $Fusarium fujikuroi$),which produces gibberellins. Thus,this pair is correctly matched.

(B) Gibberellins are a group of plant growth regulators that promote stem elongation.
In genetically dwarf plants, the application of $Gibberellic \text{ } acid$ $(GA_3)$ induces internode elongation, thereby overcoming the dwarf phenotype and allowing the plant to grow to a normal height.
Therefore, $Gibberellic \text{ } acid$ is used to control or reverse dwarfism in plants.

(B) Gibberellins are plant growth regulators that play a crucial role in seed germination.
In germinating cereal seeds,gibberellins are released from the embryo and diffuse into the aleurone layer.
This triggers the synthesis of hydrolyzing enzymes,such as $\alpha$-amylase,which break down stored starch into simple sugars to provide energy for the growing embryo.
Therefore,the correct answer is the production of hydrolyzing enzymes in germinating seeds.

(A) Gibberellins are plant hormones that play a crucial role in breaking seed and bud dormancy. Specifically,$GA_3$ (Gibberellic acid) is widely used in agriculture to break the dormancy of potato tubers,thereby promoting their sprouting. $ABA$ (Abscisic acid) acts as an antagonist to gibberellins and promotes dormancy,while $IAA$ (Indole$-3-$acetic acid) is an auxin involved in cell elongation and root initiation.

(D) During the germination of barley seeds,the embryo releases gibberellins.
These gibberellins diffuse to the aleurone layer of the seed.
In the aleurone layer,they stimulate the synthesis of the enzyme $\alpha$-amylase.
This $\alpha$-amylase enzyme then hydrolyzes the stored starch in the endosperm into simple sugars,which provide energy for the growing embryo,thus stimulating germination.

(D) The 'bakanae' or 'foolish seedling' disease in rice is caused by the fungus $Gibberella \text{ fujikuroi}$.
In $1926$, $E$. Kurosawa reported the appearance of symptoms of this disease in uninfected rice seedlings when they were treated with sterile filtrates of the fungus.
The active substance responsible for this growth was later identified as Gibberellic Acid $(GA)$.
Therefore, the discovery of the cause of this disease led to the identification of $GA$.

(A) During seed germination,the embryo produces $Gibberellin$ $(GA)$.
This hormone diffuses into the endosperm and stimulates the synthesis of hydrolytic enzymes,such as $\alpha-amylase$.
These enzymes break down stored starch into simple sugars,which are then transported to the growing embryo to provide energy and nutrients for germination.

(C) Gibberellins are a group of plant growth regulators that promote stem elongation.
Spraying sugarcane crops with Gibberellins increases the length of the stem,which significantly increases the yield of the crop by as much as $20$ tonnes per acre.
Therefore,Gibberellins are used in the sugarcane industry to enhance productivity.

(N/A) $(1)$ $GA$ stands for $Gibberellic \, Acid$. It is a plant hormone that promotes stem elongation, seed germination, and flowering.
$(2)$ $ABA$ stands for $Abscisic \, Acid$. It is a plant hormone that acts as a growth inhibitor, promotes seed dormancy, and helps the plant respond to stress, such as drought.

(N/A) The discovery of the plant hormone $Gibberellins$ was made by chance. It happened in rice fields where some rice plants were observed to be unusually taller than the normal ones.
Scientific investigation revealed that these plants were infected with a fungus known as $Gibberella$ $fujikuroi$.
This fungus releases the plant hormone $Gibberellic$ $acid$ $(GA)$ in excess concentrations,which causes the plant to grow unusually tall.
The term used for such accidental findings is $Serendipity$,which means a fortunate happenstance. It was coined by $Horace$ $Walpole$ in $1754$. He defined it as making discoveries by accident and sagacity.

(C) Gibberellins are a group of plant growth regulators that promote stem elongation. When sprayed on sugarcane crops,they increase the length of the stem,which can increase the yield by as much as $20$ tonnes per acre.

(C) Gibberellins are plant growth hormones that promote internodal elongation in many plant species. This specific phenomenon of rapid internodal elongation,especially just prior to flowering,is known as bolting. Gibberellins were first discovered in the fungus $Gibberella$ $fujikuroi$ ($Fusarium$ $moniliforme$).

(A) The rapid growth of internodes in rosette plants just before flowering is known as Bolting.
This process is typically triggered by environmental factors such as long days or cold nights.
Exogenous application of Gibberellins is known to induce bolting in these plants,effectively promoting stem elongation.

(A) Gibberellins are a group of plant growth regulators that are chemically classified as diterpenes.
They are known to be weakly acidic in nature due to the presence of carboxyl groups in their structure.
Therefore,the correct chemical nature of gibberellins is acidic.

(B) Rapid and dramatic increase in shoot length is called $Bolting$.
$Gibberellins$ induce stem elongation in 'rosette plants'.
For example,in plants like cabbage and henbane,such plants show retarded internodal growth and profuse leaf development.
In these plants,just prior to the reproductive phase,the internodes elongate enormously,causing a marked increase in stem height,which is known as $Bolting$.

(A) The effect of gibberellins had been known in Japan for over a century, where certain rice plants were found to suffer from the 'Bakane' (foolish seedling) disease.
This disease was identified by $E$. Kurosawa in $1926$.
It is caused by a fungus named $Gibberella$ $fujikuroi$ (a pathogen).
The infected seedlings grew excessively tall and became weak, which led to the discovery of the plant growth regulator known as gibberellin.

(C) The germination of seeds,especially in cereals,is triggered by soaking the seeds in water.
After the imbibition of water,the embryo secretes $Gibberellin$,which diffuses into the aleurone layer.
This hormone stimulates the synthesis of hydrolytic enzymes such as $amylase$,$protease$,and $lipase$.
These enzymes solubilize the stored food reserves within the endosperm of the seed to provide energy for the growing embryo.

(A) Gibberellins are the hormones that induce seed germination.
These hormones stimulate the synthesis of $mRNA$ and various hydrolytic enzymes such as amylases,lipases,and proteases.
These enzymes decompose the stored food reserves within the seed,providing the necessary nutrients for the embryo to grow during germination.

(A) Gibberellins are a group of plant hormones that were first isolated from the fungus $Gibberella$ $fujikuroi$.
They play a crucial role in plant development,including the induction of flowering.
Specifically,gibberellins can induce flowering in long-day plants even under short-day conditions,effectively substituting for the required photoperiod.

(B) The phytohormone that induces cell elongation is $Gibberellin$ $(GA)$.
It was first discovered by $E. Kurosawa$ from the rice seedlings infected with the fungus $Gibberella$ $fujikuroi$ (the sexual stage).
The asexual stage of this fungus is known as $Fusarium$ $moniliformae$.

(A) The application of $Gibberellins$ to certain dwarf mutants is known to restore normal growth and development in many plants,such as dwarf pea and dwarf maize. $Gibberellins$ stimulate internode elongation,which helps dwarf plants reach their normal height. In contrast,$Auxins$ are primarily involved in cell enlargement and apical dominance,while $Cytokinins$ promote cell division and organ formation.

(C) The correct answer is $GA_{3}$.
More than $100$ gibberellins have been reported from widely different organisms,such as fungi and higher plants.
They are denoted as $GA_{1}, GA_{2}, GA_{3}$,and so on.
However,$GA_{3}$ was the first gibberellic acid to be discovered and is the most intensively studied form.

(D) $GA$ (Gibberellic Acid) is known to delay the senescence of fruits. By delaying the aging process,the fruits can be left on the tree for a longer duration,which helps in extending the market period for the produce.

(C) Vernalization is the process of inducing flowering in plants by exposing them to low temperatures for a specific period.
In many biennial plants,the requirement for cold treatment (vernalization) to induce flowering can be replaced by the application of the plant hormone $Gibberellins$ $(GA)$.
$Gibberellins$ promote stem elongation and can trigger the transition from the vegetative phase to the reproductive phase,effectively bypassing the need for cold exposure.

(C) The functions of Gibberellin are as follows:
$(i)$ Increase in the length of the axis (used to increase the length of grape stalks).
$(ii)$ Causes fruits like apples to elongate and improve their shape.
$(iii)$ Delays senescence of fruits,allowing them to stay on the tree longer.
$(iv)$ Used to speed up the malting process in the brewing industry.
$(v)$ Spraying sugarcane crops with gibberellins increases the stem length,thereby increasing the yield.
$(vi)$ Promotes early seed production in conifers.
$(vii)$ Promotes bolting (internode elongation just prior to flowering) in rosette plants like beet and cabbage.
Gibberellins generally break seed dormancy rather than inducing it. Therefore,inducing dormancy is not an effect of gibberellin.

(B) The phytohormone that increases the production of starch-hydrolyzing enzymes (like $\alpha$-amylase) during the germination of maize seeds is $Gibberellin$.
$Gibberellins$ are widely used in agriculture for various purposes.
Specifically,they are employed to increase the length of stalks and induce the production of seedless fruits (parthenocarpy) in grapes.
Therefore,the correct application among the given options is the induction of seedless fruits in grapes.

(D) Gibberellic acid $(GA)$ is a plant growth regulator that promotes seed germination,bolting (internode elongation just prior to flowering),and delays senescence in leaves and fruits. Ripening of fruits is primarily promoted by the gaseous plant hormone ethylene. Therefore,ripening is not a function of gibberellic acid.

(A) Gibberellins like $GA_3$ are used to speed up the malting process in brewing industry and are also used to hasten the maturity period in conifers,thus leading to early seed production. Therefore,the match $GA_3$ - Early seed production in conifers is correct.

(B) Gibberellins $(GA)$ are plant hormones that promote internodal elongation. One of their most well-known physiological effects is the ability to cause stem elongation in genetically dwarf plants,effectively overcoming the dwarfism trait.

(A) Gibberellins are a group of plant hormones that can substitute for the requirement of long days and low temperatures (vernalization) to induce flowering in many plant species. By applying gibberellins,plants that normally require specific environmental cues to flower can be induced to flower prematurely or under non-inductive conditions.

(A) The Assertion is correct because Gibberellic acid $(GA)$ is widely used in the brewing industry to speed up the malting process of barley grains.
The Reason is also correct because $GA$ induces the synthesis of hydrolytic enzymes like $\alpha$-amylase,protease,and others in the aleurone layer of germinating cereal seeds.
These enzymes break down the stored starch and proteins in the endosperm into simpler sugars and amino acids,which are essential for the growth of the embryo and the production of malt.
Therefore,the Reason correctly explains why Gibberellic acid increases the yield of malt.

(D) The Assertion is incorrect because seeds actually sprout when the inhibitory effect of $ABA$ (Abscisic Acid) is overcome by Gibberellins $(GA)$. Gibberellins promote seed germination by counteracting the dormancy induced by $ABA$.
The Reason is also incorrect because $GA$ (Gibberellins) promotes protein and $RNA$ synthesis,which is essential for germination. It is $ABA$ that inhibits protein and $RNA$ synthesis,thereby inducing dormancy.

(N/A) In the early part of the $20^{\text{th}}$ century,the 'bakane' (foolish seedling) disease of rice was reported to be caused by a fungal pathogen,$Gibberella$ $fujikuroi$.
The symptoms shown by the infected plants were abnormally elongated stems,little or no production of grains,and the plants became weak.
Later,it was identified by $E$. Kurosawa that the active substance secreted by the fungus,which caused these symptoms,was gibberellic acid.

(N/A) In genetically dwarf plants,the endogenous level of $GA$ (Gibberellic acid) is typically low.
When $GA$ is supplied externally to these plants,it stimulates internode elongation by promoting both cell division and cell enlargement.
This rapid growth overcomes the genetic limitation,resulting in the reversal of the dwarf phenotype.

(N/A) The fungus $Gibberella$ $fujikuroi$ causes 'bakanae' (foolish seedling) disease in rice plants.
This fungus secretes a plant growth regulator known as $Gibberellin$.
$Gibberellins$ are responsible for internode elongation,which leads to the excessive and abnormal height increase in the infected rice plants.

(N/A) Minute quantities of gibberellins profoundly stimulate the growth of many plants.
The major sites of $GA$ production in plants are embryos,roots,and young leaves close to the shoot tip.
Gibberellins are chemically gibberellic acid $(GA_3)$.
They are of isoprenoid nature and possess the same general carbon skeleton.

(N/A) The hormone,gibberellin:
$(i)$ Produces the phenomenon of bolting,i.e.,the growth of the internodal region of the stem in rosette plants.
$(ii)$ Induces seed germination and breaks bud and seed dormancy.
$(b)$ The rice seedling/plant shows excessive growth in its internodal region when infected with the fungus $Gibberella$ $fujikuroi$.
$(i)$ This fungus produces an excessive amount of the plant hormone $GA$ (Gibberellic Acid),which causes the plants to grow taller than normal,leading to the 'foolish seedling' appearance and often resulting in the death of the plant.

(A) In $Cannabis$,gibberellins are known to promote the development of male flowers on genetically female plants.
Conversely,ethylene promotes the development of female flowers on genetically male plants.
This demonstrates the role of plant growth regulators in sex expression.

(A) Rice plants infected with the fungus $Gibberella$ $fujikuroi$ exhibit abnormal and excessive elongation of the stem.
This rapid growth makes the plants too tall and weak to support their own weight.
Consequently,the plants collapse and eventually die.
Due to this characteristic appearance of weak,elongated,and dying seedlings,the disease is known as the 'foolish seedling' disease or 'bakanae' disease.

(D) The discovery of $Gibberellic$ $Acid$ occurred during the study of the '$Bakanae$' (foolish seedling) disease.
$E. Kurosawa$ $(1926)$ observed that this disease in rice plants is caused by the fungus $Gibberella$ $fujikuroi$.
When he applied the cell-free filtrate of this fungus to healthy rice seedlings,they exhibited the same symptoms of the disease (excessive elongation).
Therefore,all the given options are correct.

(C) Gibberellins are a group of plant growth regulators.
More than $100$ gibberellins have been reported from widely different organisms such as fungi and higher plants.
They are denoted as $GA_1, GA_2, GA_3$ and so on.
$GA_3$ (Gibberellic acid) was one of the first gibberellins to be discovered and remains the most intensively studied form.

(B) Gibberellins are a group of plant growth regulators that promote various physiological processes. One of their most significant roles is the elongation of internodes in plants. In sugarcane,spraying the crop with $GA_3$ (a type of Gibberellin) increases the length of the stem,thereby increasing the yield of sugar by as much as $20$ tonnes per acre.

(B) Gibberellins are a class of plant hormones that promote growth and development. One of their specific physiological effects is the elongation of stems and the improvement of fruit shape. In commercial fruit production,gibberellins (specifically $GA_3$) are used to increase the length and improve the shape of fruits like apples,allowing them to elongate and improve in quality.

(B) The process of increasing the length of internodes just before flowering is known as $Bolting$. This phenomenon is typically induced by the application of $Gibberellins$ in rosette plants like cabbage and beet. $Bolting$ helps the plant to elevate its flowers for better pollination and seed dispersal.

(C) Spraying juvenile conifers with $Gibberellic Acid$ $(GA)$ hastens the maturity period of the plants.
This physiological effect leads to early seed production in these conifers.
Therefore, $Gibberellic Acid$ is used in forestry to shorten the breeding cycle.

(A) Sugarcanes store carbohydrates as sugar in their stems. Spraying sugarcane crops with gibberellins increases the length of the stem,which leads to an increase in the yield by as much as $20$ tonnes per acre.

(B) Gibberellins $(GA)$ are plant hormones that promote stem elongation. In plants like cabbage,which exhibit a rosette habit (short internodes),the application of $GA$ induces 'bolting',which is the rapid elongation of the internodes just before the reproductive phase. Therefore,the rosette habit can be changed by inducing stem elongation using $GA$.