Plant Water Relation Short Question

 1) What turgor pressure?

In plant cells the pressure component arises from the force exerted out wardly against the cell wall by expanding protoplast is called Turgor pressure.

2) What are diffusion and diffusion pressure deficit?

Diffusion is the net movement of molecules or atoms from a region of high concentration(or high chemical potential) to a region of low concentration (or low chemical potential).This is also referred to as the movement of a substance down a concentration gradient.

 

The difference  in the diffusion pressure between a solution and its solvent is called diffusion pressure deficit (DPD).It was coined by B.S Meyer in 1938.The DPD of a solution is always lesser than its pure solvent.

 

3) What is plasmolysis? Give an example.

The shrinkage of protoplast of cells due to exosmosis when the cell is placed  in hypertonic solution is called plasmolysis.

 

When a living plant cell is placed in a sufficiently concentrated solution of a suitable agent (e.g. cane sugar), plasmolysis occurs.

 

4) What is water potential?

Water potential is a measure of the potential energy in water as well as the difference between the potential in a given water sample and pure water. Water potential is represented by the equation Ψ _system = Ψ _total= Ψ _s + Ψ _p + Ψ _g + Ψ _m.

 

5) What is diffusion pressure gradient?

 

 

6) What  incipient plasmolysis?

The initial stage of  plasmolysis in plant cell when  the protoplasm just  begins to separate from cell wall is called  incipient plasmolysis.

 

7) What is suction pressure?

The actual pressure with which cell absorbs water is called "suction pressure”.

 

 

8)What is  the difference between  semi-permeable and a selectively permeable membrane?

Semi permeable membrane permits the entry of solvent through it but Selectively permeable membrane permit  the entry of solvent as well as some low molecular weight solute particle through it.

 

9) What is a saturation vapour pressure?

Vapor pressure is a measurement of the amount of moisture in the air. It is technically the pressure of water vapor above a surface of water.When air reaches the saturation vapor pressure, the water vapor in it will condense. At this time, the dew point temperature is the same as the air temperature. A solute has a lower saturation vapor pressure than pure water, which means that there is a wider range of air pressures for which the solute can condense than for the pure water. It is easier for the solute cloud droplet to grow.

The saturation vapor pressure is the pressure of a vapor when it is in equilibrium with the liquid phase. It is solely dependent on the temperature. As temperature rises the saturation vapor pressure rises as well.

 

10) What are active and passive absorption?

The intake of water by plantwith the use of wnergy is called active absorption.The  intake of water by plants due to transpiration pull from the top of the plant and without using energy is called passive absorption.

 

11) What is meant by physiologically dry soil?

Physiologically dry soil is that kind of soil in which, concentration of salts are very high. That's why halophytes grow in that kind of soil. It is found in  coastal area like Sunderbans area, India.

 

12) What is wilting coefficient?

Wilting coefficient is defined as the ratio of  amount of transpired water and of absorbed water by a plant kept in optimum condition.

 

13) What is root pressure?

Root pressure is osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day.

 

14) What are apoplast and symptast?

 

 

 

15) What are peristomatal and lenticular transpiration?

Peristomatal transpiration: Peristomatal transpiration is defined as the relative high local rate of cuticular water loss from external and internal surfaces around the stomatal pore.

 

Lenticular transpiration Sometimes water may evaporate through certain other openings present on the older stems. These openings are called Lenticels and the transpiration that takes place through term is known as Lenticular Transpiration.

 

16)Which hormone is responsible for hydroactive stomatal closure?

Abscisic acid (ABA) is an isoprenoid plant hormone, which is  is responsible for hydroactive stomatal closure.

 

17) What is antitranspitant? Give two examples.

Antitranspirants are compounds applied to the leaves of plants to reduce transpiration.They are used on Christmas trees,on cut flowers, on newly transplanted shrubs, and in other applications to preserve and protect plants from drying out too quickly.Eg: ABA, Phenylmercuric acetate.

 

18) Name two commercial antitransirants.

Phenylmercuric acetate and Silicone oil.

 

19)What is guttation? Name one plant where guttation is observed.

Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface. It is common in Lycopersicon esculentum.

20) What is the function of hydathode?

A hydathode is a type of secretory tissue in leaves, commonly found in Angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration.

 

21) What is bleeding of plant?

Bleeding is leakage of sap from a wound or pruning cut on a tree, shrub or woody climber. Sometimes this may be a gentle seeping, other times a copious flow.Bleeding occurs due to the pressure of sap within the tissues that conduct water and sugars around the plant.

 

22)What sunken stomata? Where is it observed?

A sunken stomata is a stomata in a small pit, which protects the escaping water vapor from air currents, decreasing water loss from the leaf. Sunken stomata are commonly found in plants in arid environments as one of their adaptations to preserve water. Plants with sunken stomata often have fewer stomata in general than plants in moister environments.

 

24)Which ion predominantly regulates guard cell opening and closing?

K⁺ Ion.

 

25) What is ascent of sap?

The upward movement of water and minerals from the root to aerial parts of the plant body is called ascent of sap or often called translocation of water.  It occurs in the xylem tissue of plants from the root to the crown.

 

26)What is evapotransanspiration?

Evapotranspiration (ET) is the sum of evaporation and plant transpiration from the Earth's land and ocean surface to the atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and water bodies.