31 Years NEET Previous Year Questions: Transport in Plants - 1 (Old NCERT) - NEET MCQ

• Such water loss in its liquid phase is known as guttation.
• Cohesion – mutual attraction between water molecules.
• Adhesion – attraction of water molecules to polar surfaces (such as the surface of tracheary elements).
• Surface Tension – water molecules are attracted to each other in the liquid phase more than to water in the gas phase.

Root pressure (positive pressure)  can be responsible for pushing up water to small heights in the stem. “It also observable at night and early morning when evaporation is low, and excess water collects in the form of droplets around special openings of veins near the tip of grass blades, and leaves of many herbaceous parts.
 

Such water loss in its liquid phase is known as guttation. Imbibition is the adsorption leading to absorption of water by hydrophillic substances. Plasmolysis is the shrinking of the cell membrane and cytoplasm when a cell is undergoing exosmosis. The loss of water in the form of water vapor from the aerial parts of the plant is called transpiration.

Xylem is a type of transport tissue which is present in vascular plants. The basic function of xylem is transportation. Xylem  majorly transports water from roots to the parts of plants. Some times it also transports nutrients like mineral salts needed by the plant.

By the process of diffusion, water travels from high to low pressure. If atmospheric pressure is low, water will move out of the plant into the atmosphere as water vapour. Plants will lose water at higher rates by transpiration process. Hence, at low atmospheric pressure, the rate of transpiration increases. 

Substance that have a hydrophilic moiety, find it difficult to pass through the membrane, their movement has to be facilitated by the membrane protein without  expenditure of ATP energy. Facilitated diffusion cannot cause net transport of molecules from a low to a high concentration or uphill transport. Transport rate reaches a maximum when all of the protein transporters are being used (saturation). Facilitated diffusion is very specific.

 The main cause of guttation in plants is root pressure. During night when root pressure is high sometimes due to this 
high pressure watery drops ooze out with the assistance of special structures which help in guttation called hydathodes.

Guard cells help in transpiration. Transpiration is the evaporation of water from the aerial parts of plants, especially leaves but also stems, flowers and roots. Stomatal opening allowing the diffusion of carbon dioxide and oxygen during photosynthesis.

Carbohydrates are commonly found as starch in plant storage organs. It is chemically non-reactive and osmotically inactive polysaccharides of much greater molecular weight. Carbohydrates performs a vital role in living organisms. Starch and other polysaccharides serve as energy storage in plants, particularly in seeds, tubers, etc. which provide a major energy source for animals, including humans. 

The rupture and fractionation do not usually occur in the water column in vessel/ tracheids during the ascent of sap because of cohesion and tension. The water molecules have a great mutual attraction with each other or in other words we can say that they have tremendous cohesive power which is sometimes as much as 350  atmospheres. Thus, the transpiration pull develops a negative pressure in the uppermost xylem cells. It is transmitted from there into the xylem of stems, and from there into the xylem of stems, and from there to the roots. 

 Extensive use of chemical fertilizers may lead to eutrophiction of nearby water bodies. 

Movement of water will be from low DPD to high DPD i.e from A to B

Munch's Mass Flow Hypothesis is the theory which explains the flow of food materials through the phloem from the higher concentration regions to lower concentration regions. The force is needed to move organic food materials downwards in the phloem. The energy for the translocation of the food is provided by the ATP which acts as a ligand to the sucrose and hydrogen ion symporter and allows the movement of the food through the sieve tubes. 

Thus, the correct answer is option A. 

Sulphur is an important nutrient of pulse crops. Pulses contain protein. Sulphur is an integral part of proteins.

 Potometer : It is an apparatus for measuring the rate of transpiration.

Bending of tentacles in Venus fly trap or Drosera after coming in contact with an insect is thigmonastic or chemonastic movement of variation or Turgor movements.
The mechanism by which the trap snaps shut involves a complex interaction between elasticity, turgor and growth. In the open, untripped state, the lobes are convex , but in the closed state, the lobes are concave  It is the rapid flipping of this bistable state that closes the trap, but the mechanism by which this occurs is still poorly understood. When the trigger hairs are stimulated, an action potential  involving calcium ions is generated, which propagates across the lobes and stimulates cells in the lobes and in the midrib between them

Cohesion is the force of attraction between similar molecules.  Osmosis is the movement of solvent molecules from  a region of low solute concentration to a region of  high solute concentration through a semipermeable membrane.

During day time, due to photosynthesis, malic acid forms which breaks to H+ and malate. H+ move out of guard cells and K+ enter forming potassium malate which makes guard cells turgid and stomata opens.

The pressure required to stop the flow of pure water into a solution across a semi permeable membrane is a characteristic of the solution, and is called the osmotic pressure. Thus water will move from a region oflow osmotic pressure to a region of high osmotic pressure. Turgor pressure is the hydrostatic pressure set up within a cell by the water present acting against the elasticity of the wall. Suction pressure when referred to a cell, is the force which is available for taking in water.

Nerium is a xerophytic plant and have sunken stomata to reduce the rate of transpiration, confined to lower epidermis.

Movement of ions against concentration gradient involves the expenditure of energy. Diffusion involves the movement  of solute particles from region of higher concentration to a region of lower concentration. Pinocytosis is cell drinking. Brownian movement is the random to and fro movement of atoms and molecules

Water potential is regarded as the tendency of water to leave a system. Pure water has the highest possible water  potential which  is zero. All solutions have a water potential lower than that of water.

D.P.D. or suction pressure (S.P.) = O.P. – T. P.
Hence D.P.D. for A = 4 bars, B = 0 bars, C = 5 bars, D = 4 bars We know that direction of movement of water is from lower D.P.D. (S.P.) to higher D.P.D. (S.P.). \ flow will be from B to A, C, and D.

Osmotic potential is the potential of a solution to cause water movement into it across a semi- permeable membrane. Water potential is the tendency of water  to leave a system.

Pure water has maximum water potential (O). Water potential in the leaf tissue becomes greater than pure water under conditions of excessive humidity when the leaves cannot lose water by transpiration. Hence water is lost as droplets via hydathodes by the process of guttation.

After sunrise, photosynthesis is carried out using CO₂. Hence concentration of  CO₂ decreases hence increasing pH.