Foods are stored at low temperatures to prevent the growth of microorganisms, activity of enzymes, and purely chemical reactions. Freezing prevents the growth of most foodborne microorganisms and refrigeration temperatures slow down the growth of microorganisms. Answer : (a)

Chemotaxis is movement of a motile cell or organism, or part of one, in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance. Another-ozoids simply oozes into the area around the antheridium and further dispersal is by gradient of increasing or decreasing concentration Answer : (b)

Phototaxis is an organism's movement in response to light. A Chlamydomonas cell perceives light at its eyespot, the photoreceptive organelle observed as an orange spot located near the cell equator. a - 5, Thermotaxis is a behavior in which an organism directs its locomotion up or down a gradient of temperature. b - 1, Chemotaxis is movement of a motile cell or organism, or part of one, in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance. another-ozoids simply oozes into the area around the antheridium and further dispersal is by gradient of increasing or decreasing concentration c - 4, Hyponasty an upward bending of leaves or floral organs, caused by increased growth on their lower surface. d - 2, Seismonasty is a nastic movement. When any organ of Mimosa pudica is touched, the stimulus reaches the base of the leaf. Owing to this stimulus, the turgor of lower half of pulvinus is lost and the leaf droops down. e - 3 Answer: (b)

Cytokinins modulate a number of important developmental processes, including the last phase of leaf development, known as senescence, which is associated with chlorophyll breakdown, photosynthetic apparatus disintegration and oxidative damage. . Answer : (a)

Phytochrome regulates the expression of nuclear genes. Phytochrome plays a central role in the synthesis of RUBISCO, the chlorophyll a/b-binding protein, and many other chloroplast proteins. Answer : (d)

A tropism is a growth movement whose direction is determined by the direction from which the stimulus strikes the plant. High auxin concentrations promote cell elongation and hnce the growth Answer : (a)

Pfr (P730) is the physiologically-active form of the protein; exposure to red light (~730 nm) yields physiological activity in the plant. Exposure to far-red light converts the Pfr to the inactive Pr form, inhibiting phytochrome activity. Answer : (a)

Abscission is the natural detachment of parts of a plant, typically dead leaves and ripe fruit. Senescence loss of a cell's power of division and growth. Photoperiodism the response of an organism to seasonal changes in day length. Vernalisation the cooling of seed during germination in order to accelerate flowering when it is planted. Answer : (b)

The higher concentration of auxin on the shady side causes the plant cells on that side to grow more so it bends toward the light. This bending toward light is called phototropism. Answer : (b)

The phytochrome pigment was discovered by Sterling Hendricks and Harry Borthwick at the USDA-ARS Beltsville Agricultural Research Center Answer : (d)

IAA is the main auxin in plants, regulating growth and developmental processes such as cell division and elongation, tissue differentiation, apical dominance, and responses to light, gravity, and pathogens. Answer : (a)

Nepenthes (pitcher plant) is an insectivorous plant. In this the leaf lamina is modified to form a pitcher and leaf apex forms a coloured lid. When the insect enter the pitcher it is an external stimuli, so the closure of the lid is paratonic movement. Paratonic movements also of three kinds:- Tropic movements Tactic movements Nastic movements Answer : (c)

During bud development in citrus, the application of GA3 has shown to inhibit flower production, leading to greater ratio of terminal flowers in the leafy shoots thus higher development of fruits Answer : (b)

Cytokinin production slows down the process of senescence. However, accumulation of sugars during senescence, due to the breakdown of accumulated starch or the preferential export of N2 from the leaf, can block the effect of cytokinin, especially in low light. Answer : (a)

Tropic movement is the movement of the plant in response to the stimulus present in the environment. Nastic movements are plant movements that occur in response to environmental stimuli but unlike tropic movements, the direction of the response is not dependent on the direction of the stimulus. Tactic movement is a type of movement in plants which is directed towards (positive) or away from (negative) a stimulus. Answer : (d)

Growth regulator ethylene is used for speeding up ripening of fruits Answer : (b)

Gibberellins are growth promoting phytohormones. Gibberellins promote stem elongation in many plants. When gibberellin is applied to a plant, particularly certain dwarf varieties, this elongation may be spectacular. These varieties put less of their resources into stem height and more resources into grain production. Answer : (c)

Abscisic acid (ABA) is a plant hormone involved in the response of plants to reduced water availability. Reduction of guard cell turgor by ABA diminishes the aperture of the stomatal pore and thereby contributes to the ability of the plant to conserve water during periods of drought. Answer : (d)

Thigmonasty or seismonasty is the nastic response of a plant or fungus to touch or vibration. Conspicuous examples of thigmonasty include many species in the leguminous subfamily Mimosoideae, active carnivorous plants such as Dionaea and a wide range of pollination mechanisms. Answer : (b)

Pfr absorbs far-red light (~730 nm) and is quickly converted back to Pr. Pfr is the physiologically-active form of the protein; exposure to red light yields physiological activity in the plant. Answer : (d)

Gibberellins (GAs) to promote bolting and flower formation in long-day (LD) and biennial plants under conditions that would not normally permit flowering contributed to the realization that these compounds may function as endogenous growth regulators Gibberellin showed significant effects in promoting maleness in monoecious genotypes and increasing male inflorescences in male plants. Answer : (c)

Chemonasty is the nastic movement of a plant in response to a chemical stimulus. The antherozoids are chemotactically attracted towards archegonia. Answer : (b)

The growing part of a root tip is divided into four regions: 1. Root cap – A cap of cells that protects the apical meristem behind it from abrasion and damage as the root tip grows through the soil. 2. Region of cell division - The growing point (meristem) a region of rapid mitosis, which produces the new cells for root growth. 3. Region of elongation: The zone where cells increase and elongate in size in the direction of the axis of the root. It is at this time that they are sensitive to gravity and respond with gravitropism. 4. Region of maturation (or differentiation): the zone where develop the differentiated tissues of the root. Here are located the root hairs which greatly increase the surface area available for the uptake of water from the soil. Answer : (b)

The climacteric is a stage of fruit ripening associated with increased ethylene production and a rise in cellular respiration Answer : (b)

Embryonic ABA plays a central role in induction and maintenance of seed dormancy and also inhibits the transition from embryonic to germination growth. Answer : (c)

Short-day plants are those plants that flower when they are exposed to long periods of darkness and short periods of light. Dark period of short day plants is interrupted by a brief exposure of light the plants then it will not flower at all. Answer : (a)

Epinasty is a nastic movement in which a plant part, such as a flower petal is bent outward and often downward. Answer : (a)

Thigmotropism the turning or bending of a plant or other organism in response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils. Answer : (a)

The moisture-control available in many refrigerators also helps slow the deterioration of foods, so that two of the three favorable situations for microorganism growth are eliminated. Microorganisms released relatively low CO2 at low temperatures. Answer : (c)

Most seeds germinate best under dark conditions and might even be inhibited by light e.g., Phacelia and Allium spp. Answer : (c)

Ethylene production is inhibited at low O2 concentrations; the receptor has an O2 affinity closely similar to that of cytochrome oxidase Answer : (a)

Albinism is defined as a plant's inability to produce chloroplasts and thus carry out the process of photosynthesis. Etiolation is a physiological enomenon shown by green plants when kept in dark. Answer : (a)

Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. Answer : (d)

Rapid growth of the dwarf stem called "bolting" Cold nights, hot days and late frosts may also contribute to premature initiation of flowering. under long days in the spring and flowers are formed on the elongated stem. 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 Etiolation in plants is a natural phenomenon and is simply a plant’s way of reaching for a light source. Which causes bending of shoot tip Read more at Gardening Know How: What Is Etiolation: Learn About Etiolation Plant Problems https://www.gardeningknowhow.com/garden-how-to/info/what-is-etiolation.htm Chlorosis is loss of the normal green coloration of leaves of plants, caused by iron deficiency in lime-rich soils, disease, or lack of light Removal of stamens or anthers or killing the pollen of a flower without the female reproductive organ is known as emasculation. Tanning - process in which skin pigmentation darkens as a result of exposure to ultraviolet light. Answer : (c)

Gibberellins cause cell elongation of intact plants in general and increased internodal length of genetically dwarfed plants. Answer : (b)

Bolting is induced by plant hormones of the gibberellin family Physiological effects of Auxin are 1. Cell elongation 2. Apical dominance 3. Root initiation 4. Prevention of Abscission 5. Parthenocarpy 6. Respiration 7. Callus formation 8. Vascular differentiation Answer : (a)

Drosera, commonly known as the sundews. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous glands covering their leaf surfaces. Drosera able to move their tentacles in response to contact with edible prey Thigmonasty or seismonasty is the nastic response of a plant or fungus to touch or vibration. Answer : (c)

Answer : (c)

Gibberellin, the name is derived from Gibberella fujikuroi, a hormone-producing fungus in the phylum Ascomycota that causes excessive growth and poor yield in rice plants Answer : (b)

Answer:(a)

Apical dominance occurs when the shoot apex inhibits the growth of lateral buds so that the plant may grow vertically Gibberellin reduced the number of elongating buds and promoted growth of the first or second uppermost axillary bud, thus restoring apical dominance. It is concluded that gibberellin participates in the expression of apical dominance. That is it work against Apical dominance Answer : (c)

The shoot tip is sensitive to light and produces auxin – if the tip is covered phototropism doesn't occur. Answer : (b)

Answer : (c)

Cytokinins Functions 1. Cell division 2. Cell differentiation 3. Leaf senescence 4. Inflorescence growth 5. Nutrient mobilization 6. Cotyledon expansion 7. Apical dominance 8. inhibit ageing Answer : (a)

Phytochromes are signaling proteins that promote photomorphogenesis in response to red light and far-red light. Phytochromes are proteins with a light absorbing pigment attached called a chromophore. Answer : (a)

Abscisic acid	Gibberellic acid
It inhibits growth	It promotes growth
It promotes the dormancy of seeds, buds and tubers	It overcomes the natural dormancy of seeds, tubers, etc
It inhibits the synthesis of RNA and proteins	It promotes the synthesis of RNA and proteins
Causes abscission of flowers and fruits.	Promotes development of fruits
Promotes leaf senescence	Prevents leaf senescence
Promotes stomata closure	Promotes stomatal opening
Prevents amylase activity	Promotes amylase activity during seed germination

Answer : (a)

Auxins hormone controls a plant response to light and gravity. It is made by the cells present at the tip of a stem and roots. Answer : (c)

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)

Shoot apical meristem produces auxin which prevents axillary buds from growing Answer : (a)