Throughout the day, as the sun shines on the bag, condensation will form and the water droplets will collect in the reservoir. Related questions. The transpiration rate of commodities often declines over time after harvest. In general, the stomata close at temperatures about 0°C and progressively increase in aperture up to about 30°C (Devlin 1975). (a) Potometer is an instrument used for demonstration of transpiration occurring from the lower surface of a leaf. In the evening or during the night, the stomata are constricted and the temperature is not high, therefore, there is no loss of water through transpiration and the turgidity of the leaves is re-acquired and they stand out erect. Question 9. Humidity Most of the transpiration in tall trees occurs through (a) Stomata (b) Lenticels (c) Cuticle (d) Bark. The rate of transpiration is fastest when air temperature is between 20°C to 30°C (Moore et al. (g) The structure in a leaf that allows guttation. Narrow leaves:-The leaves may become narrower to reduce surface area. (ii) Which leaf would show least limping? Solution:-. However, during a cloudy day, the. They remain open all the time. It evaporates most of the water and allows more molecular space for more to come. Plant takes water, dissolved essential plant nutrients and minerals from the soil with the help of the roots through the process of osmosis. When there is a high rate of wind activity, transpiration is relatively higher since the moist or humid air around the plant is quickly replaced by less humid air allowing the plant to release even more water into the atmosphere. Transpiration helps in creating suction force and in eliminating excess water. List any three major factors that accelerate the rate of transpiration. 7. Transpiration will be fastest when the day is (a) cool, humid and windy (b) hot, humid and still (c) hot, humid and windy (d) hot, dry and windy Solution:- (d) hot, dry and windy 8. (c) What is the role played by the air-bubble in this experiment? 5. Why? The second bell jar (B) would also show a similar condensation and at the same time, the initially blue cobalt chloride paper in it would turn pink. Leaves have pores all over them that you can see if you look closely on the bottom side with a magnifying glass. Enclose the pot completely within a polythene bag and tie the mouth of the bag firmly around the base of the stem. Solution:-. (B) coated on the lower surface. 3. 1. A humid environment hampers transpiration while the roots continue to absorb water from the soil. Transpiration, in botany, a plant’s loss of water, mainly though the stomates of leaves. Transpiration will be fastest when the day is (a) cool, humid and windy (b) hot, humid and still (c) hot, humid and windy (d) hot, dry and windy. The root pressure generated by a plant assists in bleeding. Hydathodes is the structure in a leaf that allows guttation. The topics covered in this chapter are a demonstration of transpiration, measurement of transpiration, kinds of transpiration, factors that affect transpiration, adaptation in plants to reduce excessive transpiration, the significance of transpiration, direct loss of water by plants. Will you expect any difference in weight? 8. Differentiate between guttation and bleeding in plants. (d) Suggest a suitable control for this experiment. Give a reason to support your answer. If the rate of transpiration increases, the rate of absorption of water by the root increases too. Water escapes in the form of sap from the injured part of the plant. 9. When it is cloudy during the day, the stomata are partially closed and transpiration is reduced. (e) Cork and bark of trees help in preventing loss of water. Directly measuring the amount of water leaving the leaves through transpiration b. Set-up C. Take a third bell jar without the plant, but still containing a similar piece of cobalt chloride paper (C). Before keeping the leaf in between the cups, anhydrous calcium chloride (CaCl2) contained in two small vials were weighed and placed in both the cups. The setup was kept in sunlight for two hours. Transpiration will be fastest when the day is (a) cool, humid and windy (b) hot, humid and still (c) hot, humid and windy (d) hot, dry and windy . 1. Solution:-. In such cases, the rate of transpiration during midday exceeds the rate of absorption of water by the roots. The water travels from the roots where it is absorbed, up through the stem, and exits as vapor from tiny holes on the bottom of the plant's leaves. Justify. The first bell jar (A) would show water vapour condensing on its inner walls. Answer 7 (d) hot, dry and windy. As transpiration proceeds, i.e., as the water is lost from the twig, a suction force is set up which pulls the water from the beaker and the bubble in the capillary tube moves along. (a) Intensity of light Potometer is an instrument used to find the rate of transpiration. Bark is thick with an outermost layer made of dead cells and the cork is hydrophobic in nature. At these temperatures the stomatal apertures or opening are generally widest. The purpose of putting oil in the test tube is to prevent the loss of water by evaporation. Are these dew drops? It may retain some of the taste of the foliage, but is clean, potable water that is safe for drinking. It is the removal of excess of water from the plants because of excess water buildup in the plant. Download pdf of Class 10 in their respective links. These properties make them water-proof and hence they prevent transpiration. 1. Before the process of transpiration, there are a series of processes for a plant to undergo. Factors that affect the rate of transpiration also affect water uptake by the plant. 6. Solution:-. (iii) If the apparatus is kept in front of a fan, the rate of transpiration will be more. Transpiration is the process of water evaporating through stoma, or pores, in the foliage of plants. Temperature Plants transpire more rapidly at higher temperatures because water evaporates more rapidly as the temperature rises. The entire apparatus is filled with water so that no air spaces are present. The readings on the capillary tube would give the volume of water lost in a given time. With decrease in atmospheric pressure, the rate of transpiration will, 3. The leaf D become most limp. (b) What is the purpose of putting oil in the test tube? Your email address will not be published. (d) Would it make a difference if the experimental set-up is kept in bright sunshine? 2. Droplets of water may sometimes be seen along the margins of the leaves of a banana plant, growing in wet soil in the mornings. (c) Water transpired is the water absorbed. Transpiration in plants is a crucial process. THE WIND CARRIES AWAY THE WATER MOLECULES FROM THE SURFACE ND COOLS THE SURFACE FASTER. balsam, the leaves of the plants wilt during the midday in spite of the fact that there is plenty of water in the soil. 4. A small lightweight potted plant can be weighed before and after the end of a certain period of time. As Cork and Bark of trees are tissues of old woody stems. Second fastest in the sun, but no wind. The loss of water as water vapour from the aerial parts of a plant is known as, 7. The leaves of certain plants exhibit droplets of water along their margins in the morning. The readings on the capillary tube moves along. Glass slides are placed over the dry cobalt chloride papers so as to retain the strips in their position. The main aim is to help students understand and crack these questions. (a) Name the phenomenon being demonstrated. Special pore-bearing structures called hydathodes are present on the margins of the leaf to allow this exudation. Fewer stomata:- The number of stomata may be reduced. Hence, the water in the test will get reduced. Therefore, more transpiration occurs during the day. (b) The process by which the intact plant loses water in the form of droplets. Transpiration would occur faster. Lab 9 Transpiration Introduction Transpiration is the process through which water is lost from a plant by evaporation. Cork and bark of trees help in preventing loss of water. 4. More transpiration occurs from the undersurface of a dicot leaf. (D) left uncoated. The transpiration rate will increase. sun is mostly behind the clouds making evaporation difficult. Selina Solutions Concise Biology Class 10 Chapter 5 Transpiration, is a very useful process for plants for two reasons, one creating suction force in the stem to enable the roots to absorb water and minerals nutrients, and two for cooling. Required fields are marked *. Thus, the weight of the entire set will decrease. As a result, the movement of the air bubble would be larger since there would be more loss of water due to transpiration as the velocity of wind/air increases. Transpiration is the loss of water as water vapour from the aerial parts of the plant. (d) A plant in which the stomata are sunken. Plants regulate transpiration by opening and closing stomata, but transpiration is also influenced by environmental conditions around the leaf. In some plants, e.g. Fastest transpiration rate in the sun with wind. Transpiration will be fastest . The stomata may be sunken or covered by hairs. As the stomata open during the daytime, the diffusion of gases in and out starts fulfilling the need for photosynthesis as well as allowing transpiration. Give reason in support of your answer. These Selina Solutions help students to clear doubts quickly and assist in learning the topic effectively. If the wind blows faster, the water vapour released during transpiration is removed faster and the area outside the leaf does not get saturated with water vapour. (d) The spring balance progressively measures the change in weight of the set-up. We all know that plants need water. More the, (e) Cork and Bark of trees are tissues of old woody stems. (iii) Wind velocity has an effect on transpiration. Hence, the stoma from the diagram can be of a monocot leaf or of a dicot leaf. 2. Stomates are necessary to admit carbon dioxide for photosynthesis and to release oxygen, hence transpiration is generally considered to be merely an unavoidable phenomenon that accompanies the real functions of … Leaves of some plants wilt during midday and recover in the evening. The rate of transpiration is more when, (a) atmosphere is dry (b) temperature is high, (c) humidity is high (d) atmosphere is dry and temperature is high, 4. (a) Open stomata, dry atmosphere and moist soil, (b) Open stomata, high humid atmosphere and well irrigated soil, (c) Open stomata, high humid atmosphere and dry soil, (d) Closed stomata, dry atmosphere and dry soil, 2. Most of the transpiration in tall trees occurs through, (b) evaporation of water from the aerial surfaces of a plant, (c) loss of water, as water vapour, by a plant, (d) release of water by a plant into the atmosphere. To release the water into the capillary tube by opening the stop cock. There is a general belief that forests tend to bring more frequent rains. Hydathodes are special pore-bearing structure present on the margins of the leaf to allow this exudation. The loss in weight by the plant during that time is due to loss of water by transpiration. 5. Why? Set-up A. As a result, the movement of the air bubble would be larger since there would be more loss of water due to transpiration. 1. This evaporation reduces the temperature of the body surface and brings about cooling in the body of the organism. Method: 1. Given below is an example of a certain structure and its special functional activity: In a similar way, write the functional activity against each of the following: The purpose of using the monometer in order to measure the pressure exerted by the fluid. The water vapour condensing on its inner walls. Give a reason to support your answer. Set-up B. Slowest transpiration rate in the plant that had the bag around it. The third bell jar in this experiment is a control which proves that there was no moisture in the air due to transpiration as there was no plant in it. Cuticular transpiration: Cuticle is an impermeable covering present on the leaves and stem. If so, give reason. Transpiration will be fastest when the day is (a) cool, humid and windy (b) hot, humid and still (c) hot, humid and windy (d) hot, dry and windy Solution:-(d) hot, dry and windy 8. 2. Hence a huge amount of water is escaped into the atmosphere by forests. Name the following: Solution:-(d) hot, dry and windy. Stomata are minute openings in the epidermal layer of leaves. Droplets of water were then seen inside the bell jar. Solution A.7 (d) hot, dry and windy. Lenticels are special opening that develops on the barks of the older stem in place of stomata. Leaves of some plants wilt during midday and recover in the evening. This because as the plant transpires, it creates the suction force in plant which allows roots to absorb more water from the test tube. 1. 1. The remaining 97–99.5% is lost by transpiration and guttation. The ends of the cups were closed with corks through which two mercury manometers were connected. In some plants, e.g. (e) Most transpiration occurs during mid-day. In such cases, the rate of transpiration during midday exceeds the rate of absorption of water by the roots. (c) Yes, the transpiration rate will increase. Many plants and especially those which grow in a dry climate have evolved a variety of permanent adaption to cortical transpiration. Answer 8 (b) Lenticels. (b) Excessive transpiration results in the wilting of the leaves. Stomata remain open during daytime for gaseous exchanges for photosynthesis and respiration. (i) Most transpiration occurs at midnight. (b) Closing of ………… and shedding of leaves reduce …………. However, it only uses a small amount. The paper may be pinned to a wooden stick or to a strip of cork sheet. (C) coated on both surfaces The factors that accelerate the rate of transpiration are. Solution:-, Leaf spines and protection and reduced transpiration, (c) Lenticels and…………………………………. (b) After few hours CaCl2 vials were taken out and weighed again. After few hours, CaCl2 vials were taken out and weighed again. All the four leaves A, B, C and D were left in a room for about 24 hours. 1. Fill in the blanks with suitable terms given below: (Fast, Leaves, Stomata, Conducting, Ascent, Humid). As transpiration proceeds, i.e., as the water is lost from the twig, a suction force is set up which pulls the water from the beaker and the bubble in the capillary tube moves along. At night they are closed. (c)  What is the purpose of the spring balance in the set-up? (i) Which leaf would become most limp? 6. (f) List three adaptations in plants to reduce the above mentioned process. Most of the transpiration in tall trees occurs through (a) Stomata (b) Lenticels (c) Cuticle (d) Bark. Transpiration is the process is beneficial to plants. Because both surfaces of the leaf is coated with Vaseline. It causes around 20% of transpiration in plants. ICSE Rankers is a free educational platform for icse k-12 students. Some plants show wilting of their leaves at noon even when the soil is well watered. How would you demonstrate transpiration in it? Which of the following statements are true and which ones are false? 2. Study the diagram and answer the following questions. Ganong’s potometer is used to measure the rate of water intake by a plant. Following are the steps which will help you understand the complete process. An apparatus as shown below was set up to investigate a physiological process in plants. Wind Velocity: The velocity of wind greatly affects the rate of transpiration. As a result, there would be no movement of the air bubble and it would remain stable. Transpiration will be fastest when the day is (a) cool, humid and windy. Suppose you have a small rose plant growing in a pot. Transpiration is the process of water moving through plants and its evaporation from leaves, stems and flowers. There are more stomatal openings on the lower surface of a dorsiventral leaf and therefore, more transpiration occurs from the lower surface. Also on a cloudy day, the air is already dense with the water molecules and can not fill anymore. High humidity in the air reduces the rate of outward diffusion of the internal water vapour across stomata, thereby reducing the rate of transpiration. The purpose of the spring balance in the set-up is to measure the change in weight of the set-up. Adaptations in plants to reduce excessive transpiration, Direct loss of water by plants – Guttation and Bleeding. ADVERTISEMENTS: The below mentioned article includes a collection of thirteen experiments on transpiration. Transpiration is reduced if the air outside is humid. (b) Is the experimental leaf a monocot or a dicot? Arrange another similar plant and cover it with a bell jar exactly in the same manner as the first one, except that here you also keep a piece of dry cobalt chloride paper by the side of the plant inside the bell jar (B). C.5.Differentiate between guttation and bleeding in plants. 2. (c) Why was the pot covered with a plastic sheet? Transpiration occurs as long as the stomata are open, but it stops when they are closed. (a) Transpiration is the loss of water as water ………… from the ………… parts of the plant. Most of the transpiration in tall trees occurs through (a) Stomata (b) Lenticels (c) Cuticle (d) Bark Solution:-(b) Lenticels Transpiration is the process intended for study. Take a small well-watered potted plant, preferably one with broad leaves. Transpiration will be fastest when the day is, (a) cool, humid and windy (b) hot, humid and still, (c) hot, humid and windy (d) hot, dry and windy, 8. Most of the transpiration in tall trees occurs through (a) Stomata (b) Lenticels (c) Cuticle (d) Bark. Soil Water Content: Many plants and especially those which grow in a dry climate have evolved a variety of permanent adaptions to curtail transpiration. (b) Potometer is an instrument used for measuring the rate of transpiration in green plants. On a bright sunny day, the rate of transpiration is much higher than any other days. (c) Transpiration helps in creating …………. Therefore, more transpiration occurs during the day. Transpiration in the leaf Water is taken into a plant through roots and root hairs by osmosis, and it exits the plant through ting openings on the underside of leaves known as stomata. The air bubble can be brought back to its original position by releasing some more water from the reservoir the capillary tube by opening the stop cock. Bark is thick with outermost layer, (f) In both perspiration and transpiration, water is lost by evaporation from the body of the, (g) On a bright sunny day, the rate of transpiration is much higher than any other days. Question A.8. 3. Mention one major difference between lenticular transpiration and stomatal transpiration. A twig of some suitable plant cut with a sharp knife is fixed in an apparatus as shown in fig. Question 8. 1. (d) More transpiration occurs from the lower surface of a dorsiventral leaf. Why is it so? (c) The structure of stoma remains same in monocots as well as in dicots. The three adaptations in plants to reduce the transpiration are, 1. Xylem and conduction of water and mineral salts. The cells, therefore, lose turgidity. 2. So no water is lost from the leaf through transpiration since the stomatal openings get blocked by vaseline. Light also speeds up transpiration by warming the leaf. So, excessive transpiration results in wilting of the leaves. Also Read: Transportation in Plants Potometer is a device that measures the rate of water intake by a plant (L. poton: drink, meter: measure), and this water intake is almost equal to the water lost through transpiration. Stomata are minute openings in the epidermal layer of leaves. The observable changes will occur in less time. High humidity in the air reduces the rate of outward diffusion of the internal water vapour across stomata, thereby reducing the rate of transpiration. 1. (b) Rewrite the false statements in (a) above, in the correct form by changing either the first or the last word only. Water is transported faster during daytime because rate of transpiration is higher during daytime. Solution:-(b) Lenticels. The soil surface and the pot should be fully covered to prevent evaporation from the surfaces other than the plant. (ii) The least limping would be shown by leaf C since its upper and lower surfaces have been coated with vaseline.