202110188-APEX-STUDENT-WORKBOOK-SCIENCE-G07-PART2

Science Workbook_7_P_2.pdf 1 18-10-2019 17:34:23 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Table of Contents 1 29 9 REFLECTION OF LIGHT 46 10 NUTRITION IN PLANTS 65 11 RESPIRATION IN ORGANISMS 86 12 REPRODUCTION IN PLANTS 99 13 SEED DISPERSAL 122 17 CHANGES AROUND US 123 PROJECT BASED QUESTIONS ADDENDUM: ADDITIONAL AS-BASED PRACTICE QUESTIONS TABLE OF CONTENTS

9. REFLECTION OF LIGHT SESSION 1 INTRODUCTION TO LIGHT AND RAYS OF LIGHT 1.1 Mind Map SESSION 1. INTRODUCTION TO LIGHT AND RAYS OF LIGHT 1

1.2 Terminology i. Reflection – is the throwing back of light, heat, or sound by a body or surface without absorbing it. ii. Incident ray –is a ray of light falling on a mirror or surface. iii. Reflected ray – is the ray that represents the light returning from or reflected by the surface. 1.3 Key Concepts i. Any object becomes visible to our eyes when light rays are reflected from its surface. ii. Light follows a straight path and when any obstruction falls on its way by an object it changes direction. iii. The change in the path of light following obstruction caused by an object is known as reflection. iv. The ray of light which falls on an object or mirror is called incident ray. v. The ray of light returned back from the surface of an object or mirror is called reflected ray. SESSION 1. INTRODUCTION TO LIGHT AND RAYS OF LIGHT 2

1.4 Communication Through Drawing and Model Making Q1. Draw reflected ray in the figure given here. [Refer to TB page 94 Q2](i)) A. SESSION 1. INTRODUCTION TO LIGHT AND RAYS OF LIGHT 3

SESSION 2 LAWS OF REFLECTION AND APPLICATIONS 2.1 Mind Map SESSION 2. LAWS OF REFLECTION AND APPLICATIONS 4

2.2 Terminology i. Normal – At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror, known as the normal line. ii. Angle of incidence –is the angle between the normal and the incident ray. iii. Angle of reflection –is the angle between the normal and the reflected ray. iv. Periscope –is an optical instrument containing lenses and mirrors for viewing objects that are above the level of direct sight or in an otherwise obstructed field of vision. 2.3 Key Concepts i. When a light ray falls on a plane surface and is reflected, its behavior (the reflected ray) is the same as that of the incident ray. This is explained by the laws of reflection. ii. The ray that is perpendicular to the surface of reflection is known as the normal. iii. The incidence ray represents the original ray (light ray falling on the object from the source of light), and it forms an angle of incidence as it meets the normal at the plane. iv. The angle of reflection is the angle formed when the reflected ray diverges from the plane surface and the normal ray. v. The angle of incidence and the angle of reflection fall at opposite sides from the nor- mal ray. vi. The law of reflection states that when light falls upon a plane surface and is reflected, the angle of incidence is equal to the angle of reflection. SESSION 2. LAWS OF REFLECTION AND APPLICATIONS 5

vii. This law is used when the incidence ray, the reflected ray and the normal all fall upon a plane area of incidence. viii. For the arrangement of mirrors in a periscope, the above principles are taken into account. 2.4 Conceptual Understanding Q1. How do you relate angle of reflection and angle of incidence? What will be the angle of reflection when the angle of incidence is [Refer to TB page 95 Q3] (i) 60°(ii) 0° A. According to the laws of reflection, the angle of reflection is always equal to the angle of incidence. i. If the angle of incidence is 60°, the angle of reflection will also be 60°. ii. If the angle of incidence is 0°, the angle of reflection will also be 0°. 2.5 Experimentation and Field Investigation Q1. Vidya made a periscope making slits like this as shown in the figure. Will it work or not? Explain your answer. Try to make a periscope like this and see whether it works or not. [Refer to TB page 94 Q1] A. The periscope made by Vidya will not work. 6 SESSION 2. LAWS OF REFLECTION AND APPLICATIONS

i. With slits as shown in the figure, plane mirror strips which are inserted into these slits are not parallel to each other. ii. According to the law of reflection, an image is formed only when the incident ray, reflected ray and the normal all lie in the same plane. iii. This is achieved by adjusting the mirrors parallel to each other. iv. However, in the model of periscope prepared by Vidya, the mirror strips are not parallel to each other. Hence, it will not work. 2.6 Information Skills and Projects Q1. Take an empty toothpaste box and two mirror strips of required size and make a periscope. [Refer to TB page 95 Q14] A. Students’ Activity 2.7 Appreciation and Aesthetic Sense, Values Q1. Army people can see their enemies while hiding themselves with the help of periscopes. How do you appreciate the use of periscope for their security? [Refer to TB page 96 Q19] A. i. Army people hide in trenches dug below the ground surface and observe the move- ments of enemy soldiers with the help of periscopes. ii. The plane mirrors in a periscope are arranged parallel to each other such that the incident ray, reflected ray and the normal all lie in the same plane. iii. Due to this, images of objects lying at a higher level can be seen by the soldiers hiding at a lower level. iv. Thus, the phenomenon of reflection is an appreciable phenomenon which helps them to see the movements of enemies without being noticed by them. SESSION 2. LAWS OF REFLECTION AND APPLICATIONS 7

SESSION 3 IMAGE IN A MIRROR AND MULTIPLE IMAGES 3.1 Mind Map SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 8

3.2 Terminology i. Plane mirror – a mirror with a flat ( planar ) reflective surface. The size of image in plane mirror equals the size of the object. ii. Lateral inversion –In a mirror, right of an object appears left, and left of an object appears right. This interchanging of the sides is termed as lateral inversion. iii. Kaleidoscope –is an optical instrument with bits of pieces of glass held loosely in a rotating tube that are shown in continually changing symmetrical forms by reflection in two or more mirrors set at angles to each other. 3.3 Key Concepts i. Formation of the image in a mirror is due to reflection of light rays from the mirror. ii. The image formed by a mirror is laterally inverted means there is a reversal of the mirror image’s left and right when compared with the object. iii. For plane mirrors, the object distance is equal to the image distance. iv. In a plane mirror, the dimensions of the image are the same as the dimensions of the object. v. A plane mirror forms single, virtual image. vi. Multiple images can be obtained by arranging two or more plane mirrors at certain angles. vii. The principle of the kaleidoscope is obtaining multiple images by arranging plane mir- rors at an angle. viii. As the angle between the two mirrors is decreased, the number of images increases. SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 9

3.4 Conceptual Understanding Q1. What is the angle between two plane mirrors when there are five images? [Refer to TB page 96 Q15] A. The number of images = 360◦ − 1 , where θ = angle between the mirrors θ i.e., 5 = 360◦ − 1 θ or, 6 = 360◦ θ or, θ = 60◦ Thus, if five images are formed between two plane mirrors inclined at an angle then the angle between them is 60º. 3.5 Asking Questions and Making Hypothesis Q1. Sai lighted a candle in his house when power went off. His mother placed it in front of a mirror. Sai observed something that excited him. What change would have excited Sai? Some questions came to his mind. Can you guess the questions? Write a few such questions. [Refer to TB page 95 Q11] A. The questions that Sai would have got in his mind and excited him could be as follows: i. Why does the candle give more light on keeping in front of the mirror? ii. Is it because of the reflection of light from the candle? iii. Is the size of the image of candle equal to the size of the candle? iv. Is the distance of the candle before the mirror equal to the distance of image behind the mirror? Q2. Imagine that all the houses in your street have elevation with mirrors. Suppose you and your friends are walking in the street. Would you experience any difficulties when you SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 10

walk through that street? Predict and explain. Is it difficult for birds to live or fly in that street? Why? [Refer to TB page 95 Q13] A. i. If all the houses in our street have elevation with mirrors, an infinite number of im- ages of me and my friends will appear in the mirrors which would create confusion and chaos, and walking in such street would become extremely difficult. ii. The traffic in the street will create confusion and there will be increased chances of accidents. iii. Birds will also find it difficuIt to fly in such street as due to multiple images, there would be confusion in finding the right direction for flight. iv. It might appear to them that many birds are flying towards them and they have to change their direction of flight. They may even collide against the mirrors. 3.6 Experimentation and Field Investigation Q1. Observe the following figures. How many images would you observe in the mirrors in the above cases? Write your guesses. Do experiments and check whether your guesses are correct or not. Give reasons. [Refer to TB page 95 Q8] A. Students’ Activity Hints: SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 11

i. One image will form in the first case and three images will be formed in the second case. ii. Students can perform the activity and verify. They can also verify using the formula, n = 360◦ − 1 , where n = number of images and θ = angle between the mirrors. θ 3.7 Information Skills and Projects Q1. You are given the mirror image of a name. Can you find out the actual name? [Refer to TB page 95 Q6] A. i. Yes, the name is S U R Y A. ii. By placing a plane mirror in front of the given pattern we can find the original name, S U R Y A. iii. Due to lateral inversion, the letters and their direction get reversed in the image. iv. And, we can observe the corrected image in the mirror. Q2. Collect information from your elders and shopkeepers about where we use more mirrors and why? [Refer to TB page 96 Q22] A. i. The shopkeepers in a sweet shop arrange plane mirrors parallel to each other so that the sweets kept in glass jars would appear in uncountable number. ii. A barber arranges mirrors in parallel in his saloon so that the customer can look at the back of his head during his hair cut. iii. In a temple in Kanchi (a pilgrim place in Tamil Nadu), two plane mirrors are ar- ranged opposite to each other and the idol of the Goddess is located at a place where it is visible through both the mirrors. During “Harathi”, it gives an appear- ance as if several priests are offering Harathi to the idol of God. iv. Spherical mirrors are used as rear view mirrors in vehicles and in head lights and lamps. Q3. Collect information about which objects of your school and home work like a mirror and why? Identify the similarities among those objects. [Refer to TB page 96 Q23] A. Some objects found both at my school and home which work like mirror are: SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 12

i. I find the glass fittings of the windows act as mirrors. ii. The surface of water in the overhead tank acts as a plane mirror. iii. My steel lunch–box and all the plates, spoons made of shining stainless steel act as mirrors. iv. The dome of the electric lamp hanging from the ceiling of my school and my home works as mirror and spread the light of the lamp in all directions. Q4. Get three mirror strips, two rubber bands, card board sheet, translucent paper, and broken bangle pieces and make a kaleidoscope. (TB–Pg 95:Q7) A. Students’ Activity i. Take three mirror strips of the same size and tie them with rubber bands to form a triangular tube. ii. While tying the strips together, remember to keep their reflecting surfaces facing each other inside the tube. iii. Cover one end of the tube with translucent paper using a rubber band. Cover the second end with a cardboard sheet and make a hole in it, so that you can look inside it. iv. Now put few small pieces of coloured glass bangles inside the triangular tube and look through the hole. Your kaleidoscope is ready. SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 13

3.8 Communication Through Drawing and Model Making Q1. Mark the position of the image in the figure given here by dotted lines. [Refer to TB page 94 Q2](ii)) A. 3.9 Appreciation and Aesthetic Sense, Values Q1. Mirrors help us to see all the objects around us without turning our heads. How do you appreciate the role of mirrors in our life? [Refer to TB page 96 Q18] A. i. Mirrors help us see objects behind us without turning our heads due to reflection and this property is used in many saloons and other places. ii. If there was no rearview mirror attached to a vehicle, it would be difficult for the driver to see vehicles coming from behind. It also gives information about ambu- lance and other emergency vehicles so that we can give space to them to pass through. iii. They are also used in sunglasses to reflect sunlight. iv. In a magnifying glass, two convex mirrors are placed back to back. v. Use of convex mirrors in securities in bank ATMs and on inspection rods to check the underside of cars and other vehicles is another important use of convex mirror. vi. Concave mirrors are used in torches and head lights of vehicles. vii. Dentists use concave mirror to examine our teeth. viii. With so many applications, mirrors have a useful role in our life. SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 14

3.10 Application to Daily Life, Concern to Bio Diversity Q1. Imagine that your sister is viewing a cricket match on a T.V. and you are viewing the same cricket match in a mirror which is opposite to the T.V. What difference do you notice in the match? [Refer to TB page 95 Q4] A. i. Due to lateral inversion of the image, I observed that the right side of the cricket field appeared as if it was on the left side of the field. ii. When a batsman hit a boundary towards his right hand side, it appeared as if he had hit the ball towards his left side. iii. Also, the left–handed players appeared to be playing with their right hands and vice versa. iv. Even the score on the score board looked reversed. Q2. Write the mirror image of your name: [Refer to TB page 95 Q5] A. Students’ Activity Q3. Write examples of multiple images formed in your daily life. [Refer to TB page 95 Q9] A. Examples of multiple images formed in our daily life: i. If we go to a hair cutting salon, the barber arranges two plane mirrors one opposite to the other which allows us to see the front and back of our head along with other images. ii. In a kaleidoscope, three plane mirrors are arranged in the form of a prism such that they are inclined at an angle of 60°. We see many beautiful symmetric patterns due to multiple reflections in the form of colorful design. iii. The sunlight entering our room through a window brightens up the entire room after multiple reflections through various objects. iv. In trial rooms, we can check the fit of a new dress from each angle due to multiple reflection from the mirrors fitted at each side of the room. Q4. While constructing a new house, Kishan’s uncle rejected his wife’s request of glass elevation to the building saying that “It is harmful to the birds and also ourselves”. How do you appreciate the decision of Kishan’s uncle? [Refer to TB page 96 Q21] SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 15

A. i. Kishan’s uncle has taken a wise and judicious decision by rejecting his wife’s re- quest to construct glass elevation to their new building. ii. The glass elevation would create a lot of confusion due to multiple images formed in the glass. iii. The people coming towards the house would also be confused and it might be dan- gerous for vehicles passing through the house as the images in the glass elevation would create confusion while driving. iv. It might also mislead the animals like stray dogs and cats and birds flying towards the mirrors confusing them about the direction. SESSION 3. IMAGE IN A MIRROR AND MULTIPLE IMAGES 16

SESSION 4 IMAGES IN SPHERICAL MIRRORS 4.1 Mind Map SESSION 4. IMAGES IN SPHERICAL MIRRORS 17

SESSION 4. IMAGES IN SPHERICAL MIRRORS 18

4.2 Terminology i. Rear view mirror –is a mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle’s backlight. It produces a smaller image of the object in the rear. ii. Spherical mirrors –are mirrors which possess curved reflecting surfaces. iii. Convex mirror – is a spherical mirror in which the reflective surface bulges towards the light source. They are made from a section of an outer silvered ball. iv. Concave mirror – is a spherical mirror with reflection surface defined by an interior of a sphere. The word concave means curving in or hollowed inward. v. Real image –is the one which is formed at the point where light actually converges. It is obtained on a screen. vi. Virtual image –is formed at a location where light appears to have converged. It cannot be obtained on a screen but can be viewed only in a mirror. vii. Regular reflection –is the reflection from a smooth surface like that of a mirror which produces a clear image. viii. Irregular reflection –the reflection from a rough or irregular surface which produces an unclear image. 4.3 Key Concepts i. A spherical mirror is that mirror whose reflecting surface is the part of a hollow sphere or curve. ii. There are two types of spherical mirrors, namely (i) convex mirrors (bulging outward) and (ii) concave mirrors (bulging inward). iii. Convex mirrors form diminished image of objects and have a wide range. iv. Concave mirrors give enlarged image of the object. v. A real image can be obtained on a screen. vi. The image that cannot be obtained on a screen but can be viewed in the mirror is called a virtual image. vii. Reflection from a smooth surface (Regular reflection) forms a clear image of the ob- ject. viii. Reflection from a rough surface (Irregular reflection) gives unclear dim images. SESSION 4. IMAGES IN SPHERICAL MIRRORS 19

4.4 Conceptual Understanding Q1. Observe the figure and identify which type of mirror is used. [Refer to TB page 95 Q10] How do you justify it? A. i. A concave mirror is used in this experiment. ii. The image of the flame formed on the cardboard is real and inverted which is produced only in a concave mirror. Hence, our answer is justified. Q2. Unexpectedly some water sprinkled on a mirror while Madhu was shaving his face. Did he observe any difference in the image? If yes, explain why? [Refer to TB page 95 Q12] A. i. Yes, there was a difference in the image because there was an irregular reflection of light by the water droplets on the mirror. ii. Due to irregular surface of the mirror because of sprinkled water droplets on the mirror, an unclear image was observed. Q3. Can we use rearview mirror in place of plain mirrors? Yes/No, give reasons. A. Yes we can use rearview mirror in place of plain mirror but the image size will be smaller in that case. 4.5 Communication Through Drawing and Model Making Q1. What is the difference between convex and concave mirrors? Draw the diagrams of concave and convex mirrors. [Refer to TB page 96 Q16] SESSION 4. IMAGES IN SPHERICAL MIRRORS 20

A. Differences between convex and concave mirrors: Convex Mirror Concave mirror 1. Reflecting surface is Reflecting surface is like curved outwards like outer inside of a hollow ball in a surface of a sphere in a concave mirror. convex mirror. 2. Images formed are The size, nature and position always diminished and of images formed differ virtual. according to the position of the object. The diagrams below show the structure of a concave mirror and a convex mirror: 4.6 Appreciation and Aesthetic Sense, Values Q1. Imagine what would happen it there are no rear view mirrors attached to the vehicles and there are no concave mirrors in head lights of the vehicles. [Refer to TB page 96 Q20] A. i. If there are no rearview mirrors attached to a vehicle, it would be difficult for the driver to see vehicles coming from behind. ii. It would be difficult to give space for ambulance and other emergency vehicles and vehicles will be more prone to accidents. iii. Concave mirrors in head lights and torches increase the brightness of the small bulb fitted inside. iv. The concave mirror converges the rays and produces a bright ray of light. SESSION 4. IMAGES IN SPHERICAL MIRRORS 21

4.7 Application to Daily Life, Concern to Bio Diversity Q1. Where do you find irregular reflection in daily life? Give some examples. [Refer to TB page 96 Q17] A. Reflection from a rough or irregular surface is called irregular reflection. Examples: i. The image formed in a rough window glass is due to irregular reflection. ii. The image formed on the surface of disturbed water in a pond is due to irregular reflection. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 9.1 ] (i) Based on what factors does change in shape of shadows occur? (ii) What happens when light falls on an object? (iii) What is an incident ray? (iv) What do you mean by a reflected ray? (v) How do we see an object? 2. State true or false. [Refer to Session 9.2 ] (vi) Angle of incidence is denoted as ‘I’. [] CHAPTER 9. REFLECTION OF LIGHT 22

(vii) Angle between normal and incident ray is called angle of reflection. ] [ (viii) Angle of incidence = Angle of reflection. [] (ix) Any line between the incident ray and the reflected ray is called normal. ] [ (x) We can see an object only when incident ray and reflected ray lie in the same plane. [] 3. Fill in the blanks. [Refer to Session 9.2 ] (xi) The line that bisects the plane of reflection at 90°is called the . (xii) The angle between the normal and incident ray is called . (xiii) The angle between the normal and the reflected ray is called the . (xiv) The angle of incidence is always equal to the . (xv) The incident ray, the reflected ray and the normal always lie in the . 4. State true or false. [Refer to Session 9.3 ] (xvi) In a mirror, left hand appears to be left. [] (xvii) Irrespective of the size of a plane mirror, the size of image and the size of object are equal. [] CHAPTER 9. REFLECTION OF LIGHT 23

(xviii) Two plane mirrors can form two images. [ ] ] (xix) Formation of multiple images is due to multiple reflection. ] [ ] ] (xx) Change of sides in the mirror is called vertical inversion. ] ] [ ] 5. State true or false. 24 [Refer to Session 9.4 ] (xxi) Only diminished images are formed by convex mirrors. [ (xxii) An image that can be obtained on a screen is called a real image. [ (xxiii) Convex mirrors are used in the headlights of vehicles. [ (xxiv) Convex, concave, and plane mirrors together form spherical mirrors. [ (xxv) Concave mirrors converge light rays. [ 6. Match the following. Column B a. Real image [(Session 9.4)] Column A i. Curved reflecting surfaces ii. Inner surface of a spherical mirror b. Regular reflection iii. Outer surface of spherical mirror c. Spherical mirror iv. Image that can be obtained on screen d. Convex v. Reflection from a smooth surface e. Concave CHAPTER 9. REFLECTION OF LIGHT

Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 9.2)] What is the relation between angle of incidence and angle of reflection? Explain using equation. (ii) [(Session 9.2)] Define normal, angle of incidence and angle of reflection. 8. Answer the following questions in 3-4 sentences. (i) [(Session 9.4)] State one useful property of convex mirrors. Where is it used? (ii) [(Session 9.4)] What kind of images are seen in smooth and rough surfaces? Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 9.4)] How do we get an image in a mirror? Define virtual image. AS2-Asking questions and making hypothesis Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 9.3)] Seema saw an ambulance on her way to school. She noticed that on the front side of the ambulance, the word ‘AMBULANCE’ was written as ‘ What questions she would have in her mind? AS3-Experimentation and field investigation Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 9.2)] Devise an experiment to show that any object shows lateral inversion in the mirror. CHAPTER 9. REFLECTION OF LIGHT 25

Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 9.2)] How will you make your own periscope? (ii) [(Session 9.2)] Explain with the help of an experiment that light is reflected after strik- ing an object. AS4-Information skills and projects Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 9.3)] Two plane mirrors are joined together along one edge. As the angle between them decreases, the number of images is found to be varying. But, there is a definite formula for the number of images for any given angle. Research it and try to derive it. 14. Answer the following questions in 6-8 sentences. (i) [(Session 9.4)] Collect information about various types of mirrors and their uses. AS5-Communication through drawing and model making Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 9.4)] What is regular reflection and irregular reflection? Explain with a diagram. AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 16. Answer the following questions in 3-4 sentences. (i) [(Session 9.3)] Give three properties of a plane mirror that are useful in our daily life, with examples. CHAPTER 9. REFLECTION OF LIGHT 26

17. Answer the following questions in 3-4 sentences. (i) [(Session 9.4)] Give examples where you find regular and irregular reflections in daily life. (ii) [(Session 9.4)] What would happen if there was no rearview mirror attached to a ve- hicle? Long Answer Type Questions 18. Answer the following questions in 6-8 sentences. (i) [(Session 9.4)] Sharmila went to a shopping mall with her parents. In the garage parking of the mall, she saw a huge spherical mirror at corners and turns. Explain to her what kind of a mirror is it and what is the purpose in putting it in a parking garage. Give other uses of this kind of spherical mirror. Objective Questions AS1-Conceptual Understanding 19. Choose the correct answer. (i) mirrors are used in rearview mirrors. (A) Concave (B) Convex (C) Plane (D) Biconvex (ii) The mirror that is used in the headlights and torches is . (A) concave (B) plane (C) convex (D) biconcave (iii) Reflection from a is called regular reflection. (A) rough surface (B) smooth surface (C)rough uneven surface (D)porous surface CHAPTER 9. REFLECTION OF LIGHT 27

(iv) A plane mirror forms . (A) four images (B) triple images (D)a single image (C)double images (v) The number of images , when we reduce the angle between two mirrors. (A) increases (B) decreases (D) vanishes (C)doesn’t change . (vi) For a plane mirror, (B) ∠i >∠r (A) ∠i = ∠r (D)∠i ∠r (C)∠i <∠r (vii) images cannot be obtained on the screen. (A) Real (B) Regular reflection (C) Virtual (D)Irregular reflection (viii) images are formed in case of regular reflection. (A) Clear (B) Irregular (C) Diffused (D) Hazy (ix) The mirror used by dentists is . (A) concave (B) convex (C) plane (D) biconvex (x) A ray of light falling on a surface is called a . (A) reflected ray (B) incident ray (C)smooth ray (D)irregular ray CHAPTER 9. REFLECTION OF LIGHT 28

10. NUTRITION IN PLANTS SESSION 1 NUTRITION IN PLANTS - INTRODUCTION 1.1 Mind Map 1.2 Terminology i. Nutrition –is the process of providing or obtaining the food necessary for health and growth. ii. Autotroph –is an organism capable of synthesizing its own food from inorganic sub- stances, using light or chemical energy. iii. Photosynthesis –is the process used by plants, algae and certain bacteria to har- ness energy from sunlight into chemical energy. SESSION 1. NUTRITION IN PLANTS - INTRODUCTION 29

1.3 Key Concepts i. The process by which an organism takes in food and assimilates it is called nutrition. ii. Plants which prepare food materials on their own are called autotrophs. iii. Green parts of plants use carbon dioxide in the presence of sunlight (as well as other sources of light) along with water to make glucose, starch and other food materials. iv. This process of making food materials is called photosynthesis. v. The green substance in leaves is essential for photosynthesis and is called chloro- phyll. vi. The substances needed for the plants to grow do not come from soil alone. 1.4 Conceptual Understanding Q1. Fill in the blanks and give reasons: [Refer to TB page 103 Q5](i), (ii)) (i) Green plants are in nature. (ii) The food synthesized by the plants is stored as . A. (i) Green plants are autotrophic in nature. Reason: Because they synthesize their own food. (ii) The food synthesized by the plants is stored as starch. Reason: Because starch is insoluble in water while glucose is soluble. When needed by the plants, starch is broken down into glucose. SESSION 1. NUTRITION IN PLANTS - INTRODUCTION 30

1.5 Asking Questions and Making Hypothesis Q1. Do you agree with Von Helmont? If nutrients absorbed by plant from soil is equal to mass of plant/tree what will happen? Think and write your hypothesis. [Refer to TB page 103 Q10] A. i. I agree with Von Helmont’s findings that “The substances needed for the growth of a plant do not come from soil only”. ii. Plants selectively absorb nutrients from the soil which are continuously being re- generated in the soil by decomposition, decay and other microbial action. iii. Thus, mass of soil and mass of plant cannot be correlated to estimate the nutrients absorbed or the growth of the plant. iv. Increase in the mass of a plant is due to accumulation of food prepared by the plant using nutrients, water and gases from the soil and air. 1.6 Information Skills and Projects Q1. Collect information about experiments of Joseph Priestly and Ingen Houz from internet and make a brief note on them. [Refer to TB page 103 Q9] A. Students’ Activity Hints: • Experiments of Joseph Priestley: He demonstrated that what animals were doing to the air was being reversed by plants. That is, according to him, if animals were making the air impure, plants were making it pure. • Experiments of Ingen Houz: Ingen Houz followed the footsteps of Priestley’s ex- periments, but under different conditions. He found that only the green parts of plants when exposed to sunlight could purify the air. SESSION 1. NUTRITION IN PLANTS - INTRODUCTION 31

SESSION 2 PLANTS USE WATER, AIR AND LIGHT TO MAKE FOOD 2.1 Mind Map 2.2 Terminology i. Autotroph – is an organism capable of synthesizing its own food from inorganic sub- stances, using light or chemical energy. ii. Chlorophyll –is the green pigment present in leaves of plants required for the process of photosynthesis. iii. Photosynthesis – is the process used by plants, algae and certain bacteria to harness energy from sunlight into chemical energy. iv. Stomata –are small pores present in leaves guarded by specialized called guard cells SESSION 2. PLANTS USE WATER, AIR AND LIGHT TO MAKE FOOD 32

which help the plant in gaseous exchange. v. Herbarium –is a collection of preserved plant specimens. vi. Micronutrients –are nutrient elements required by the plants in minute quantities for producing food by the process of photosynthesis. 2.3 Key Concepts i. During photosynthesis, green parts of plants use carbon dioxide in the presence of sunlight along with water to make glucose, starch and other food materials. ii. Plants get water and other nutrients dissolved in it from the soil through their roots. iii. The main nutrients needed by plants are nitrogen, potassium and phosphorus. iv. Plants require other nutrients in minute quantities called as micronutrients such as zinc, boron, copper etc. v. Exchange of gases in plants take place through small openings in leaves called as stomata. vi. Transpiration of excess water from the plant body also takes place through stomata present on leaves. vii. Starch is the end product of photosynthesis. viii. Sunlight is necessary for production of starch in plants by the process of photosyn- thesis. 2.4 Conceptual Understanding Q1. A potted plant is kept in light for a day and one of its leaves is tested for starch. The same plant is kept in the dark for two days and another leaf is tested for starch. Will there be a difference in the results of the two experiments? Give reasons for your answer. [Refer to TB page 102 Q1] A. Yes, there will be a difference in the results of the two experiments. i. In the first case, the leaf tests positive for the presence of starch. After being boiled in alcohol and water, the leaf gives blue–black colour when a few drops of iodine solution are added to it. ii. This shows that the formation of starch takes place in the presence of light. SESSION 2. PLANTS USE WATER, AIR AND LIGHT TO MAKE FOOD 33

iii. In the second case, the leaf does not test positive for starch test and does not give blue–black colour on adding iodine solution to it. iv. This shows that starch is not formed in the leaf in the absence of sunlight and confirms that light is essential for photosynthesis. Q2. What happens if leaves of a green plant are coated with oil? [Refer to TB page 102 Q2] A. i. Coating the leaves with oil will negatively affect the growth of plant. ii. Oil closes the stomata present on the surface of leaf which are essential for gaseous exchange. iii. This prevents air containing carbon dioxide from entering the leaf. iv. In the absence of carbon dioxide, photosynthesis does not take place in the leaves of the plant and starch will not be produced and the plant may eventually die. Q3. Name the following: [Refer to TB page 103 Q6](i)) Pores through which leaves exchange gases. A. Pores through which leaves exchange gases are known as Stomata. Q4. Choose the correct answer: [Refer to TB page 103 Q7](iii)) Raw materials involved in the process of photosynthesis (A) Carbon dioxide (B) Water (C) Sunlight (D) All of them A. (D) All of them 2.5 Experimentation and Field Investigation Q1. Collect a leaf. Take peels from both sides of the leaf and observe stomata size, shape and number under microscope. Write your findings. [Refer to TB page 103 Q13] A. Students’ Activity Hints: The size and number of stomata vary depending upon the size and type of leaf. The shape depends on whether the stomata is open or closed. SESSION 2. PLANTS USE WATER, AIR AND LIGHT TO MAKE FOOD 34

2.6 Information Skills and Projects Q1. Designery leaves –Select any broad–leaved potted plant. Cut a cardboard with a design of your choice and seal the selected leaf with the cardboard. Let the plant stand under the sun for a week, then remove the cardboard. You will get designery leaves plant. Try to make more leaves with designs and display your plant but don’t forget to present your write–up. [Refer to TB page 103 Q12] A. Students’ Activity 2.7 Appreciation and Aesthetic Sense, Values Q1. “Photosynthesis is the way the plants make food in every leaf by using different items.” Write your feelings on this. [Refer to TB page 103 Q15] A. The above statement should be reframed as: i. Photosynthesis is the way green plants make food in every leaf using similar items in each leaf. ii. Green leaves possess chlorophyll which is essential for photosynthesis to take place. iii. Other items required for photosynthesis are sunlight, water and carbon dioxide. iv. In the absence of any one of these items, the leaf cannot photosynthesize. SESSION 2. PLANTS USE WATER, AIR AND LIGHT TO MAKE FOOD 35

SESSION 3 OTHER MODES OF NUTRITION IN PLANTS 3.1 Mind Map 3.2 Terminology i. Heterotrophic nutrition –When organisms like humans, animals and some plants like Cuscuta depend on food produced by other plants, the mode of nutrition is termed as heterotrophic nutrition. ii. Haustoria –are special roots developed by parasitic plants which penetrate into the tissues of host plant and absorb food materials from them. iii. Saprophytes –are plants that grow on dead and decaying matter and absorb organic materials from them. iv. Fungi –are saprophytic organisms which do not possess chlorophyll and absorb or- ganic nutrients from decaying matter. v. Insectivorous plants –are plants which prepare their own food but also have the ability to obtain a part of their nutrition from insects by trapping them with their leaves which are specially modified for this purpose. vi. Carnivorous plants – are plants that derive some or most of their nutrients from trap- ping and consuming animals or protozoans, typically insects and other arthropods. vii. Symbiosis –is an association of two or more organisms such that both the groups of organisms benefit from each other. SESSION 3. OTHER MODES OF NUTRITION IN PLANTS 36

viii. Lichens –are colonies of algae and fungi living together in a symbiotic relationship. 3.3 Key Concepts i. Plants which do not possess chlorophyll depend on other organisms for food. This type of nutrition is called heterotrophic nutrition. ii. Cuscuta is a heterotrophic climber which derives food from the host plant through special roots called haustoria. iii. Plants (like fungi) that grow on dead and decaying matter are called saprophytes. iv. Plants which can also derive their nutrition by trapping insects through their specially modified leaves are called insectivorous plants. v. Insectivorous plants fulfill their nitrogen deficiency by trapping insects. vi. Association of two or more organisms such that they mutually benefit each other by sharing food and shelter etc. is called symbiotic relationship. 3.4 Conceptual Understanding Q1. Do you think saprophytes help us in keeping the environment clean? [Refer to TB page 103 Q3] A. Yes, saprophytes help us in keeping the environment clean. • Saprophytes feed on dead and decaying organic matter. • For this, they degrade and break down the decaying plant and animal wastes and remains. • In this way, they derive their nutrition and help the environment to get rid of these wastes, thereby keeping it clean. • The remnants are added to the soil in inorganic forms adding to its fertility. Q2. Name the following: [Refer to TB page 103 Q6](ii), (iii), (iv)) i. Plants that act as scavengers of nature ii. Plants those cannot make their own food and obtain it from host. iii.Those plants that share food and shelter. A. i. Saprophytes act as scavengers of nature. SESSION 3. OTHER MODES OF NUTRITION IN PLANTS 37

ii. Parasitic plants obtain their food from the host plant. iii. Symbionts or symbiotic organisms share food and shelter. Eg. Lichens. Q3. Choose the correct answer: [Refer to TB page 103 Q7](i), (ii)) (i) Cuscuta is an example of (A) Autotroph (B) Parasite (C) Saprophyte (D) Symbiont (ii) Haustoria are (A) Roots (B) Stems C) Leaves (D) All of them A. (i) (B) Parasite (ii) (A) Roots Q4. Circle the insectivorous plant among the plants given below. [Refer to TB page 103 Q8] (a) Hibiscus (b) Teak (c) Nepenthes (d) Aloe vera A. (c) Nepenthes Q5. Why are some plants called insectivorous plants? Give reasons. [Refer to TB page 103 Q11] A. Some plants are called Insectivorous plants because of the following reasons: i. These plants grow in areas deficient in nitrogen. ii. Although autotrophic, they meet their nitrogen requirements by assimilating in- sects. iii. Leaves of these plants are specially modified to trap insects. iv. Hence, these plants are also called insectivorous or carnivorous plants. Drosera, Utricularia, Venusfly trap etc. are some examples. Q6. Prathima said, “Mushroom is also a plant”. Is she correct? How would you support her? [Refer to TB page 103 Q14] A. No, Prathima is not correct. SESSION 3. OTHER MODES OF NUTRITION IN PLANTS 38

• According to the accepted system of classification, Mushrooms belong to king- dom fungi, and not plantae to which plants belong. • They are saprophytic in nature and feed on dead and decaying matter for their nutrition. • Their modes of reproduction are also different. Most plants reproduce through seeds whereas fungi reproduce through spores. • The only similarity between mushrooms and plants is that they both grow in soil. Q7. Fill in the blanks and give reasons. [Refer to TB page 103 Q5](iii)) Saprophytes depend on for food. A. Saprophytes depend on dead and decaying matter for food. Reason: Saprophytes are heterotrophs, i.e. they do not make their own food, but they obtain their nutrients from dead and decaying organic matter. Q8. Differentiate between the following giving examples: [Refer to TB page 103 Q4] (i) Parasite and saprophyte (ii) Host and parasite A. (i) Parasite Saprophyte 1. Parasites derive their Saprophytes obtain their nutrition from living host. nutrition from dead and decaying organic matter. 2. Parasitic plants absorb There are no roots, stem nutrients from the host plants and leaves in through special roots called saprophytes (fungi). haustoria. (ii) SESSION 3. OTHER MODES OF NUTRITION IN PLANTS 39

Host Parasite 1. Host is the Parasites are plants that grow on plant on which hosts. parasites grow. 2. They prepare They do not possess leaves and food through the chlorophyll and depend on host for process of their food which they absorb through photosynthesis. special roots called haustoria by penetrating into the host tissue. 3. Hosts do not Parasite gets food and shelter from the get anything from host, and thus are benefitted. the parasite, thus are not benefitted in any way. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Match the scientists based on their work. Column B [(Session 10.1)] Column A i. Scientist who said plants produce ev- a. Stephen Hales erything from what they take from soil ii. Scientist who proved that plants need b. Joseph Priestley soil and water to grow iii. Scientist who discovered leaves as or- c. Aristotle gans of transpiration iv. Scientist who showed that plants d. Ingenhousz breathe opposite to animals v. Scientist who showed that green parts e. Jan Baptista Von Helmont when exposed to sunlight can breathe CHAPTER 10. NUTRITION IN PLANTS 40

2. Answer the following questions in one sentence. [Refer to Session 10.1 ] (i) What is the process of making food materials in plants called? (ii) What is the green substance present in plants? (iii) What are the plants that make food material by photosynthesis called? (iv) What is the process of exchange of gases called? (v) When animals make the air impure, plants make it . 3. Answer the following questions in one sentence. [Refer to Session 10.2 ] (vi) Why do we add urea to rice fields? (vii) What do we observe when a leaf is placed under a microscope? (viii) Why do we boil leaves in alcohol? (ix) What is a herbarium? (x) Do plants produce only starch? 4. Fill in the blanks. [Refer to Session 10.2 ] (xi) Plants take water from . (xii) Small holes present in the leaves for exchange of gases are called (xiii) Carbon dioxide + Water + Oxygen. CHAPTER 10. NUTRITION IN PLANTS 41

(xiv) To test the presence of starch, we use . Short Answer Type Questions 5. Answer the following questions in 3-4 sentences. (i) [(Session 10.1)] What is transpiration? 6. Answer the following questions in 3-4 sentences. (i) [(Session 10.2)] What are the functions of root, stem and leaves in plants? Long Answer Type Questions 7. Answer the following questions in 6-8 sentences. (i) [(Session 10.1)] Write short notes on the contributions of scientists regarding plants in early days. 8. Answer the following questions in 6-8 sentences. (i) [(Session 10.3)] Write a not on insectivorous plants. AS2-Asking questions and making hypothesis Short Answer Type Questions 9. Answer the following questions in 3-4 sentences. (i) [(Session 10.3)] You want to know more about saprophytes. Prepare a list of questions to know more about saprophytes. Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 10.2)] Do you agree that there are colonies of algae and fungi living together in a symbiotic relationship? Think and state your hypothesis. CHAPTER 10. NUTRITION IN PLANTS 42

AS3-Experimentation and field investigation Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 10.1)] How can you say that plants take nutrients from the soil? Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 10.2)] Show the effect of light on the formation of starch. AS4-Information skills and projects Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 10.1)] Collect information about experiments of Stephen Hales and Ingen- housz from the internet. AS5-Communication through drawing and model making Long Answer Type Questions 14. Answer the following questions in 6-8 sentences. (i) [(Session 10.2)] Draw a neatly labelled and coloured diagram of stomata. AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 15. Answer the following questions in 3-4 sentences. (i) [(Session 10.3)] What do you understand by symbiotic relationship present in some organism? Long Answer Type Questions 16. Answer the following questions in 6-8 sentences. (i) [(Session 10.2)] Sun is called the ultimate source of energy for all living organisms. Comment. CHAPTER 10. NUTRITION IN PLANTS 43

Objective Questions AS1-Conceptual Understanding 17. Choose the correct answer. (i) According to , plants could produce everything from what they take from the soil. (A) Von Helmont (B) Aristotle (C) Priestley (D)Stephen Hales (ii) described the leaves as organs of transpiration. (A) Von Helmont (B) Aristotle (C) Priestley (D)Stephen Hales (iii) demonstrated that what animals were doing to the air was being reversed by plants. (A) Ingenhousz (B) Priestley (C)Von Helmont (D) Aristotle (iv) Carbon dioxide + water (B) Glucose + Ozone + (D)Sucrose + Ozone (A) Glucose + Oxygen (C)Sucrose + Oxygen (v) Plants take water and air through their and . (A) stem, stomata (B) roots, stem (C)lenticels, loose tissues (D)roots, stomata (vi) The presence of the coloured pigment in leaves is essential for photosyn- thesis. CHAPTER 10. NUTRITION IN PLANTS 44

(A) yellow (B) green (C) red (D) black (vii) is present in green leaves. (A) Oxygen (B) Carbon dioxide (C) Chlorophyll (D) Air (viii) Loss of excess water from plant body is called . (A) photosynthesis (B) transpiration (C) respiration (D) assimilation (ix) Plants that grow on dead and decaying matter are called . (A) autotrophs (B) heterotrophs (C) saprotrophs (D) insectivores (x) Parasitic plants develop special roots called . (A) tap roots (B) fibrous roots (C) haustoria (D) lenticels CHAPTER 10. NUTRITION IN PLANTS 45

11. RESPIRATION IN ORGANISMS SESSION 1 INTRODUCTION TO BREATHING 1.1 Mind Map 1.2 Terminology i. Breathing –is the process by which air goes in and out of our body. ii. Inhale –refers to breathing in air, smoke, or gas into our lungs. iii. Exhale –refers to sending air out of our lungs. iv. Inspiration –is the process of breathing in air. v. Expiration –is the process of breathing out air. vi. Respiration rate –refers to the number of times we breathe in and breathe out air in one minute. SESSION 1. INTRODUCTION TO BREATHING 46

1.3 Key Concepts i. The process by which air goes in and out of our body is called breathing. ii. The process of breathing in air is called inspiration, and breathing out air is called expiration. iii. The number of times we breathe in air and breathe out air in one minute is called the rate of respiration. iv. Respiration occurs in all living organisms. 1.4 Conceptual Understanding Q1. What is respiration? How is it different from breathing? [Refer to TB page 111 Q3] A. i. Respiration allows for gas exchange to take place so that oxygen can be absorbed from the lungs into the blood and carbon dioxide is removed from the blood and breathed out from the lungs. It results in the release of energy from the break down of glucose in living cells. ii. Respiration is different from breathing in the following ways: Respiration Breathing 1. Respiration is a process of Breathing is a simple breathing in oxygen and process of taking in processing it to produce energy oxygen and giving out and glucose. carbon dioxide. 2. It is a chemical process. It is a physical process. 3. It occurs in cells of the body. It occurs in lungs. Q2. Select the correct answer and give reasons. [Refer to TB page 111 Q2](i)) (i) The process which involves the exchange of gases is called: a) respiration b) circulation c) digestion d) breathing A. a) respiration SESSION 1. INTRODUCTION TO BREATHING 47

SESSION 2 WHAT HAPPENS DURING BREATHING 2.1 Mind Map 2.2 Terminology i. Expiration rate –refers to the total volume of air expired or exhaled per unit time. ii. Inhale –refers to breathing in air, smoke, or gas into our lungs. iii. Exhale – refers to sending air out of our lungs. 2.3 Key Concepts i. During breathing our chest expands and contracts rhythmically. ii. The air that we breathe in fills our lungs. iii. There is difference in the air that we inhale in and exhale out. iv. Inhaled air is cool while the exhaled air is warm and contains moisture. v. Oxygen is essential for combustion to take place. SESSION 2. WHAT HAPPENS DURING BREATHING 48