UNIT Living World of Plants - 6 Plant Physiology

Learning Objectives

At the end of this unit the students will be able to understand, „„ that Plants too have certain autonomic movements „„ how do plants produce their food through the process of photosynthesis? „„ that Plants are the primary producers that feed the rest of the living organisms

Introduction (sunflower) follows the path of the sun from dawn to dusk, (from east to west) and Animals move in search of food, shelter and during night it moves from west to east. for reproduction, even microorganisms The dance of Desmodium gyrans (Indian show movement. telegraph plant) leaf is mesmerizing.

Do plants show such movement We see a branch of a tree shaking in heavy thunder storm; and leaves dancing in gentle wind. These movements are caused by an external agency.

Do they Move on their 6.1 own Accord

In short, do plants have spontaneous movements without external agency? Do they breathe? In this chapter we will study some of the biological functions of plants.

6.2 Do Plants Move

The leaves of Mimosa pudica (touch-me- not plant) closes on touching, and in like manner, the stalk of Helianthus annuus Mimosa pudica

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IX_Science Unit-6.indd 133 27-03-2018 12:31:36 Activity 1

Roots grow down and shoots grow up You can do this experiment with some of your friends.

Step -1 It is easy and fun. Take four or ve earthen cups or small pots and ll them with soil from a eld. Add a little cow Helianthus annuus dung to the soil. Make sure the cups have a hole at the bottom. Label them as A, B, and C. Put some seeds of green gram in all the cups, water them daily. As soon as the seeds sprout, select a shoot of same height from each of the cups. Remove all the other shoots from the cups.

Step-2 Desmodium gyrans You will need a rectangular box with These movements are triggered by an a small window in one of its sides. A external stimuli. Unlike animals, plants shoe box would be ideal. Cut a 1 × 1 cm may not move on their own from one window in one side. When the shoots location to another, but can move their are 10 cm long, cover the plants in all the body parts for getting sunlight, water and cups except cup A with the rectangular nutrients and are sensitive to external box. When covering the cups, place the factors like light, gravity, temperature etc. box such that opening in each of them face different directions. Keep all the More to Know cups including ‘A’ in open sun light.

In Desmodium gyrans (Indian telegraph Step-3 plant), the compound leaf shows three leaets, one terminal large leaet and two Wait for three to four days. Remove very small lateral opposite leaets. e the box and look at the plants again. two lateral leaets move up, move back Are the plants tilted? To which side are and then move down and nally back to the plants tilted? With opening facing the original position showing rhythmic different direction, did all the plants tilt movement. Desmodium gyrans is also the same direction? called the dancing plant. is plant was used by Indian scientist Jagadish Chandra Compile the results and discuss Bose for his experiment. with your friends.

Mimosa pudica is called Perhaps you have done such as Thotta surungi and experiments in earlier classes and have Desmodium gyrans is called as ozhu kanni in Tamil. found that plants do grow towards the sunlight.

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IX_Science Unit-6.indd 134 27-03-2018 12:31:37 Do Plants Actually developed Darwin’s experiments. He found 6.3 Sense Light that if he removed the coleoptiles, plant growth stopped.  en he inserted a piece of agar and then placed the coleptile on top of it You would have studied in earlier classes about the plant again was able to curve towards the seed germination. In monocot plants like grass, light. Hence this chemical was predicted to there is only one rst leaf (called cotyledon). be water soluble. He reasoned that chemicals Once germinated, the embryo sends a primary that controlled the light sensitive movement root downward into the soil and pushes the (phototropism) moved through agar. primary shoot to the soil surface.  e tip of the embryonic shoot (plumule) is covered by a protective sheath called coleoptile. It is the coleoptile covered embryonic shoot that grows above the ground. In one of the experiments initially Darwin noticed that germinated seeds also grow towards light. If, in a dark room light is placed in one end, the growing seedlings bend towards the light. In the next experiment, he carefully removed the tip from growing seedlings.  e shoot did not bend towards the light. When he covered the tip (Coleoptile) with foil, preventing light from entering, the shoot did not bend. In the next step, he covered the elongating part of the shoot, but le the tip open. Now the bending could be In his next experiment he replaced the noticed. Covering the elongating part of the agar block with butter.  e above mentioned shoot did not a ect the response to light at water soluble chemical did not dissolve in all! Darwin concluded “some ‘in uence’ is butter, as expected the chemical did not pass transmitted from the tip to the more basal through butter.  is water soluble “in uence” regions of the shoot thereby regulating growth was later identi ed as the plant hormone and inducing curvature”.  is demonstrated Auxin. In response to light, auxin elongates clearly that something within the tip of the the cells on the dark side of a stem so that the coleoptile controlled growth of the plant. plant literally bends towards the light source.

C e w n Pete Bo en en en

What is this in uence? In 1913 Peter Boysen-Jensen, a Danish Botanist further Bend ng o t e te tow d g t

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IX_Science Unit-6.indd 135 27-03-2018 12:31:38 Types of Tropisms in Tropism is generally termed 6.4 Plants “positive” if growth is towards the signal and “negative”, if it is away from the signal. While the shoot in a plant moves Tropism is a growth movement, the direction towards the light, the roots move away in of which is determined by the direction of the the opposite direction.  us the shoots are stimuli. Unidirectional movement of plant said to have positive phototropism, while part to light stimulus is called Phototropism. the roots have negative phototropism. Heliotropism or motion of plant parts like Can you think of an example of a negative  owers or leaves in response to the direction hydrotropism? of the sun is a kind of phototropism.  e plant may also respond to gravity and it is termed Geotropism or Gravitropism.  e response to water is called Hydrotropism. Climbing vines have to nd a suitable support shortly a er germination. Once the shoot touches a suitable support, it grows towards the surface it is touching.  is is called  igmotropism. Po t e otot o Growth or movement of a plant in response to chemical stimuli is called neg t e geot o c Chemotropism. During fertilization, pollen tube grows down the style in response to the sugars in the style is an example of chemotropism.

Neg t e otot o o t e geot o c

Activity 2 P otot o Experiment to demonstrate phototropism Info bits i) Take pea seeds soaked in water „„ Tropism allows plant to get the best overnight. conditions for its survival. ii) Wait for the pea seeds to germinate. „„ Tropic movements are slow, iii) Once the seedling has grown put it directional movements towards in a box with an opening for light or away from the stimulus and it on one side. depends on growth. iv) After sometime, you can clearly „„ Nastic movement is an immediate see how the stem has bent and action. grown towards the light.

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IX_Science Unit-6.indd 136 27-03-2018 12:31:38 Info bits Some halophytes produce negatively geotropic roots (E.g. Rhizophora).  ese roots turn 180° upright for respiration.

Activity 3 Water or gravity When a seed germinates the primary shoot, Experiment to demonstrate (plumule) goes up while the primary Geotropism root, (radicle) goes down. What stimulus i) Two Clinostats are taken and a is making the primary root to go down? potted plant on each is fixed on a Is it gravity or water that is principally horizontal position. responsible for the direction of the growth ii) One Clinostat is rotated and the of a primary root? We can do an interesting other is kept stationary. experiment to find out for ourselves. Observations made after sometime will What do you need? Glass trough, show that the shoot of the plant fixed on sand, flower pot, plugged at the bottom, the stationary clinostat bends upwards pea or bean seeds and water. showing negative geotropism and the root bends downwards showing positive ow to do geotropism. 1. A glass trough is taken and is filled But there is no bending in the with sand. A flower pot containing root and shoot of the plant fixed on water, plugged at the bottom is kept the rotating clinostat. This is due to the at the centre of the glass trough. fact that gravitational stimulus is not 2. Soaked pea or bean seeds are placed unilateral as it affects the sides of the around the pot in the sand, what do rotating organs equally. we observe after 6 or 7 days? What do you observe? It will be observed that radicle has grown towards the pot and moisture instead of growing vertically downward. What do you conclude? It proves that primary root is positively hydrotropic and that hydrotropism is stronger than geotropism in this case.

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IX_Science Unit-6.indd 137 27-03-2018 12:31:39 More to Movement 6.5 than Growth

The flower of Taraxacum officinale (common Dandelion) blooms in the morning and evening it closes (Photonasty). Ipomoea alba (Moon  ower) does exactly the opposite.  ey open in the night and hence the name moon  ower and closes in the day time. Just a casual touch is enough Night to make the Mimosa pudica (Touch-me- Photonasty in Moon fl ower not) leaves fold up and droop (Seismonasty or thigmonasty). The root and shoot move towards the direction of the stimuli, whereas the movement of the opening and closing of the flowers are not directed towards stimuli. Such movements in plants are called as Nastic movements. Unlike tropic movement, nastic movements are independent of the stimuli direction and may or may not be growth movement.

Day

Some plants feed on insects and small animals, even a frog. (Example: Nepenthes, Drosera and Venus  ytrap).  e Venus Flytrap (Dionaea muscipula) presents a spectacular example of thigmonasty. It exhibits one of the fastest known nastic movements.

Night

P oton t n nde on

Day

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IX_Science Unit-6.indd 138 27-03-2018 12:31:40 Types of Nastic movements 3. Thermonasty – temperature Example: Tulipa sp 1. Thigmonasty or Seismonasty – touch - Example: Brunnichia ovata and Mimosa pudica

4. Photonasty – changes in light intensity - Samanea saman

2. Nictinasty – darkness - Example Leucaena leucocephala

Plant parts move as they have clear adaptive advantages. Roots going down are more likely to find water and minerals they need. Stem growing up and towards light is more likely to get sunlight for photosynthesis and display its flowers prominently for pollinators to arrive. It also has better chance of spreading its seeds (Table 1). T e Diff erences between tropic and nastic movements

T o c o e ent N t c o e ent

Unidirectional response to the stimulus Non-directional response to the stimulus Growth dependent movements Growth independent movements More or less permanent and irreversible Temporary and reversible Found in all plants Found only in a few specialized plants Slow action Immediate action

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IX_Science Unit-6.indd 139 27-03-2018 12:31:41 Oxygen Carbon dioxide

The leaves take in carbon dioxide from the air

The plant draws up Sunlight gives water and minerals energy to chloroplasts from the ground to make glucose through roots

Minerals Water

What is The overall equation of photosynthesis 6.6 Photosynthesis can be given as follows:

‘Photo’ means ‘light’ and ‘synthesis’ means ‘to build’ thus photosynthesis literally means “building up with the help of light”. During this process, the light energy is converted into chemical energy. Green plants are autotrophic in their mode of nutrition because they prepare their food materials through a process called photosynthesis. Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 Carbon Water Chlorophyll Gluose Oxygen Info bits dioxide Only plants can photosynthesize and

release oxygen (O2). This is converted into ozone (O3), which protects our The end product of photosynthesis is mother Earth. glucose which will be converted into starch and stored. Plants take in carbon dioxide for photosynthesis; but for its living, plants also need oxygen to carry on cellular respiration.

C6H12O6 (C6H12O6)n Glucose Starch

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IX_Science Unit-6.indd 140 27-03-2018 12:31:41 More to Know He was able to see that the plant gained Look at a gigantic banyan tree. Many 74.7 kg (77.0 – 2.3 = 74.7) in five years, years ago it would have been just a but the soil had lost only 0.1 kg (90.9 – sapling. It has grown into a huge tree. 90.8 = 0.1 kg) in five years. So, we can How did it gain the mass? Whether it is see that soil is not the major contributor from soil/water/air? A Belgian scientist, to the gaining of the mass of the plant. Jan Baptist van Helmont was intrigued Perhaps like vitamins in Humans, soil by this question and performed an may supply vital elements and crucial, experiment in 1648 to test how much but that is not how plants make their the plant gains from extracting food is clear. Van Helmont thought water materials out of soil. He devised an alone was the cause of the increase in interesting experiment to find out. weight. Do you agree? Can you think of He took soil and heated it to make any other factor that could have added it dry. He then measured the weight of the mass to the growing tree? The next step soil. It was 90.9 kg. Can you guess why in our understanding is the process by he rst dried the soil? He placed this soil which plants produce food came from in a container which can transport water the experiments of Joseph Priestley. through its pores but without soil. He took Priestley devised an extraordinary a small sapling of willow tree, cleaned it experiment in 1771. First he burned a and measured its weight.  e tree weighed candle inside a jar and converted all the 2.3 kg. He closed the container with a lid oxygen into carbon dioxide. (How can having number of holes permitting free you be sure that all the oxygen inside movement of air and light, but not dust. the jar has been converted into carbon  e experiment went on for ve years, dioxide?) Now he placed a sprig of mint and he added only inside the jar, without outside air mixing water to the pot. with the gases inside the jar. He waited A er ve years the for ten days. Using a lens he re-lit the sapling grew into candle from outside. (Why he did not a small tree. He use a matchstick?)  e candle burned. uprooted the tree  is means that oxygen was once again carefully, cleaned inside the jar. Priestley concluded that it and measured its sprig of mint had absorbed the carbon weight. Now the dioxide and released oxygen.  at is why, tree weighed 77.0 he said, the candle was lit again. Priestley kg. Once again he concluded that the plant was converting dried the soil in the carbon dioxide back into oxygen. the container and an aptist van measured its weight. elmont Soil weighed 90.8 kg.

oseph Priestley

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IX_Science Unit-6.indd 141 27-03-2018 12:31:42 6.6.1 What else is needed for ow to do photosynthesis Variegated leaf is plucked from Coleus Photosynthesis is the process by which plant kept in sunlight after de-starching plants make their food. A small speck of by keeping it in dark room for 24 hours. seed grows and gains weight into a giant The picture of the leaf is drawn and the tree, due to photosynthesis. Almost all patches of cholorphyll on the leaf are the other organisms rely on plants for marked. After immersing the leaf in their food directly or indirectly. Even a boiling water then in alcohol it is tested carnivore depends ultimately upon plants for starch with iodine solution. for its food, how? Can you highlight? Four What do you observe? The patches of the important things needed by plants for leaf with chlorophyll turn blue-black. The photosynthesis: other portions remain colourless. 1) Chlorophyll - Green pigment present What you conclude? The chlorophyll is in leaves essential for photosynthesis. 2) Water 3) Carbon dioxide (from air) 4) Light Let us examine two of these factors

Info bits Structurally chlorophyll resemble haemoglobin but differ with the central molecule.

Plants take up water through their roots and air through stomata of their leaves. Chlorophyll is present in the leaf. What Chlorophyll else is needed for photosynthesis? The question that remains to be answered is Aim: To show that chlorophyll is essential whether the process of forming starch by for photosynthesis. combining carbon dioxide and water also We need Coleus (croton) plant with requires light. Let us do an experiment. variegated leaves, boiling water, alcohol and iodine solution.

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IX_Science Unit-6.indd 142 27-03-2018 12:31:42 Light Scientists have discovered Aim: To show that sunlight is necessary a brilliant emerald green for photosynthesis. sea slug, Elysia chlorotica What do you need? potted plant, black that was photosynthetic to paper, boiling water, alcohol and iodine produce energy. The sea slug consumes solution. alga Vaucheria litorea, which is not fully digested. Instead, the algae ow to do remain in the creature’s system and continue to provide food for the slug A potted plant is placed in a dark room for through continued photosynthesis. about 2 days to de-starch its leaves. One of its leaves is covered with the thin strip of black paper as shown in the picture. make sure that the leaf is covered on both sides.

Sunlight can penetrate 100 m to 200m into the oceans, gradually dims as the depth increases. Is it possible for the organisms that live deep into the ocean to do photosynthesis? A team of researchers including a photosynthesis expert from ASU (Arizona State University, USA) have The potted plant is kept in bright sunlight found that photosynthesis taking place for 4 to 6 hours. The selected covered leaf deep within the Paci c Ocean.  ey is plucked and the black paper is removed. discovered a green sulphur bacteria The leaf is immersed in boiling water for a living near hydrothermal vents nearly few minutes and then in alcohol to remove 2400m deep into the ocean of Mexico. chlorophyll. The leaf is now tested with  is bacteria lives in the razor-thin iodine solution for the presence of starch. interface between extremely hot water The covered part of the leaf does not (350° C or 662° F) and very cold water turn blue-black whereas the uncovered (2°C or 36° F) surrounding it. “ is part of the leaf turns blue-black colour. is just one example of life in extreme The covered part of the leaf which did environments.” not receive the sunlight was unable to synthesize starch. Hence it does not turn blue-black colour. But the uncovered part of the leaf which received sunlight was able to All these four things must be in the leaf, synthesise starch and so it turns blue-black the site where plants make their food. That in colour. raises an interesting question. Of the four,

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IX_Science Unit-6.indd 143 27-03-2018 12:31:43 chlorophyll is present in the leaf. Sunlight More to Know falls on the leaf. But how do plants take air and water to its leaf? How does the water Plant absorbs water from soil and reach the leaves from the roots? What uses it for photosynthesis. A chemical path does it follow? How does air enter analysis shows that 100 grams of water the leaf? reacts with 260 grams of carbon dioxide to form 180 grams of carbohydrate. 180 grams of oxygen is created in this 6.6.2 E change of gas process. But the plant does not use all Roots of the plant take the water from the the water it absorbs through its roots soil and transport it to leaves. How water to produce carbohydrates. Actually, and other nutrients reach the leaf from the most of this water evaporates in roots? Is the only question that we need the air. to find out? We will see this later. This leaves us with only one question? How E periment 1 does the plant get air? The leaves have tiny If you tie a plastic bag over a leaf and place holes, called stomata, through which the the plant in light, you will be able to see exchange of air takes place. These holes water condensing inside the plastic bag. are so minute that we need a microscope The water is let out by the leaves. to see them. The air exchange takes place continuously through the stomata. Plants inhale and exhale continuously through these stomata.

6.6.3 Transpiration The loss of water in the form of water vapour from the aerial parts of the plant body is called as transpiration. There are three types of transpiration: 1. Stomatal transpiration - This is the most dominant form of transpiration being responsible for most of the The leaves have tiny, microscopic holes water loss in plants. It accounts for called stomata. Water evaporates through 90-95% of the water transpired from these stomata. Each stomata is surrounded leaves. by guard cells. These guard cells help in 2. Cuticular Transpiration – This type regulating the rate of transpiration by of transpiration is responsible for opening and closing of stomata. the loss of water in plants via the Typically, only 0.1 percent of cuticle. water taken up by the plant is used by 3. Lenticular Transpiration – This the plant for producing carbohydrates. type of transpiration is the loss of That is, if a plant absorbs one litre of water from plants as vapor through water, only one millilitre will be used to the lenticels. The lenticels are tiny produce carbohydrate. The remaining 999 openings that protrude from the millilitres evaporates from the leaf. You barks in woody stems and twigs as will be able to see how much water a plant well as in other plant organs. releases in the air.

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IX_Science Unit-6.indd 144 27-03-2018 12:31:43 Guard cells of stomata Info bits are green but can’t photosynthesize. Plant use only 1% of water absorbed and remaining 99% is lost through Why transpiration. A maize plant transpire 54 gallons of water during its life span. It is Because, Enzymes RUBISCO and NADP-dehydrogenase are absent.

Transpiration is a necessary evil Activity 4 „„ creates a pull in leaf „„ creates a pull in stem To observe the impression of stomata. „„ creates an absorption force in roots, so takes more water Nail polish is applied on the lower surface of the leaves of a potted plant. A er a few But minutes, the nail polish is gently peeled „„ this is necessary for continuous o .  is nail polish peeling is placed a supply of minerals drop of water on a slide.  e cover slip „„ This regulates the temperature is placed and the peeling is observed of the plant. under the microscope.  rough the microscope, we can see the impression of the cells and the stomata. We know that more water evaporates when the weather is hot. In such a situation, the stomata begin to close.  is lessens the amount of water that evaporates from the leaves. Like manner plants adapted to dry land and desert habitat have special adaptations to ensure conservation of water.

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IX_Science Unit-6.indd 145 27-03-2018 12:31:44 Suppose the weather is hot and the stomata The conifers have a close; what would be the effect of such pyramid shape - Isn’t it a situation in the absorption of carbon wonderful? Coniferous dioxide? Will the rate of photosynthesis be trees like spruces, pines and the same? If the plant does not get water firs have a unique geometrical three- at this time, what effect would this have sided pyramid shape. They rely on on its growth? Relate your answer to the the sunlight all around the year for problem of drought affecting agricultural photosynthesis. Their pyramidal shape growth. Global warming implies increased allows all the branches to receive more level of average temperature. Can you sunlight since the top branches don’t reason what all the effect it can have on shade the bottom branches. The major photosynthesis? branches of the conifers are layered with an open area between the layers. 6.6.4 Macronutrients and This helps in passing through light and the tree to get enough light especially micronutrients for plants when sunlight comes in at a low angle Nutrients such as carbon, hydrogen, during the winter months. oxygen, nitrogen, potassium, calcium, magnesium, sulphur and phosphorus, are required in substantial quantity and are called macronutrient. Plants also require many other nutrients like iron, manganese, copper, boron, molybdenum, chlorine, silicon, cobalt, and zinc, but only in minute quantities, hence, they are called micronutrients. The water transportation systems of the plants take these nutrients from the soil and circulate it in the plant.

The plants trap solar energy for photosynthesis. Do the insects also trap solar Why do we get more energy? Tel Aviv University rainfall in the Amazon? Scientists have found out that Vespa The Amazon is the most orientalis (Oriental Hornets) have biodiverse terrestrial place similar capabilities to trap solar energy. on the planet. In the Amazon, deep- It has a yellow patch on its abdomen rooted trees increase local transpiration and an unusual cuticle structure which and high tree cover increase local is a stack of 30 layers thick. The cuticle interception evaporation. These does not contain chlorophyll but it increased evapotranspiration fluxes contains the yellow light sensitive have positive effects on forests as they pigment called xanthopterin. This stimulate rainfall. ¾ of the rainfall works as a light harvesting molecule received by the Amazon tropical transforming light energy into rainforest comes from plant transpired electrical energy. water vapour, which is visible as a mist.

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IX_Science Unit-6.indd 146 27-03-2018 12:31:44 animals eat the animals that graze and gather energy from the plants. e dead plants and animals are decomposed by microorganisms. Some of the microorganisms decompose and make some of the nutrient available in a manner for the plants to absorb from soil. us a series of organisms each dependent on the next as a source of food. is link is called as food chain.

6.8 Respiration in plants Food chain the Link 6.7 between Plants Animals Like animals, plants too respire. During and Microorganisms respiration, plants inhale oxygen and exhale carbon dioxide like animals. This Plants are called primary producers. ey process goes on 24 hours of the day and produce starch, protein and fats from night. It is during the photosynthesis sunlight, water and carbon dioxide and that it uptake carbon dioxide and exhale other nutrients. Some of the animals and oxygen. Obviously photosynthesis microorganism consume the plants and occurs in most plants only during the grow and gain weight. e carnivorous daytime.

GLOSSARY

1. Tropism Growth movement whose direction is determined by the direction of the stimulus. 2. Phototropism The unidirectional movement of a plant part to light stimulus. 3. Geotropism Response of a plant part to gravity stimulus. 4. Hydrotropism Response of a plant part to water stimulus. 5. Thigmotropism Response of a plant part to touch stimulus. 6. Chemotropism Response of a plant part to chemical stimulus. 7. Nastic movement Non-directional, response of a plant part to stimulus. 8. Thigmonasty The non-directional movement of a plant part in response to the touch of an object. 9. Photonasty The non-directional movement of a plant part in response to the light. 10. Photosynthesis The process by which plants prepare their food material. 11. Transpiration The loss of water in the form of water vapour from the aerial parts of the plant body. 12. Stomata Minute opening on the leaves.

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IX_Science Unit-6.indd 147 27-03-2018 12:31:45 EXERCISE

I. Multiple Choice Questions II. State whether the following (MCQs) statements are true or false. If false write the correct 1. A big tree falls in a forest but its roots statement are still in contact with the soil. The branches of this fallen tree straight 1. The response of a plant part to up. This happens in response to the chemical stimulus is called ______. phototropism. a) water and light 2. Shoot is positively phototropic and b) water and minerals negatively geotropic. c) gravity and water 3. Scientific term used to represent the d) light and gravity bending of roots towards water is called geotropism. 2. The tropic movement that helps 4. Joseph Priestley devised an the climbing vines to find a suitable experiment to find out that water support is ______. alone was the cause of the increase a) phototropism in the weight of the plant. b) geotropism 5. When the weather is hot, water c) thigmotropism evaporates lesser which is due to d) chemotropism opening of stomata.

3. The chemical reaction occurs during photosynthesis is ______. III. Fill in the blanks 1. The shoot system grows upward in a) CO2 is reduced and water is oxidized response to ______

b) water is reduced and CO2is oxidized 2. ______is positively

c) both CO2 and water are oxidized hydrotropic as well as positively d) both CO2 and water are produced geotropic.

4. Transpiration is best defined as 3. The green pigment present in the ______. plant is ______a) loss of water by the plant 4. The minerals like nitrogen, potassium b) evaporation of water from the and phosphorus, are required in aerial surfaces from the plant substantial quantity by the plants are c) loss of water in the form of water called ______vapour from the underground parts of the plant body d) release of water from the plant into the atmosphere

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IX_Science Unit-6.indd 148 27-03-2018 12:31:45 IV. Match column A with column B

Column A Column B

1. Roots growing Positive downwards into phototropism soil

2. Shoots growing Negative towards the light geotropism b) What are the other movements seen in this plant? 3. Shoots growing Negative 4. What is the end product of upward phototropism photosynthesis? 4. Roots growing Positive 5. Name the minute openings seen on downwards away geotropism the lower surface of the leaf. from light VII. Answer the following in one or two sentences V. Analog 1. What is nastic movement? 1. Towards a stimulus :______2. Name the plant part Away from the stimulus : Negative tropism a) Which bends in the direction of 2. Hydrotropism : Response towards gravity but away from the water Phototropism : ______light. 3. Photosynthesis : ______b) Which bends towards light but Transpiration : Stomata away from the force of gravity.

VI. Answer in a word or two 3. Differentiate phototropism from photonasty. 1. Give an example for a plant whose leaf shows a mesmerizing movement. 4. Photosynthesis converts energy X 2. Write the scientific terms used to into energy Y. represent the following: a) What are X and Y? a) Growing of roots towards the b) Green plants are autotrophic in gravity. their mode of nutrition. Why? b) Bending of roots towards the water. 5. Define transpiration. 3. Observe the given picture. a) Identify this plant. What type of VIII. Answer in detail special movement is shown by 1. Design an experiment to demonstrate this plant? hydrotropism.

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IX_Science Unit-6.indd 149 27-03-2018 12:31:45 WORK BOOK

I. Multiple Choice Questions 5. The non-directional movement of a plant part in response to temperature 1. The bending of root of a plant in response to water is called is called ______. ______. a) thermotropism b) Thermonasty a) thigmonasty c) chemotropism b) phototropism d) thigmonasty c) hydrotropism d) photonasty 6. Dandelion flowers open the petals in bright light during the day time 2. A growing seedling is kept in the dark but close the petals in dark at night. room. A burning candle is placed near it This response of Dandelion flowers for a few days. e top part of the seedling is called ______. bends towards the burning candle. a) geonasty is is an example of ______. a) chemotropism b) thigmonasty b) thigmotropism c) chemonasty c) phototropism d) photonasty d) geotropism 7. During photosynthesis plants exhale ______. 3. The root of the plant is ______. a) Carbon dioxide i) positively phototropic but negatively geotropic b) oxygen ii) positively geotropic but negatively c) hydrogen phototropic d) helium iii) negatively phototropic but 8. Chlorophyll in a leaf is required for positively hydrotropic ______. iv)negatively hydrotropic but positively a) photosynthesis phototropic b) transpiration a) (i) and (ii) c) tropic movement b) (ii) and (iii) d) nastic movement c) (iii) and (iv) d) (i) and (iv) 9. A plant is kept in a dark room for about 24 hours before conducting 4. The plant part which exhibits any experiment on photosynthesis in negative geotropism is ______. order to ______. a) root a) remove chlorophyll from the leaf b) stem b) remove starch from the leaves c) branch c) ensure that photosynthesis occurred d) leaves d) to prove transpiration

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IX_Science Unit-6.indd 150 27-03-2018 12:31:45 10. Transpiration takes place through This is an example of thigmonasty. ______. 2. The petals of moon flower open up in a) fruit b) seed morning and closes in the evening. This is called photonasty. c) flower d) stomata 3. Photosynthesis produces glucose II. Fill in the blanks and carbon dioxide. 4. Photosynthesis is important in 1. The solar tracking of sunflower in accordance with the path of sun is releasing oxygen to keep the due to ______. atmosphere in balance. 2. The response of a plant part towards 5. Plants lose water when the stomata gravity is ______. on leaves are closed. 3. When the leaves of a sensitive plant are touched with a nger, they fold IV Match the following up and when light fades at dusk the petals of a Dandelion ower close. S. Column A Column Column ese two plants show ____ and_____ No. B C movements. 1. Photonasty Response to Tulipa sp 4. Opening and closing of Moon temperature flower is not a tropism because the movement in this is ______. 2. Thigmonasty Response to Mimosa light pudica 5. The raw materials for photosynthesis are ______and ______. 3. Thermonasty Response to Moon 6. When iodine solution is added for touch flower testing starch, part of the leaf with ______turn blue-black colour. V. Answer in a word or two 7. In leaves, the food is stored in the 1. Give the technical terms for the form of ______. following: 8. Plants may inhale carbon dioxide a) Growth dependent movement in for photosynthesis but need plants. ______for their living. b) Growth independent movement 9. Plants utilize only ______% of the in plants. absorbed water for photosynthesis 2. Study the pictures below and then and the other activities. complete the table by putting a 10. Plants inhale and exhale continuously plus (+) if the shoot or root grows through the ______. towards the stimulus and a minus (-) if it grows away from it. III. State whether the following statements are true or false. If false write the correct Stimulus statement: Light Gravity 1. When the leaves of Mimosa pudica Shoot + _ plant are touched with the finger, they fold up quickly. Root ? +

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IX_Science Unit-6.indd 151 27-03-2018 12:31:45 ii) What is the phenomenon known as? 4. What is the difference between movement of flower in sunflower plant and closing of the leaves in the Mimosa pudica.? 3. Name the movement seen in 5. Define photosynthesis. Pneumatophores of Avicennia. 6. Suppose you have a rose plant 4. What is the other name for growing in a pot, how will you thigmonasty? demonstrate transpiration in it? 5. Which flowering plant shows 7. Draw the diagram of open stoma and photonasty just opposite to that of label the parts. Dandelion? 8. A potted plant is kept horizontally 6. Give an example for negative for a considerable time. The three hydrotropism. positions of the part A and B of 7. Fill in the blanks: the potted plant are shown in the following figures. 6CO + ___ Sunlight ___ + 6H O + 6O 2 2 2 (i) Potted plant with shoot Chlorophyll and root growing downward. 8. Which gas is evolved during (Diagram to be drawn) photosynthesis? 9. What is chlorophyll? 10. Give an example for micronutrients. (ii)

VI. Answer the following in one or two sentences 1. Name the part of plant which shows (iii) Potted plant with shoot and positive geotropism. Why? root growing upward (Diagram 2. What does a Mimosa pudica plant to be drawn) do in response to touch? What is the a) Which figure shows the correct phenomenon known as? position taken by the parts A and 3. i) What happens to the dandelion B of the plant? flower b) What type of phenomenon is a) during the daytime? exhibited by the figure by (A) in b) at night? the figure (ii)?

9. Complete the following table with the different types of tropism: Stimulus Gravity Unilateral light Water Tropism Geotropism ? Hydrotropism Response Shoot ? Positive No response Root Positive ? ?

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IX_Science Unit-6.indd 152 27-03-2018 12:31:45 10. Cover the tip of the shoot with tin VII. Assertion and reason foil cap and light it from the side as 1. Assertion (A): If the plant part moves shown in the given picture. What in the direction of gravity, it is called would you expect to happen? Why? positive geotropism. Reason (R) : Stem shows positive geotropism a) A and R are incorrect b) A is incorrect, R is correct c) A is correct, R is incorrect 11. In the given photosynthetic d) Both A and R are correct experiment, what will happen to the leaf closed with black paper in starch 2. Assertion (A): The loss of excess test? Why? water from the aerial parts of the plant in the form of water vapour is known as transpiration. Reason (R) : Stomata of the leaf perform transpiration. a) A and R are incorrect b) A is incorrect, R is correct c) A is correct, R is incorrect d) Both A and R are correct

VIII. igher order thinking questions ( OTS)

12. Label the diagram with the 1.  ere are 3 plants A, B and C.  e raw materials and products of  owers of A open their petals in photosynthesis. bright light during the day but close them when it gets dark at night. On the other hand, the  owers of plant B open their petals at night but close them during the day when there is bright light.  e leaves of plant C fold up and droop when touched when ngers or any other solid object. 13. Mention the differences between a) Name the phenomenon shown by stomatal and lenticular transpiration the flowers of plant A and B. 14. Give an example for the movement b) Name one flower each which plant part which is very quick and behaves like the flowers of plant A can be observed easily. and B. 15. To which directional stimuli do (a) c) Name the phenomenon exhibited roots respond (b) shoots respond? by the leaves of plant C. 16. Name the cell that surrounds the d) Name a plant whose leaves behave stoma. like those of plant C.

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IX_Science Unit-6.indd 153 27-03-2018 12:31:46 2. While conducting experiments to a) What is (i) organism A (ii) food study the effects of various stimuli B and food H? on the plants, it was observed that b) What are C and D? the roots of a plant X grow and bend towards two stimuli A and B but c) Name (i) green pigments E and bend away from a third stimulus C. organ F. The stem of the plant X however d) What is the process G? bends away from stimulus A and B 4. Imagine that student A studied the but bends towards the stimulus C. importance of certain factors in The stimulus B is known to act on photosynthesis. He took a potted the roots due to factors related with plant and kept it in dark for over Earth. Keeping these points in mind, 24 hours. In the early hours of the answer the following questions: next morning, he covered one of the a) What could be stimulus A ? leaves with dark paper in the centre b) Name the stimulus seen in B. only. Then he placed the plant in sunlight for a few hours and tested c) What could be stimulus C ? the leaf which was covered with 3. An organism A which cannot move black paper for starch. from one place to another makes a a) What aspect of photosynthesis simple food B from the substances C was being investigated? and D available in the environment.  is food is made in the presence of b) Why was the plant kept in the green coloured substance E present dark before the experiment? in organs F in the presence of light c) How will you prove that starch is energy in a process called G. Some of present in the leaves? the simple food B also gets converted d) What are the other raw materials into a complex food H for storage for photosynthesis? purposes.  is food gives blue-black colour with iodine solution?

REFERENCES 1. Plant physiology by Devlin and Witham first Indian edition 1986. 2. Modern practicals botany B.P. Pandey vol. II. New print 2003. 3. Plant physiology by V.K. Jain first edition 2003.

INTERNET RESOURCES 1. http://web.mit.edu/esgbio 2. http://www.cellbiol.com/bioinformatics_web_development 3. http://www.bioedonline.org/ 4. http://www.biology.arizona.edu/default.html 5. https://www.gbif.org/

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