Rate of transpiration experiment using potometer

The below mentioned article includes a collection of thirteen experiments on transpiration. Take a well-watered, healthy potted plant and cover the pot with the help of rubber sheet. Only aerial parts of the plant should remain uncovered. Set another experiment exactly in the same way except that the pot should be without any plant. Water drops appear inside the wall of the bell jar containing a potted plant while there is no drop in the another bell jar which is without any plant.

Because water drops appear only in the bell jar in which pot is having a plant with its only aerial parts exposed, so it can be concluded that these drops appeared due to the process of transpiration from the aerial parts of the plant.

The same can also be concluded by the observations of the control apparatus, in which no water drop appears due to the absence of plant in the pot. Some pieces of the filter paper are dipped in cobalt chloride solution and then dried off. They are blue coloured. Now, two such pieces of filter paper are taken and pressed on both the surfaces of the leaf of a potted plant with the help of a clip.

Bubbling Plants Experiment to Quantify Photosynthesis

This apparatus is kept for some time as such. After a few hours, when it is observed, the cobalt chloride paper of the lower surface of the leaf becomes pink coloured. The dried blue coloured cobalt chloride paper turns red as it becomes moist. The stomata are confined mostly on the lower surface of the leaf, and therefore, the cobalt chloride paper of that surface becomes moist and turns red.

The paper of the upper side of the leaf may also become pink to some extent, as few stomata are found on this side. To demonstrate the transpiration from the leaf surface, four banyan leaves are taken. Both the surfaces of the A leaf, lower surface with stomata of B leaf, upper surface without stomata of C leaf are vaselined.

The Vaseline is not applied on the D leaf. Now, as shown in the figure the leaves are hanged so that they may transpire freely. When the observations are taken after a day or two, they are as follows — the A leaf, which is vaselined on its both the surfaces, looks fresh and green, as no surface transpires. The B leaf is vaselined on its lower surface with stomataand transpiration takes place only from the upper surface which is negligible. This leaf also remains turgid and green like the A leaf.

If few stomata are present on the upper surface of the leaf, then it shrivels to some extent. The C leaf is vaselined on its upper surface, which contains less number of stomata or no stomata. The transpiration takes place from the lower stomatal surface, and the leaf shrivels to a large extent. The D leaf is not vaselined and both the surfaces transpire freely releasing much water. The leaf wilts completely in this case.

This experiment proves that the rate of stomatal transpiration is fairly higher than the cuticular transpiration. With the help of this apparatus, the comparative study of the transpiration from both the surfaces of the leaf is being done. This apparatus consists of two small bell-jars, which are kept together in close contact as shown in the figure.

A leaf of a potted plant is kept in between these two bell-jars. In each of these bell-jars a small test tube is kept.

rate of transpiration experiment using potometer

Each small test tube contains equal amount of anhydrous calcium chloride CaCl 2. The apparatus is made air-tight, applying vaseline where they press the leaf in between. There are two manometers at the two ends of the bell-jars. They are partially filled with oil.

These manometers, however, maintain the vapour of the bell-jars.Using a potometer, the amount of water absorbed by a leafy shoot can be measured. It is also known that most of the water absorbed by a plant is lost through transpiration.

Hence, the amount of water absorbed can be considered approximately to be the amount of water transpired though the result is not very accurate since some amount of water absorbed is retained for use by the leafy shoot for its metabolic activities.

The apparatus was filled with water. A leafy twig cut under water to prevent air clogging was inserted through the cork of the vertical tube of the potometer. Some water was poured into the reservoir funnel, and the stop cock was closed. The apparatus is made airtight by proper sealing.

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An air bubble was inserted in the horizontal limits of the apparatus. Then, the twig is exposed to sunlight for hrs and allowed to transpire. As water was lost by transpiration, the inserted bubble moved in the horizontal graduated tube toward the transpiring twig. Three readings of the time taken by a bubble to cover a distance of 1 cm were taken, and mean value was also calculated. There are many reasons why we need to treat our water, and there are also many different ways we can treat our water.

Water is very important to our survival. Regulations are set so that our water is healthy for us to drink. Without those regulations there could be things in our water to cause us to be sick. Some problems in parts of the country are heavy metals. One of the best ways to see if you So, in the experiment, the leafy twig transpired at the rate of ml min-1 on the assumption that rate of absorption and that of transpiration are the same. Micro-filters can also be Bacteria and viruses can Water should be consumed before, during, and The amount of water, and when the water is consumed are imperative to staying constantly First, the composition water: water is odorless, tasteless and a transparent liquid.

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Measuring Rate of Transpiration

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Similar Papers Water Purification Water The Clean Water Act Of Water Pollution Not Enough Drinking Water You must cite our web site as your source.Transpiration cannot be measured directly so instead it is measured indirectly, either by measuring the decrease in mass of a plant due to water loss, or by measuring the volume of water absorbed.

The decrease in mass of a plant due to transpiration can be investigated using the following method:. The results are shown here. What conclusions can you make from the results above? Give two pieces of evidence to support your conclusion.

You can conclude that most transpiration happens from the lower surface of the leaf:. Transpiration cannot be measured directly as some of the water will be used in photosynthesis. The rate of transpiration can be calculated by measuring the distance travelled by an air bubble in a capillary tube over a given time. The faster the bubble moves, the greater the rate of water uptake — and so the greater the assumed rate of transpiration. The potometer is set up underwater to avoid unwanted air bubbles in the xylem of the plant which may disrupt the transpiration stream.

All joints are sealed with petroleum jelly to make it as airtight as possible. The faster the bubble moves, the greater the rate of water uptake — and so the greater the rate of transpiration.

The rate of transpiration is affected by several factors, including:. This table shows the effects of different factors on the rate of transportation. Investigating transpiration Transpiration cannot be measured directly so instead it is measured indirectly, either by measuring the decrease in mass of a plant due to water loss, or by measuring the volume of water absorbed. Decrease in mass The decrease in mass of a plant due to transpiration can be investigated using the following method: Select four leaves of similar size.

Cover the surfaces of the leaves with petroleum jelly as shown in the diagram. Record the initial mass of the leaves. After 24 hours record the mass of the leaves and calculate the percentage decrease in mass. Reveal answer up. Upper only. Lower only. Evaporation and diffusion are faster at higher temperatures. Humidity decreases the concentration gradient between the inside and outside of the leaf — this reduces transpiration.

Wind speed. Moving air removes water vapour, increasing the rate of diffusion of water vapour from the leaf. Light intensity. The stomata open wider to allow more carbon dioxide into the leaf for photosynthesis.Your browser seems to have Javascript disabled.

We're sorry, but in order to log in and use all the features of this website, you will need to enable JavaScript in your browser. To measure the rate of transpiration we use a piece of equipment called a potometer. A potometer measures how factors such as light, temperature, humidity, light intensity and wind will affect the rate of transpiration.

The potometer measures the amount of water lost from a leafy shoot by monitoring the rate at which an air bubble moves along the narrow tube as the leafy shoot sucks up water to replace the water lost by the transpiration of the plant. A potometer provides an indirect measurement of the transpiration rate — it measures how fast water is absorbed, which is related to how fast water vapour is being lost.

It cannot measure how fast water vapour is being given off directly. As the leafy twig transpires, the air bubble moves to towards the plant. The quicker the air bubble moves, the faster the leafy twig is transpiring. To determine the effect of environmental conditions on transpiration rate using a simple potometer.

A potometer measures the rate of transpiration by measuring the movement of water into a plant.

Practical Biology

The following experiment uses a simple hand made potometer. Learners will be divided into four groups as each group will investigate a different factor and then all the results can be shared at the end of the investigation. Each of the four groups that investigated different environmental conditions should contribute their results for the final analysis.

Write down anything you observed about the plants, the plastic bags and the rate of water loss from the plant.

rate of transpiration experiment using potometer

What can you conclude regarding the rate of transpiration at different light intensities? Was there higher or lower water loss when you left the plant overnight compared to when you monitored it throughout the day? How can you improve this experiment to determine the effects of different light intensities on transpiration?

In this experiment what are the key variables we are controlling for?

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Have we properly controlled for these? This is a lesson from the tutorial, Plant Systems and you are encouraged to log in or registerso that you can track your progress. Log In. Register or login to receive notifications when there's a reply to your comment or update on this information.

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Toggle navigation. Search Log In. Measuring Rate of Transpiration.A potometer is a piece of apparatus designed to measure water uptake in a leafy shoot. There are 2 types of potometer — the bubble potometer and the weight potometer. As water is transpired from the leaves, the shoot absorbs water from the potometer. The distance the air bubble moves in a certain period of time can be used to calculate the rate of water uptake. The apparatus is set up under water to prevent the entry of any unwanted air bubbles.

The junction between the shoot and potometer is sealed usually with petroleum jelly to prevent any air leaks. The apparatus is reset using the reservoir or syringe so that water uptake in the same leafy shoot can be measured — making the investigation more reliable. It can also be reset in order to investigate the effect of a different environmental factor e.

When investigating the effect of an environmental factor it is important that all others factors are kept constant to ensure the experiment is valid.

The apparatus and plant is weighed and then left for a period of time. When reweighed the amount of water lost by the plant can be calculated. A top pan balance that measures to two decimal points provides great accuracy.

Principles of addition

A potometer can measure the amount of water taken up by a leafy shoot but cannot provide an accurate value for the amount of water transpired, because some water will be used in photosynthesis and to provide turgor. Potometer A potometer is a piece of apparatus designed to measure water uptake in a leafy shoot. Bubble potometer As water is transpired from the leaves, the shoot absorbs water from the potometer.

Weight potometer The apparatus and plant is weighed and then left for a period of time. Uses of water A potometer can measure the amount of water taken up by a leafy shoot but cannot provide an accurate value for the amount of water transpired, because some water will be used in photosynthesis and to provide turgor.To demonstrate that different environmental factors has different effects on the rate of transpiration.

Transpiration is the loss of water in the form of water vapors from the surface of the plant.

Determination of Rate of Transpiration by Ganong’s Potometer

Set up the apparatus as given in the diagram. Made the apparatus air tight with the help of wax. Select a healthy shoot and cut it under water by bending it in the trough. With water hanging on the cut end of the shoot transfer it to the Potometer. Fix the potometer on stand and check that no water drops falls from the open end.

This will ensure that apparatus is air tight. If water drop fall, check the corks and stop the leakage with wax. Repeat the process until complete water filled and air tight apparatus stage is attained. Leave the apparatus as such on the stand. This will not only show that apparatus is air tight but also allow an air bubble to enter in the open end of the potometer. When the bubble attains a length of lcm dip the open end in water contained in a beaker.

Note the time for the movement of bubble through one major division on the graduated tube of potometer. Depending upon the speed of the bubble select a division equal to 0.

Top 13 Experiments on Transpiration | Plants

Trial No Time taken by the bubble to move through gradation equal to 0. Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email.

Objective To demonstrate that different environmental factors has different effects on the rate of transpiration. It can be, Stomatal Transpiration: When the water vapors are lost through stomata.

Lenticular Transpiration: When the water vapors are lost through lenticels Openings in the corky tissue covering stem and twigs small. Cuticular Transpiration: When the water vapors are lost from the surface of the leaves, other than stomata and herbaceous stems. Potometer Apparatus.

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Factors Affecting Transpiration Experiment. Leave a Reply Cancel reply Your email address will not be published. Time taken by the bubble to move through gradation equal to 0.

rate of transpiration experiment using potometer

Relative humidity; leaves sprayed with water plant covered with moist cloth.In this activity the rate of water uptakedue to transpirationby a shoot from a woody plant, is measured by timing how long a bubble takes to move a set distance, in the capillary tube of an h-shaped potometer. Decisions will depend on the availability of suitable potometers.

This could be a demonstration or an experiment for groups of up to three individuals — observer, timekeeper and scribe. For each working group — equipment to investigate factors affecting rate of transpiration:. Take care when assembling and handling the glass potometer: it is easy to break the long glass tubes and cut or stab yourself with the broken ends. Be prepared with first aid for cuts from broken glass, and brief students how to deal with breakages.

Leaves with thicker waxy cuticles very glossy leaves do not work as well. This requires a large sink. If air gets into the xylem vessels of the plant, it can form air locks which will prevent the plant taking up water and so prevent steady transpiration. Alternatively dry the leaves gently with a paper towel.

The potometer will not work properly until any excess water on the leaves has evaporated or been removed. This will give the leaves time to dry, and give technicians a chance to check they are working before the students begin to take measurements. Make sure students know what to do if anything gets broken. Have first aid kit ready for cuts. Make as many marks as possible at least 6. To do this, loosen the screw on the boss and slide the boss up the clamp stand so that the capillary tube comes out of the water in the beaker.

Retighten the screw on the boss. Note that many plants close their stomata when the light intensity is insufficient for photosynthesis.

rate of transpiration experiment using potometer

Stems harvested in the autumn or winter may not transpire very much. You can use a high-intensity light to promote photosynthesis and get transpiration going again. Fluorescent strip lights or halogen lamps are better than ordinary bench lamps.

You could give students guidance on investigating a particular factor affecting the rate of transpiration, or they can choose from a list and develop their own ideas. Use five or six values for each variable tested. Method 1 : Measure the water uptake by the shoot.

Remove a number of leaves from the shoot and measure the rate of water uptake again. Keep removing leaves until all the leaves are off the plant shoot.

Label the leaves as you remove them, then estimate their area by placing on squared paper and tracing their outlines. Add together the areas of the leaves to find the total area and multiply by two to get the total surface area, as each leaf has an upper and a lower side.

Add the leaf areas together in the reverse order that they were removed to get figures for the change in the surface area of leaves attached to the plant shoot. Method 2 : Measure the water uptake by the shoot.