IAA is an auxin but has potential role of herbicide and weedicide. ABA is stress inducing plant growth regular. It can induce closure of stomata, Ethylene on other hand increases climactic rate and hence used for fruit ripening, GA or gibberlic acid are known to cause bolting in crucifers. Cytokinins were first isolated from Herring sperm DNA.

Insulin is secreted by Islets of Langerhans of the pancreas and serves to lower the blood glucose level by stimulating the uptake of glucose by cells, specifically muscle cells, liver cells and adipose tissues cells. 

Gibberellins are used to speed up the malting process in brewing industry. They increase the yield of malt from barley grains.

i) Gibberilic Acid (GA) suppresses flowering in mango, GA$ _3$, it is applied periodically to mango plants in their 1-4 yrs of growth to inhibit flowering and promote vegetative growth. GA plays a role in internode elongation in submerged parts of the rice plant.

ABA is regarded as the stress hormone or a growth inhibitor. In conditions of water stress ABA initiates closure of stomata to prevent water loss through transpiration. It is antagonistic to GA as the latter promotes seed germination,  while ABA prevents seed germination.

(A) Auxin - (ii) Phototropism

(B) Cytokinin - (v) Growth of lateral buds

(C) Abscisic acid - (iv) Stomatal opening and closing

(D) Ethylene - (i) Fruit ripening

Abscisic acid is growth inhibiting hormone whereas auxin, gibberellin and cytokinin are growth promoting hormones. Options A,B, and C include all growth promoting hormones whereas option D includes both growth promoting and growth inhibiting hormones. Therefore, this combination of hormones will show slowest growth.

• The main function of Auxin is to promote stem elongation and inhibition of growth of lateral buds to maintain apical dominance.
• It is produced in the stem tips, buds and root tips to promote growth and it also helps to repair wounds in plants.
• The function of cytokinins is to increase the cell division by stimulating the process of mitosis which helps in plant growth and formation of shoots and buds.
• Cytokinins promote sprouting of lateral buds and overcome apical dominance.
• Cytokinin and auxin are antagonistic for apical dominance.
  
• So the correct answer is 'Apical dominance'.

• Auxin hormone causes apical dominance. Apical dominance is referred to the growth of plants attaining height. As a result of this, the plant will grow tall. Cytokinin is the phytohormone which is responsible for the multiplication if cells or cell division. 
• In other words, cytokinin influences mitosis. Gibberellin is the hormone that induces internodal elongation. It is also called as bolting. This is commonly found in cabbage when this hormone is more in amount.
•  The ethylene hormone is responsible for the ripening of fruits. Spraying of ethylene will promote early fruit ripening.

Etheophon is the most widely used growth regulator for the source of ethylene, Auxins used to promote shoot elongation and carbohydrates are produced in mature leaves and will get transported to other parts of the plants. but gibberellins won't promote the growth of plumule and radicle in seed germination.

Auxin induces shoot apical dominance. The axillary buds are inhibited by auxin, as a high concentration of auxin directly stimulates ethylene synthesis in lateral buds, causing inhibition of their growth and potentiation of apical dominance. When the apex of the plant is removed, the inhibitory effect is removed and the growth of lateral buds is enhanced. Auxin is sent to the part of the plant facing the light, and this promotes growth towards that direction. 

Gibberellins regulate the cell growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence. Ethylene promotes ripening. Auxins are responsible for apical dominance. Abscisic acid regulates the rate of transpiration. 

Abscisic acid regulates leaf fall and dormancy.

• Plant hormones are also known as phytohormones, they are chemicals that regulate plant growth. 
• Plant hormones are signal molecules produced within the plant and occur in extremely low concentrations. 
• Hormones regulate cellular processes in targeted cells locally and, moved to other locations, in another functional part of the plant. 

• Gibberellins are phytohormones that initiate mobilization of storage materials in seeds during germination. 
• They also cause elongation of stems, stimulate bolting in biennials stimulate pollen tube growth. 
• Gibberellins include a large range of chemicals that are produced naturally within plants and by fungi. 
• Gibberellins are important in seed germination, affecting enzyme production that mobilizes food production used for the growth of new cells. 

• In animals, there are various glands that produce different hormones but such glands are absent in the plants. Instead, each cell is capable of producing hormones. 
• Plant hormones shape the plant, affecting seed growth, time of flowering, the sex of flowers, senescence of leaves, and fruits. 
• They affect which tissues grow upward and which grow downward, leaf formation and stem growth, fruit development and ripening, plant longevity and even plant death. 
• Hormones are vital to plant growth and lacking them, plants would be mostly a mass of undifferentiated cells. So, they are also known as growth factors or growth hormones.

• A class of plant hormones called auxins coordinates the root growth process.
•  Auxins play a key role in bending the plant roots towards the water because they cause one side of the root to grow faster than the other and thus the bending of the root. 

Cytokinin is a plant hormone which promotes cell division. Rest all are present in human body.

• Auxins- play a key role in tropism (controlling the direction of plant growth). 

The gibberellins are plant growth hormones which enhance the longitudinal growth of stem when applied to the intact plant. Gibberellins produce extraordinary elongation of stems and leaf sheaths in intact plants. The elongation of the stem is caused due to cell division and cell elongation induced by gibberellic acid. Thus option D is the correct answer.

The directional growth of organisms in response to light is called phototropism. In plants, aerial shoots usually grow towards the light. The phototropic response is controlled by auxin.

• Ethylene is a gaseous hormone, which stimulates transverse or isodiametric growth but retards the longitudinal one. 
• It is a gas that forms through the break down of methionine, which is in all cells. 
• It has very limited solubility in water and does not accumulate within the cell but diffuses out of the cell and escapes out of the plant.
• Thus, the correct option is D.

• There are various plants which are used in the process of bioremediation. 
• The plants are capable of taking up the toxic constituents and accumulating them in the plant body. 
• The plant Gibberella fusarium can take up the toxic material like cyanide. 
• The cyanide is reduced by this plant and converted to a non-toxic form. 
• Thus, the correct answer is option C. 

• Abscisic acid is a carotenoid-derived plant hormone known to regulate critical functions in growth, development and responses to environmental stress.
• It plays a key role in the regulation of stomatal closure by regulating ion channel activities and water exchanges across the plasma membrane of guard cells.
• It increases the influx of calcium ions and efflux of potassium ions, which results in the closure of stomata.
• So, the correct option is D.

Abscisic acid is the plant growth hormone which is responsible for inhibiting growth. 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. 

Auxin is a plant hormone that plays important role in plant growth. It stimulates stem elongation by increasing permeability of cells which in turn increases uptake of water by cells. It also enhances plasticity of cell walls which results in cell enlargement. It also increases the respiration rate.

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. When auxin is applied to the base of petiole of young leaf, the abscission is greatly suppressed. Also, it is observed that the intact leaf does not fall off because it synthesizes auxin.

Auxin is a plant hormone which is involved in various physiological processes. It is present on the tip of the stem and helps in phototropic movement in response to light. It also maintains apical dominance where there is more growth on the stem tip and growth of lateral bud is inhibited. Auxin along with cytokinin and gibberellin helps in the process of parthenocarpy. It does not cause bolting. It does not influence flowering in the plant.

Cytokinin is a plant hormone that promotes cell division. It delays senescence. Auxin promotes stem elongation and thus regulate apical dominance. Ethylene is also called as ripening hormone as it helps in the ripening of fruits. Gibberellic acid prevents falling of immature leaves. 

Abscisic acid is a plant hormone. It is also called as stress hormone as its concentration increases during stress condition. During unfavorable environmental condition, it inhibits seed germination and induces seed dormancy. Ethylene is a plant hormone. It is also called as ripening hormone as it hastens fruit ripening in plants. Cytokinin is a plant hormone that induces cell division. It delays the abscission of leaves. A 2, 4-D is a synthetic auxin, a plant hormone. It acts as herbicide as it kills weeds.

Phytohormones are important plant growth regulators. The phytohormones, like auxins and gibberellins (GA), have positive growth-promoting effects whereas abscisic acid (ABA) and ethylene have growth inhibiting effects. Abscisic acid (ABA) was discovered for its role in regulating abscission and dormancy. It triggers fall of mature leaves and fruits from plants. Hence, it is called abscisic acid because of the formation of abscission layer which is responsible for fall of mature leaves and fruits from plants.  But like other PGRs, abscisic acid also has other wide-ranging effects on plant growth and development. It acts as a general plant growth inhibitor and an inhibitor of plant metabolism. ABA inhibits seed germination. ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses. Therefore, it is also called the stress hormone. ABA plays an important role in seed development, maturation and dormancy. By inducing dormancy, ABA helps seeds to withstand desiccation and other factors unfavorable for growth. In most situations, ABA acts as an antagonist to GAs.

Cytokinins have specific effects on cytokinesis and were discovered as kinetin (a modified form of adenine, a purine) from the autoclaved herring sperm DNA. Kinetin does not occur naturally in plants.

Plant hormones can work in combination and are dependent on the environmental cues or signals to act. They are also active in plant embryos within the seed such as Gibberellic acid.

Meristem is the actively dividing cells at the root and shoots apices that are mitotically active.

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers.

• Auxin is a plant hormone that is produced in the tip of the stem that works in elongation.
  
•  Auxin helps the plant to move to the darker side, the cell grows larger than corresponding cells present on the lighter side of the plant.

Auxin and cytokinin both contain nitrogen in their structure. 

In the course of research on auxin biology, many compounds with noticeable auxin activity were synthesized. Many of them had been found to have the economical potential for man-controlled growth and development of plants in agronomy. Auxins are toxic to plants in large concentrations. They are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides, including 2,4-D and 2,4,5-T, have been developed and used for weed control. However, synthetic auxins, especially 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA), are also commonly applied to stimulate root growth when taking cuttings of plants or for different agricultural purposes such as the prevention of fruit drop in orchards. Used in high doses, auxin stimulates the production of ethylene. Excess ethylene (also native plant hormone) can inhibit elongation growth, cause leaves to fall (abscission), and even kill the plant. 

• Auxins are a group of hormones that positively influence cell enlargement, bud formation, and root initiation. 
• In conjunction with cytokinins, they control the growth of stems, roots, and fruits, and convert stems into flowers. Auxins were the first class of growth regulators discovered. 
• They affect cell elongation by altering cell wall plasticity. Auxins act to inhibit the growth of buds lower down the stems, and also to promote lateral and adventitious root development and growth. 
• Leaf abscission is initiated by the growing point of a plant ceasing to produce auxins. Auxins in seeds regulate specific protein synthesis, as they develop within the flower after pollination, causing the flower to develop a fruit to contain the developing seeds. 
• Auxins are toxic to plants in large concentrations, they are most toxic to dicots and less so to monocots. 

• Abscisic acid is one of the most important plant growth regulators. This class of PGR is composed of one chemical compound normally produced in the leaves of plants, originating from chloroplasts, especially when plants are under stress. In general, it acts as an inhibitory chemical compound that affects bud growth, and seed and bud dormancy. 
• It mediates changes within the apical meristem, causing bud dormancy and the alteration of the last set of leaves into protective bud covers. 
  

There are five major types of plant hormones. Abscisic Acid also called ABA is one of the most important plant's growth regulators and under water stress, this hormone plays a role in closing the stomata. Auxins are hormones that  positively influence cell enlargement, bud formation and root initiation. Cytokinins tend to positively influence cell enlargement, bud formation and root initiation. Others are ethylene regulates the fruit ripening and Gibberellins stimulates the flower production, cell elongation. Whereas 2, 4-D is not a plant hormone but a chemical weedicide. 

Cytokinin is a plant hormone that produces the Richmond Lang effect. It inhibits ageing process of the plant. Auxin is a plant hormone that induces apical dominance. It promotes the growth of stem tip and inhibits the growth of lateral buds. Abscisic acid is a plant hormone. It is also called as stress hormone as under stress environmental condition, its concentration increases. It induces seed dormancy. Ethylene is a plant hormone. It is also called as ripening hormone as it induces ripening of fruits. 

Gibberellic acid is a plant hormone. 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. Auxin is a plant hormone which is used to induce flowering in pineapple as it induces synthesis of ethylene. Cytokinin is a plant hormone that stimulates cell division. It delays the senescence in leaves. 

• The plant growth regulators (PGRs) or phytohormones are small, simple molecules of diverse chemical composition. For example, auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
• NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic)are synthetic auxins.
• 6-Benzylaminopurine, benzyl adenine, BAP  is a first-generation synthetic cytokinin that elicits plant growth and development responses, setting blossoms and stimulating fruit richness by stimulating cell division.
  
• Hence 2,4-D, NAA, BAP  are synthetic phytohormone.
• So, the correct answer is '2,4-D, NAA, BAP '.

Pytohormone which causes mobalization of nutrients is cytokinin and  it also helps in the formation of new leaves and chloroplast. 

A- Phytohormones are plant hormones. These are organic substances which are produced in the plants. They bring about total control over growth and other physiological functions in the organism.

•  Plant hormones/phytohormones are numerous organic chemical substances that control the growth and differentiation of plant cells, tissues, and organs.
  
• Plant enzymes are both organic and inorganic nature. They are not involved in the regulation of growth directly.
  
• The plasma membrane regulates the transport of materials entering and exiting the cell. so option A is the correct answer.
  

Phytohormones are produced by plants, that regulate germination, growth, metabolism, or other physiological activities.

Phytohormones are also called as plant hormones. These are chemicals which play important role in growth and development of plants. These are involved in various physiological processes of plants like growth, flowering, fruiting, shoot and root development, etc. Phytohormones liks auxin, cytokinin act as growth promoter whereas hormones like abscisic acid, ethylene act as growth inhibitor. 

Phytohormone is the plant hormone that is involved in various processes of plants. Hormones like gibberellin induce flowering and abscisic acid inhibits flowering in plants. In plants, flowering is controlled by light and dark periods (photoperiod) and temperature in specific environments. Plant generally requires either long day or cold condition for flowering.

When concentration of hormones in the plant body increases, growth of the plants decreases.

So, the correct option is cause stunting in plants’.

A hormone is not produced in tissue but instead in an organ. The effect caused by that by that hormone can be seen in various parts of the body including the site of production. For example, insulin produced by pancreas converts the glucose present in the bloodstream into the glycogen.  

Ethylene is a plant hormone. It accelerates fruit ripening in tomato. Maleic hydrazide is a type of auxin, plant hormone. It delays sprouting of potato tubers. Both these hormones have common precursor that is formed due to the catalytic activity of pyruvic dehydrogenase complex.