NCERT Exemplar Class 11 Biology Solutions Chapter 11 Transport in Plants

Multiple Choice Questions:

Question:1

Which of the following statements does not apply to reverse osmosis?

(a) It is used for water purification.
(b) In this technique, pressure greater than osmotic pressure is applied to the system.
(c) It is a passive process.
(d) It is an active process.

Answer:

Question:2

Which one of the following will not directly affect transpiration?
(a) Temperature
(b) Light
(c) Wind speed
(d) Chlorophyll content of leaves

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Question:3

The lower surface of leaf will have more number of stomata in a
(a) Dorsiventral leaf
(b) Isobilateral leaf
(c) Both (a) and (b)
(d) None of the above

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Question:4

The form of sugar transported through phloem is
(a) Glucose
(b) Fructose
(c) Sucrose
(d) Ribose

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Question:5

The process of guttation takes place
(a) when the root pressure is high and the rate of transpiration is low
(b) when the root pressure is low and the rate of transpiration is high
(c) when the root pressure equals the rate of transpiration
(d) when the root pressure, as well as rate of transpiration, are high.

Answer:

Question:6

Which of the following is an example of imbibition?

(a) Uptake of water by root hair
(b) Exchange of gases in stomata
(c) Swelling of seed when put in soil
(d) Opening of stomata

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Question:7

When a plant undergoes senescence, the nutrients may be
(a) Accumulated
(b) Bound to cell wall
(c) Translocated
(d) None of the above

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Question:8

Water potential of pure water at standard temperature is equal to
(a) 10
(b) 20
(c) Zero
(d) None of these

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Question:9

Choose the correct option. Mycorrhiza is a symbiotic association of fungus with root system which helps in
A. Absorption of water
B. Mineral nutrition
C. Translocation
D. Gaseous exchange

(a) Only A
(b) Only B –
(c) Both A and B
(d) Both B and C

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Question:10

Based on the figure given below, which of the following statements is not correct?
(a) Movement of solvent molecules will take place from chamber A to B
(b) Movement of solute will take place from A to B
(c) Presence of a semipermeable is a prerequisite for this process to occur
(d) The direction and rate of osmosis depends on both the pressure gradient and concentration gradient.

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Question:11

Match the following and choose the correct option.

Answer:

• Leaves- Transpiration, this is due to the fact that leaves are the main source of conducting the process of transpiration due to the presence of stomata, which aid and regulate the process.
• Seed- Imbibition, seeds grow and foster through the process of imbibition which happens through the retention of water and leads to the seed's germination.
• Roots - absorption, this is due to the reason that roots are the primary way of absorption of nutrients through the soil to nurture the plant and aid in the growth of the shoot.
• Aspirin- anti transpirant, this fits because aspirin is a metabolic inhibitor which is a type of anti transpirant.
• Plasmolysed cell pairs with negative osmotic potential as plasmolysis occurs due to the hypertonic surrounding which causes the shrinking of the protoplasm.This creates a negative osmotic potential.

Question:12

Mark the mismatched pair.
(a) Amyloplast—Store protein granule
(b) Elaioplast—Store oils or fats
(c) Chloroplasts—Contain chlorophyll pigments
(d) Chromoplasts—Contain coloured pigments other than chlorophyll

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Very Short Answer Type Questions:

Question:1

Smaller, lipid soluble molecules diffuse faster through cell membrane, but the movement of hydrophilic substances are facilitated by certain transporters which are chemically ________.

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Question:2

In a passive transport across a membrane, when two protein molecules move in opposite direction and independent of each other, it is called as ________

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Question:3

Osmosis is a special kind of diffusion, in which water diffuses across the cell membrane. The rate and direction of osmosis depends upon both _______

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Question:4

A flowering plant is planted in an earthen pot and irrigated. Urea is added to make the plant grow faster, but after some time the plant dies. This may be due to ________.

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Question:5

Absorption of water from soil by dry seeds increases the ________ thus helping seedlings to come out of soil.

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Question:6

Water moves up against gravity and even for a tree of 20 m height, the tip receives water within two hours. The most important physiological phenomenon which is responsible for the upward movement of water is _________

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Question:7

The plant cell cytoplasm is surrounded by both cell wall and cell membrane.The specificity of transport of substances are mostly across the cell membrane, because _________

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Question:8

The C₄ plants are twice as efficient as C₃ plants in terms of fixing CO₂ but lose only _________ as much water as C₃ plants for the same amount of CO₂ fixed.

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Question:9

Movement of substances in xylem is unidirectional while in phloem it is bidirectional. Explain.

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Question:10

Identify the process occurring in I, II and III.

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Question:11

Given below is a table. Fill in the gaps.

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Question:12

Define water potential and solute potential.

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Question:13

Why is solute potential always negative. Explain y_w = y_s + y_p

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Question:14

An onion peel was taken and
(a) Placed in salt solution for five minutes.
(b) After that it was placed in distilled water. When seen under the microscope
what would be observed in (a) and (b)?

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Question:15

Differentiate between apoplast and symplast pathways of water movement. Which of these would need active transport?

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Question:16

How does most of the water moves within the root?

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Question:17

Give the location of Casparian strip and explain its role in the water movement?

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Question:18

Differentiate between guttation and transpiration.

Answer:

• Guttation takes place at night while transpiration occurs during the day.
• Guttation is the process through which water is lost by the leaves in the form of water droplets, transpiration where water is lost through water vapour.
• Guttation is facilitated through the leaves and their vein endings while stomata in the leaves carry out transpiration.
• Guttation is not a voluntary or a controlled process while transpiration is regulated and controllable.

Question:19

Transpiration is a necessary evil in plants. Explain.

Answer:

Many processes in plants are regulated and dependant on the process of transpiration, such as the ascent of sap. The plant functions are dependent on this process and regulate the growth of plants, especially tall plants. The process helps in the loss of water through the form of water vapour and regulate the water level, but sometimes can lead to an excess loss, thus creating a shortage. Thus there is less water available for photosynthesis, and most of it is lost through transpiration. Thus in some, the process is very necessary, but on the other hand, it also causes certain issues, thus making it a necessary evil.

Question:20

Describe briefly the three physical properties of water which help in the ascent of water in xylem.

Answer:

• Cohesion is the ability by which water molecules stick to each other, which helps the ascent of water in a continuous stream.
• Adhesion helps the ascent of water in the xylem as this is the ability by which water sticks to a surface causing easy transport.
• Surface tension helps the ascent of water in the xylem as this helps the water molecules to occupy the least surface area possible and helps in the maximum amount to move.

Question:21

A gardener forgot to water a potted plant for a day during summer, what will happen to the plant? Do you think it is reversible? If yes, how?

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Question:22

Identify a type of molecular movement which is highly selective and requires special membrane proteins but does not require energy.

Answer:

Facilitated diffusions the molecular movement and the diffusion of the substance is highly dependent on the liquid solubility. The diffusion cannot happen if the substance has hydrophilic moiety and to facilitate it, the special membrane proteins come to the rescue. As diffusion occurs from a region of high concentration to low concentration,energy is not spent; instead, the process is natural. This process is highly selective and does not allow all substances to pass through.

Question:23

Correct the statements.
(a) Cells shrink in hypotonic solutions and swell in hypertonic solutions.
(b) Imbibition is a special type of diffusion when water is absorbed by living cells.
(c) Most of the water flow in the roots occurs via the symplast.

Answer:

Short Answer Type Questions:

Question:1

Minerals absorbed by the roots travel up the xylem. How do they reach the parts where they are needed most? Do all the parts of the plant get the same amount of the minerals?

Answer:

Minerals in the soil cannot all be taken by the plant and need to be regulated. The transportation is different, and sometimes it can be active or passive. Passive transportation occurs through the root hairs, where the special membrane proteins present in the epidermal cells regulate the active movement of nutrients. The transport proteins are also present in the endodermal cells, which help in the restricted uptake of nutrients. The proteins in these cells act as guards and allow selective entry of solutes to enter the xylem. Moreover, the endodermis; layer of suberin allows only one direction of transport.

Question:2

If one wants to find minerals and in the form they are mobilized in the plant,how will an analysis of the exudate help?

Answer:

It helps in understanding the ways and structure in which the transportation of minerals happens. The xylem and its analysis depict that the maximum amount of nitrogen is converted into organic forms to facilitate movement and not in the inorganic form. The xylem and phloem also facilitate the exchange of nutrients, and while sodium and potassium are transported in organic compounds, it is not necessarily a compulsion. Therefore it cannot be determined that the xylem causes only the inorganic substances transportation and the phloem of the organic ones.

Question:3

From your knowledge of physiology, can you think of some method of increasing the life of cut plants in a vase?

Answer:

The life of a plant which is cut in a vase can be lengthened by placing the plant in water and watering it regularly, adding extra external nutrients to the water it is placed in as well as the exposure to certain chemicals such as cytokinin hormone to not only increase the life span but also cause the plant growth.

Question:4

Do different species of plants growing in the same area show the same rate of transpiration at a particular time? Justify your answer.

Answer:

The number and concentration of stomata, openings of the stomata as well as the water level and the structure of the leaf are the main determinants which regulate the process of transpiration. These differ from plant to plant even if they are growing in the same area and can show different levels of transpiration.

Question:5

Water is indispensable for life. What properties of water make it useful for all biological processes on the earth?

Answer:

Water is regarded as the universal solvent, and it dissolves most compounds causing easy transport and absorption. It majorly forms the protoplast and is the primary element of most cells, thus being a part of their composition. The medium for most transportation is water, and it makes the process faster and easier through various membranes and processes.
Availability of nutrients in water is high, which helps the life of many organisms, such as the presence of oxygen. It helps in regulating temperature and processes like pollination and also helps in the relief of heat and regulation of temperature.

Question:6

How is it that the intracellular levels of K⁺ are higher than extracellular levels in animal cells?

Answer:

A quiescent cell has a quite static membrane potential, and the stage is known as the potential resting stage. The intracellular intensity of K + in the cell membrane is far higher than the animal extracellular levels. This is known as the sodium/proton pump and is caused by positive sodium and potassium ions. For every three positive sodium ions leaving, two positive potassium ions enter, and the positive ions increase and cause the change.

Question:7

Cut pieces of beetroot do not leave colour in cold water but do so in hot water. Explain.

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Question:8

In a girdled plant, when water is supplied to the leaves above the girdle, leaves may remain green for some time then wilt and ultimately die. What does it indicate?

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Question:9

Various types of transport mechanisms are needed to fulfil the mineral requirements of a plant. Why are they not fulfilled by diffusion alone?

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Question:10

How can plants be grown under limited water supply without compromising on metabolic activities?

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Question:11

Will the ascent of sap be possible without the cohesion and adhesion of the water molecules? Explain.

Answer:

For the ascent of sap, a lot of factors are considered, such as the pressure of the roots, forces of cohesion and adhesion as well rate of transpiration and the action of the capillary. Adhesion makes the water molecules stick to a surface while cohesion helps the water molecules to stick together to move as one unit, without these forces, the water molecules will lose their tendency, ability, and agility to seamlessly transport nutrients and move disrupting the ascent of sap.

Question:12

Keep some freshly cut flowers in a solution of food colour. Wait for some time for the dye to rise in the flower, when the stem of the flower is held up in light, coloured strands can be seen inside. Can this experiment demonstrate which tissue is conducting water up the stem?

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Question:13

When a freshly collected Spirogyra filament is kept in a 10% potassium nitrate solution, it is observed that the protoplasm shrinks in size:
(a) What is this phenomenon called?
(b) What will happen if the filament is replaced in distilled water?

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Question:14

Sugar crystals do not dissolve easily in ice cold water. Explain.

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Question:15

Salt is applied to tennis lawns to kill weeds. How does salting tennis lawns help in killing of weeds without affecting the grass?

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Question:16

What is the chemical composition of xylem and phloem sap?

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Question:17

If you are provided with two tubes (A and B), where one is narrow and the other is relatively wider and if both are immersed in a beaker containing water as shown in the figure given.

Why does B show higher water rise than A?

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Question:18

What are 'aquaporins'? How does the presence of aquaporins affect osmosis?

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Question:19

ABA (abscisic acid) is called a stress hormone.
(a) How does this hormone overcome stress conditions?
(b) From where does this hormone get released in leaves?

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Question:20

We know that plants are harmed by excess water. But plants survive under flooded condition. How are they able to manage excess water?

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Question:21

Differentiate between diffusion and translocation in plants.

Answer:

• Diffusion is a passive process, while translocation is an active one.
• Translocation employs energy in the form of ATP from the cell, while diffusion occurs naturally and does not require energy.
• Diffusion causes the water to move as well, along with certain gases, but translocation involves the movement of only organic substances.

Question:22

How is facilitated diffusion different from diffusion?

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Question:23

Explain the mass flow hypothesis of transport in the phloem.

Answer:

Mass flow hypothesis is regarded as the pressure-flow hypothesis and is the movement of food along the phloem. The concentration of glucose causes the osmosis gradient to form, and the movement of water is facilitated to the phloem through the xylem to maintain the concentration.

The turgor pressure causes the phloem sap to transport sugar to the sink from the source, and the pressure which plays a key role here is the flow hypothesis. The substance is moved in bulk and is known as the mass flow hypothesis.

Question:24

Observe the diagram and answer the following:


(a) Are these types of guard cells found in monocots or dicots?
(b) Which of these shows a higher water content (i) or (ii)?
(c) Which element plays an important role in the opening and closing of stomata?

Answer:

Question:25

Define uniport, symport and antiport. Do they require energy?

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Long Answer Type Questions:

Question:1

Minerals are present in the soil in sufficient amounts. Do plants need to adjust the types of solutes that reach the xylem? Which molecules help to adjust this? How do plants regulate the type and quantity of solutes that reach xylem?

Answer:

There are several elements and nutrients placed and located in the soil, but the plant needs to regulate and adjust the kind of minerals that travel to the xylem.

Some of these ions present in the soil travel from the soil to the root hair, in a passive way. The active transport of ions in the soil is regulated by the epidermal cell special membrane proteins. Transportation of certain proteins can also be facilitated by the endodermal cells, which regulate and allows selective entry of ions. The proteins located in these cells screen and take care of which ions to allow entry. The suberin layer of the endodermis allows transport in only one direction.

Question:2

Plants show temporary and permanent wilting. Differentiate between the two. Do any of them indicate the water status of the soil?

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Question:3

Which of these is a semipermeable membrane (S.P) and which is selectively permeable (S.L)
(a) Animal bladder
(b) Plasmalemma
(c) Tonoplast
(d) Parchment membrane
(e) Egg membrane

Answer:

Question:4

Halophytes may show precell pressure very much higher than atmospheric pressure. Explain how this can happen?

Answer:

Halophytes are plants which are conditioned and have adapted to growing in a salt-based and concentrated environment. Concentration in the soil is much higher than the water present in the stem of the plant. Water potential is much less in the soil and can cause excessive water loss of the plant creating a stressful situation. Therefore the plants adapt to this situation by storing high concentrated salts thus increasing the water potential of the soil and causing intake of water. This helps the plant to regulate and maintain its cell composition and pressure.

Question:5

The radio-labelled carbon in carbon dioxide supplied to potato plants in an experiment was seen in the tuber eventually. Trace the movement of the labelled carbon dioxide.

Answer:

To observe the creation of Carbohydrate and the following movement of starch from various parts of the plant to the others, the radiolabelled carbon dioxide is supplied. Photosynthesis occurs in the leaves; the radioactive carbon dioxide will travel to the leave parenchyma.

Following the process of photosynthesis, the radioactive carbon will be the Carbohydrate in the leaves. This can also be proved by the presence of starch which is a by-product of photosynthesis. The carbohydrates soon transform into starch and are moved to the other organs to store it. Thus the radioactive carbon can be detected in the tubers, as the starch is stored in tubers.

Question:6

Water molecule is very polar. Polar end of molecule attracts opposite charges on another water molecule (acts like magnet). How will you explain this property of water with reference to upward movement of water? Comment on the upward movement of water given the intermolecular hydrogen bonding in water.

Answer:

Water is known to be a highly polar molecule; the hydrogen atom is positive by the oxygen atom is negative, which creates the polar charge. Therefore the two atoms attract each other and create a force which is one of the major determinants for or the surface tension that is formed on any liquid, complemented by certain intermolecular forces. This helps the plant to absorb water from the soil through the root and the xylem, eventually reaching the leaves. The forces of cohesion and adhesion help molecules to stick to each other as well as a surface and enable it to be transported in a continuous fashion. All these factors help and assist the ascent of sap.

Question:7

Comment on the experimental setup.


(a) What does the setup demonstrate?
(b) What will happen to the level of water if a blower is placed close to setup.
(c) Will the mercury level fluctuate (go up/ down) if phenyl mercuric acetate is sprayed on leaves?

Answer: