Thigmotropism is the directional response of a plant organ to touch or physical contact with a solid object. The tendrils actually "feel" the solid object, which results in the coiling response. Answer : (b)

Negative phototropism is growth away from light. Shoots, or above-ground parts of plants The root shows negative phototropism because the movement of root is in the direction opposite to that of light. Answer : (a)

Bolting is induced by plant hormones of the gibberellin family, 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 : (a)

Ethylene is a gaseous hormone that affects the ripening and flowering of many plants. It it widely used to control the freshness in horticulture and fruits. Answer : (c)

Rhizobia respond by releasing nodulation factor (sometimes just called nod factor), which stimulates nodule formation in plant roots. The root nodules were found to contain more IAA Some plant-associated bacteria, including rhizobia, have the capacity to produce the plant hormone indole-3-acetic acid (IAA) Answer : (b)

Artificial ripening of fruits/banana is accomplished by treatment with ethylene gas Answer : (c)

The slime mold glides along, lifting and engulfing food particles, especially bacteria Answer : (c)

Nastic movements are non-directional responses to stimuli, and are usually associated with plants. Opening and closing of flowers in response to light and darkness is called photonasty. Answer : (a)

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)

IAA hormone is responsible for apical growth Answer : (a)

Gibberellins were first isolated from the fungus Gibberella fujikuroi, the cause of the foolish seedling disease of rice Answer : (c)

Exogenously applied auxins were not crucial for root formation, however their application resulted in higher percent of more qualitative leafy cuttings. IBA proved as the most efficient treatment and it additionally induced earlier root formation Answer : (d)

2,4-D, is a herbicide used to kill any dicot plant tissue. The substance is a synthetic auxin, which is a type of plant hormone that is absorbed by the leaves of a plant. Answer : (d)

Zeatin is a cytokinin derived from adenine, which occurs in the form of a cis- and a trans-isomer and conjugates. Leucine is an essential, branched-chain amino acid (BCAA) Phytochromes are a class of photoreceptor in plants Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula C2H4 or H2C=CH2. Answer : (d)

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. Answer : (b)

Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night length, or photoperiod, which they take as signals to flower. Answer : (c)

Turgor movements are reversible only if the osmotic pressure within the cells can decrease again after some time. Such changes can be observed in some petiole joints (pulvinus) that cause the circadian lifting and lowering of leaves. seismonasty is the nastic response of a plant or fungus to touch or vibration. Answer : (c)

Thigmotropism is the directional response of a plant organ to touch or physical contact with a solid object. The tendrils actually "feel" the solid object, which results in the coiling response. Answer : (d)

Foolish seedling disease/bakane of Rice helped in discovery of hormone Gibberellin Answer : (a)

Banana is seedless because, it reproduces asexually The mature banana plant forms rhizomes that grow into little plants known as pups that can be removed and planted elsewhere Answer : (a)

A high ratio of cytokinin to auxin favours shoot production, whereas a high auxin to cytokinin ratio favours root production. Intermediate levels of both hormones enhance callus formation. Answer : (a)

Antiauxin a plant substance that opposes or suppresses the natural effect of an auxin Triidobenzoic Acid is an inhibitor of polar auxin transport and more commonly known as TIBA. It is Used as a plant growth regulator and controller. It suppresses somatic embryo formation and postembryonic shoot / root development TIBA is sprayed on the cotton plants to defoliate. This will help in machine picking of cotton balls. Answer : (b)

Abscisic acid is called stress hormones as it induces various responses in plants against stress conditions. It increases the tolerance of plants toward various stresses. It induces the closure of the stomata during water stress. It promotes seed dormancy and ensures seed germination during favourable conditions. It helps seeds withstand desiccation. It also helps in inducing dormancy in plants at the end of the growing season and promotes abscission of leaves, fruits, and flowers. Answer : (d)

Flowering in short day plants is induced by Short days and uninterrupted long nights Answer : (b)

Kenneth V. Thimann (1904-1997) became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Answer : (b)

Cytokinins were discovered by F. Skoog, C. Miller and co-workers during the 1950s as factors that promote cell division (cytokinesis). Answer : (a)

Short-day plants (SDP) form flowers only when day length is less than about 12 hours. Many spring and fall flowering plants are short day plants, Short-day plants flower if light period is less than critical period. Answer : (d)

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 : (d)

When the apical bud is removed, the lowered IAA concentration allows the lateral buds to grow and produce new shoots, which compete to become the lead growth. Answer : (d)

Quiescence is the reversible state of a cell in which it does not divide but retains the ability to re-enter cell proliferation. Some adult stem cells are maintained in a quiescent state and can be rapidly activated when stimulated reside. Answer : (a)

Florigen is produced in the leaves, and acts in the shoot apical meristem of buds and growing tips. It is known to be graft-transmissible, and even functions between species. Florigen (or flowering hormone) is the hypothesized hormone-like molecule responsible for controlling and/or triggering flowering in plants. Answer : (a)

The apical bud produces a hormone, auxin, (IAA) that inhibits growth of the lateral buds further down on the stem towards the axillary bud. plant hormone auxin likely regulates apical dominance. a- 3, Kinetin is a type of cytokinin, a class of plant hormone that promotes cell division. Kinetin isolated as a compound from autoclaved herring sperm DNA that had cell division-promoting activity. b - 1, inhibitors of gibberellin biosynthesis indicate that gibberellin synthesis is required in this tissue for the induction of α-amylase. c - 5, Ethylene was the intermediate which caused epinasty or seed germination. Auxin and gibberellin primarily induced their response by stimulating ethylene production. d - 4, Abscisic acid inhibits stimulatory effects of other hormones. Inhibits shoot growth but will not have as much affect on roots or may even promote growth of roots. It inhibits cell division in the vascular cambium. e - 2 Answer : (a)

Vernalization the cooling of seed during germination in order to accelerate flowering when it is planted. The gibberellin class of plant hormones has been implicated in the control of flowering in several species. In Arabidopsis, severe reduction of endogenous gibberellins delays flowering in long days and prevents flowering in short days. Answer : (b)

Typical growth curve in plants is Sigmoid Answer:(b)

Perception of Photoperiodic Stimulus and Presence of a Floral Hormone. It is now well established that the photoperiodic stimulus is perceived by the leaves. Answer : (a)

Vernalization is the subjection of seeds or seedlings to low temperature in order to hasten plant development and flowering Biennial plants, such as carrot (Daucus carota), will remain in their non-flowering rosette form until subjected to cold treatment. Answer : (d)

Auxin, derived from the terminal bud, inhibits the growth of axillary buds, Answer : (a)

Pr absorbs red light (~667 nm) and is immediately converted to Pfr. Answer : (a)

In 1928, Went developed a method of quantifying this plant growth substance. His results suggested that the curvatures of stems were proportional to the amount of growth substance in the agar. The Avena (oat) coleoptile curvature test for auxin was established by pioneers in phytohormone determination. In this test, the coleoptile stump of a decapitated seedling will curve in darkness after a small gelatin block containing auxin is placed on one side of a straight coleoptile stump. This test was called the avena curvature test. Answer : (b)

In 1957, Richmond and Lang showed that this senescence could be postponed to several days in detached Xanthium leaves by kinetin treatment. This effect of kinetin in delaying the senescence is called as Richmond-Lang effect. Answer : (d)

Gibberellins are biochemically described as tetracyclic diterpene acids and are associated with flowering induction in several species. When exogenously applied, these plant growth regulators lead to petal growth and flowering induction in long-day plants under conditions of short days. Answer : (b)

Thigmonasty or seismonasty is the nastic response of a plant or fungus to touch or vibration. Answer : (b)

Wilting is an effect of the plant growth-inhibiting hormone, abscisic acid. Abscisic acid (ABA) is a plant hormone. ABA functions in many plant developmental processes, including seed and bud dormancy, the control of organ size and stomatal closure Ethylene causes what is known as the "triple response" in plants: it causes plants to have short shoots, fat shoots, and increased lateral root growth. In seedlings, ethylene also stimulates root hair production by the radicle. Answer : (d)

Fruit ripening is accelerated by 80%Ethylene and 20%CO2 Answer : (d)

Plant senescence is the process of aging in plants. ABA causes oxidative stress to promote the senescence Answer : (c)

Answer : (a)

Long-day plants flower and grow when the daylight they obtain is more than their critical (required) photoperiod, like in summer season. Examples of long day plants are wheat, spinach, lettuce, radish, sugar beet Answer : (a)

Pruning temporarily destroys apical dominance and stimulates the growth of lateral bud (orlateral buds) into shoots. Answer : (c)

Nyctinastic leaf movements is due to photoreceptor in plants is phytochrome, a pigmented protein. Thus option "c" is NOT related to auxin level Eastern side of the sunflower stem elongates more than the western side during the day, turning the stem and flower westward to track the transiting sun. At night, the western side grows faster, turning the flower head back east in time to capture the rays of the rising sun. Thus option "d" is related to auxin level Answer : (c)

Closure of lid in Pitcher Plant is NOT related to growth and whole of plant does not move. The paratonic (induced) movement of growth is called tropic movements. Here the stimuli are external and unidirectional. Tropic movement is the movement of the plant in response to the stimulus present in the environment, this movement is in response to root and shoot growth. Turgor movement is due to the difference of turgidity of the cells in the lower half and upper half of pulvinus (petiole of leaf). Hence, leaf droops down for a short time. Autonomic movement is the spontaneous movement of the protoplasm seen in aquatic plants due to internal stimulus.. Answer : (c)