Answer : (d)

Thiobacillus denitrificans is a chemoautotrophic microorganism which is able to denitrify utilizing sulphides as electron donors. Its presence resulted in a high denitrification rate, oxidizing sulphide to sulphate, and reducing nitrate to nitrogen gas. Answer : (d)

During flowering, photoperiodic stimulus is perceived by leaves of plants Answer : (d)

Plant hormone auxin induces flowering in pineapple. Ethylene also helps in synchronization of flowering and fruit set up in pineapple. Answer : (a)

Answer : (c)

The important functions of bulliform cells are: It is mainly concerned with storage of water. During the water stress condition in leaf minimize by curling the leaf inwards. It is concerned with the rolling and unrolling of the leaves (Turgor movement). Answer : (d)

Definition of epinasty. : a nastic movement in which a plant part (such as a flower petal) is bent outward and often downward. Hyponasty an upward bending of leaves or other plant parts, caused by increased growth on their lower surface. The movements which allow organs of plants to move in or the other direction is called movements of curvature. These movements are of two types i.e. mechanical (found in non living organs of plant) and another is vital movements (found in living organs of plants) Answer : (b)

Zeatin is a natural cytokinin first isolated from maize. It is an adenine derivative. The name zeatin was coined by Letham. It stimulates cell division Answer : (c)

When an insect touches these hairs, this stimulus causes rapid turgor pressure changes which closes the leaf. Answer : (c)

The phytochrome molecule is the photoreceptor for red light responses. It exists in two forms, Pr and Pfr Pfr is the physiologically-active form of the protein; exposure to red light yields physiological activity in the plant. Exposure to far-red light converts the Pfr to the inactive Pr form, inhibiting phytochrome activity. Together, the two forms represent the phytochrome system If, we subject a plant to continuous red light, the level of phytochrome in the plant decrease below a critical value and triggers the de novo synthesis of more phytochromes in the Pr form. The result is an equilibrium in the plant between the synthesis and the destruction of phytochrome Answer : (d)

Frits Warmolt Went was among the first to demonstrate the importance of hormones in plant growth and development. in 1928 experiment he demonstrated the existence of auxin in plants. Where as Charles Darwin was among the first scientists to dabble in plant hormone research. In his book "The Power of Movement in Plants" presented in 1880, he first describes the effects of light on movement of canary grass (Phalaris canariensis) coleoptiles. Answer : (a)

Search Results Web results 2,4-Dichlorophenoxyacetic Acid (2,4-D) acts as a plant growth promoter while at higher doses it induces symptoms in plants similar to those induced by higher doses of auxin (IAA). Answer : (d)

Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. Answer : (a)

2,4-D (2,4 dichlorophenoxy acetic acid) is an auxin hormone. It over stimulates the growth activities of the cells of the root due to which roots get destroyed and thus plants finally destroyed Answer : (d)

Auxin is produced by shoot tip and acts as a growth promoter for apical bud and inhibit the growth of lateral buds. When a terminal bud is removed, the nearest axillary buds begin to grow and the plant branches rapidly. In case of mulberry plants, pruning is done to remove apical dominance and cause more branching of the main body of the plant. Answer : (a)

Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Answer : (b)

Stratification involves the treatment of seed at low temperature ( 5-10°) under sufficiently moist conditions to break its dormancy and to induce germination. Scarification involves any damage or breakage of seed coat by physical methods (e.g., Use of scalpel, wooden hammer etc.) or chemical methods (use of mild acids) to break seed dormoney. Vernalization and Chelation is the chill treatment of plant in its early stages of life history to stimulate or induce early flowering. Answer : (c)

Biennial plants are changed into annual plants by the process of vernalisation and induces flowering Answer : (d)

Phytochrome is a plant pigment that is involved in the initiation and regulation of photoperiodism and photomorphogenesis. Phytochromes absorb red and far-red light and signals for a photomorphogenetic response. Answer : (a)

Parthenocarpy is the production of fruits without the fertilisation of ovules Hormones, auxins, gibberellins, and cytokinins, especially the first two, are well known to induce parthenocarpy. Thus, auxin treatment of young, unpollinated ovaries in certain cultivars of strawberry, tomato, grape, and orange is known to cause production of parthenocarpic fruit. Answer : (c)

Short day plant needs short-light period and uninterrupted long night period and a flash of light in dark inhibits flowering in short day plant (SDP). LDP or Long Day Plants flower when the days are longer. Light period is very critical in these plants.LSDP are Lond Day Short Plants.DNP stands for 2, 4- Dinitrophenol. Answer : (a)

An auxanometer is an apparatus for measuring increase of growth in plants. Answer : (b)

Florigen (or flowering hormone) is the hypothesized hormone-like molecule, florigen is an understanding of how plants use seasonal changes in day length to mediate flowering—a mechanism known as photoperiodism. Plants which exhibit photoperiodism may be either 'short day' or 'long day' plants, which in order to flower require short days or long days respectively, although plants in fact distinguish day length from night length Answer : (d)

Skototropism Growth or movement away from light. Answer : (a)

Answer : (a)

Hormones like Abscisic Acid (ABA), ethylene are growth inhibitor. These hormones accelerate abscission process and are involved in inhibition of growth. Naphthaleneacetic acid (NAA) is a synthetic auxin hormone that promotes growth. Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than corresponding cells on the lighter side of the plant. Answer : (b)

Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Auxin is highest at the tip — promoting the production of new cells at the meristem, and lowest in the region of differentiation — promoting the elongation and differentiation of root cells. Answer : (a)

Etiolation is a process in flowering plants grown in partial or complete absence of light. It is characterized by long, weak stems; smaller leaves due to longer internodes; and a pale yellow color (chlorosis). Answer : (d)

Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Answer : (b)

Gibberellic acid is a plant growth regulator, which can improve the quality of malts when used in the malting process, which could speed up barley germination in the brewing industry Answer : (b)

Bolting is when agricultural and horticultural crops prematurely produce a flowering stem before the crop is harvested, in a natural attempt to produce seeds and hence reproduce. Bolting is induced by plant hormones of the gibberellin family,[citation needed] and can occur as a result of several factors, including changes in day length, the prevalence of high temperatures at particular stages in a plant's growth cycle, and the existence of stresses such as insufficient water or minerals. Answer : (d)

Phytochromes have two photo-interconvertible forms: Pr and Pfr. Pr absorbs red light (~667 nm) and is immediately converted to Pfr. Pfr absorbs far-red light (~730 nm) and is quickly converted back to Pr. Answer : (a)

Abscisic acid (ABA) is often referred to as a inhibitory rather than stimulatory hormone. It is involved in the closure of stomata, bud and seed dormancy and is known to inhibit other hormonal actions. It triggers fall of mature leaves and fruits from plants Answer : (c)

Hormones, auxins, gibberellins, are well known to induce parthenocarpy. Five naturally occurring (endogenous) auxins in plants include indole-3-acetic acid (IAA) , 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid (IBA), and indole-3-propionic acid. Synthetic auxin analogs include 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and many others. Answer : (d)

cytokinins influence plant growth, development and physiology, including cell division, chloroplast differentiation and delay of senescence, the interaction with other organisms, including pathogens Answer : (a)

An auxanometer is an apparatus for measuring increase of growth in plants. Answer : (d)

Under stress, abscisic acid accumulates in plants, inhibiting stem elongation and inducing bud dormancy. The plant hormone ethylene controls fruit ripening, flower wilting, and leaf fall by stimulating the conversion of starch and acids to sugars. Abscisic acid is a sesquiterpene, which has important roles in seed development and maturation, in the synthesis of proteins and compatible osmolytes, which enable plants to tolerate stresses due to environmental or biotic factors, and as a general inhibitor of growth and metabolic activities. Answer : (b)

Auxin, indole-3-acetic acid (IAA) was then isolated first from human urine, then from fungi, and finally from higher plants Answer : (c)

ABA binds to receptors at the surface of the plasma membrane of the guard cells that triggers closing of the stomata when soil water is insufficient to keep up with transpiration. Answer : (b)

Photonasty a nastic movement that is associated with changes in light. intensity Nyctinastic movements are associated with diurnal light and temperature changes and controlled by the circadian clock and the light receptor phytochrome. Answer : (c)

Geotropism is the growth of the parts of plants in response to the force of gravity. The upward growth of plant shoots is an instance of negative geotropism ; the downward growth of roots is positive geotropism. Answer : (c)

Ethylene (C2H4) is a gas and is known as the “fruit-ripening hormone.” Every fruit has a certain level of ethylene production throughout its lifecycle. However, in some fruits, ethylene levels shoot up when the fruit starts ripening. Abscisic acid (ABA) is often referred to as a inhibitory rather than stimulatory hormone. It is involved in the closure of stomata, bud and seed dormancy and is known to inhibit other hormonal actions. It triggers fall of mature leaves and fruits from plants Answer : (b)

Photonasty a nastic movement that is associated with changes in light. intensity Nyctinastic movements are associated with diurnal light and temperature changes and controlled by the circadian clock and the light receptor phytochrome. Answer : (a)

Gravity is sensed in the root tip and this information then be relayed to the elongation zone Answer : (c)

The phenomenon in which each meristem influences other meristems is called as growth correction. Answer : (b)

Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. Phytochrome regulate the timing of flowering in adult plants and regulate the germination of seeds (photoblasty), the synthesis of chlorophyll, the elongation of seedlings, the size, shape and number and movement of leaves . Answer : (b)

Vernalisation the induction of a plant's flowering process, it is cooling of seed during germination in order to accelerate flowering when it is planted. Answer : (b)

Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night length, or photoperiod, The phytochromes also differ in their absorption spectrum; that is, which wavelengths (e.g., red vs. far-red) they absorb best. Answer : (d)

The plant hormone ethylene plays a key role in climacteric fruit ripening. The means by which ethylene selects the ripening-related genes and interacts with other signaling pathways to regulate the ripening process are still to be elucidated. Answer : (c)

The Avena geo-curvature test is a bioassay for auxin-type growth regulators. a - iii, Gibberellin bioassay is performed through dwarf pea and maize test. b - iv, Cytokinins are a particular type of plant hormone that are involved in regulation of cell proliferation, cell cycle progression, and cell and plastid development c - ii, Colouring test of lemon is based on the property of ethylene in inducing ripening. d - i Answer : (a)