31 Years NEET Previous Year Questions: Transport in Plants - 2 (Old NCERT) - NEET MCQ

Under water logged conditions roots die due to lack of air for respiration.

A non ionic Mg atom is held in the centre of porphyrin (of chlorophyll) held by N atom of pyrrole ring.

Minerals can move upward and downward (bidirectional movement) as well as laterally in phloem. Phloem plays an important role in translocation of minerals.

Wall pressure is equal and opposite to the turgor pressure.

Osmosis is the movement of solvent particles  from a region of low solute concentration to a region of high solute concentration through a selectively  permeable membrane. Active  absorption involves  use of ATP.

Pitcher plant is an insectivorous plant which catches insects. The paratonic movements are induced in response to an external stimulus caused by insects due to which lids close and the insects are trapped inside the pitcher.

 Active transport always involves the expenditure of energy for the movements of substances against concentration gradient.

Stomata present on lower surface of plant leaves effectively exchange gases without allowing much loss of water from the leaves.

During scarcity of water in the soil, stress hormone abscisic acid is produced which brings about stomatal closure. ABA inhibits the uptake of K⁺ by the guard cells and promotes leakage of malic acid from guard cell. This result in loss of water from guard cell due to its lower osmotic potential. Guard cell become flaccid leading to closure of stomatal aperture. ABA also causes stomatal closure under high concentration of CO2 in the guard cells.

a-ketoglutaric acid are the precursors of amino acid.

When sugar is converted into starch, the osmotic concentration of guard cells fall and they lose water to adjacent cells and stomata closes.

The rate of transpiration is inversely proportional to the atmospheric pressure. Increased height above the sea level lower the atmospheric pressure and increases the rate of evaporation.

Starch is converted to malic acid (organic acid) through the action of an enzyme phosphoenol pyruvate carboxylase (PEPC) under condition of high pH when most of the CO₂ is utilized due to high photosynthetic rate during daytime.

Transpiration is responsible for saturation of the atmosphere.

Loss of water from margins of leaves is called guttation. Guttation occurs when transpiration rate is very low as compared to rate of water absorption. Due to which root pressure is developed and water is pushed out through stomata like pores called hydathodes. It occur in more saturated atomosphere.

Potometer is an apparatus used for measuring the rate of transpiration.

Water is absorbed by a system having higher DPD from another system with lower DPD. The net force with which water is drawn into a cell is equal to the difference of osmotic pressure (OP) and turgor pressure known as diffusion pressure deficit (DPD).
DPD = OP – TP

Transpiration pull and cohesion theory was put forward by Dixon and Jolly in 1894. According to this theory water rises due to the transpiration pull, continuity of water column and the cohesive power of water molecules from the lower part of the roots  to the higher peaks of the trees.

After rain a portion of water percolates downwardly under the influence of gravity. It is not available to plants. Hygroscopic water is also not available for plants because soil particles hold water by strong attractive forces. Chemically bound water is combined with chemicals. Capillary water is present in narrow spaces of soil and is held in soil by capillary forces and is absorbed by root.

Water movement occurs through the trachaery elements of xylem.

The absorption of water by the solid particles of an adsorbent causing it to increase in volume without forming a solution is called imbibition. 

Turgor pressure is the pressure that develops in a cell due to osmotic diffusion of water  inside  it and is responsible for pushing the membrane against cell wall. Stomata open under conditions of increased turgor pressure of guard cell and stomata get closed under conditions of decreased turgor pressure of guard cells. When turgid, they swell and bend outward. As a result, the stomatal aperture opens. When they are flaccid, the tension from the wall is released and stomatal aperture closes.

Water potential is defined as the difference between chemical potential of water at any point in a system and that of pure water under standard conditions. The unit of measurement of water potential is pascal, Pa (1 mega pascal, Mpa = 10 bars). It is represented by greek letter PSi (ψ). Water potential has two components solute potential which is always negative and pressure potential which is usually positive. Therefore water potential ψ_w is expressed as: ψ_w = ψ_s + ψ_p

Transpiration is a process of loss of water in the form of vapours from the aerial parts of the plants. Transpiration is inversely proportional to the atmospheric humidity. The rate of transpiration would be higher when humidity is low.

Phenyl Mercuric Acetate (PMA) is an antitranspirant. Antitranspirants are compounds applied to the leaves of plants to reduce transpiration without affecting gaseous exchange. They are used on Christmas trees, cut flowers, newly transplanted shrubs, and in other applications to preserve and protect plants from drying out too quickly. They have ‘also been reportedly used to protect leaves from salt burn and fungal diseases.
Anti Transpirants are of two types: 1. Metabolic inhibitors 2. Film forming antitranspirants