Science Diaries: It Narrates the Interesting History of a Discovery Or an Invention Which Is Discussed

Reduce Spine P-324 GSM-70 C M Y K Sp-14.742 mm

Pruquest Science series 1-8 follows interactive and scientific format. The book has an attractive layout to appeal to the children of the respective age group.

The Key Features of the Book: n It draws on the real life experiences of a child through the activities and experiences of central character Manav, his family and friends. These experiences are presented throughillustrations and wide range ofin-text activities . n Precursor: This is the introduction of the chapter that gains instant attention of the child through warm up exercises/ recap of already learned concepts or thought provoking questions. n Activities: This unique feature provides in-text activities in the form of hands-on and practice exercises based on the pedagogy of learning by doing. n Illustrations: Thevibrant illustrations connect the child to the real world and develop basic understanding of the concept. n Sci-Info: Extra bits of interesting information are provided under this which is related to the topic. n Enquire and Discuss: It has questions related to the topic which encourages a child to seek answers not necessarily provided in the book. It generates curiosity and knowledge-seeking attitude in a young learner. n Science Diaries: It narrates the interesting history of a discovery or an invention which is discussed

in the chapter. Science n Pictorial Flow Charts and Table: These have been introduced to make learning easy and interesting. reserved. n Assessment Part: Assessments are spread over a variety of different exercises enabling the learner to revisit the concepts and to think beyond. n Additional Learning Resource: Each book in the series is accompanied by a teachers' resource in the form of a CD and a Manual. iOS rights Rejoice Hindi Hindi Mere Geet ABCD Kids 1234 Kids Joy of Learn Learn Learn and Grow Swarmala Varnmala Rhymes Colours Kids Fruits Kids Vehicles All

Practise ur Reso ce fo tal r ISBN 9789387786752 gi Te i HFI.a D c h e e e r r MBD MBD MBD s MBD MBD F MBD MBD MBD MBD MBD MBD ©MBD 7 MBD MBD 7 9 789387 786752 MBD 2002H0365A5941 MBD MBD An ISO 9001:2015 Certified Company MBD MBD MBD Price : 430.00 7 reserved.

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HFI. © reserved.

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Authors

Ms Veena Tyagi Dr Anusmita Goswamy Ms Suchandrima Chowdhury HFI.M Sc, LLB, BEd, CTET M Sc, MBA, PhD (Botany) M Sc, BEd, PGDID © Authors HOLY FAITH INTERNATIONAL (P) LTD. 7 Ms Veena Tyagi Dr Anusmita Goswamy Ms Suchandrima Chowdhury M Sc, LLB, BEd, CTET M Sc, MBA, PhD (Botany) M Sc, BEd, PGDID

Pru_Sci_G7_FM.indd 1 7 8/9/2019 4:53:42 PM reserved. © All rights reserved We are committed to serve students with best of our knowledge and resources. We have taken utmost care and paid much attention while editing and printing this book but we would beg to state that authors and publishers should not be held responsible for unintentional mistakes that might have crept in. However, errors brought to our notice shall be gratefully acknowledged and attended to.

HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. © All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission of the publisher. Any breach will entail legal action and prosecution without further notice. rights Updated Edition All

HFI. Published by Manik Juneja © HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. HOLY FAITH INTERNATIONAL (P) LTD. Printed at: MBD House, Gulab Bhawan, 6, Bahadur Shah Zafar Marg, M. GULAB SINGH & SONS (P) LTD. New Delhi-110 002 B-5/14, Site IV, Industrial Area, Sahibabad (U.P.)

H0365A5941

Pru_Sci_G7_FM.indd 2 8/10/2019 11:47:21 AM C M Y K

The PruQuest Science series comprises eight textbooks from grades 1 to 8, aligned with the vision and theme of the National Curriculum Framework 2005. The PruQuest Science series aims at nurturing inventiveness, creativity and competence in children. The books of grades 6 to 8 try to achieve this by inculcating the following in learners:

l scientific skills

l scientific values and temperament l awareness and sympathy towards the environmentreserved. In this endeavour, the series includes numerous well-structured activities, hands-on experiments, enquiry-based questions, assignments, creative projects and well-formulated questions, which address the different cognitive levels of children and discourage rote learning. This makes the series not an overload of information but a journey that each student will enjoy as a participant in learning process, rather thanrights being only the receiver of knowledge. The PruQuest Science series has adapted an interactive format and attractive lay out to make the books appealing for the children of the respective age groups. Each book in theAll series is accompanied by a teachers’ resource in the form of a CD and a Manual and a student CD.

HFI. ©

Pru_Sci_G7_FM.indd 3 8/31/2019 5:27:48 PM C M Y K Class-7 C M Y K

Off the Wall: This section presents Key Features interesting extended information related to any scientific concept. The content has been presented in a child-centric manner with the help of the following key features: Science Diaries: This section presents the related history about the discovery or the We Will Explore: This feature presents the learning objectives that are invention. to be covered in the chapter. Precursor: A warm-up exercise in the form of hands-on/practice exercise that connects to the real life or relates to the knowledge previously gained is presented at the beginning of the chapter, through which the child is drawn to the unknown world from the known. Concept Flow: At the end of each chapter, the key concepts and the relations among them are Activity: These are the hands-on activities/ presented in a unique and logical way. experiments that connect the concepts of science to thereserved. real world. Interesting activities are presented in this section in a well-structured Flow Charts, Tables and Graphs: To reinforce learning, format. colourful flow charts, tables and graphs relevant to the concepts are presented wherever possible.

The assessment part is also a learning tool that includes a variety of questions to address different cognitive levels and multiple intelligences in children. This part is divided into six Sci-Info: This section presentsrights the levels, moving from the lowest to the highest order according to the Bloom’s taxonomy. application of scientific concepts in real-life. Check your knowledge: It includes knowledge-/recall-based questions. Think and Apply: This section includes questions where children have to apply the acquired All knowledge/concept to real life. Analyse: This part includes questions in which the children use analysing skills to solve Enquire and Discuss: In this section, students are problems. asked to enquire about some scientific concepts Think Beyond: This part includes questions based on higher-order/critical-thinking skills. that we experience in real-life, discuss open- Values to learn: This part includes activities that help in inculcating life skills and values (self- ended questions or investigate a real-life situation awareness, decision-making, empathy, compassion and respect) in the child. HFI. that leads them to acquire extended knowledge. Create and Learn: This section emphasises on the synthesising skill and creative thinking. CD-ROM: Each book in the series is accompanied by a teacher resource in the form of CD and a © teacher's manual. Teacher’s Corner: It is a guiding tool for the teacher to help the child understand the concept in a better way.

Pru_Sci_G7_FM.indd 4 C M Y K 9/2/2019 4:33:51 PM C M Y K Class-7 C M Y K

Off the Wall: This section presents Key Features interesting extended information related to any scientific concept. The content has been presented in a child-centric manner with the help of the following key features: Science Diaries: This section presents the related history about the discovery or the We Will Explore: This feature presents the learning objectives that are invention. to be covered in the chapter. Precursor: A warm-up exercise in the form of hands-on/practice exercise that connects to the real life or relates to the knowledge previously gained is presented at the beginning of the chapter, through which the child is drawn to the unknown world from the known. Concept Flow: At the end of each chapter, the key concepts and the relations among them are Activity: These are the hands-on activities/ presented in a unique and logical way. experiments that connect the concepts of science to the real world. Interesting activities reserved. are presented in this section in a well-structured Flow Charts, Tables and Graphs: To reinforce learning, format. colourful flow charts, tables and graphs relevant to the concepts are presented wherever possible.

The assessment part is also a learning tool that includes a variety of questions to address different cognitive levels and multiple intelligences in children. This part is divided into six Sci-Info: This section presents the levels, moving from the lowest to the highestrights order according to the Bloom’s taxonomy. application of scientific concepts in real-life. Check your knowledge: It includes knowledge-/recall-based questions. Think and Apply: This section includes questions where children have to apply the acquired knowledge/concept to real life.All Analyse: This part includes questions in which the children use analysing skills to solve Enquire and Discuss: In this section, students are problems. asked to enquire about some scientific concepts Think Beyond: This part includes questions based on higher-order/critical-thinking skills. that we experience in real-life, discuss open- Values to learn: This part includes activities that help in inculcating life skills and values (self- ended questions or investigate a real-life situation awareness, decision-making, empathy, compassion and respect) in the child. that leads them to acquire extended knowledge. HFI. Create and Learn: This section emphasises on the synthesising skill and creative thinking. CD-ROM: Each book in the series is accompanied by a teacher resource in the form of CD and a ©teacher's manual. Teacher’s Corner: It is a guiding tool for the teacher to help the child understand the concept in a better way.

C M Y K Pru_Sci_G7_FM.indd 5 9/2/2019 4:33:54 PM Contents 1. Nutrition in plants...... 1–16

2. Nutrition in animals...... 17–33

3. Animal fibres...... 34–48

4. Heat...... 49–65

5. Acids, bases and salts...... 66–80

6. Physical and chemical changes...... 81–95 7. Soil...... 96–117reserved. 8. Climatic adaptation in animals...... 118–137

9. Respiration in organisms ...... 138–154

10. Transportation of substances in animals and plants...... 155–173 11. Reproduction in plants.rights ...... 174–193 12. Motion and time...... 194–210 13. Electric currentAll and its effects...... 211–225 14. Winds, storms and cyclones...... 226–242

15. Light...... 243–261 16.HFI. Water is precious ...... 262–280 17. Forests: our friends...... 281–298 © 18. Wastewater management ...... 299–313

Revision test 1 to 5 ...... 314-318

Pru_Sci_G7_FM.indd 6 8/31/2019 5:27:55 PM reserved.

rights 1 NutritionAll in Plants HFI.We Will Explore 1.1 Modes of nutrition 1.2 Autotrophic nutrition in plants © 1.3 Heterotrophic nutrition in plants 1.4 Replenishment of nutrients in the soil

...... 1 Nutrition in Plants

Pru_Sci_G7_C01.indd 1 8/3/2019 11:42:55 AM We know that all living organisms need food to survive. Look at the pictures of a few plants and animals. Can you say how these living organisms get their food? Choose the appropriate option from the ones below, and write the correct number in each box.

reserved.

Figure 1.1 Living organisms 1. They prepare their own food. 2. They depend on both plants and animals for their food. 3. They depend only on plants for theirrights food. 4. They depend only on animals for their food. 5. They depend on dead and decaying matter for their food. AllPlants make their food themselves, but animals, including human beings, cannot make their own food. They depend on plants and animals for their food. Some animals depend only on plants and some depend only on animals, whereas some other animals depend on both plants and animals. Saprophytic organisms depend on dead and decaying matter. HFI. Thus, ultimately all living organisms directly or indirectly depend on plants. As discussed, we now know that all living organisms need © food but the mode of taking food and its utilisation in the body are different.

2 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 2 8/3/2019 11:43:00 AM The process through which an organism obtains food and uses it is called nutrition.

1.1 Modes of Nutrition

Living organisms show two types of nutrition: autotrophic nutrition and heterotrophic nutrition.

AUTOTROPHIC NUTRITION

The mode of nutrition in which the organisms make their own food Organisms themselves is called autotrophic (auto means‘self’; trophic means ‘relating to feeding’) nutrition. Such organisms are called autotrophs. Plants make their own food. They are hence examples Autotrophs Heterotrophs of autotrophs. reserved. They make their They cannot make own food their own food HETEROTROPHIC NUTRITION

The mode of nutrition in which animals and most other organisms depend Green plants Animals, parasites and directly or indirectly on green plants saprophytes for their nutrition is called heterotrophicrights (hetero means ‘others’; trophic means ‘relating to feeding’) nutrition. Such organisms are called heterotrophs. Most animals, parasites, saprophytes and decomposersAll that cannot make their own food are examples of heterotrophs.

Enquire and Discuss 1.1 1 Is foodHFI. made in all parts of the plant? 2 We cannot make our food as plants do. Why? 3 What are raw materials and how do the plants obtain the raw materials required for food ©making?

...... 3 Nutrition in Plants

Pru_Sci_G7_C01.indd 3 8/3/2019 11:43:00 AM 1.2 Autotrophic Nutrition in Plants Autotrophs: organisms that make their own food Can you recall what the food factories of a plant and the food- Heterotrophs: organisms making process are called? which depend on other Leaves are the food factories of the plant, and the food-making organisms for their food process of the plant is called photosynthesis. Water and minerals, carbon dioxide, chlorophyll and sunlight are the raw materials ScienceScience DiariesDiariesneeded for photosynthesis. The energy for this process comes from the Sun. During the process, glucose is formed and oxygen is released. This glucose is stored in the form of starch. Starch in leaves indicates the occurrence of photosynthesis.

ScienceScience DiariesDiaries

History of Photosynthesis: In 1893, Charles Barnes (1858–1910) proposed the use of the term photosyntax and, as an alternative, photosynthesis, for the biosynthetic, light-dependent process in green plants through which carbon dioxidereserved. is reduced to organic matter. Later Prof. Conway MacMillan (1898) expressed preference for the word ‘photosynthesis’, which finally came into general use to describe the production of carbohydrates by green tissues under Figure 1.2 Charles the action of light. Reid Barnes Activity 1.1 rights Aim: To show that green plants make their own food. Materials required: A potted plant, iodine solution and a dropper. Procedure: All 1. Select a potted leafy plant, which has been exposed to sunlight for 6–7 hours. 2. Perform the iodine test with any one leaf of the plant.

3. Keep the same plant in the dark for three days. Again perform Figure 1.3 the iodine test with any one leaf. Observation:HFI. What do you notice? Do you find any difference in the colour after the first and the second iodine test? Record your observation. © Conclusion: Colour change after the iodine test confirms the presence of ______. It is hence confirmed that _____ of the plant make food.

4 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 4 8/3/2019 11:43:03 AM Can you think of life on Earth without photosynthesis? There would be no life without photosynthesis. There would not be any food for the survival of living organisms, as all living beings directly or indirectly depend on food that comes from plants.

THE PROCESS OF PHOTOSYNTHESIS

1. The process of using light energy to convert water and carbon dioxide into carbohydrate and oxygen is called photosynthesis. Sunlight Carbon Dioxide + Water Glucose + Oxygen Chlorophyll

Oxygen is released throughreserved. stomata of leaf.

Glucose is produced and stored in the form of starch.

Light energy is trapped Carbon dioxide enters by chlorophyll. through stomata of leaf. rightsMinerals Water and minerals from Water the soil are absorbed by All the roots.

Figure 1.4 Process of photosynthesis 2. Minerals and water are absorbed from the soil through the roots and are carried to the leaves by stems and its Vessels: pipe-like branchesHFI. through vessels which run like pipes. conducting tissues 3. Carbon dioxide enters through tiny pores called stomata Guard cells: a pair of cells surrounding the stoma ©(‘stoma’ for singular) in the leaves. These pores are surrounded by guard cells. Stomata are present on both

...... 5 Nutrition in Plants

Pru_Sci_G7_C01.indd 5 8/3/2019 11:43:05 AM the upper and the lower surface of leaves, but more stomata are present on the lower surface.

Carbon dioxide

Oxygen and water Stoma Guard cell

Figure 1.5 Stoma and guard cells of leaf

4. The green pigment, chlorophyll, is present within the chloroplast. Chloroplasts are structures in the plant cell. The raw materials (carbon dioxide and water) enter the green cells having chloroplastsreserved. in the leaf. 5. Sunlight is captured by the chlorophyll. Its energy is used to convert carbon dioxide and water into food (glucose), and oxygen is released. Glucose is converted into starch, which is an insoluble carbohydrate. 6. Because the synthesis of food occurs in the presence of sunlight,rights it is called photosynthesis (‘photo’means ‘light’; ‘synthesis’ means ‘to combine’). It is a unique process in Allwhich solar energy is converted into chemical energy. CONDITIONS NECESSARY FOR PHOTOSYNTHESIS

Following are the conditions necessary for photosynthesis: • The presence of the green pigment called chlorophyll HFI. • The presence of sunlight • Availability of carbon dioxide © • Availability of water

6 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 6 8/3/2019 11:43:06 AM Enquire and Discuss 1.2 Off the Wall Do you know how You would have noticed that some plants have coloured chlorophyll, stomata and leaves. guard cells are arranged in 1 How does photosynthesis take place in those leaves? a leaf? Observe the cross section of a leaf below. 2 Does photosynthesis take place in the other green parts of the plant than leaves? Chlorophyll

Air space Guard cells Stomata Figure 1.6 Figure 1.7 Cross section of a leaf

Activity 1.2 reserved.

Aim: To show that carbon dioxide is required for photosynthesis. Materials required: A small potted plant, potassium hydroxide solution, a small flask and iodine solution. Procedure: rights 1. Keep the potted plant in a dark room for 6 to 7 hours. 2. Pour potassium hydroxide solution into the flask. Figure 1.8 3. Place one of the leavesAll inside the flask without breaking it. Keep it in sunlight. 4. Using iodine solution, test the leaf in the flask after a few hours. Observation: What do you notice? Upon adding the iodine solution, is there any change in colour? Conclusion:HFI. Potassium hydroxide solution absorbed carbon dixiode. The leaf inside the © flask did not show photosynthesis. So, there was no change in colour.

...... 7 Nutrition in Plants

Pru_Sci_G7_C01.indd 7 8/3/2019 11:43:09 AM Have you ever seen smooth, slippery, green patches in ponds Algae: small simple green or in any stagnant waterbodies? plants They are formed by the growth of some small organisms called algae. They are green in colour, as they contain chlorophyll. Because of the presence of chlorophyll, they prepare their own food by photosynthesis.

SYNTHESIS OF FOOD OTHER THAN CARBOHYDRATES Figure 1.9 Algae in a pond We have learnt that carbohydrates are synthesised by plants through photosynthesis. How do other components of food, such as proteins and fats, get synthesised? Do green plants make other components of food? Let us discuss. reserved. Carbohydrates are made up of carbon, oxygen and hydrogen. They are used to synthesise other components of food. Proteins are nitrogenous substances made up of carbon, nitrogen, oxygen and hydrogen. So from where do plants obtain nitrogen? Although nitrogen is present in abundance in gaseous form, plants cannot absorb it in that form. There are a few nitrogen-fixing bacteria present in soil. They fix the nitrogenrights present in the soil and convert this gaseous nitrogen into a usable form. The soluble nitrogen is then absorbed by plants. Sometimes farmers add nitrogen fertilisers to the soil. Do you know how plants which have no chlorophyll Allsynthesise their food?

1.3 Heterotrophic Nutrition in Plants

There are some plants which do not have chlorophyll, so HFI. they cannot make their own food. Such plants depend on food produced by the other plants to survive. They show heterotrophic mode of nutrition. Plants that follow © heterotrophic mode of nutrition are called heterotrophic plants. Parasitic plants, saprophytic plants, insectivorous plants and symbiotic plants are heterotrophic plants. 8 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 8 8/3/2019 11:43:10 AM Parasitic plants Host: the organism that provides food and shelter to Saprophytic plants the parasite Heterotrophic plants Insectivorous plants

Symbiotic plants

PARASITIC PLANTS

The plants that partially or completely depend on other plants (a) Cuscuta (dodder) plant (host) for their nutrition are called parasitic plants.

Look at Figure 1.10. The yellow tubular structure twining around the stem and the branches is a plant called Cuscuta (dodder). Cuscuta does not have chlorophyll and is a complete reserved. parasite, as it is completely dependent on the host plant. Another plant (sandalwood tree) is also a parasite, but it is a partial root parasite that attaches to the roots of other trees. (b) Sandal wood tree In a parasitic relationship, only the parasitic plant benefits. It Figure 1.10 (a) and (b) harms the host plant.

Enquire and Discuss 1.3 Sci-Info rights Fungi were earlier considered We and all animals directly or indirectly depend on plants for to be plants. But now it is kept under separate food. kingdom ‘fungi’. They have 1 Are we all parasites? Discuss in the class. a different mode of nutrition. 2 Give a few examples of animalAll parasites in your surroundings. They secrete digestive juices on the dead and decaying matter and convert it into a SAPROPHYTIC PLANTS solution. Then they absorb the nutrients from it. This Saprophytic plants obtain their nutrition from the dead and mode of nutrition in which decaying plant and animal matter. These plants often have no organisms take in nutrients leaves at HFI.all. They are usually whitish, but some have bright in the form of solution from coloured flowers. TheIndian pipe and coral roots are examples dead and decaying matter is called saprotrophic nutrition. of such plants. The roots of such plants contain fungi. The Plants which use saprotrophic fungi© convert dead and decaying matter into nutrients. Fungi mode of nutrition are called are also called saprotrophs. saprotrophs.

...... 9 Nutrition in Plants

Pru_Sci_G7_C01.indd 9 8/3/2019 11:43:11 AM (a) Indian pipe (b) Coral root Figure 1.11 (a) and (b) Activity 1.3

Aim: To grow and observe fungi at home. Materials required: A piece of bread and water. Procedure: reserved. 1. Take a piece of bread and sprinkle a few drops of water to moisten it. Figure 1.12 2. Cover it with a plastic bag. 3. Keep it in a warm moist place (away from sunlight) for a few days. Observation: You will see some patches (green, blue and violet) appear on the bread. Conclusion: The patches in the breadrights are due to the growth of ______. SYMBIOTIC PLANTS AllSome plants live in association with other organisms, in which both the partners mutually gain from each other. This kind of association is called symbiosis. Such plants are called symbiotic plants. Certain fungi live in the roots of the trees. The tree provides nutrients to the fungus. In return, fungus helps in taking certain useful nutrients from the soil. Thus HFI. both help each other. Mycorrhizal root is a good example of this relationship. Lichen is another example of a symbiotic plant. It is an © association between alga (chlorophyll-containing partner) and fungus. The alga provides food by photosynthesis, whereas fungus helps in providing shelter to alga. 10 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 10 8/8/2019 3:11:16 PM INSECTIVOROUS PLANTS

Do you know some plants eat certain small animals? There are a few plants which have special adaptations to obtain nutrients from small animals such as insects. These are called insectivorous plants. These plants are typically found at places where the soil is deficient in nitrogen-containing minerals. Their ability to capture insects using specially (a) Mycorrhizal roots modified structures and derive nitrogen-containing nutrients helps them survive on such soil. These can also be considered carnivorous as these plants derive a part of their nutrition from animals. These plants also have chlorophyll to conduct photosynthesis. So, insectivorous plants are both autotrophic as well as heterotrophic in nature.

(b) Lichen Figure 1.13 (a) and (b) reserved.

rights Pitcher plant showing lid Venus flytrap

The leaves of this plant are modified to form a pitcher- The leaves of this plant are modified to trap like structure. When an insect lands in the pitcher, insects. The inner surface of the leaves have stiff the lid closes and the trapped insect gets entangled hair. When an insect touches the hair, the leaves into the hair inside it. The insectAll is digested by the snap shut within a second. The insect is digested digestive juices secreted in the pitcher. within. Figure 1.14 1.4 Replenishment of Nutrients in the Soil Replenish: to fill up again Do you knowHFI. why fertilisers and manures are added to the soil? Fertilisers and manures are used to replenish the nutrients in the soil. Let us discuss replenishment of nutrients in the soil. We© know that the plants absorb water and nutrients from the soil. The amount of nutrients in the soil keeps on declining in the due course of time. So the nutrients need to be added from ...... 11 Nutrition in Plants

Pru_Sci_G7_C01.indd 11 8/3/2019 11:43:16 AM time to time to avoid depletion of certain nutrients. If we fulfil the nutrient requirement, we will be able to grow healthy plants. Usually most crops require a lot of nitrogen to make proteins. Plants cannot use the nitrogen gas directly which is present in maximum amount in air. They need nitrogen in soluble form.Certain bacteria (Rhizobium) with the help of roots of some legume-type plants fix the atmospheric nitrogen into the soil in soluble form. Most of the pulses (dals), such as mung, gram, beans and peas, are leguminous plants. Thus bacteria help in fixing nitrogen, and in return, leguminous plants provide food and shelter to the bacteria. Now, can you say what this type of relationship is called? It is called symbiotic relationship. Concept F L O reserved.W To grow healthy plants, we need to fulfil the nutrient requirement of plants. This is called replenishment of nutrients in the soil.

Parasitic plants Nutrition in Plants The plants that partially or completely depend on other plants for their nutrition Autotrophic Nutrition rightsHeterotrophic Nutrition are parasitic plants. Example: dodder plant

Green plants: They Insectivorous plants Non-green Saprophytic plants have chlorophyll The plants that eat plants: They and they make their All depend on The plants that obtain insects and digest their nutrition from own food through them are insectivorous food made by photosynthesis. other plants, dead and decaying plants. Example: Venus plant or animal matter flytrap on animals, or on dead are saprophytic plants. and decaying Example: coral root matter. HFI. Symbiotic plants Insectivorous plants The plants that live in The plants that are capable of capturing association with other and digesting insects to derive organism and both get © nitrogenous nutrients from them are benefit from each other called insectivorous plants. are called symbiotic plants. Example: lichen 12 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 12 8/3/2019 11:43:16 AM ...... Check Your Knowledge 1. Write T for the true and F for the false statements. (a) Green plants are called autotrophs. (b) During photosynthesis light energy is converted into chemical energy. (c) Carbon dioxide is released during the process of photosynthesis. (d) The food prepared by the plant is stored as glucose. (e) Mycorrhizal root is a good example of a parasitic plant.

2. Give one word for the following: (a) An organism living on dead and decaying matter. (b) The leaf is modified to form a structure having a lid to capture insect. (c) The association where both the partners mutually gain from each other. (d) The food component which is made up of nitrogen, carbon, hydrogen and oxygen. (e) A plant that shows both autotrophic and heterotrophic reserved.mode of nutrition. 3. Match the columns.

A B Complete parasite Lichen Symbiotic plant Indian pipe Saprophytic plant Venus flytrap Insectivorous plant rightsDodder

4. Give two examples of each. (a) parasitic plants All (b) insectivorous plants (c) saprophytic plants

5. Why do insectivorous plants eat insects? 6. Give HFI.a brief description of the process of photosynthesis in green plants. 7. Explain the difference between (a) parasites and saprophytes ©(b) autotrophs and heterotrophs

...... 13 Nutrition in Plants

Pru_Sci_G7_C01.indd 13 9/2/2019 10:15:22 AM 8. What are the conditions necessary for the process of photosynthesis?

9. How do you define a parasitic plant? Explain with example.

10. What do you mean by the replenishment of nutrients? Why this is important?

11. Look at Figure 1.15. A (a) What does the figure show? (b) Label the parts that are marked. B (c) Mention two ways in which they are useful to plants. C

Figure 1.15 ?...... Think and Apply 1. Tick the correct option. (a) Which of the following is a saprotroph? reserved. (i) a lichen (ii) a pitcher plant (iii) a mushroom (iv) a dodder plant

(b) Parasites are the organisms that (i) cannot make their own food (ii) harm the organisms they live in (iii) live on other organisms (iv) all of the above (c) Which of the following structurerights is involved in both photosynthesis and transpiration process? (i) guard cells (ii) stomata (iii) chlorophyll (iv) petioles (d) What is common betweenAll lichen, mycorrhizal root and leguminous plants? (i) All of them have symbiotic association

(ii) All are parasites

(iii) All of them trap insects (iv)HFI. All depend on dead matter for their food (e) A farmer wants to grow legume crops after harvest of wheat crop. Which of the © following plants should he choose for rotation? (i) rye (ii) oat (iii) rice (iv) mung bean

14 ...... Pruquest Science VII

Pru_Sci_G7_C01.indd 14 9/2/2019 10:15:24 AM 2. What would happen (a) if plants do not possess chlorophyll? (b) if there is no exchange of gases in plants?

3. Categorise the following plants according to their mode of nutrition: Venus flytrap plant, China rose plants, dodder plants, leguminous plants, coral roots, bread mould, banana plants, croton plants, sundew plants...... Analyse Light energy 1. Observe Figure 1.16. Photosynthesis occurs in the leaf of the plant, but we get stored food from its root. Analyse and answer. Glucose Oxygen 2. Observe Figure 1.17. The leaves of this plant have Carbon tentacles-like structure. Each tentacle produces a sticky substance. reserved.dioxide Water

rights Figure 1.16

Figure 1.17 Can you analyse the roleAll of tentacles and the sticky substance? 3. Why do farmers grow leguminous plants (pulses) alternately with other crops?

...... HFI.Think Beyond

1. We cook our food by using different ingredients. Why are we not called autotrophs? ©2. What would happen if there is no stoma on leaves? 3. How does energy flow occur in our ecosystem?

...... 15 Nutrition in Plants

Pru_Sci_G7_C01.indd 15 9/2/2019 10:15:27 AM ...... Values to Learn (Moral)

One day Manav saw a greenish white growth on an orange kept in the fruit basket (Figure 1.18). Manav tried to peel it, but her mother stopped him and advised him not to eat it. 1. What was the greenish white growth on the orange? 2. Write the mode of nutrition exhibited by greenish white patches. Figure 1.18 3. Why did Manav’s mother stop him from eating the orange? ...... Create and Learn 1. Make a model to show the opening and the closing of stomata.

Requirements: Procedure: 1. Two long balloons 1. Take two balloons and inflatereserved. them 2. Straws half (40% – 50%). 3. Glue 2. Tape the inflated balloons and tie them on the construction paper and glue the 4. Construction paper inside ends of balloons. Stoma open 3. Take two same balloons and inflate them fully. 4. Tape the inflated balloons and tie them on the constructionrights paper and glue the balloons to the upper and the lower inner parts leaving an opening in the Stoma closed Allmiddle. Figure 1.19 2. Make a list showing useful and harmful effects of fungi. You can collect data from the Internet.

Teacher’s Corner

1. HelpHFI. the students know the conduction of water and minerals, demonstrating an experiment. ©2. Make them understand the importance of photosynthesis.

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Pru_Sci_G7_C01.indd 16 9/2/2019 10:15:28 AM reserved.

rights 2 NutritionAll in Animals HFI.We Will Explore 2.1 The mode of taking food 2.2 Nutrition in Amoeba © 2.3 Nutrition in humans 2.4 Nutrition in grass-eating animals

...... 17 Nutrition in Animals

Pru_Sci_G7_C02.indd 17 8/8/2019 4:34:02 PM We have learnt that all animals are heterotrophic. They cannot prepare their own food. They are dependent on plants directly or indirectly for their food. They consume ready-made food in the form of complex food components. Do you know what such food components are called? Look at the picture. Identify and write the name of food components in the boxes provided below the pictures.

reserved.

rights

AllFigure 2.1 Food components Carbohydrates, fats, proteins, vitamins and minerals are the complex food components that cannot be utilised in the body unless they are broken down into simpler substances. The process of breaking down of complex food components into simpler forms is called digestion. HFI. Do you know the steps involved in the process of digestion? The first step of taking in food or eating is calledingestion . This © is followed by digestion. The digested food is then absorbed in the wall of the small intestine, and this process is called absorption. The absorbed food is then used up by the cells 18 ...... Pruquest Science VII

Pru_Sci_G7_C02.indd 18 8/3/2019 12:17:52 PM for growth and other functions. This is called assimilation. Finally, the undigested food is discharged from the body through a process called egestion. These steps take place in all animals, whether they are simple, single-celled, highly complex or multi-celled animals.

Ingestion Digestion Absorption Assimilation Egestion

Figure 2.2 Steps of nutrition in animals Thus, animal nutrition includes nutrient requirement, mode of taking food, and its utilisation in the body. Let us discuss the different ways of taking food.

2.1 The Mode of Taking Food

The ways of taking in or ingesting food into the body vary from organism to organism. Some small insects, such as reserved. bees and butterflies, have special mouthparts to suck nectar from plants. Smaller animals, such as Hydra and Paramecium, use their tentacles and cilia, respectively, for ingesting food. Snakes swallow their food whole. The beak of a bird helps it to catch its food. Human beings and some other mammals take in food through their mouth. Some water animals filter small food particles floating and feed rightson them. All

HFI. ©

Figure 2.3 Different modes of food intake ...... 19 Nutrition in Animals

Pru_Sci_G7_C02.indd 19 8/3/2019 12:17:57 PM Enquire and Discuss 2.1

Observe some animals in your surroundings. Write the type of food and mode of taking food (sucking, swallowing, chewing, etc.) of such animals.

Name of Animal Type of Food Mode of Taking Food

Thus, we have learnt that the mode of taking in or ingesting food is different in different animals, although the basic process Sci-Info of digestion is the same in all animals. However, there are Do you know how starfish many small microscopic animals which do not have a mouth gets its food? and a proper digestive system. Let us learn an interesting way of food intake and digestion in reserved.the simplest animal.

2.2 Nutrition in Amoeba

Do you know what is Amoeba and where it is seen? Amoeba is a microscopic single-celled animal found in ponds and ditches. It has a cell membrane, round nucleus, and many small bubble-likerights vacuoles in its cytoplasm. These vacuoles Figure 2.4 are called food vacuoles. Most Amoebas have a contractile The starfish finds its food vacuole which helps them to expel excess water from the cell. by using the tips of its legs. When it finds food, it wraps Contractile the food around the backside All vacuole of its body. Its stomach comes Cell out through its mouth to eat membrane the food. Then it goes back Food into the body, and the food is vacuole digested. HFI. Cytoplasm (digests food) © Pseudopods Nucleus Figure 2.5 Amoeba 20 ...... Pruquest Science VII

Pru_Sci_G7_C02.indd 20 8/3/2019 12:17:59 PM Amoeba constantly changes its position and shape. It pushes out one or more finger-like projections called pseudopodia for moving and capturing food.

FEEDING IN Amoeba

Amoeba feeds on small microscopic organisms found in waterbodies. It pushes out its pseudopodia when it senses its food. Pseudopodia completely enclose the food, resulting in the formation of a cavity called food vacuole. Digestive juices are secreted into the food vacuole. They act on the food and break it down into simple substances. The digested food is absorbed and assimilated through the cell. The undigested food is discharged outside by the cell membrane.

1 2 3 reserved.

Amoeba senses Pseudopodia The food is enclosed its food . surround the food. in a food vacuole.

4 5 6 rights Digestion occurs inside Digested food is absorbed Undigested waste is the food vacuole. and assimilated. expelled. AllFigure 2.6 Nutrition in Amoeba 2.3 Nutrition in Humans

Do you know what happens to the food inside our body? The food passes through a continuous canal which begins at the mouth cavity and ends at the anus. This canal is called the alimentaryHFI. canal or the digestive tract. It is divided into various parts, mouth or oral cavity, food pipe or oesophagus, stomach,© small intestine, large intestine, rectum and anus. Other than the parts mentioned earlier, various glands, such as salivary glands, the liver and the pancreas, are also ...... 21 Nutrition in Animals

Pru_Sci_G7_C02.indd 21 8/3/2019 12:18:00 PM Mouth cavity Oesophagus

Liver Stomach Gall bladder Pancreas Large intestine Small intestine Rectum Anus

Figure 2.7 Human digestive system Figurereserved. 2.8 Alimentry canal, along with liver, gall bladder and pancreas

associated with our digestive system, though they are not the parts of our alimentary canal. These glands secrete digestive juices that convert complex food particles to simpler form. Thus our alimentary canal and the associated glands together constitute digestive system. Now let us learn different steps of the digestionrights process in detail. INGESTION: The process of taking food into the body is called ingestion. Food enters the body through our mouth. We chew the food by using our teeth. We have different Alltypes of teeth that help us in breaking down our food into small pieces. Can you see the arrangement of teeth in following figures? Which type of teeth do you have right now? Human beings develop two sets of teeth in their lifetime: milk teeth or temporary teeth (Figure 2.9a) and adult teeth HFI. or permanent teeth (Figure 2.9b). Around the age of 5 to 6 years, the milk teeth start falling out. These are replaced by © permanent teeth. Milk teeth are 20 in number (10 in each jaw) and permanent teeth are 32 in number (16 in each jaw).

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Pru_Sci_G7_C02.indd 22 8/3/2019 12:18:02 PM Incisors (2) Incisors (2) Canine (1) Canine (1) Premolars (2) Upper teeth Molars (2) Molars (3) Wisdom tooth

Lower teeth

Figure 2.9a Milk teeth Figure 2.9b Permanent teeth reserved. Activity 2.1

Aim: To observe, locate and know the functions of different types of teeth. Procedure: rights 1. Look into the mirror. Open your mouth. 2. Observe both the upper and lower jaws. Count the number of teeth.All 3. Eat a small piece of carrot. Observe the steps of Figure 2.10 biting, piercing and chewing.

Observation: Are the number of teeth in both the jaws the same or different? Note down the number. While eating, name the teeth used for biting, used for tearing, and those used forHFI. grinding and chewing. Compare your observations to the text you have studied before. ©

...... 23 Nutrition in Animals

Pru_Sci_G7_C02.indd 23 8/3/2019 12:18:05 PM We have four different types of teeth. These have different structures which are best suited for different functions. These are summarised in the table below: Types of Teeth Number Shape Function Incisors Eight These have flat, These help (or biting teeth) (Four each in sharp and chisel- in biting and upper and lower shaped ends. cutting the food, jaws) for example Incisor biting an apple. Canines Four These have sharp These help in (or tearing teeth) (Two each in and pointed tearing tough upper and lower edge. food items, for jaws) example tearing meat from the Canine bone. Premolars Eight These have broad These help in (or grinding (Four each in and flat surface grinding and teeth) upper and lower withreserved. small chewing the jaws) humps on it. food. Premolar Molars Twelve These are bigger These help in (or crushing and (six each in upper than premolars further grinding grinding teeth) and lower jaws) and have broad, and crushing the flat surface with food. Molar rightssmall humps on it. Tooth decay is a common problem among individuals. If we do not clean our teeth and mouth properly, the bacteria present in our mouth begin to live and grow in it. These bacteria break down the sugars present in leftover food and release acids. This acid gradually damages theAll teeth causing a hole in the cavity. This is called tooth decay. If it is not treated in time, it causes severe toothache and even tooth loss. Therefore, we should clean our teeth twice a day and rinse the mouth after every meal. Oral health is an important aspect of our body. We should visit a dentist every six months. We should minimise eating sugar products, such as chocolates, ice creams and soft drinks, to avoid tooth decay. HFI.

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Pru_Sci_G7_C02.indd 24 8/3/2019 12:18:09 PM Discuss 2.2 Saliva: a watery liquid Enquire and secreted in the mouth Can you recall what are the functions of our tongue? Make a Amylase: an enzyme found list of those functions. in saliva and pancreatic fluid

Off the Wall Saliva is a mixture of a slimy substance called mucus and an enzyme called amylase. Enzymes are chemicals produced by the cells of an organism. The enzyme amylase breaks down the starch in food into sugar. This is the first step of digestion of food.

The food is chewed in the mouth till it is soft and pulpy. The tongue pushes the food while it is being chewed. The food particles are mixed with liquid called saliva, which is produced in the salivary glands present in our mouth. Do you know the function of saliva? Let us try to understand about it. reserved. The Activity 2.2 shows that the process of digestion starts in the mouth itself. Activity 2.2

Aim: To know the action of saliva on food. Materials required: A piece of boiledrights potato, two test tubes, iodine solution and a dropper.

Procedure: X Y 1. Take two test tubes.All Label them X and Y. 2. In test tube X, put the smashed boiled potato, and in test tube Y, put the boiled potato after chewing properly for 4 minutes. Add little water in both the test tubes. Figure 2.12 3. Add a few drops of iodine solution in both the tubes with the help of dropper. Observation:HFI. What do you notice? Is there any change in colour in the test tubes? Note down your observation. Conclusion: Test tube X shows _____ colour whereas test tube Y shows_____. The © saliva in test tube Y breaks down starch into sugar.

...... 25 Nutrition in Animals

Pru_Sci_G7_C02.indd 25 8/3/2019 12:18:10 PM Besides mixing saliva with food during chewing and swallowing, tongue has taste buds that detect different taste Sci-Info of food. Now recall the parts of our body that help in the Sometimes while eating in ingestion process. They are mouth, teeth and tongue. a hurry, we get hiccups. It occurs when the food particles DIGESTION enter the windpipe. The windpipe runs adjacent to our food pipe, and inside the throat the Let us discuss the roles of other parts of the alimentary canal passage is common for air and in the process of digestion. food. A flap-like valve called The oesophagus: Once swallowed, the food passes into the epiglottis closes the passage of food pipe or oesophagus (Figure 2.7). The food pipe runs the windpipe. This prevents along the neck and the chest. It lies behind the windpipe. The from choking of food while swallowing. walls of the food pipe produce a wave-like movement. These movements help move the food into a large bag-like organ called the stomach. The stomach: Further digestion of food takes place in the stomach. The stomach is the widest part of alimentary canal. At one end, it receives food fromreserved. the food pipe, and at the other end, it opens to the small intestine. The inner lining of the stomach secretes mucus, hydrochloric acid and digestive juices. The hydrochloric acid kills the bacteria in the food and Figure 2.13 Stomach provides an acidic medium for the enzymes to work. The digestive juices contain a protein-digesting enzyme called pepsin. This enzyme breaks down the protein into simpler Pepsin: a chief digestive substances. The mucus protects the walls of the stomach from enzyme in the stomach, the actionrights of digestive enzymes and acid. Inside the stomach, which breaks down proteins the food is turned into a semi-solid creamy liquid. It then passes into the small intestine.

ScienceScience DiariesDiariesAll A hole in the stomach enabled scientists to know digestion. In 1882, Alexis St Martin, a 20-year-old young man was accidentally shot. This left him with a large hole in his stomach. He was looked after by a surgeon called William Beaumont. The doctor saved him, but he could not close the hole properly andHFI. left it bandaged. Beaumont took it as a great opportunity to see the inside of the stomach through the hole. He found that the stomach was churning food. Its wall secreted a kind ©of fluid which could digest the food. He also observed that Figure 2.14 the end of the stomach opens into the intestines only after the digestion of the food inside the stomach is completed.

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Pru_Sci_G7_C02.indd 26 8/3/2019 12:18:12 PM The small intestine: The small intestine is highly coiled and is about 8-metre long. It receives secretions from liver and pancreas. In addition, its wall also secretes some juices containing enzymes. The partly digested food reaches the lower part of the small intestine where the intestinal juice completes the process of digestion of all components of food. • The carbohydrates are changed into simple sugars. • The fats get changed into fatty acids and glycerol. • The proteins are changed into simpler chemicals called the amino acids.

Role of the liver, the pancreas and the gall bladder in digestion. Liver: It is the largest reddish brown organ in the human body. It is situated near the stomach. It secretes bile juice which is secreted in a sac called gall bladder. The bile plays an important role in the digestion of fats. Bile also neutralises the acid from the stomach and reserved. makes the food basic. Pancreas: It is a creamy coloured gland located just below the stomach. It secretes pancreatic juices that act on carbohydrates, fats and proteins and change them into simpler forms. Figure 2.15 Liver, pancreas and gall bladder

rights Bile: a bitter fluid helps in digestion and is secreted by the liver

Off the WallAll Gastritis and acidity are two common disorders related to the stomach. Gastritis: It is an inflammation of the lining of the stomach. It can occur suddenly or gradually. It can be caused because of infections by bacteria and virus or because of use of certain medications, such as aspirin. If it is left untreated, it can lead to loss of blood and stomachHFI. cancer. Symptoms of gastritis vary among individuals but most common symptoms include abdominal pain, vomiting and indigestion. Acidity: Have you ever felt a burning sensation in your stomach part? It is the sign of ©acidity. Acidity is a regular and natural process. Our stomach produces acid to digest the food we eat, but the problem of acidity occurs when large amount of acid is produced than our stomach needs. When this happens, we suffer from acidity.

...... 27 Nutrition in Animals

Pru_Sci_G7_C02.indd 27 8/3/2019 12:18:12 PM ABSORPTION

The digested food then passes into the blood vessels in the wall of the intestine. This process is called absorption. Role of the small intestine: The inner lining of the small intestine has finger-like projections called villi. Do you know the role of villi in the intestine? Villi increase the Figure 2.16 Villi in intestine surface area for absorption of digested food. They are richly supplied with thin-walled blood vessels. The surface of the villi absorbs the digested food materials. Thus nutrients present in these fine blood vessels are absorbed into blood.

ASSIMILATION Villi: finger-like projections which emerge from the wall The nutrients are absorbed in thereserved. blood and are transported of the intestine to the rest of the body. The absorbed food is used by the body Amino acids: end products to build new cells to repair old cells and to provide energy of protein digestion and the for various life processes. This is called assimilation. The final building blocks for synthesis product of carbohydrates, that is, glucose, is broken down of new proteins into carbon dioxide and water to release energy. Amino acids Glycerol: a colourless, are used for the growth of cells, and fatty acids and glycerol viscous liquid and structural act as energy reserves and are stored for further use. The food component of fats and lipids that remainsrights undigested and unabsorbed enters into the large intestine.

EGESTION

AllThe removal of undigested food or faecal matter through the anus is called egestion. Role of the large intestine: The large intestine is wider and shorter than the small intestine. Its function is to absorb water and some salts from the undigested food. No digestion takes place in the large intestine. The remaining waste passes into HFI. the rectum as semi-solid faeces. Role of the rectum: The rectum acts as a temporary storage for © faeces before being discharged out. It terminates in the anus. Role of the anus: The faecal matter is discharged through anus from time to time. This is the process of egestion. 28 ...... Pruquest Science VII

Pru_Sci_G7_C02.indd 28 8/3/2019 12:18:14 PM Off the Wall Diarrhoea is usually a symptom of an infection in the intestinal tract, which can be caused by a variety of bacterial, viral and parasitic organisms. Infections spread through contaminated food or drinking water or from person to person as a result of poor hygiene. The most severe threat posed by diarrhoea is dehydration. During diarrhoea, water and chemicals (sodium, chloride, potassium and bicarbonate) are lost through liquid stools, vomit, sweat, urine and breathing. Dehydration occurs when these losses are not replaced. Severe dehydration results in death if fluids and electrolytes are not replenished in the body, either through the use of oral rehydration salts (ORS) solution or through an intravenous drip.

2.4 Nutrition in Grass-eating Animals

Have you ever seen a cow chewing continuously? Why do they do so? Cows and some grass-eating animals swallow their food after chewing once. They store the half-chewed food in a part of stomach called rumen. This partly digested food is called cud. Later they bring back the swallowed food (cud) into the reserved. mouth and chew it again. This process in grass-eating animals is called rumination. Therefore, the grass-eating animals are called ruminants. Their digestive system is different from Cellulose: an insoluble ours. They have a unique way of digesting large amount of carbohydrate cellulose in their food, as grass is rich in cellulose. INGESTION rights Ruminants have sharp incisors and large molars to bite and chew grass. DIGESTION All After being chewed once, the food passes to the stomach through the long oesophagus. The stomach of ruminants has the following four chambers: rumen, reticulum, omasum and abomasum. The food passes through all the four chambers. From here onwards,HFI. the digestion, absorption, assimilation and egestion are the same as in the other animals. As© discussed earlier, we have studied that the basic process of digestion of food and release of energy is the same in all the animals...... 29 Nutrition in Animals

Pru_Sci_G7_C02.indd 29 8/3/2019 12:18:14 PM Rumen Abomasum Rumen: It is the first and the largest Omasum Reticulum chamber of stomach. The partially digested food (cud) is stored here. The cud is then brought back to the mouth and rechewed.

Reticulum: This is the second chamber and it helps in bringing back the swallowed food into the mouth for further chewing. It opens into the omasum.

Omasum: This is the third and the smallest Oesophagus chamber. It absorbs excess water. Intestine Anus Abomasum: This is the last chamber of the stomach. The walls of abomasum secrete digestive juices. Figure 2.17 Digestive system of a ruminant Concept F L O Wreserved. The basic process of nutrition involves five stages. Nutrition in Animals

Processes Nutrition in Nutrition in human Nutrition in grass- Involved Amoeba rightsbeing eating animals Ingestion Pseudopodia Mouth Mouth

Mouth, stomach and Mouth, four- Digestion FoodAll vacuole small intestine chambered stomach and small intestine

Total body Small Small Absorption (single cell) intestine intestine

Total body Absorbed nutrients Absorbed nutrients AssimilationHFI. (single cell) are transported are transported through blood for through blood for © energy and growth. energy and growth. Egestion Cell membrane Anus Anus 30 ...... Pruquest Science VII

Pru_Sci_G7_C02.indd 30 8/3/2019 12:18:16 PM ...... Check Your Knowledge 1. Write T for true and F for false. (a) Ruminants are grass-eating animals. (b) In human beings, the process of digestion starts in the liver. (c) Bile is stored in the pancreas. (d) Amoeba captures its food through its mouth. (e) Canines are used for grinding and chewing. 2. Write one word for the following: (a) a fleshy muscular organ present in our mouth (b) the finger-like projection found in Amoeba for movement and to capture food (c) the intake of food into the body (d) the digestive juice secreted by the liver (e) the enzyme found in saliva secreted in the mouth 3. Give one example for each of the following: (a) an animal having four-chambered stomach reserved. (b) a gland that secretes juice containing fat-digesting enzymes (c) a juice that acts only on carbohydrates (d) an enzyme helps in digesting protein food (e) type of teeth which help in biting 4. Differentiate between (a) incisors and molars (b) small intestine and large intestine (c) ingestion and egestion 5. Explain the following terms: rights (a) villi (b) absorption (c) assimilation (d) rumination 6. Name the five stages involved in the process of digestion. 7. Discuss nutrition in AmoebaAll with the help of a diagram. F B A 8. Briefly describe the process of digestion and assimilation in human beings. C 9. Explain the process of digestion in grass-eating animals. D E 10. Identify and label the parts of the animal in Figure 2.18. ?...... ThinkHFI. and Apply Figure 2.18 1. Tick the correct option. ©(a) Which option shows the correct order about nutrition of animals? (1-assimilation; 2-egestion; 3-ingestion; 4-absorption; 5-digestion) (i) 1-2-3-4-5 (ii) 3-5-4-1-2 (iii) 3-5-1-2-4 (iv) 3-5-2-1-4 ...... 31 Nutrition in Animals

Pru_Sci_G7_C02.indd 31 9/2/2019 10:17:08 AM (b) What is common in the following: bile, digestive juice and pancreatic juice? (i) All are organs of digestion. (ii) All of them help in the digestion of fat. (iii) All of them are enzymes. (iv) All of them contain enzymes that help in digestion. (c) Change of shape and position is frequent in Amoeba. It is due to (i) pseudopodia. (ii) food vacuole. (iii) contractile vacuole. (iv) cell membrane. (d) The teacher asked a few students the name of the teeth from back of the mouth to the front in correct order and their numbers. She got four answers. Which of the following shows correct order? (i) 3 incisors, 1 canine, 1 premolar, 2 molars (ii) 2 incisors, 2 canines, 3 premolars, 2 molars (iii) 3 molars, 1 premolar, 2 canines, 1 incisor (iv) 3 molars, 2 premolars, 1 canine, 2 incisors (e) Which of the following is incorrectly matched? (i) pancreas–bile (ii) saliva–amylase (iii) intestine–absorption (iv) liver–bile 2. Think and explain why (a) we cannot use our incisors for chewing. (b) the food moves in opposite direction during vomiting. reserved. (c) we cannot digest cellulose like the cattle do. (d) the wall of the stomach is not digested by its own enzymes. 3. Arrange the following organs in proper order as they are found in alimentary canal and write the major role played by them in digestion. Oesophagus, large intestine, stomach, mouth, rectum, small intestine, anus 4. Find the odd one from the following groups. (a) liver, pancreas, gall bladder, stomachrights (b) molar, canine, incisor, rumen (c) carbohydrate, bile, protein, fat ...... Analyse All 1. A girl of five years is asked to count her teeth (Figure 2.19). (a) The total number of teeth would be ______. (b) Name the kind of teeth she has. (c) What kind of teeth are missing in her mouth? Figure 2.19 2. You areHFI. given four types of solution. 1 (a) sugar solution (b) salt solution (c) tamarind (imli) juice (d) bitter gourd juice 2 ©If you taste these solution separately closing your eyes, which areas of 3 your tongue could detect the sweet, salty, sour and bitter substances. Label 1, 2, 3 and 4 in Figure 2.20. 4 Figure 2.20 32 ...... Pruquest Science VII

Pru_Sci_G7_C02.indd 32 9/2/2019 10:17:09 AM ...... Think Beyond

1. We eat glucose to get instant energy. Give reason. 2. Can we survive only on vegetables and fruits? Write your comments...... Values to Learn

One day, Falak was crying due to stomach pain. The next day she got a mild fever with frequent passage of watery stool. Her brother took her to a nearby hospital. The doctor prescribed a few medicines and advised her to take ORS liquid in every 2 to 3 hours. It took 3 to 5 days for her to recover. (a) What values are shown here and by whom? (b) Name the disease from which Falak was suffering. (c) Give two preventive measures of this disease. (d) What are the causes of this disease? reserved...... Create and Learn

1. Observe some animals in your surroundings. List them and collect their pictures. Gather information about their feeding habits and digestion. Make a book on “Animals’ Nutrition” and write details of each animal in the format as shown. rights Name of the animal Photo of the animal FoodAll

Digestive system :______

Teacher’sHFI. Corner ©1. Help the students know the involvement of various organs in the process of digestion. 2. Make them understand the role of each and every part of the alimentary canal.

...... 33 Nutrition in Animals

Pru_Sci_G7_C02.indd 33 9/2/2019 10:17:10 AM reserved.

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Pru_Sci_G7_C03.indd 34 8/3/2019 12:01:17 PM Look around in your house and collect samples of different types of fibres. A few household materials are shown in Figure 3.1. Cut a very small portion of each material and feel the fibres. On comparing materials of the samples collected, you will find that they are made up of different fibres.

reserved.

rights FigureAll 3.1 Objects made up of different fibres The above-mentioned objects were made up of cotton, silk, wool, nylon, jute and some other synthetic material. In the previous class you studied that fibres can be both natural and man-made. Cotton, jute, silk and wool are natural fibres whereas nylon is a man-made fibre. Furthermore, we know that cottonHFI. and jute are examples of plant fibres, whereas silk and wool are animal fibres. We have studied about plant fibres in the previous class and we shall study about animal fibres© in this class.

...... 35 Animal Fibres

Pru_Sci_G7_C03.indd 35 8/3/2019 12:01:25 PM 3.1 Animal Fibres

Animal fibres are natural fibres which we get from various animals. Examples of such fibres include wool, feather and silk. Wool and silk are the most common animal fibres.

Activity 3.1

Aim: To differentiate between pure silk, artificial silk and wool fibre. Materials required: Strands of pure silk, artificial silk, wool fibre and a match box. Procedure: One by one burn each strand and observe them. Be careful while burning the fibres. Observation: Observe the following characters of each fibre while burning.

Type of the fibre Smell while burning Residue Dull black with hollow Pure silk Smells like burning of hair bead-like appearance. Emits a characteristic smell Dark coloured with hard Artificial silk like burning of plastic beadsreserved. Dull black with beads Wool Smells like burning of hair easily crushable.

Conclusion: Pure silk and wool turn to ash and stop burning when the thread is taken away from the flame. Artificial silk does not turn into ash and keeps on burning even when the thread is taken away from the flame. rights 3.2 Wool

Wool is essentially animal hair obtained from different Coarse outer hairAllanimals. Wool protects us from the cold during winters. SOURCES OF WOOL

The fleece of hairy animals such as sheep, goat, camel, yak, etc. is the main source of wool. There are two types of hair HFI. present on a sheep’s body. One is the coarse outermost layer of hair and the other is the soft under hair which is close to the skin. The hairs next to the skin are very fine textured and are ©Fine inner hair the main source of wool. Figure 3.2 Fleece of a goat Some breeds of sheep only have fine inner hairs and no coarse hairs. Such kind of breeds are specially chosen for 36 ...... Pruquest Science VII

Pru_Sci_G7_C03.indd 36 8/3/2019 12:01:26 PM breeding purposes as they inherit the special characters of their parents. The process in which parents are selected to Fleece: the woolly covering produce desirable breed is called selective breeding. of a sheep or a goat Inherit: to receive by succession

Enquire and Discuss 3.1

Touch your arms and legs and feel the hair on them. Now touch the hair of your head. Which hairs are soft and which are coarse to feel? Discuss with your teacher.

TYPES OF WOOL

Different kinds of sheep and goats produce different kinds of wool. • The sheep wool is obtained from sheep and is the most common source of wool. • The yak wool is obtained from yak, which is common in Angora goat Tibet and Ladakh. reserved. • Angora wool is obtained from Angora goats which are found in hilly regions. • Pashmina wool is obtained from Kashmiri goats which have a fine under hair. Kashmiri goats • Camel wool is obtained from the hair of the Llama and Alpaca breed of camel, found in Southrights America.

All Indian sheep Indian yak Alpaca camel Llama camel Figure 3.3 Wool-producing animals Off the Wall The region of Jammu and Kashmir, Himachal Pradesh and Uttarakhand has nearly 5 million sheep (8%HFI. of India) producing 8,500 tons of wool annually (about 1–2 kg of wool per sheep per year). Wool from the sheep of this region is of superior quality used for making shawls, ©lohis, pashmina, pattus and costly woolen goods. The country’s best quality sheep are found in Kashmir, Kullu, Chamba and Kangra valleys at an altitude of 2,000 m.

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Pru_Sci_G7_C03.indd 37 8/3/2019 12:01:30 PM Processing of Wool

The wool is obtained from the soft under hair of sheep and goat. The hair of the animal has to undergo a series of processes to produce wool or other woollen material we use. These steps can be summarised as: 1. Rearing and breeding of sheep: To obtain wool, a herd of sheep are reared and bred in different parts of the world. The farmers take care of the sheep and their young ones, and provide them with food and fodder as can be seen in Figure 3.4. Sheep and goats are herbivores, and farmers often leave them to graze on the green grass of hill-tops. Sheep and goats are good mountain climbers and can go to the mountaintops to eat grass. The rearers provide them with a mixture of pulses, corn, jowar, oil cakes (ma- Figure 3.4 Rearing of sheep terial left after taking out oil from seeds) and minerals. During extreme winters, sheep are kept indoors and are fed on leaves, grain and dryreserved. fodder. 2. Shearing: The removal or cutting of sheep hair using hair cutter or a machine is called shearing of sheep. You may Under hair: sheep and goats think that shearing may hurt the sheep but it is not so. Do have soft inner layer of hair you get hurt when you have a hair cut? It is the same for next to their skin called a sheep (Figure 3.5). under hair Rearing: caring and bringing up of babies of animals until rights they are fully grown All

Figure 3.5 Shearing of sheep Usually, the sheep hair is removed during the summer season and not in the winter season. Can you think of a reason? The HFI. hairs removed are woven into yarn to give us fleece. 3. Scouring is the technical word for washing. It is done in big water tanks or through machine (Figure 3.6). The fleece © is processed through hot soapy water to remove dirt, oil, grease and dry plant matter. The process is repeated several Figure 3.6 Scouring of wool times until the water used for washing becomes dirty. 38 ...... Pruquest Science VII

Pru_Sci_G7_C03.indd 38 8/8/2019 3:16:42 PM 4. Sorting: The fleece comprises many types of wool. The wool is not uniform over the entire body of the sheep. The fleece is longer, finer or cleaner in some parts than the other parts. It is therefore important to divide the heap of fleece into groups to get uniform and desired wool (Figure 3.7). The strands that are coarse, knotted or too short are removed first. Generally, more than one person is involved in this process. The best wool comes from the Figure 3.7 Sorting of wool sides of the sheep, and the second best from the back and the thighs. Wool from the belly and throat is inferior, and the poorest wool comes from the lower parts of the legs.

Enquire and Discuss 3.2 The first thing that is done after shearing is sorting of wool. Wool from ewes, rams and lambs are sorted from each other and are kept separately. While sorting wool, factors such as the length of fibres and wool’s ability of absorbing dyes, etc. are taken into consideration. Wool which is going to be the source of soft and glowing yarns should be supple, resilient and soft. The quality of wool varies not only due to the difference in types of breeds but also duereserved. to the difference in geographic conditions of the animals, season of shearing, quality of fodder, etc. 1 Find out from the Internet, the types of wool produced by ewes, rams and lambs. 2 What are the different uses of wool? 3 Discuss the reasons responsible for producing different kinds of wool.

5. Drying: After repeated washing and thorough rinsing, the wool is dried. On a commercial scale, large mechanical dryers (something like the dryers inrights washing machines) are used (Figure 3.8). The wool is set on the screen tables with hot air circulation. On a domestic scale, the wool is placed on a sheet and in a warm, dry place but out of direct sunlight. All 6. Dyeing: The natural colour of fleece is brown, black or off-white. To make the wool look attractive, the fleece is Figure 3.8 Wool dryer dyed in different colours (Figure 3.9). The wool can be dyed HFI.easily as it readily accepts dye colours. ©

Figure 3.9 Dyed wool ...... 39 Animal Fibres

Pru_Sci_G7_C03.indd 39 8/8/2019 3:18:41 PM 7. Rolling into yarn: The fleece fibres are finally straightened, combed and rolled into yarn. The straightening and stretching the fibres to obtain maximum spinning capacity is called combing. Both the longer and the shorter fibres have different use. The longer fibres are used in making wool for sweaters and the shorter fibres are spun and woven to make woollen cloth.

Figure 3.10 Wool rolled into yarn

Enquire and Discuss 3.3 reserved.

Rearrange the steps for processing of wool in the correct order. How much time do you think each step would take? Try to find out by discussing with your elders or from the Internet. Make a report on the complete process. A. Rolling yarn B. Comb wool C. Wash fleece (five single strands of wool (removes shorter fibres) (removes dirt and fat) yarn twisted together) rights

D. Spin wool E. Sort wool (into a single strand of yarn)All(separating cleaner wool from unclean wool)

HFI. Figure 3.11 © Health hazards in the wool industry 1. Workers, who are involved in processing of raw wool, often suffer from sorter’s disease, also known as anthrax. 40 ...... Pruquest Science VII

Pru_Sci_G7_C03.indd 40 8/8/2019 3:22:13 PM This used to be a deadly disease. However, now we have good treatment for this disease. We also have effective vaccines against it. 2. Asthma, bronchitis and allergies are some of the common respiratory problems faced by the workers in this industry. These are caused by inhalation of small hair of sheep during the process of sorting and scouring, over a long duration of time. 3. Some other common health problems included back pain, neck pain, dehydration, fatigue, cuts and skin problems.

3.3 Silk

Silk is a cherished material which people have liked since ancient times. It has a smooth and shiny texture. The silk fibre is an insect fibre obtained from a number of different types of silkworms. The silk fibre is an insect fibre obtained from a particular type reserved. of silkworm.

SOURCES OF SILK

The main source of silk is the silkworm obtained from mulberry trees. The rearing of silkworm is called sericulture. It involves rearing of silkworms for the production of raw silk, which is the yarn obtained out of cocoonsrights spun by certain species of insects. To understand the process of sericulture, let us first understand about the life cycleAll of a silkworm, also called silk moth (Figure 3.12). A silk moth is found on a mulberry tree. The silk yarn is obtained from the cocoon of the silk moth (step 4, Figure 3.12). You may have seen different types of silk clothes. Some silk clothes are very soft, whereas others are coarser.HFI. TYPES OF SILK The© texture of the silk cloth largely depends on the type of the thread (yarn) produced by the silk moths. Not all silk moths produce the same kind of silk fibre. There are various types ...... 41 Animal Fibres

Pru_Sci_G7_C03.indd 41 8/8/2019 3:22:25 PM Life cycle of silkworm

1. Egg stage An adult female moth lays 300–500 pinhead-sized eggs.

6. Mating stage 2. Larval stage The adult moth looks for a The moth larvae feast on mate so that females can lay large quantities of mulberry more eggs and continue the leaves. For the next 40 to life cycle. Adults lie about 2 45 days, the larvae eat and to 3 days after leaving the co- grow. They moult (shedding coon. skin) to accommodate their growing size. Silk fibre

People unwind the silk thread from the cocoon reserved. to weave into silk cloth.

5. Adult stage 3. Cocoon stage The pupa changes into a After the final moult, the moth. The moth comes rights larvae (caterpillars) spin out of the cocoon. a cocoon of silk threads 4. Pupa stage around themselves. Inside the cocoon, the larvae change into pupa, a transforma- Alltion stage between larva and adult. After 14 – 18 days inside the cocoon, the pupa is ready to emerge as an adult moth. HFI. © Figure 3.12 Life cycle of a silk moth

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Pru_Sci_G7_C03.indd 42 8/8/2019 3:22:37 PM of silkworms found at different trees and produce different kinds of yarn.

Table 3.1 Different types of silk and silkworms

Silk Type Silkworm Diet of the Silkworm Mulberry silk Mulberry Mulberry leaves Tussar (Kosa) silk Wild silk moth Arjun and sal tree leaves Muga silk Silk moth found in Assam only Aromatic plants of Som and Soalu Eri/Endi/Errandi Open-ended cocoons (different Castor leaves silk from regular cocoons)

Production of Silk

Hatching of eggs: Bombyx mori, a type of silk moth, is allowed to lay eggs. An adult female moth may lay 300 to 400 eggs at a time. These eggs are kept under a controlled environment to ensure hatching of the eggs and emergence of the larvae. These larvae are also called caterpillars. reserved.

The feeding period: These larvae are kept on separate fine layer of gauze trays and large amounts of mulberry leaves till they grow large.

Cocoon formation: Once the larvae attain their maximum size, they spin a silk cocoon around themselves. This stage of life of a silk moth is also called pupating.rights Mature larvae are placed on baskets for the larvae to get attached and spin a silk cocoon. Reeling the filament: CocoonAll are treated under hot water to kill the worm inside and loosen the silk filament. These filaments are twisted to make strong silk threads. Finally, these threads are dyed and woven into silk fabric. OffHFI. the Wall Apart from silkworm, there are other insects also that produce silk fibres. ©The web made by spider is made up of silk yarn. This yarn is nearly five times stronger than steel and is waterproof and stretchable.

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Pru_Sci_G7_C03.indd 43 8/3/2019 12:01:50 PM Activity 3.2

Aim: To understand different types of silk fibre. Materials required: Different samples of silk pieces. Procedure: 1. Go to a tailor’s shop. 2. Ask for some small pieces of silk clothes from the heap of waste cut pieces. 3. Observe each piece and paste all silk pieces in your scrapbook. Observation: 1. Do all silk pieces have same texture? 2. Observe them to know how many were coarse and how many were soft pieces. 3. Try flame test also to see which pieces are real silk fibre and which are artificial silk fibre. Conclusion: Make your own conclusions. reserved. Steel fibre: thin fibres made Strength of a silk fibre from steel, e.g. steel wool A silk fibre is as strong as a steel fibre. This is due to a used at homes for cleaning peculiar habit of the caterpillar. The caterpillar while in the vessels pupa, weaves a net to hold itself. It then swings its head from side to side in the form of the number eight (8) and produces the silk fibre. The fibre secreted during these movements is made up of protein and is hardened when exposed to air. Figure 3.13 rights ScienceScience DiariesDiariesAll History of the silk Hsi Ling Shi, the wife of Chinese Emperor Huang Ti, is known to be the first person to discover the silk fibre. Story: One day, when the empress was sipping tea under a mulberry tree, a cocoon fell into her cup and began to unravel. The empress became so enamoured with the shimmering threads, she discovered their source, the Bombyx mori silkworm found in the white mulberry. The empress soonHFI. developed the art of sericulture, the cultivation of silkworms, and invented the reel and loom. Thus began the history of silk. The fact: The Chinese were the first to discover silk and they had a global monopoly on silk production for nearly 3000 years. A handful of Chinese immigrants in Korea, during the 200 BC, ©realised the emergence of their own silk industry. By about 300 BC, this industry had spread into India, Japan and other countries.

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Pru_Sci_G7_C03.indd 44 8/8/2019 3:21:15 PM Health hazards of sericulture

Health risks faced by workers in any industry are called occupational hazards. The workers who work in silk industry are prone to the following hazards. 1. The need to dip hands constantly in boiling water (for the cocoons) to judge whether the silk threads have become soft enough to be extracted or not, causes burning of skin, blisters and open wound injuries. 2. Boiling of cocoons in water releases lots of fumes and vapours causing respiratory problems such as asthma and bronchitis. 3. 14–16 hours of standing required for silk extraction and to focus on reeling of fine silk leads to backbone problems and eye diseases. 4. Noisy conditions produced due to loud and constant sound of the spinning and weaving machines generally leads to hearing problems. reserved.

Concept FLOW Animalrights Fibres Wool Silk

Processing of wool Processing of silk and life cycle All of a silk moth 1. Shearing of sheep hair → fleece 1. Egg stage → eggs laid by female silk moth 2. Scouring of fleece → washed fleece 2. Larval stage → larvae feeding on huge 3. Sorting, dyeing and combing → clean quantity of mulberry leaves and dyed fleece 3. Cocoon stage → larvae spin cocoon of silk 4. Spinning of fleece → yarn thread 5. HFI. Yarn 4. Pupa stage → (a) Larvae change into pupa. It is a stage Knitting Weaving between larva and adult © Sweater woollen fabric (b) Silk thread is unwound from cocoon to weave into silk 5. Adult stage → pupa changes into adult moth

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Pru_Sci_G7_C03.indd 45 8/3/2019 12:01:52 PM ...... Check Your Knowledge 1. Fill in the blanks. (a) Angora wool is obtained from ______. (b) ______and ______are the two types of camels which give us wool. (c) Sheep feeds on ______, ______and ______. (d) The caterpillar spins a ______of silk thread around itself. (e) Silkworms feed on ______. 2. How do we obtain silk thread from cocoons? Explain the steps. 3. Which was the first country to produce silk? 4. List some occupational hazards of silk industry. 5. List the type of animal fibres and their sources. 6. How much time does a caterpillar take to form a cocoon? 7. Give examples of different varieties of silk. 8. List and explain the steps of wool extraction. reserved. 9. Draw the life cycle of a silk moth and answer the following questions: (a) In which stage does the silk moth feed on the plant leaves? (b) In which stage is the cocoon formed? (c) How is cocoon formed? (d) What happens to the caterpillar inside the cocoon? 10. Complete the matrix. rights Step Procedure Shearing ______The sheared skin with thick coat of hair is then washed ______Allthoroughly in tanks to remove grease dirt and dust. The dyed fibres are passed through metal teeth to ______straighten them. Spinning ______?...... ThinkHFI. and Apply 1. Tick the correct option. ©(a) Silk and wool fibres are made of (i) fats (ii) proteins (iii) carbohydrates (iv) all of these

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Pru_Sci_G7_C03.indd 46 9/2/2019 10:17:38 AM (b) From which of the following sheep do we obtain carpet wool? (i) Marwari sheep (ii) Merino sheep (iii) Lohi sheep (iv) Nali sheep (c) The removal of black wool fibres from brown fibres is called (i) shearing (ii) scouring (iii) sorting (iv) drying (d) Which of the following is eco-friendly fibre? (i) nylon (ii) acrylic (iii) artificial silk (iv) jute (e) Shearing of sheep is preferred in the summer season because (i) rearers get good fleece in this season (ii) hairs of sheep is its adaptive feature for the winter (iii) sheep will be free of unwanted hairs (iv) both (ii) and (iii) 2. The Figure 3.14 shows a shearing machine. (a) Define shearing. (b) Why is it done in summers? (c) Shearing is painful for sheep. Yes/No. Give reasons. reserved. 3. Give reasons: (a) Animals living in cold region have a thick coat of hair. Figure 3.14 (b) Woollen clothes keep us warm in winter. (c) Smell of burning wool and silk is similar.

...... Analyse rights A table related to Indian breeds of sheep and quality of wool is given below. Answer the questions based on this table.All Name of Breed Quality/Type of Wool State Where Found Lohi Good quality wool Rajasthan, Punjab Rampur bushair Brown fleece Uttar Pradesh, Himachal Pradesh Nali Carpet wool Rajasthan, Haryana, Punjab HFI.Bakharwal For woolen shawl Jammu and Kashmir Marwari Coarse wool Gujarat © Patanwadi For hosiery Gujarat 1. Which breed of sheep is good for woollen shawls? 2. Which is the best breed for hosiery products? ...... 47 Animal Fibres

Pru_Sci_G7_C03.indd 47 9/2/2019 10:17:39 AM 3. Name two states where Lohi breed is found. 4. From which variety of sheep is carpet wool obtained? 5. Which state produces ‘Marwari’ and ‘Patanwadi’ variety of wool? 6. Which variety of wool is native to ‘Uttar Pradesh’ and ‘Himachal Pradesh’? 7. Name two important breeds of sheep.

...... Think Beyond

1. Why lots of mulberry leaves are required during the larval stage of silkworm? State the characteristics of mulberry silk. 2. Differentiate between: (a) Plant fibres and animal fibres (b) Sorting and scouring 3. Can you think of any occupational hazards of wool industry? ...... Values to Learn reserved.

Manav and Urja visited a sericulture unit on a school trip. When they saw a number of cocoons being boiled in water, they felt aversion towards the sight. They could not digest the fact that thousands of cocoons were being boiled so that we could wear silk. They vowed never to work in a silk processing factory and thought of telling their mother for reducing the use of silk. 1. What values of Manav and Urja were being depicted in the passage? 2. We discourage the use of leatherrights but why do not we discourage the use of silk? 3. Can you name other insects that provide thread-like fibre? 4. What are the hazards of working in a silk factory? ...... Create and LearnAll Make a picture puzzle of the stages of the life history of the silk moth. You can take chart paper and make cut-outs of different stages of life cycle of the silk moth and paste them separately on cardboard pieces. Jumble them and try to arrange the stages in the correct sequence. Teacher’sHFI. Corner For Analyse Questions: Some students may not be able to understand and analyse the table. They should be helped in it by© giving sufficient practice. For example, you may tell them that the names of the breeds may be learnt by repeating the names many times.

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Pru_Sci_G7_C03.indd 48 9/2/2019 10:17:40 AM