Question 1

Question 3Fill in the blanks with suitable terms given below:(fast, leaves, conducting, ascent, humid)Transportation in plants is carried out by a ............... system.The upward movement of sap that contains water and minerals is called ............... of the sap.Transpiration is more when the wind is blowing ...............Most water gets evaporated from the plant from its ...............Transpiration is reduced if the air is ...............

Accepted Answer

Transportation in plants is carried out by a conducting system.The upward movement of sap that contains water and minerals is called ascent of the sap.Transpiration is more when the wind is blowing fast.Most water gets evaporated from the plant from its leaves.Transpiration is reduced if the air is humid.

Question 2

Question 2Given below is an experimental set up. Study the figure and answer the following questions:(a) What is the main objective of the experiment?(b) Name the tissue which is responsible for the process shown in the figure.(c) Name two dyes which can be used in the above experiment to make a coloured solution.

Accepted Answer

(a) The main objective of the given experiment is to show how the water is transported in plants.(b) The tissue which is responsible for the process shown in the figure is xylem.(c) Two dyes which can be used in the above experiment to make a coloured solution are Eosin and Red ink.

Question 3

Question 3The set up shown below kept was in sunlight for an hour. It was observed that drops of water appeared on the inside surface of the polythene bag.(a) Name the process which is being demonstrated.(b) Why was the pot with its soil left uncovered by the polythene bag?(c) Why was the pot left in sunlight?(d) Suppose that the pot in this experiment was placed inside a dark room instead of placing it in sunlight for some time. What difference would be noticed?

Accepted Answer

(a) Transpiration is being demonstrated here.(b) The pot and its soil were left uncovered by the polythene bag because in the experiment we need to observe the loss of water occurred by plants. If the pot is covered, the water from the soil may also get evaporated and we will not get accurate results.(c) In sunlight, the rate of transpiration is faster as the stomata are open to allow inward diffusion of carbon dioxide for photosynthesis. Hence, the plant was left in sunlight.(d) If the pot was placed inside a dark room, transpiration will hardly occur as the stomata of the plant are closed. Hence, negligible water droplets will get condensed on the inner side of polythene bag.

Question 4

Question 4Briefly explain, how transpiration helps in the upward conduction of water in plants?

Accepted Answer

As water evaporates from the leaves during transpiration, it creates a suction force or tension in the xylem vessels. As a result of transpiration, a suction force is created in the xylem vessel. This force causes the water to be pulled up from the xylem in the roots to the stem and then to the leaves. This suction force helps draw more water up through the stem, which in turn causes the roots to absorb more water from the soil. This pulling force is called transpirational pull.

Question 5

Question 5How does temperature, light intensity and wind affect transpiration?

Accepted Answer

Temperature — Higher temperatures increase the rate of transpiration due to faster evaporation of water.Light intensity — With Sunlight the rate of transpiration is faster as stomata are open to allow inward diffusion of carbon dioxide for photosynthesis. During night time, the stomata remain closed and hence transpiration hardly occurs.Wind — Transpiration is more when the wind is blowing faster as water vapour moves away faster from the surface of leaves.

Question 6

Question 6Draw a magnified view of the root hair and label all its parts neatly. From the parts labelled by you, name the parts matching the description given below:(a) Outermost layer of the root(b) Unicellular outgrowth(c) Part that is freely permeable(d) Part that is semi-permeable

Accepted Answer

Magnified view of the root hair with its parts labelled is shown below:(a) Outermost layer of the root — Cell wall(b) Unicellular outgrowth — Root Hair / Epidermal cell(c) Part that is freely permeable — Cell wall(d) Part that is semi-permeable — Cell membrane

Question 7

Question 1(g)Transpiration is defined as:the rise of water up to the stem of a plant.the elimination of water with dissolved water products.the loss of water as water vapour from the aerial parts of a plant.the loss of water as water vapour from the roots as well as the leaves of the plant.

Accepted Answer

the loss of water as water vapour from the aerial parts of a plant.Reason — Transpiration is the loss of water in the form of water vapour from the aerial parts of a plant.

Question 8

Question 1(j)Root hairs are the epidermal outgrowths of the outermost layer of roots. They are well-suited for absorption of water from soil due to which of the following features ?P. Large surface area.Q. Lower concentration of cell sap.R. Semi permeable nature of the cell membrane.Only POnly QOnly P and QOnly P and R

Accepted Answer

Only P and RReason — The root hairs are well-suited for absorption of water from soil due to their larger surface area, higher concentration of cell sap, and semi permeable nature of the cell membrane.

Question 9

Question 1(k)Xylem tissue forms a tubular passage to transport water and mineral salts from the roots to the aerial parts of a plant. It consists of different types of cells.P. Sieve tubes and companion cellsQ. Wood parenchyma and wood fibresR. Tracheids and vesselsWhich of the following are xylem components?Only POnly P and ROnly Q and RAll P, Q and R

Accepted Answer

Only Q and RReason — The Xylem tissue consists of tracheids, vessels, wood parenchyma and wood fibres. Sieve tubes and companion cells are part of phloem, the tissue responsible for transporting prepared food, not water.

Question 10

Question 2(a)Write two important functions of Xylem.

Accepted Answer

Two functions of Xylem are:Transportation of water and minerals from roots to the aerial parts.Tracheids, vessels and xylem sclerenchyma provide physical support.

Question 11

Question 2(b)Write two important functions of Phloem.

Accepted Answer

Two functions of Phloem are:Transportation of food prepared by leaves to all parts of plant.Storage of food by phloem parenchyma.

Question 12

Question 4What do xylem vessels carry?

Accepted Answer

Xylem vessels carry water and mineral salts from the roots to the aerial parts of the plant.

Question 13

Question 5Under what conditions do plant transpire (a) more quickly and (b) most slowly?

Accepted Answer

(a) Plants transpire more quickly on hot, dry, windy days as Sunlight, higher temperatures, fast winds and low humidity increase the rate of transpiration.(b) Transpiration is most slow on cool, humid, still days as lower temperatures, still winds and high humidity decrease the rate of transpiration.

Question 14

Question 6Mention two ways in which transpiration helps the plants.

Accepted Answer

Two ways in which transpiration helps the plants:Cooling effect — Transpiration from the aerial parts of the plant, cools down the plant surface.Ascent of sap and distribution of minerals — Transpiration results in the development of low water potential in the leaf tissues. Thus, water moves from the xylem tissue to the leaf cells and helps in the ascent of sap. Mineral ions also move up along with water due to the transpiration pull.

Question 15

Question 7Write three important uses of water in the plants.

Accepted Answer

Three important uses of water in the plants are:Transportation of food/sugars or minerals occur in solution form.Water is required for photosynthesis.Transpiration of water helps to keep the plant cool.

Question 16

Question 8What are the three special features of root hairs which make them suitable for the absorption of water from the soil?

Accepted Answer

The three special features of root hairs which make then suitable for the absorption of water from the soil are:The numerous root hairs provide a large surface area. More the surface area, greater is the absorption.Root hairs contain cell sap which is of a higher concentration than the surrounding soil water.The cell wall is freely permeable, i.e., permits movements of all types of substances. But the cell membrane is semi-permeable. It allows only some substances to pass through it.

Question 17

Question 9(a)Give reasons — Transpiration is reduced if the air is humid.

Accepted Answer

On a humid day, air already contains moisture. This reduces the concentration gradient between the leaf's internal air spaces and the external environment. Therefore, transpiration is reduced if the air is humid.

Question 18

Question 9(b)Give reasons — Transpiration, despite resulting in loss of water from the plant, remains a crucial process for its overall well-being.

Accepted Answer

Despite resulting in loss of water, transpiration remains a crucial process for the overall well-being of the plant because:Transpiration provides cooling effect helping the plant to cool itself when it is hot outside.Transpiration helps in maintaining the concentration of the sap inside the plant body.Transpiration creates the suction force called transpirational pull that is necessary for ascent of sap.

Question 19

Question 10(a)Distinguish between the following pairs on the basis of words indicated in the brackets:Diffusion and active transport (concentration gradient)

Accepted Answer

PropertyDiffusionActive transportConcentration gradientMovement of molecules occur from their higher concentration to lower concentration.Movement of molecules occur from their lower concentration to a higher concentration at the expense of plant's energy.

Question 20

Question 10(b)Distinguish between the following pairs on the basis of words indicated in the brackets:Nitrogen and Potassium (role in plants)

Accepted Answer

PropertyNitrogenPotassiumRole in plantsMajor constituent of all proteins.More abundant in growing tissues, involved in the opening and closing of stomata.

Transport in Plants

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