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Stomata and transpiration - class-XI

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Loss of water in the form of vapours from the living tissues of aerial plant parts is called _________________.

  1. Transpiration

  2. Guttation

  3. Bleeding

  4. Precipitation


Correct Option: A
Explanation:

The loss of water in the vapour form from the exposed parts of a plant is called transpiration. The loss of water due to transpiration is quite high. It is 22 litre per day in sunflower, 364536−45 litres in apple and upto 11 tonne per day in elm tree.

Leaf pores/ stomata help in _______.

  1. Intake of $CO _2$ during photosynthesis

  2. Release of $O _2$ during photosynthesis

  3. Release of water vapour during transpiration

  4. All of these


Correct Option: D
Explanation:

Stomata has 3 major functions:

1. Transpiration causing release of water vapour
2. Intake of carbon dioxide during photosynthesis
3. Release of oxygen during photosynthesis
So the correct answer is 'All of these'.

The mechanism of transpiration in plants is performed by:

  1. Stem

  2. Only leaves

  3. Flowers

  4. All of these


Correct Option: D
Explanation:
Water loss by transpiration may take place from any part of the plant exposed to external atmosphere. It occurs, however, principally from the leaves and is known as foliar transpiration. Only, a relatively small quantity of water is transpired from the stem and is called cauline transpiration.
So, the correct answer is D.

The process of transpiration in plants helps in

  1. Opening of stomata.

  2. Absorption of $CO _2$ from atmosphere.

  3. Upward conduction of water and minerals.

  4. Absorption of $O _2$ from atmosphere.


Correct Option: C
Explanation:
In plants transpiration develops a transpiration pull that pulls water and minerals upwards from root towards leaves
So, the correct answer is 'Upward conduction of water and minerals'

Which force arises between the water molecules of leaves due to transpiration?

  1. Cohesive forces

  2. Pressure force

  3. Suction force

  4. Adhesive force


Correct Option: A
Explanation:

A.Cohesive force – force of attraction present between the water molecules is called cohesive force. Due to this, water column maintains tensile strength.

B.Pressure force – force developed to accumulation of pressure.

C.Suction force – force exists in the sucking of water.

D.Adhesive force – force of attraction exists between the water molecules and walls of the vessels is called adhesive force. Due to this, capillarity exists in the water column.

So, the correct option is ‘cohesive force’.

The process of transpiration in plants helps in the

  1. Opening of stomata

  2. Closing of stomata

  3. Upward conduction of water and minerals

  4. Both B and C


Correct Option: C
Explanation:

Transpiration is the loss of water by the stomatal openings of the aerial parts of the plant. This helps in the upward movement of water and minerals from the roots to the leaves by a cohesion-adhesion mechanism. 

Which is used to measure the rate of transpiration?

  1. Atmometer

  2. Psychrometer

  3. Potometer

  4. Porometer


Correct Option: C
Explanation:

Atmometer is a device used to measure the rate of water evaporation from a wet surface to the atmosphere and can be used to measure the rate of evapotranspiration. 

A psychrometer is a device used to measure the rate of relative humidity in the atmosphere. 
Potometer is a device used to measure the rate of water uptake by plants  porometer is a device used to measure the area of the stomatal opening of leaves.
 So, the correct answer is 'Potometre'.

The process of transpiration is a

  1. Diffusion

  2. Osmosis

  3. Active transport

  4. facilitated Diffusion


Correct Option: A
Explanation:
During the process of transpiration, the water moves up the xylem vessels to the leaves through diffusion. Diffusion takes place because there is a difference in water potential between water in the xylem vessel and the leaf (as water is transpiring out of the leaf). There is also a pressure change between the top and bottom of the xylem vessels, due to water loss from the leaves. This reduces the pressure of water at the top of the vessels. This means water moves up the vessels and then out of the leaves through diffusion.
So, the correct option is 'Diffusion'.

Water movement against gravity is caused by?

  1. Imbibition

  2. Transpiration

  3. Osmosis

  4. Diffusion


Correct Option: B
Explanation:
Water movement against gravity is caused by transpiration. Transpiration is the process by which water is carried through plant roots to small pores of the leaves, where it changes to vapor and is released to the atmosphere. The mechanism of transport of water against gravity is by cohesive forces of water molecules. Water molecules cohere and are pulled up the plant by the tension, exerted by evaporation at the leaf surface. 

Thus, the correct answer is option B.

The shade of the tree is often cooler than exposed atmosphere, because of

  1. Photosynthesis

  2. Respiration

  3. Transpiration

  4. Guttation


Correct Option: C
Explanation:

Transpiration is a process of loss of water from a plant in vapour form. One of the benefits of transpiration is that it causes surface cooling because evaporation of water requires energy. Consumption of energy leads to a cooling effect on the leaf surface. Also because of more water vapour content in shade, a tree shade is cooler than area exposed to sunlight. 

Silicon emulsions are

  1. Antitranspirants

  2. Antirespirants

  3. Hormones

  4. None of these


Correct Option: A
Explanation:

Antitranspirants are substances that are applied to the leaves to reduce transpiration. They are used on trees, cut flowers and shrubs. They reduces transpiration in fruit plants like apples, pears, orange, crop plants like cotton, tea, roses, tuber crops like potato, carrot and vegetable plants like chillies, tomato, cabbage. These are also used to protect plants from drying out too quickly. Various antitranspirants include abscisic acid (ABA), aspirin, silicon emulsions, plastics, waxes.

Thus, the correct answer is option A.

The loss of water from the plants is known as

  1. Respiration

  2. Transpiration

  3. Replication

  4. Ascent of sap


Correct Option: B
Explanation:

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transpiration also cools plants, changes osmotic pressure of cells and enables mass flow of mineral nutrients and water from roots to shoots.

Therefore, the correct answer is option B.

Absorption of water is increased when

  1. Transpiration is increased.

  2. Photosynthesis is increased.

  3. Respiration is increased.

  4. None of the above.


Correct Option: A
Explanation:

According to the transpiration pull theory, loss of water from aerial parts due to transpiration is a physical process and the loss of water generates the pulling force. Water is present as a continuous column in vascular tissues due to cohesive and adhesive forces. The loss of water due to transpiration is equal to the amount of water absorbed from the soil. More the transpiration loss of water, more the absorption of water from the soil and vice versa.

For plants, transpiration is

  1. Not very important

  2. Important to some

  3. A necessary evil

  4. An important burden


Correct Option: C
Explanation:

Transpiration generates tension in plants. This tension is the main pulling force, which pulls water to great heights in vascular plants. Thus, transpiration leads to the ascent of sap. Without transpiration, water and minerals will not rise from roots to aerial parts of plants and trees. 

At the same time, it is essentially a wasteful process. As much as 99 percent of water absorbed by a plant goes waste into the atmosphere. Thus, transpiration has been called as a necessary evil.

Leaves of submerged hydrophytes are

  1. Epistomatic

  2. Hypostomatic

  3. Astomatic

  4. Both A and B


Correct Option: C
Explanation:

Hydrophytes are plants growing in water. They may be submerged or floating. Floating hydrophytes have stomata on floating parts, for example, floating leaves of lotus have stomata on the upper surface. 

Submerged hydrophytes do not have stomata. Submerged hydrophytes absorb minerals and water and exchange gases through general epidermal surface.

Wilting of a plant results from excessive

  1. Respiration

  2. Photosynthesis

  3. Absorption

  4. Transpiration


Correct Option: D
Explanation:

Transpiration is a loss of water in vapour form stomata. The rate of transpiration depends on a number of factors, like carbon dioxide concentration, temperature, light, humidity etc. The most important factor which governs the rate of transpiration is the vapour pressure gradient, which exists between leaf mesophyll and atmosphere. It has been estimated that almost 99 percent of water absorbed by plants is lost in transpiration. As transpiration generates the tension, which is the most important force responsible for water absorption.

When excessive water is lost from the plant than can be absorbed from soil, plant shows wilting. In wilting leaves droop down and there is a general loss in turgidity of leaf cells.

Who stated transpiration to be an unavoidable evil?

  1. Blackman

  2. Steward

  3. Priestley

  4. Curtis


Correct Option: D

Plants get rid of excess water by

  1. Photosynthesis

  2. Respiration

  3. Transpiration

  4. None of the above


Correct Option: C
Explanation:

Plants produce carbon dioxide and water as respiratory waste products. Plants get rid of excess water by transpiration and guttation. Transpiration is evaporation of water from plant leaves by stomata.

Transpiration is

  1. The absorption of water and minerals by the roots of a plant.

  2. The movement of sap upward in a plant against the force of gravity.

  3. The loss of water and waste material through stomata and lenticels.

  4. The absorption of waste materials from the blood by nephrons.


Correct Option: C

Loss of water in the form of water vapour from plants to atmosphere is called as

  1. Photosynthesis

  2. Respiration

  3. Transpiration

  4. Excretion


Correct Option: C
Explanation:

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. 

Therefore, the correct answer is option C.

Which of the following processes keeps the plant cool?

  1. Photosynthesis

  2. Transpiration

  3. Respiration

  4. Translocation


Correct Option: B
Explanation:

Water moves from the soil into plant roots, up through the sapwood into the leaves. The water, warmed by the sun, turns into vapor (evaporates) and passes out through thousands of tiny pores (stomata) mostly on the underside of the leaf surface. This process is transpiration. It has two main functions: cooling the plant and pumping water and minerals to the leaves for photosynthesis. Photosynthesis, respiration and translocation can not keep the plant cool. Therefore, the correct answer is option B.

Transpiration is a useful process as it is involved in 

  1. Loss of water

  2. Food translocation

  3. Ascent of water and minerals and reduce the impact of temperature on plants

  4. Growth and curvature of plants


Correct Option: C
Explanation:

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Translocation is not involved in food translocation and growth and curvature of plants.

Therefore, the correct answer is option C.

The loss of the water from leaves of plants is called as

  1. Translocation

  2. Trasnspiration

  3. Transfusion

  4. None of the above


Correct Option: B
Explanation:

Transpiration is the process by which moisture or water is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transfusion and translocation do not involve the loss of water. 

Therefore, the correct answer is option B.

Which of the following do not transpire?

  1. Algae

  2. Fungi

  3. Submerged hydrophytes

  4. All of the above


Correct Option: D
Explanation:

Submerged hydrophytes do not show transpiration, because they are submerged in water. Fungi do not come under plants. Algae do not have leaves and stomatal pores. So, they also do not show transpiration.

In both transpiration and evaporation, water is lost in the form of vapour yet they differ, because

  1. Both transpiration and evaporation are similar but the rate of water loss in transpiration is always more

  2. Frequency of water loss is different in both of them.

  3. Transpiration is a physical process and evaporation is a physiological process.

  4. Transpiration is a physiological process and evaporation is a physical process.


Correct Option: D
Explanation:

Transpiration is loss of water in vapor form, from living plant cells thus it is a physiological process while evaporation is loss of water from any free surface in vapor form, thus it is a physical process. 

By which process atmospheric temperature is maintained?

  1. Transpiration

  2. Respiration

  3. Photosynthesis

  4. Phosphorylation

  5. None of the above


Correct Option: A
Explanation:

Transpiration results in loss of water in vapour form. Water vapours are a prominent green house gas, responsible for maintenance of temperature on earth.

Plants lose most of water through leaves by 

  1. Respiration

  2. Guttation

  3. Photosynthesis

  4. Transpiration


Correct Option: D
Explanation:

Water is essential for plants, it absorbs water from the soil through roots. However, plants absorbs much water, but only a small amount of water is used for their growth and metabolism. Persisting 97 - 99.5% of absorbed water is lost by transpiration. Transpiration is the process of elimination water in the form of water vapour from the aerial parts such as leaves, flowers and stem.

So, the correct answer is option D.

The loss of water vapour by a plant is called as transpiration.

  1. True

  2. False


Correct Option: A
Explanation:

Water is transient in plants. Less than 1 per cent of the water reaching the leaves is used in photosynthesis and plant growth. Most of it is lost through the stomata in the leaves. This water loss in vapour form is known as transpiration.

The function of Anti-transpirants is:

  1. Reduce the rate of transpiration without affecting carbon assimilation

  2. Reduce the rate of transpiration affecting carbon assimilation

  3. Reduce the rate of transpiration affecting growth of plant

  4. Reduce the rate of transpiration affecting protein synthesis of plant


Correct Option: A
Explanation:

Anti-transpirants are compounds applied to the leaves of plants to reduce transpiration. They are used to preserve and protect plants from drying out too quickly. They are also used to protect leaves from the salt burn and fungal diseases. Anti-transpirants reduce the stomatal opening and increase the leaf resistance to water vapour diffusion without affecting carbon dioxide uptake.

So, the correct answer is 'Reduce the rate of transpiration without affecting carbon assimilation'.

Water lost by transpiration is?

  1. Pure water

  2. Rich in dissolved salts

  3. Rich dissolved minerals

  4. None of the above


Correct Option: A
Explanation:

Transpiration is a process by which the moisture is carried through plants from the roots to the stomata where it is converted into vapour and is released out to the atmosphere that is the evaporation of water from plant leaves. Transpiration along with evaporation of moisture from land produced two-third of atmospheric moisture.

Plant loses most of its absorb water by transpiration process through stomata. The water which is lost annually is pure water.
So, the correct option is 'Pure water'

Which one of the following helps in the upward movement of water and dissolved minerals from the roots to the leaves through the stem ?

  1. translocation

  2. transportation

  3. transpiration

  4. transaction


Correct Option: C
Explanation:

The continuous evaporation of water (or transpiration) from the cells of a leaf crates a kind of suction which pulls up water through the xylem vessles. Thus, transpiration helps in the upward movement of water and dissolved minerals from the roots to the leaves through the stem.

The process in which loss of water occurs in the form of water vapour is

  1. Respiration

  2. Guttation

  3. Transpiration

  4. Exosmosis


Correct Option: C
Explanation:
Respiration  is a process in which living organisms produces energy, with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.
Guttation is the loss of water in the form of water droplets from hydathodes (small pores) on the leaf margin of a plant.
Transpiration is the process where plants absorb water through the roots and then give off water vapor through pores in their leaves.
The passage of material through a semi-permeable membrane from a region of higher to a region of lower concentration, especially the passage of water through a cell membrane into the surrounding medium, is called exosmosis. 
Thus, the correct answer is option (C). 

A leafy twig of mesophytic plant dipped in water would demonstrate 

  1. Photosynthesis

  2. Transpiration

  3. Respiration

  4. Gutttation


Correct Option: B
Explanation:
Mesophytic plants are the plants which grow in the areas/lands which is not too dry not too wet.
When this type of plant is dipped in water (making hydrophytic) then it will demonstrate transpiration More will be the amount of water and more will be the transpiration rate.
Biochemical processes like photosynthesis, respiration and guttation do not depend upon the nature of land but transpiration depends upon the amount of water present in the soil.
So, the correct answer is 'Transpiration'.
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