Other plant hormones - class-XII

Ethylene affects fruit - ripening. Normally, when the seeds are mature, ethylene production increases and builds - up within the fruit, resulting in a climacteric event just before seed dispersal. The nuclear protein 'Ethylene Insensitive 2' is regulated by ethylene production, and in turn, regulates other hormones including ABA and stress hormones.

Ethylene is a plant hormone. It is also called as ripening hormone. It is responsible for ripening of fruits. Fruit ripening is accompanied by increased rate of respiration. Ethylene rich atmosphere is used to accelerate the process of ripening of fruits like banana.

There are five classes of naturally occurring plant growth regulator. These are auxins, gibberellins, cytokinins, abscisic acid and ethylene. Ethylene is also called as ripening hormone as it is responsible for ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. It is also involved in abscission of leaves, fruits and flowers.

Ethylene is a gaseous plant hormone. It is also called as ripening hormone as it increases ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. It is also involved in abscission of leaves, fruits and flowers.

Many hormone-like abscisic acid (for closing)  cytokinin (for opening) and ethylene (for opening and closing both) are responsible for opening and closing of stomata. 

Abscisic acid is a plant hormone. It is also called as stress hormone. During unfavourable environmental conditions like drought, it induces seed dormancy. When there is favaourable condition, seed dormancy is broken and germination takes place.

Ethylene and abscisic acid both are the plant hormones. Ethylene hormone is also called as ripening hormone as it helps in the ripening of fruits. Abscisic acid is also called as a stress hormone. It promotes stomatal closure when insufficient water is available in the soil. 

Abscisic acid is a plant hormone. It is also called as stress hormone as under stress environmental condition, it induces seed dormancy. It promotes stomatal closure under water stress condition to decrease the rate of transpiration.

Berry size of many seedless table grape cultivars can be substantially increased by applying gibberellic acid.

• Ethylene is a simple gaseous Plant growth hormone. It is synthesized in large amounts by tissues undergoing senescence and ripening fruits.
• Ethylene promotes senescence and abscission of plant organs, especially of leaves and flowers.
  
• Ethylene is highly effective in fruit ripening. It enhances the respiration rate during the ripening of the fruits. 
• Ethylene promotes elongation of the stem in paddy.
• Ethylene also promotes root growth and root hair formation, thus helping the plants to increase their absorption surface.
• Hence Ethylene inhibits the growth of roots is a wrong statement about ethylene.
• So, the incorrect option is 'Inhibit growth of root'.

Abscisic acid is a plant hormone which causes abscision. It never promotes flowering in plants. ABA owes its name to its role in the abscission of plant leaves. In preparation for winter, ABA is produced in terminal buds. This slows plant growth and directs leaf primordia to develop scales to protect the dormant buds during the cold season. ABA also inhibits the division of cells in the vascular cambium, adjusting to cold conditions in the winter by suspending primary and secondary growth. It also promotes dormancy in buds.

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers. Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called as respiratory climactic.

Senescence refers to a number of controlled processes which finally culminate in death of the plant part. Senescence is a controlled process and is generally responsible for conservation of precious part nutrients like nitrogen and phosphorous. The senescing plant part is separated from plant due to formation of an abscission layer which finally separated the plant part.

Abscisic acid is the plant growth hormone which is responsible for inhibiting growth. This is the natural growth inhibitor which is produced in the plants. The hormone causes inhibition in the growth of the roots and shoots. The hormone also causes abscission which is the falling of the leaves, fruits and flowers. The hormone suppresses all the processes in the plants during unfavourable conditions. 

Ethylene is the gaseous hormone that stimulates growth and development of floral organs and promotes fruit ripening. It does so by causing softening of fruit due to enzymatic breakdown of cell walls, starch hydrolysis, sugar accumulation and disappearance of organic acids and phenolic compounds. Thus, option A is correct. 

During drought and other unfavorable climatic conditions it is very important to maintain viability of the seeds. Abscissic acid is released during this condition and interacts with growth hormone in order to inhibit the growth of plant.

Ethylene is gaseous hormone promotes fruit ripening and abscission. It diffuses from the rotten apple to other apples in the barrel and thereby causing spoilage of the whole barrel. ABA, auxins, gibberellins and cytokines are not gaseous hormones and therefore can not diffuse from one fruit to other. Thus, the correct answer is A.

Ethylene gas is the plant hormone that promotes fruit ripening and rotting. It also controls flower wilting and leaf fall by stimulating the conversion of starch and acid to sugars. Therefore, it is said that one bad apple will spoil the whole barrel because of ethylene gas.

ethylene gas is an aging hormone used for fruit ripening but may also cause the plant to die. Ethylene gas is released when the plant is damaged mechanically or physically.

Artificial ripening of pomegranate and coconut is useless. It is not useful in these fruits because of their inner structure. In other fruits, calcium carbide is used for artificial ripening.

ABA hormone is formed during leaf fall. It is a growth inhibiting hormone in plants which accelerates aging and inhibits germination and flowering. It also causes the closing of stomatal pore.

Certain fruits ripen with sudden rise in cellular respiration and ethylene production. Such fruits are called 'climacteric fruits'. Climacteric is considered final stage in fruit ripening process during which the fruit is maximum ripened with best taste for consumption. After that period, it starts to gradually deteriorate and the respiration returns to normal rate.

Cytokinins promote cell division and delay senescence (yellowing) in leaves, while nitrogen is essential for chlorophyll synthesis, helping to maintain green leaves and improve yield in pulse crops.

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. During abscission, high synthesize of ethylene is observed along with decrease in the concentration of auxin. Ethylene synthesizes enzymes like cellulase and pectinase which are involved in cell wall degradation. These enzymes loosens the cell wall and cells separate which ultimately leads to leaf abscission. 

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. Stomatal closure under stress condition is due to this hormone. It also promotes seed dormancy under adverse condition.

Abscisic acid a plant hormone that plays important role abscission of leave. It inhibits stem elongation by inhibiting gibberellic acid. It prevents loss of dormancy in seeds. 

Ethylene is a gaseous plant hormone. It is also called as ripening hormone. It is used externally to accelerate the fruit ripening process. Also during ripening process, controlled amount of carbon dioxide and oxygen is needed. For artificially ripening fruit, 80% C$ _2$H$ _4$ and 20% CO$ _2$ is used.

Abscisic acid is a plant hormone. It is also called as stress hormone. It causes abscission of leaves. During stress environmental condition, its concentration increases and induces bud dormancy. When favorable condition returns, bud dormancy is broken.

Ethylene is a plant growth regulator. It is also called as ripening hormone as it is responsible for speeding up ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. 

Abscisic acid is a plant hormone. It is also called as stress hormone. During stress condition like drought, abscisic acid concentration increases in plants. It inhibits cell division and induces bud dormancy. It also helps in abscission of leaves and hence the name given. It also stimulates senescence in plant.

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.

Ethylene is a plant hormone. It is also called as ripening hormone as it is responsible for ripening of fruits. Fruit ripening is accompanied by increase rate of respiration. Due to increased respiration, complex carbohydrates are broken down into simpler sugars and cell wall becomes soft. It inhibits cell division. 

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. It increases the tolerance of plants toward various stresses. It is found in high concentration in roots during drought and later translocated to leaves. It causes stomatal closure during water stress. It also promotes seed dormancy under adverse condition.

GA is Gibberillic acid a plant hormone which causes foolish seedling disease in which plants grow really tall because of the internodal growth. Gibberillic acid has been reported to induce pollen sterility in many plants like sunflower, rice etc. Ethylene is a volatile hormone which induces senescence and fruit ripening. Thus, the correct option is C. 

Senescence is the process by which cells stop dividing and growth is arrested without undergoing cell death. It is also called as ageing. Abscission is also called as fall. Shedding of leaves, flowers or fruits due to change in hormone balance in plant is called as abscission. Photoperiodism is the phenomenon in which formation of flowers in plants depends on the relative length of dark or light periods. Vernalization is the process by which plant can be induced to flower by exposing it to the prolonged period of low temperature or cold. 

Abscisic acid is a plant hormone. It is also called as stress hormone as it protects the plants under stress condtion. During unfavourable environmental condition, it causes bud and seed dormancy. Only under favourable condition, the seed dormancy is broken. It also causes retardation of growth. Also, it causes abscission or fall of leaves and hence, the name given.

A 2 ,4-D is an synthetic type of auxin, a plant hormone. It acts as weedicide as it kills weeds. Benzaldehyde is a synthetic growth regulator. It acts as pesticide. NAA is a synthetic type of auxin, a plant hormone. It acts as synthetic growth regulator. It acts as rooting agent. Ethylene is a gaseous plant hormone. It acts as natural growth regulator. It hastens the ripening of fruits. 

Hence, correct option is C.

Abscisic acid is a plant hormone. It is involved in various physiological processes of plant. It promotes abscission of leaves and hence the name given. Its concentration increases as plant ages and ultimately results in the leaf fall. It is involved in the ageing process of plant.

ABA (abscisic acid) is a plant hormone. It is also called as stress hormone as its concentration increases during stress condition. During adverse environmental conditions like drought, it induces stomatal closure. This results in reduced transpiration rate during water stress condition.

6-furfurylaminopurine, also known as kinetin, is a synthetic cytokinin first isolated from autoclaved herring sperm DNA. The other options represent different chemical classes, such as plant growth regulators of other types or laboratory reagents.

Ethylene is considered as the growth hormone which regulates promoter and inhibitor as it is used to make the fruit ripen, breaks bud dormancy, initiates flowering. It acts as inhibitor as it retards the mitotic division in root and shoot meristem and also for axillary buds.

ABA
inhibits seed germination. ABA stimulates the closure of stomata in the
epidermis and increases the tolerance of plants to various kinds of stresses.

Abscisic acid (ABA) is known to promote abscission, senescence, and dormancy. It generally inhibits growth processes, but its role in flowering is complex and often considered less direct or inhibitory compared to its other primary functions.

The plant hormone ethylene is growth inhibitor and is released in plant organs that are to undergo ripening or senescence. Ethylene triggers climacteric ripening of the fruit and induces insensitivity of senescent organs to auxins due to which the nutrients are channelized to other growing parts of the plant resulting in withering away of the plant part.

Gibberellic acid increases the yield of sugarcane crop. Cytokinins inhibit apical dominance and act antagonistically to auxins which promote apical dominance. Rhizomes, corms, tubers, seeds (e.g., peanut) and other storage organs can be made to sprout early by exposing them to ethylene. Abscisic acid is a plant growth inhibitor, which inhibits seed germination.

Presence of cytokinin in an area causes preferential movement of nutrients towards it. When applied to lateral buds, they help in their growth despite the presence of apical bud. They thus act antagonistically to auxin which promotes apical dominance. Therefore cytokinin can overcome apical dominance, caused by auxins.

The most important function of cytokinins is the promotion of cell division. The varying amounts of cytokinins, along with sufficient auxins is required for the growth of callus in tissue culture experiments. Cytokinins delay the senescence of leaves and other organs by mobilisation of nutrients. It is known as Richmond-Lang effect.

Presence of cytokinin in an area causes preferential movement of nutrients towards it. When applied to lateral buds, they help in their growth despite the presence of apical bud. They thus act antagonistically to auxin which promotes apical dominance. Therefore, cytokinin can overcome apical dominance, caused by auxins.

ABA induces seed dormancy in unfavorable environmental condition, its function is antagonistic to gibberillin which promotes seed germination. It is regarded as the stress hormone as it brings about closure of stomata during water stress to prevent water loss from transpiration.

Cytokinins (Letham, 1963) are plant growth hormones which are basic in nature, either aminopurine or phenyl urea derivatives, That promote cytokinesis (= cell division) either alone or in conjunction with auxin. Coconut milk is a rich source of cytokinin.

ABA Is known as dormin as it induces dormancy in buds, underground stems and seeds in a variety of plants. e.g., ABA induces winter bud dormancy in duckweed plant.

Ethylene inhibits longitudinal growth but stimulates transverse or horizontal growth and swelling of axis. It decreases the sensitivity to gravity. Roots become Apo-geotropic while stems turn positively geotropic. Leaves and flowers undergo drooping. The phenomenon is called epinasty. Seedlings develop tight epicotyl hook. It hastens the senescence of leaves and flowers.Abscission of various parts (leaves, flowers, fruits) is stimulated by ethylene which induces the formation of hydrolases. It breaks the dormancy of buds, seeds and storage organs. Rhizomes, corms, tubers, seeds (e.g., Peanut) and other storage organs can be made to sprout early by exposing them to ethylene. Initiates germination in peanut seeds. 

So, the correct answer is 'Ethylene'

ABA (Absisic acid) is a stress hormone which is synthesised by the plant during drought or other stress conditions. It causes rapid movement of $K^+$ ions out of the guard cells, closes stomatal pores and thus reduces the transpiration rate.

A- GA or Gibberellic acid helps in promoting the growth and the elongation of cells.

Ethylene is a simple gaseous plant growth regulator (PGR). It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. the hormone enhances the respiration rate during ripening of the fruits. Ethylene helps fruits ripen by making them softer, through the breakdown components of the cell walls, and sweeter, through the conversion of starches to sugars.

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.

Abscisic acid is a plant hormone. It is also called as a stress hormone. During adverse environmental conditions, it's concentration increases. During water stress condition, it stimulates closure of stomata and hence decreases transpiration rate. Ethylene is also a plant hormone. It shows the triple response. It influences the horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot plants.

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.

The foolish seedling disease affects the rice plant through the roots or crowns. It is caused by the fungus Gibberella fujikuroi. It is the source of gibberellin hormone. The plant is usually sterile. Abscisic acid is a plant hormone that induces senescence in plants. Under stress environmental condition, it induces seed dormancy.

Abscisic acid is a plant hormone. It is growth inhibitor hormone. Its primary role is inhibition of growth of root, shoot, leaf, etc. It inhibits primary and secondary growth of shoot. During stress condition, its concentration increases.

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.

cytokinins are the plant growth regulators that promote cell division, they function similar to auxin and helps in cell elongation and are majorly present in the roots and then passes through the xylem. They perform many functions like cell division, embryo and endosperm formation, and growth of root cells etc.

Kinetin is a modified form of adenine which is discovered by Miller and Skoog as a compound from autoclaved herring sperm DNA. Herring is a fish. From it's sperm, DNA is isolated which is sterilized using steam at high pressure which is called autoclaved herring sperm DNA. From this, kinetin was isolated which has ability to induce cell division.

Ethylene is a plant hormone. It is also called as ripening hormone as it hastens fruit ripening in plants. In certain plants, it breaks seed and bud dormancy and induces germination. It also causes flowers to fall from the plant and hence, promotes senescence and abscission of plant hormones. It also causes the triple response in etiolated seedlings. It inhibits stem elongation and brings about the horizontal growth of seedlings. 

Ethylene is sprayed on fruits to promote artificial ripening, which is very commonly seen in fruit shops.
Ethylene is applied on fruits in the form of a spray. It acts to the fruit cell wall made of pectin or cellulose and promotes ripening.

Gibberellic acid promotes cell elongation, seed germination, enzyme activation such as alpha-amylase in the aleurone layer, and fruit growth. It does not cause nutrient immobilization; rather, it mobilizes stored reserves during germination. Thus, nutrient immobilization is the exception.

 Cycocel is among the most reliable and widely used plant growth regulators on the market. Cycocel may be used on any crop in the green house or nursery including but not limited to, poinsettias, hibiscus, azzaleas and geraniums to reduce stem elongation, induce early flowering, and to produce compact plants with multiple buds per shoots.

Morphactins have inhibitory effect on the stem elongation. Increases concentration produced dwarfing in the plants. Morphactins are a group of substances which act on morphogenesis and modulate the expression of plants. Chemically, they are the derivatives of fluorene compounds.

Traumatic acid is a monounsaturated dicarboxylic acid naturally occurring in plants. The compound was first isolated from wounded bean plants. Wound hormone is also called as necrohormone.

Leaf abscission is a detachment or fall of older leaves. It occurs at the base of the petiole. During leaf fall, high synthesis of abscisic acid is observed along with decrease in the concentration of auxin. It loosens the cell wall and cells separate which ultimately leads to leaf abscission

2,4-D (2,4-Dichlorophenoxyacetic acid) is a synthetic auxin widely used in plant tissue culture to induce somatic embryogenesis and callus formation. The other options like BAP, IAA, and GA3 have different primary tissue culture applications.

Gibberellins (like GA3) are well-known for their ability to stimulate stem elongation and can overcome genetic dwarfism in plants by promoting internode growth.

When sprayed on flowers, any of the plant hormones gibberellin, auxin and cytokinin could stimulate the development of parthenocarpic fruit.

Gibberellins also promote bolting (internode elongation just prior to flowering) in beet, cabbages and many plants with rosette habit.

Calcium carbide is used for ripening fruit artificially in some countries. When calcium carbide comes in contact with moisture, it produces acetylene gas, which is quite similar in reaction to the natural ripening agent ethylene.