Transpiration as a Necessary evil. It is a vital and unavoidable phenomenon of plants. The loss of water does not serve any good purpose in plant life. Besides, the transpiration also consumes energy and causes unnecessary absorption of excess water by roots Limnophila Species are known commonly as marsh weeds, shows cuticle and stomata Sagittaria is a genus of about 30 species of aquatic plants, upper epidermis shows stomata, cuticle Nymphaea is a genus of hardy and tender aquatic plants,it contains many stomata Transpiration remain absent in submerged hydrophytic plants because stomata are completely absent in leaves of submerged plants e.g., Anncharis and Potamogeton Answer : (a)

Evaporation from mesophyll cells in the leaves produces a negative water potential gradient that causes water and minerals to move upwards from the roots through the xylem. Answer : (a)

Adhesion is the tendency of dissimilar particles or surfaces to cling to one another. Water is polar and hence cling to another dissimilar polar surface. while cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another. Answer : (a)

The water potential can be calculated by the formula nRT, where n is number of moles, R the standard gas constant and T is standard temperature in Kelvin. Substituting the values of R (0.08314 lit bar per kelvin per more ), T (273 kelvin), n (0.1 moles) we get water potential 2.3 bars. As water potential of all solutions is always negative the correct answer will be -2.3 bars. Answer : (a)

The ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the crown. Answer : (d)

This turgidity is caused by the accumulation of K+ (potassium ions) in the guard cells. Answer : (c)

Wilting is the loss of rigidity of non-woody parts of plants. This occurs when the turgor pressure in non-lignified plant cells falls towards zero by Exosmosis, as a result of diminished water in the cells Exosmosis is passage of water through a cell membrane into the surrounding medium Answer : (c)

DPD = OP - TP(WP) Here WP is wall pressure. Answer : (c)

Imbibition is the process of adsorption of water by a substance. When pea seeds and wheat seeds are put in water, pea seeds will imbibe more water. Pea seed has high amount of protein present in it. Wheat seeds have high amount starch in it. The proteins imbibe more water as compared to the carbohydrates. Hence, proteinaceous pea seeds will imbibe more water than those of wheat seeds and swell up. Answer : (a)

A plant cell in a concentrated solution (lower water potential than the cell contents) Water leaves the cell by osmosis. The cytoplasm pulls away from the cell wall (plasmolysis) and the cell becomes flaccid and the plant wilts. Answer : (c)

The apoplast path of water movement includes cell wall and intercellular spaces, which are fully permeable. The water can reach up to endodermis through apoplast The apoplast pathway involves the movement of water through the adjacent cell walls of the epidermis and cortex with out entering the cytoplasm. Answer : (b)

Hydathodes occur in the leaves of submerged aquatic plants Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species. Hydathodes are the structures that discharge water from the interior of the leaf to its surface in a process called guttation. Answer : (b)

Both Assertion and reson statement are true Companion cells actively transport sucrose into the phloem tubes. This active transport creates a high concentration of sucrose inside the phloem tube, there fore reason is not a explanation for Assertion. Answer : (b)

Capillary water in soil is available for root absorption. Capillary water fills the spaces between non- colloidal soil particles and forms films around them. This water is held by the capillary forces around and between the particles and is of greatest importance to plant life. Answer : (b)

Pulsation theory was proposed by J.C. Bose Answer : (b)

Guttation is the process of elimination of water from plants through Hydathodes Answer : (b)

Surface tension is the tendency of fluid surfaces to shrink into the minimum surface area possible. Answer : (d)

Hygroscopic water: The water that held tightly on the surface of soil colloidal particle is known as hygroscopic water. It is essentially non-liquid and moves primarily in the vapour form. Answer : (c)

Hypertonic refers to a solution with higher osmotic pressure than another solution. In other words, a hypertonic solution is one in which there is a greater concentration or number of solute particles outside a membrane than there are inside it. Answer : (b)

Maximum transpiration occurs in mesophyte because Leaves are generally large and rarely small, broad, thin and varied in shape, generally oriented horizontally witho0ut hair or waxy coatings Epidermis well developed, without any hairy or waxy coatings and cells without chloroplasts Answer : (d)

Solute potential (Ψs) increases with decrease solute concentration; a increase in Ψs causes a increase in the total water potential. The internal water potential of a plant cell is lesser negative than pure water Answer : (b)

Increased temperature and presence of wide open stomata increase the rate of transpiration. Light is the most important factor in the regulation of transpiration Answer : (b)

Answer : (c)

Diffusion is the movement of a substance from an area of high concentration to an area of low concentration. Diffusion happens in liquids and gases because their particles move randomly from place to place. Answer : (b)

Ψ = Ψm+Ψs+Ψp+Ψg Ψ = Water potential ( total or combined) Ψm = matric or capillary potential Ψs = solute or osmotic potential Ψp = pressure potential or turgor pressure Ψg = Gravitational potential Answer : (c)

potometer known as a transpirometer, is a device used for measuring the rate of water uptake of a leafy shoot which is almost equal to the water lost through transpiration. porometer is an instrument for measuring the area of the stomatal openings of a leaf by the amount of a gas passing through a given area of it. Auxanometer is an apparatus for measuring increase of growth in plants. Tensiometers are devices that measure soil moisture tension. Answer : (b)

Godlewski (1884) proposed his clambering or relay-pump theory to explain the vertical movement of water through the plant. a - r The cohesion-tension theory (C-T theory) by Boehm (1893) and Dixon and Joly (1894) postulates that the water ascent in trees is exclusively due to the transpirational pull from continuous water columns in the xylem conduit running from the roots to the leafs b - s The theory behind Mass flow hypothesis which is also called as pressure flow hypothesis describes the movement of sap via phloem, proposed by the German physiologist Ernst Munch in 1930 c - t Sir J.C. Bose proposed a theory of ascent of sap known as pulsation theory. d - q Answer : (c)

Diffusion pressure deficit (DPD) Answer : (d)

Lenticel is providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark Answer : (d)

Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. The pressure exerted by the osmotic flow of water is called turgidity. It is caused by the osmotic flow of water through a selectively permeable membrane Answer : (d)