Modern Concept Science and Technology 8 New

Approved by the Government of Nepal, Ministry of Education, Science and Technology, Curriculum Development Centre, Sanothimi, Bhaktapur as an additional material for school Authors Chinta Mani Panthee M.Sc., B.Ed., Ph.D. Lok Bahadur Thamsuhang M.Sc., M.Ed. Kamal Neupane M.Sc. 8

Published by: Nova Publication Pvt. Ltd. Satungal, Kathmandu Tel.: 01-4313205 www.novapublication.com.np Authors: Chinta Mani Panthee Lok Bahadur Thamsuhang Kamal Neupane Edition: Fifth - 2080 Copyright: Chinta Mani Panthee Price : Rs. 498 /– Print Quantity : 10,000 Layout and Design: Zeeta Computer Service Ptv.Ltd. Printed in Nepal 8

PREFACE Modern Concept Science and Technology for grade 8 is written to meet the objectives of the curriculum of class 8 science and technology developed by CDC (Curriculum Development Center), Sanothimi, Bhaktapur. This edition of our textbook meets the criteria of basic knowledge in science and technology for students who study in class 8. It will help students to achieve the goals of life by gaining of knowledge, skills and values in Science and technology. Logical placing of key points and well organized matter are given high priority throughout the textbook. Appropriate pictures, matter in simplified language and organization of the content with new features are our high expectation values about popularity of this textbook among the readers. Features of Modern Concept Science and Technology A notable concern of many teachers is to follow a well-organized textbook with step by step learnings in a continuous flow. The organization of this textbook is logically designed to make the book's information more accessible. 1. Top of the first page, just below about the scientist of each unit consists of syllabus issued by CDC (Curriculum Development Center), Sanothimi, Bhaktapur for class 8. 2. Top of the first page of each unit consists about the scientist of the related topic. It inspires and motivates the students towards the scientific skill. 3. The most important idea of writing terms and terminologies on the first page of each unit is devoted to screen out the main content to be covered. 4. Highlighted definitions, catchy memory tips and bubble box on pages inside of a chapter for a quick look on important points to be remembered are provided in the first page of each unit. 5. Activities and solved numerical problems are given in each unit of the same page with corresponding to the topic to develop the scientific skill in the readers. 6. Higher Order Thinking Skill of Knowledge, Understanding, Application, and Higher Ability with their answer are given at the end of each unit under the title HOT Skill to get idea to solve the questions given in the three steps exercise. 7. This text book focuses primarily on all three level questions to test students' skill under the title three steps exercise. With these all features in a well-organized content, the central focus of this book is to encourage students and make the text user-friendly for all. The HOT skill and three levels grid based exercise will help teachers to set test papers for assessments. Students' interest will be peaked when they will find the screen out terms and terminologies, the appropriate pictures and key points throughout the textbook. We hope that this book will help teaching in learner-centered way. We wish to express our sincere gratitude to Mr. Megh Raj Poudel, Managing director of Nova Publication Pvt. Ltd. for publishing this book. Similarly, thanks are due to Mr. Deepak Bahadur Bista, Ashim (Indra) Rijal, Deepak Banjade, Dilip Belbase, JN Lamichhane and Srijan Adhikari for their valuable help during the preparation and content editing of the book. Likewise, thanks are due to Mr. Jagadish Pokhrel for his praiseworthy language editing. Finally, we owe full responsibility of misprints and other technical errors, if any, found in this textbook in spite of our best effort to make this book error-free. Constructive criticism and suggestions for improvement of this book will be highly appreciated. Authors Kathmandu, Nepal

Table of Contents 1. Scientific Study 1-13 2. Information and Communication Technology 14-40 3. Living Being and Their Structures 41-76 3.1 The Cell 42-57 3.2 Classification of Living Beings 58-76 4. Bio-diversity and Environment 77-95 5. Life Process 96-123 6. Force and Motion 124-170 6.1 Motion 125-139 6.2 Simple Machine 140-154 6.3 Pressure 155-170 7. Energy in Daily Life 171-219 7.1 Heat 172-189 7.2 Light 190-202 7.3 Sound 203-219 8. Electricity and Magnetism 220-249 8.1 Magnetism 221-235 8.2 Electricity 236-249 9. Matter 250-281 10. Materials Used in Daily Life 282-305 10.1 Acid, Base and Salt 283-294 10.2 Water 295-305 11. The Earth and Universe 306-336 11.1 Minerals 307–314 11.2 The Earth in the Universe 315–325 11.3 History of Earth 326–336

Modern Concept Science and Technology – 8 1 Key terms and terminologies of the unit 1. Scientific learning : The process of following systematic ways to learn the facts is called scientific learning. 2. Science process skills : The sets of skills that must be followed while learning scientific processes are called science process skills. 3. Practical work of science : The activity in which students must involve themselves to understand the key knowledge of the theory by using all known science process skills are called practical work of science. 4. Scientific investigation : The process of finding the answer to a question using various research methods is called scientific investigation. 5. Research : A creative and systematic science practical work undertaken to find new knowledge is called research. 6. Survey : A research method used for collecting data from a predefined group of respondents to gain information and insights into various topics of interest is called survey. 7. Hypothesis : An idea or plan that can be tested by experiments is called a hypothesis. 8. Observation : The act of noticing tiny details by using our sense organs is called observation. 9. Analysis : The process of understanding, interpreting and linking the information to get result is called analysis. 10. Report : The complete description of a science practical work is called a report. 11. Communication : The process of relaying key messages of the research survey to the public is called communication. Sequence of Curriculum Issued by CDC  Introduction, importance and example of practical work of science.  Precaution while doing practical works of science  Steps to do survey research (Selection of objective, sampling, formation of hypothesis, selection of methods for collection of hypotheses, collection of required materials, data collection, scientific listing of information, analysis, conclusion, report writing) UNIT Scientific Study 1 Estimated teaching periods Theory Practical 7 3 Galileo Galilei is well known as the father of observational astronomy, modern physics, scientific method and modern science. He was born in Italy on 15th February 1564 and died on 8th January 1642. He was an astronomer, physicist and engineer. He is popular for analytical dynamics, heliocentrism, kinematics and observational astronomy. He graduated from the University of Pisa. Galileo Galilee About the Scientist

2 Scientific Study 1.1 Introduction To believe everything without any actual fact is a superstition. The knowledge everyone believes in but does not have any scientific backup is called dogma. Science is simply the searching of answer by curious people to know the fact about natural processes and technology. Thus, scientific learning is a process of following systematic ways to learn the facts. The person who does science is called a scientist. They do not randomly study the natural processes. They use scientific learning skills while doing scientific research. The rules that must be followed while learning scientific processes are called science process skills. The first scientific skill is observation. Everything starts with observation. Other scientific skills are asking questions, collecting information, analyzing, predicting, experimenting, report writing and communication. Scientific learning is important to remove superstition and introduce newer technologies in medicine, agriculture, education, space exploration, environment conservation and transportation. Fig 1.1 : modern technologies such as tractor in fields Fig 1.2 modern satellites Fig 1.3 kids observing flower with hand lens FACTS WITH REASONS Scientific learning is important for society. Scientific learning is important for society because it helps to develop new technologies, medicine and hybrid crops for society. ACTIVITY 1 Visit a site of honey bee hive or an apiary in apiculture site. Take papers, pencils and erasers with you. Study the behaviour of different kinds of bees, their structure and hive cells. Draw pictures of what you see by studying the site. 1.2 Practical Work of Science Interest in scientific learning can be generated through practical works. Many of us can struggle with learning science because of its complex principles, laws and machines. Practical works of science can help to counter those problems. A student must actively involve himself or herself in practical work. So, they have to think a lot, collect information, design models, learn the principles, observe models, make reports and explain them to others. So, it will obviously help to develop teamwork, creativity and problem-solving skills in students. MEMORY TIPS Observation is the most important and first skill of scientific learning.

Modern Concept Science and Technology – 8 3 The activity in which students must involve themselves to understand the key knowledge of the theory by using all known science process skills is called practical work of science. It is very important because: i. It involves everyone in doing scientific work. ii. It generates lifelong interest in science. iii. It is more interesting than theoretical classes. iv. It helps all to understand the theories. However, it is not without drawbacks. It needs huge spaces, laboratories, chemicals and lots of time. There are some chances of accidents as well. FACTS WITH REASONS Practical works are very important for students. Practical works are very important for students because it helps to improve their understanding and develop problem-solving ability. ACTIVITY 2 Instead of learning about parts of plants by looking at pictures in the book, visit school garden and observe the parts of plants with a hand lens. Tell your findings in the class. Few examples of experimental/practical work of science Practical work of science can be indoor or outdoor. For example, experiments are usually indoors. Filtration, distillation, electric circuits, observation of microscope slides of onion etc. are indoor practical works. Observation of plants and animals in botanical gardens, field excursions on ICIMOD or farms, observation of natural resources etc. are some outdoor practical works. a. Observation practical works Observation practical works include visiting school gardens and observing models or experiments. Thus, observation is the act of collecting information from surrounding environment, events, processes, objects etc. It helps to form hypothesis, analyze experiments etc. b. Experiment practical works Experiment practical works include replication of experiments in a science lab or new experiments to test a hypothesis. Such as filtration and dissection of earthworms, mixing hot water with cold water to explain the principle of calorimetry etc. Thus, the activities that are designed to test a hypothesis is called an experiment. Scientific test can be done inside or outside the laboratory. c. Survey practical works Survey practical works include a field visit to collect information. Such as visiting and observing vegetable farms to know the effects of boo-insecticides on agriculture. Or find out, what ICT tools are used in the school. MEMORY TIPS Practical work develops teamwork, cooperation and critical thinking in the person.

4 Scientific Study d. Model preparation practical works Model preparation practical works include the preparation of models of machines, organs, natural processes, soil profiles and constellations. e. Project work Project work includes almost everything. It can be a replication of experiments or models, collection of various materials, research and experiments. Such as putting moist bread in dark and observing changes, enlisting positive or negative effects of microbes and demonstrating that air exerts pressure. Fig 1.4 filtration in laboratory Fig 1.5 model of lungs Fig 1.6 kids on field excursion Safety measures while doing practical work of science One of the major disadvantages of practical work of science is probability of accidents. To avoid accidents and injuries we must strictly follow safety measures. i. If we are doing observation practical works, we should never touch the models, animals or plants. ii. If we are doing experiment project work, we should follow the instruction of teachers. We should not play or eat in the laboratory. We must use safety apparatuses such as gloves and masks. We should not touch or misplace chemicals and we should never play with fire. iii. If we are doing model preparation practical work, we should not play with sharp tools, electricity and hot objects. iv. If we are doing survey practical work, we should properly wear and use safety tools based on the survey. v. If we are on a field excursion, we should not tease animals, fall or get lost. Fig 1.7 students in aprons, wearing gloves Fig 1.8 fire extinguisher and emergency exit on laboratory MEMORY TIPS Drinking any chemicals in the science laboratory is dangerous.

Modern Concept Science and Technology – 8 5 FACTS WITH REASONS We should follow safety rules in the laboratory. We should follow safety rules in the laboratory to avoid accidents such as burns, cuts, electric shocks, fire and death. ACTIVITY 3 Learn the location of a fire extinguisher in your science laboratory. Also, learn how to use it during an emergency. 1.3 Scientific Investigation, Research and Survey A scientific investigation is a process of finding the answer to a question using various research methods. A scientific investigation usually begins when someone observes the world around them and asks questions to which they do not know the answer. Then, they make more observations, make a hypothesis or develop an experiment to test a hypothesis. By collecting and analyzing data, the researcher can present findings that attempt to answer their questions. The researcher may also modify their experiment to test for conditions they did not initially consider. The results of the investigation are mentioned in a report. The report is used to communicate key knowledge to an audience. FACTS WITH REASONS Why is research carried out? The research is carried out to gather evidence and help to develop knowledge. ACTIVITY 4 Use scientific investigation methods to find out if stale food can or cannot be eaten. Research is a creative and systematic science practical work undertaken to find new knowledge. It develops greater problem-solving skills and confidence in students. A survey is a research method used for collecting data from a predefined group of respondents to gain information and insights into various topics of interest. Scientific survey is a common method used by a team to collect data for a particular objective and can be an effective tool to gain information from a target audience. The information gathered by students from their survey should be able to help the team either prove or disprove their hypothesis. Survey research is the collection of information from a sample of individuals through their responses to questions. Importance of research survey i. It is important to explore the unknown field of knowledge. ii. It is important to find errors in previous theories. MEMORY TIPS The scientific method is an empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century.

6 Scientific Study iii. It is important to actively involve students in learning science. Fig 1.9 Robots on the mars Fig 1.10 biologist researching for vaccine of monkey pox Steps of Research or Survey a. Selection of the objective We should select the topic of research for survey. Example, sunlight is necessary for the growth and development of plants. b. Sampling We should select a particular group of people for survey. We can select a certain population of animals, objects or plants for a survey. Example, few seeds of beans are collected and divided into three sample groups. FACTS WITH REASONS Why is sampling done? Sampling is done because it is difficult to collect data from an entire population. ACTIVITY 5 There are always some animals living in our surroundings. Let's use survey techniques to find out what types of animals live around our village. c. Formation of hypothesis After selecting a topic for research and deciding sample group, we can observe and form a hypothesis. A hypothesis is an idea or plan that can be tested by observations or experiments. Many questions will arise. We can list them and use them on a survey. Example, plants need three basic things to survive. They are carbon dioxide, water and sunlight. So, our predictions can be: "Plant cannot grow without sunlight." d. Selection of methods for collection of information After the questionnaire is ready, we can select the modes of collection of information. We can either visit the site, meet people and ask questions, observe samples, collect MEMORY TIPS The survey method is the technique of gathering data by asking questions to people who are thought to have desired information.

Modern Concept Science and Technology – 8 7 information from mail, use Online survey forms or use scientific reports from previous experiments. Example, since we are going to survey research on the effects of sunlight on growth of plants, "observation" is a better method to collect information than the interview, focus group and an Online survey. e. Collection of required materials We should collect materials necessary to carry out our research survey. It can be skilled manpower, computers, transportation, chemicals, scientific tools, laboratory apparatuses and safety tools. Example, materials required for the above survey are three small plastic cups, soil, water and seeds. f. Data collection We can first select the method for collection of information and use it to observe models, samples, and collect information. We can interview people to collect information. We can collect information from Online surveys too. Example, we chose observation method for this research survey. The act of noticing tiny details by using our sense organs is called observation. So, we can collect data by observing the plants growing in the pot for a few weeks. For this, we have to sow the seeds in three cups. Put one of them in sufficient sunlight. Put another in shade and put the last one in a closed dark container or room with no light. Let the plants grow for two weeks. Observe them every day, click pictures, count the number of seedlings, measure the length of the stem, and count the number of leaves and buds. In this case, i. Most seedlings in the cup kept in the bright sunlight were taller and had more leaves and more buds. ii. Most seedlings in the cup kept in the shade were shorter and had fewer leaves. iii. Most seedlings in the cup kept in a closed dark container died. g. Scientific listing of information When the information from various sources is collected it should be scientifically listed. Example: We should note down the information collected from observations of plants growing in the pots. Arrange the information obtained from the observation in charts, bar graphs or tables. MEMORY TIPS Pie charts and bar graphs are used to present information in research.

8 Scientific Study FACTS WITH REASONS Why is a scientific listing of information important? The scientific listing of information is very important to organize information so that it will be easy to analyze. ACTIVITY 6 The listed information should be analyzed to produce a result. Analysis means trying to understand, interpret and link the information to get results. h. Analysis The listed information should be analyzed in order to reach a conclusion. In order to get outcomes, analysis is attempted to compare, interpret and link to the information. Example: Analysis of the information of the above research. i. Most seedlings in the cup kept in the bright sunlight were taller and had more leaves. It can be because it received sufficient sunlight which helped them to make enough food to grow properly. ii. Most seedlings in the cup kept in the shade were shorter and had fewer leaves. It can be because they received insufficient sunlight so they made insufficient food for their growth. iii. Most seedlings in the cup kept in a closed dark container died. It can be because they received no sunlight so they could not produce food to survive. i. Conclusion We should compare the result with a hypothesis. Based on a comparison between result and hypothesis, survey is concluded. Example, from the analysis above we can see that the sunlight helps plants in photosynthesis to produce food and use it to live and grow. In the absence of sunlight, they cannot prepare food and die. Therefore, sunlight is necessary for growth and development of plants. j. Report writing When the survey is completed, a report is made. The complete description of a science practical work is called a report. It is used for communication. Communication means relaying key messages of the research survey to the public. Reports can be written in various formats. Some important parts of the report are topic, objective, materials required, procedure, observation, analysis, calculations, result, conclusion and caution. Example: The above survey research should be written in simple words in a report. MEMORY TIPS Reports are fact-based, structured pieces of writing.

Modern Concept Science and Technology – 8 9 FACTS WITH REASONS Why is a scientific report written? A scientific report is written to relay key knowledge to the audience. ACTIVITY 7 Conduct research to find out the essential materials for germination of the seeds and write its report. Title : Essential materials for the germination of the seeds. Introduction : Germination is the process in which a seed changes into a seedling. Germination needs oxygen, water and a suitable temperature. Objective : To find out what is necessary for germination. Hypothesis : Seeds need oxygen, water and a suitable temperature to germinate. Materials required : a beaker, a glass rod, three bean seeds, thread and water Procedure : i. We first collected three beans and tied them in a glass rod 3 cm apart. ii. We put the glass rod in the beaker and poured water into the beaker. iii. We immersed the first bean completely under water. We immersed half part of the second bean in the water. We kept third bean far away from the water. iv. We kept the beaker along with the seeds in the glass rod in sunlight for a week. Observation : We found that the first bean under the water did not germinate. The second bean that was immersed half in the water changed into a seedling. The third bean that was far away from water did not germinate at all. Analysis : We noted this observation in a notebook. We discussed this among our group members. The result of our discussion was: i. The first bean under the water might have not germinated because there was too much water but no oxygen gas for respiration. ii. The second bean which was half immersed in the water might have germinated because it has received sufficient water, enough oxygen and a suitable temperature. iii. The third bean which was far away from the water might have not germinated because there was oxygen and suitable temperature but no water. Seed in air Water Seed inside water Seed partially in water

10 Scientific Study Result : From the above analysis and discussion, the result of the research is all three materials oxygen, water and suitable temperature are necessary for germination. Conclusion : The result was in favour of the hypothesis. Therefore, we concluded that enough water, sufficient oxygen and suitable temperature are compulsory for germination. HOT SKILL HIGHER ORDER THINKING SKILL 1. What is the primary objective of designing an experiment? The primary objective for designing an experiment is to test the hypothesis. 2. What is the objective of a report? The objective of the report is to let the audience know the importance of our research. 3. We should follow the science processes skills while learning about any events. Give reason. We should follow the science processes skills while learning about any events because it helps to get a reliable result. 4. Differentiate between observation and hypothesis. The differences between observation and hypothesis are: SN Observation SN Hypothesis 1. The act of noticing tiny details by using our sense organs is called observation. 1. A hypothesis is an idea or plan that can be tested by experiments. 2. It is the act of collecting information. 2 It is the act of predicting probable answers to our research. 5. Let’s suppose one of our friends is carrying a lunch box while going to the chemistry laboratory. How can we convince him not to bring lunch to the chemistry laboratory? If one of our friends is carrying a lunch box while going to the chemistry laboratory, we can convince him not to bring it by explaining the dangers of doing so. We can explain to him that there are lots of chemical substances in the chemistry laboratory. Most chemicals are harmful and some are deadly. If the chemicals mix in our food, it can cause serious health problems. There may be chemicals in our hands during the experiment. If we eat by hand, chemicals can mix in the food. Some chemicals such as strong acids and bases can kill us either if eaten. So, we should never bring food to the chemistry laboratory. We should never eat any food, chewing gum, juices or water in the chemistry laboratory. 6. If one of our friend thinks that practical works are waste of time and focus on memorizing notes only, how can we motivate him to involve in practical works of science? Most students are used to cram and memorize notes but that is not the right way to learn. To understand is the meaning of learning. If one of our friend thinks that the

Modern Concept Science and Technology – 8 11 practical works of science are waste of time and focus on cramming notes, we should educate him or her about the benefits of practical works. We should involve him or her in practical works of science so that he or she can realize that practical works of science are better than cramming. It helps to increase thinking ability, problem solving ability and helps to understand the concept. It also improves team work. 7. Let's suppose we are about to research on certain topic using a survey method, what should we educate ourselves with before doing the survey? Survey is a scientific way to learn about particular topic. It is popular among scientists, students, researchers and business companies because it is quick, cheaper and easier. If we are going to research on certain topic using a survey method, we should learn few terminologies and follow the particular steps. First of all we should select the topic for survey. We should select a particular group of people for survey. After selecting a topic for research and deciding sample group, we can observe and form a hypothesis. After the questionnaire is ready, we can select the modes of collection of information. We should collect materials necessary to carry out our research survey. We can first select the method for collection of information and use it to observe models, samples, and collect information. When the information from various sources is collected it should be scientifically listed. We should compare the result with a hypothesis and conclude. Finally we should write a report. 33 STEPS STEPS EXERCISE EXERCISE STEP1 1. Select the best answer from the given alternatives. a. What is the main objective of practical work? i. to actively demonstrate experiments to students. ii. to make students learn by doing themselves iii. to use the chemicals and tools iv. to utilize leisure b. Why should we know to use a fire extinguisher? i. to put out fire in a science laboratory. ii. to do practical work. iii. to learn by doing. iv. it builds up our confidence in science. c. Sampling is important for a survey. Why? i. it will give accurate data. ii. sampling is the only way to survey.

12 Scientific Study iii. it is wrong to collect data from a large population. iv. it is difficult and expensive to collect data from a large population. d. What is the act of relaying important findings of survey called? i. report ii. scientific listing iii. communication iv. data collection e. Why should we never do unauthorized experiments? i. it is waste of time and resources. ii. it is against the rule. iii. it will reduce our intelligence. iv. it can cause accidents. 2. Write True for the correct and False for the incorrect statements. a. The person who does science is called a scientist. b. One of the major disadvantages of practical work is the probability of accidents. c. Sunlight is necessary for the growth and development of plants. d. Communication means writing the report of a survey. e. The result of the survey is compared with the hypothesis. 3. Fill in the blanks using a suitable word. superstition analysis research hypothesis observation a. To believe everything without facts is called ………… b. The first skill of scientific learning is ………… c. An effort to understand and interpret information is called ………… d. The creative and systematic science practical work performed to find new knowledge is called ………… e. An idea that can be tested by experiment or observation is called ………… 4. Answer the following questions in very short. . a . What are the set of skills used in scientific learning methods called? b. What are fact-based, structured pieces of writing called? c. Give an example of experimental practical works. d. What is the act of defining small groups for a survey called? e. What is the act of noticing tiny detail called? f. Who is the person who does science called? STEP2 5. Give reasons. a. Scientific learning is very important for society. b. Students should take part in practical work. c. Observation is the most important skill of scientific learning.

Modern Concept Science and Technology – 8 13 d. Research is a popular method for scientific learning. e. Sampling is important during survey. f. We should not eat in the laboratory. g. Observation and inquiry are important for survey. h. Available data should be listed properly. i. A report is a very important part of scientific learning. 6. Differentiate between the following. a. Observation and hypothesis b. Sampling and experimenting c. Hypothesis and conclusion d. Experiment and survey e. Result and hypothesis 7. Answer the following in short. a. What is scientific learning? b. Define science process skills and list them. c. What do you mean by practical works of science? Give four examples. d. What is a hypothesis? How is it formed? e. Define analysis. What is its importance? g. What does it mean by observation? What is its advantage? h. What is a survey? i. Define scientific report. Mention its importance. j. How is a scientific survey carried out? STEP3 8. Answer the following questions. a. What are the pros and cons of the practical work of science? Enlist. b. What role does practical work of science play in educating a child? c. What are the benefits of practicing scientific learning methods? d. What cautions must we take before experimenting in laboratory? e. The teacher asks us not to bring food and drinks into the lab. What might be the reasons? f. Why are we requested to listen to teachers and avoid playing in the laboratory? g. Explain the steps to perform a survey to your group members. h. Let’s survey to find out the ages of classmates. Prepare a questionnaire. For example, ask about the date of birth and age. Count their age. How many people had the same age? Write a survey report. i. How is the physical growth and development of a plant affected by the quantity of sunlight? Research and write a survey report.

14 Information and Communication Technology Key terms and terminologies of the unit 1. Information : Information is a set of facts. 2. Communication : The exchange of information between two or more people is called communication. 3. ICT tools : The diverse set of tools that are used to collect, create, share, exchange, transmit, store and process information is called ICT tools. 4. ATM : The electronic device that allows bank account holders to perform quick money transactions is called an automated teller machine (ATM). 5. Photocopier : A photocopier is a machine that can create photocopies of any printed document. 6. Scanner : An ICT tool that scans a document and converts them into digital data is called a scanner. 7. Printer : The machine that can print pictures and texts by receiving commands from computers is called a printer. 8. Router : A router is an electronic device that connects computers and mobiles to the Internet. 9. Wi-Fi : Wi-Fi is a wireless technology that connects computers and smart-phones to the Internet. 10. Setup box : The information device that contains TV tuner input and displays out on the TV is called a setup box. Sequence of Curriculum Issued by CDC  Introduction and use of information and communication tools such as automated tailored machine, photocopier, scanner, printer, router, Wi-Fi device, and television set up box.  Introduction to search engines, websites and internet service providers.  Introduction and uses of social networking sites  Introduction to cyber-crime, Computer ethics, cyber-law and Internet security  Introduction to robotics and virtual reality  Introduction and general uses of artificial intelligence and cloud computing. UNIT Information and Communication Technology 2 Estimated teaching periods Theory Practical 20 10 Claude Elwood Shannon is known as the father of information theory for his contributions to telecommunications. He was born in the United States of America on 30th April 1916 and died on 24th February 2001. He was a mathematician, electrical engineer and cryptographer. He invented the branch of science “information theory”. He contributed to enabling telecommunications to move from an analogue to a digital transmission system. He also designed Minivac 601 digital computer trainer. Claude Elwood Shannon About the Scientist

Modern Concept Science and Technology – 8 15 11. Internet : The global network that provides a variety of information and communication facilities using standardized communication protocols is called Internet. 12. ISP : It is a company that sells Internet facilities to common people and business customers. 12. Web pages : The hypertext documents on the World Wide Web are called web pages. 13. Website : The collection of multiple web pages under the same domain name is called a website. 14. Search engine: The software that can carry out web searches is called a search engine. 15. SNS : The Online platform where people can stay connected and create a social relationship with people of similar interests or careers is called social networking site (SNS). 16. Blogging : The act of publishing information on a certain topic, often an informal diary-style text post is called blogging. 17. Blog : A blog is a regularly updated website. 18. Cyber-crime : The use of a computer to harm other people is called cyber-crime. 19. Computer ethics : The set of moral standards that rules the use of computers is called computer ethics. 20. Cyber-law : The law which is used to stop cyber-crime and abuses is called cyber-law. 21. Internet security : The rules and measures to stop attacks over the Internet are called Internet security. 22. Robot : The programmable machine that can perform a series of complex works automatically is called a robot. 23. Robotics : The process to design, construct, operate and using robots is called robotics. 24. Virtual reality : The use of computer modeling and simulation that allows a person to interact with a three-dimensional computer-generated environment is called virtual reality. 25. Artificial intelligence : The software that can mimic human intelligence, critical thinking and problem-solving ability in the machine is called artificial intelligence. 26 Cloud computing : The delivery of various services, data storage facilities, access to servers and databases, networking and software through the Internet is called cloud computing. Introduction The Internet is a revolution in the field of information and communication technology. Various ICT tools are commonly used in our daily life. The ATM, television set up box, television remote, fax machine, printers, photocopier, biometric scanner, router, digital camera, etc. are some ICT tools. The Internet connection is installed by Internet service providers. We can access various websites through a URL address. The search engine is very useful to search for information in case we do not know web address. Most people maintain social relationships and business relationships through social networking sites such as Facebook, Wikipedia, YouTube, zoom, SMS, blog, vlog etc. With increasing use of Internet and ICT tools, various fields such as education, banking, business, research, transportation and communication are benefited. However, cyber-crime is also increasing every day. We need to follow computer ethics. We also need to use Internet security methods too to make Internet safe for everyone. Cyber-law protects us all from attacks over the Internet. Various fields of science are well developed nowadays. As a result, humans can make robots that can do particular tasks. Artificial intelligence is used to operate various social networking sites, research and robots. Virtual reality is widely used to make movies and video games. Software such as Google drive, one drive and many other cloud storages can be used to back up information from our mobile devices and computers.

16 Information and Communication Technology Fig. 2.1 ATM Fig. 2.2 icon of Facebook, YouTube etc. Fig. 2.3 VR headset 2.1 Information and Communication Tools Information is very useful to us. It is a set of facts. It helps us to communicate. The information is now digitized. Taking pictures, scanning, typing, creating documents on computers etc. creates digital information. Digital information is very important in modern society. There are tons of digital information on the Internet. The information can be copied, replicated, transferred, edited, mailed and printed. The exchange of information between two or more people is called communication. Various tools are used to collect, process, store, transfer and work with digital information. For example, cameras, smart-phones, laptops, desktops, digital cameras, biometric scanners, automated teller machines, printers, software programs, data projectors, routers, WiFi, television, T.V remote and T.V set up box work with Internet and digital information. These tools are called ICT tools. The diverse set of tools that are used to collect, create, share, exchange, transmit, store and process information is called ICT tools. Some of the ICT tools are discussed below. FACTS WITH REASONS The ICT tools are used widely in modern society. ICT tools are used widely in modern society because it has simplified the way we communicate. It has made communication easier in business, education, banking, etc. Automated teller machine An automated teller machine is an ICT tool. It is a way of doing quick and easy transactions. The electronic device that allows bank account holders to perform quick money transactions is called automated teller machines. It is a convenient tool. We do not need to visit the bank or meet an actual teller to do transactions. We can collect cash from any ATM throughout the country. ATM of some bank allows withdrawing cash in foreign countries too. Most ATMs are simple cash dispensers but some ATMs are advanced. MEMORY TIPS ICT tools enable real-time communication among people and allow them to receive new information. Fig 2.5 various models of an ATM

Modern Concept Science and Technology – 8 17 Advanced ATMs can do complex transactions such as balance transfers check deposits and bill payments. Parts of ATM An ATM (Automated Teller Machine) typically includes an input device, such as a keypad or touch screen. It is used by users to enter their banking information. The ATM also includes output devices, such as a screen, speaker, bill printer and cash dispenser. They are used to display account information and provide transaction receipts. In ATM, the processing device is usually a computer. It processes the user's input and communicates with the bank's servers to perform the requested transactions. Importance of ATM ATM helps to withdraw cash, check balance, check account, change PIN and some can help to deposit cash. FACTS WITH REASONS ATM is connected to the Internet. ATM is connected to the Internet so that it can check our balance in our bank and process the transaction. How to use ATM? i. We need to insert our debit card into the card reader of automated teller machine. Information about our bank account will be sent to the server from card reader. ii. We have to confirm the transaction by entering Personal Identification Number (PIN) from the keyboard. iii. Then we should select the account (saving or current). iv. We should select fast cash or withdrawal at monitor. v. Then we can select the desired amount or input the amount we want to withdraw. vi. We have to choose if we want a printed report or not. The output device bill printer will print the receipt. Now the transaction will be processed. First of all, we have to collect our debit cards. Then the cash will come out of cash dispenser of the machine. If we do not collect in time, the cash will be drawn back into the machine. Usually, we are requested to remove the helmet and mask while using ATMs so that they can record our faces. FACTS WITH REASONS We should not write PIN of debit card on it or anywhere. We should not write PIN of debit card on it or anywhere because other people will know it and can steal money from our account. Banks install ATMs in major city areas and hospitals. Banks install ATMs in major city areas and hospitals so that we can access money during emergency. MEMORY TIPS There are more than three million ATMs around the world. There is one in Antarctica as well. MEMORY TIPS We should never share PIN with others or write in debit card or credit card.

18 Information and Communication Technology ACTIVITY 1 Visit ATM with your parents and learn how to withdraw cash. Photocopy machine The photocopies of documents are necessary everywhere. It is necessary for schools, businesses and government offices. It is used to make copies of question papers, notes, pictures, forms, citizenship etc. A photocopier is a machine that can create photocopies of any printed document. When a hard copy is placed in a copier, then a light shines on it. Its digital copy will be made and printed on paper. We can make multiple photocopies at once. Some photocopier uses liquid ink or solid ink, ribbon ink or toner. Most photocopier use xerography technology. FACTS WITH REASONS We should never sit on a photocopy machine. We should never sit on a photocopy machine because pressure damages the glass of the machine. ACTIVITY 2 Use a photocopier to make a photocopy of your birth certificate. How to use a photocopier? i. First of all, we should start photocopier. It could be off or in sleep mode. We should feed paper in the paper tray. Usually A4 paper (8.5 x11 inch) is used. ii. We need to put a hard copy on the photocopier. The document is placed face down. iii. Then we should close the cover. iv. Now we should input the number of copies to be made. v. We can select colour preference and paper size too. vi. Then we can press the copy button. Photocopiers are used for photocopying only. However, modern photocopiers can do multiple functions such as photocopy, scanning and printing. Scanner A scanner is also an ICT tool. It is an input device. It can capture texts, documents and pictures from hard copies. It creates a digital copy of the hard copy. The digital copy can be printed, emailed or stored as an image or stored as a PDF. An ICT tool that scans documents and converts them into Fig 2.6 : various photocopiers MEMORY TIPS The photocopy machine was designed by a man who had arthritis disease. He designed it so that he could avoid writing. MEMORY TIPS Ray Kurzweil is an American inventor who invented scanner.

Modern Concept Science and Technology – 8 19 digital data is called a scanner. A bar code scanner is used in shops. It is also used in banks, schools and government offices to create soft copies of important documents. It works by using Optical Character Recognition (OCR) technology. Scanned document can be stored in computer or mobile. Mobile can use scanner applications to scan hard copies. Fig 2.7: scanners FACTS WITH REASONS Air vents of scanners should not be blocked. Air vents of scanners should not be blocked otherwise the device will overheat and start a fire. ACTIVITY 3 Use a scanner to make a digital copy of your birth certificate and passport-sized photo and save it in your Google drive. How to use a scanner? i. Scanner should be connected to the computers. ii. We should keep the document in a scanner. The document is kept face down. iii. We should close the cover. iv. Now we should press scan button. v. A powerful beam of light hits the document and creates a digital copy. vi. The scanned document can be emailed or saved.

20 Information and Communication Technology Printer Introduction to printer The printer is hardware. It is an output device. It is available in various sizes, speeds and costs. It can receive information from a computer, photocopier, scanner or mobile device and print it on paper. It can print many copies at once. The machine that can print pictures and texts by receiving commands from computers is called a printer. The inkjet printers print slowly but give highquality prints. The laser printers are very fast. Printers and photocopiers also produce certain noise, dust and other pollutants. So, using it for a long time could cause respiratory diseases. The printing speed of the printer is measured as Character Per Second (CPS), Lines Per Minute (LPM) or Page Per Minute (PPM). FACTS WITH REASONS Printers should not be kept closer to source of heat. Printers should not be kept closer to the source of heat because the ink will become thinner, creating messy printing. ACTIVITY 4 Find your birth certificate in your Google drive then print it yourself. How to use a printer? i. Printer must be connected to the computers. ii. To print word files, we can press Ctrl + P or we can go to File > Print > select printer and press print. Router and Wi-Fi devices Let’s observe which device is generating Wi-Fi signals in our home. There must be a device in our house that is receiving signals and distributing them to our smart-phones and computers. That device is called a router. A router is an electronic device that connects computers and mobiles to the Internet. The Internet service providers install them in our house. It is a device that forwards the Internet connections to our devices. It works based on MEMORY TIPS PrintStik is the world’s smallest printer. Fig 2.8 : printer Fig 2.9 : various models of routers

Modern Concept Science and Technology – 8 21 Internet Protocol address. Some of the routers are wired and some are wireless. A wired router is preferred over a wireless one because a wired router does not lose signals. Most people use wireless routers because it is convenient. It provides us with Wi-Fi. Wi-Fi is a wireless technology that connects computers and smart-phones to the Internet. We can stay anywhere within the range to use Wi-Fi and access Internet. We need to select correct network and enter the password to connect to Wi-Fi. There is always packet loss in Wi-Fi. It may be due to walls, aquarium, distance etc. FACTS WITH REASONS Routers should not be placed near the aquarium. We should not place routers near the aquarium because it will weaken the wireless signal. The wireless router is installed in homes. The wireless router is installed in homes so that it will be easier to connect smart-phones and laptops to computers ACTIVITY 5 Connect your mobile device to the Wi-Fi and observe which room of your house has a better signal. What might be blocking Wi-Fi signals in some rooms? Discuss. How to use a router? i. Select a place to fix router. ii. Plug it into a power source. iii. Connect the optical fiber to the router. iv. Arrange router gateway. ISPs gives it to us. Then connect router to gateway. We can do it by shutting down router, unplugging cables from LAN and then reconnect to WAN. Then we should plug in the router and wait few minutes. v. Connect the computers to the outgoing Ethernet cables or connect mobile and laptops to the router. vi. Set the Wi-Fi - user's name and password. vii. Update firmware of router, change Wi-Fi password. viii. We can make our internet safe by using applications of ISPs. Uses of router i. It connects our hardware to distant server. ii. It transfers data to and from our devices with or without wire. iii. It access the IP address of the recipient and sends email, data, audio video etc. iv. Wireless router can be used to share data, audio, video and internet by configuring Virtual Private Network (VPN). Wi-Fi Wi-Fi stands for wireless fidelity. It works by using radio-waves. It can connect our devices such as mobile, laptops, printers etc. to the internet without wires or fibres. It is very convenient. It MEMORY TIPS Wi-Fi devices use radio waves to transfer information.

22 Information and Communication Technology was invented by NCR corporation in 1991. Wi-Fi signals can work by the help of base station network or ethernet connection, router and ICT tools such as mobile. The base stations are fixed communication locations. TV setup box The setup box is an ICT tool. It is specially designed to receive an audio video signal from a particular Internet video provider through the Internet. The received signals are then passed to the television. Then we can view different videos and access YouTube channels or television channels on it. The information device that contains TV tuner input and displays out on the TV is called TV setup box. It is also called a cable box. It can receive a signal from Ethernet cable, satellite dish, cable or telephone line. How to use a setup box? i. Connect set up box to power cable. ii. Connect set up box to an Ethernet cable or telephone lines etc. iii. Connect the cables from set up box to the television. iv. Select the input (AV, PC, TV, HDMI etc.). v. We might need to input user name and password. vi. We can set volume, brightness and other settings from remote of setup box. vii. We can change channels and navigate from remote. 2.2 Introduction to Search Engines, Websites and Internet Service Providers Search engine If the Internet is available in our house, we can use it to access information. We can use the Internet to update our devices. We can use the Internet to update various applications on computers and smart-phones. We can access various websites and social networking sites. A web browser can be used to surf the Internet. We can visit any website if we know its URL address. But if we do not know the URL address of the website or social networking sites, then it will be difficult to access them. In such cases, we can use search engines. Search engines are software specially designed to search the information based on keywords. The software that can carry out web searches is called a search engine. Some popular search engines are the Google search engine, Bing search engine, yahoo search engine, ask.com etc. Whenever we input a keyword in a search bar, the search engine starts to search the information. The most search engine works on steps such as crawling, indexing and ranking. The search engine provides options under the search bar where we can select all or videos or news or images or maps. Whenever the result is displayed on the homepage, we can click the desired link. MEMORY TIPS Google search is the most popular search engine. Fig 2.10: TV setup box

Modern Concept Science and Technology – 8 23 Fig 2.12 : icon of search engines Google search engine, Bing search engine, yahoo search engine, ask.com etc. FACTS WITH REASONS Why is a search engine easy to use? A search engine is easy to use because it can search for information from keywords only. There is no need to remember web addresses. ACTIVITY 6 Open web browser Google chrome. Press three vertical dots on the top right > setting > search engine. Practice changing search engines. Website The World Wide Web contains text files written in Hypertext Markup Language. Those documents are called web pages. The hypertext documents on the World Wide Web are called web pages. It is stored on a web server. Whenever we access them, these files are downloaded and shown visually on the monitor. Numerous web pages are linked together under a common domain name to make a website. The collection of multiple web pages under the same domain name is called a website. Some popular websites are Google, TikTok, YouTube, Facebook, Instagram, Wikipedia etc. Each web page has a web address called a Universal Resource Locater (URL). We need a web browser to access websites. Some common web browsers are Microsoft edge, Google chrome, Firefox and opera. The website can be a personal, corporate website, government website, or business company website. Hyper-links are present on a web page. They are blue. When we click them, they take us to another web page. Fig 2.11: icon of website MEMORY TIPS The first website was invented on August 6, 1991.

24 Information and Communication Technology Public websites can be accessed by anyone. However, some private websites can be used by owners only. Parts of the website i. Web hosting: The activity of providing storage space and access for websites is called web hosting. ii. Web address: The web address also called URL should be typed in address bar to reach the sites. iii. Homepage: The first page that gives introduction of website and serves as table of content for the site is called homepage. iv. Digital materials: The homepage contains multiple digital materials. v. Navigation design: The website navigation design is architecture of all navigational elements of the website. It helps users to find what are they looking for. FACTS WITH REASONS We should remember URL of a web address. We should remember URL of a web address because it helps us to locate websites and web pages. ACTIVITY 7 Open the website https://moecdc.gov.np/ and surf the page. Internet service provider (ISP) The Internet is a global network that provides a variety of information and communication facilities using standardized communication protocols. The Internet is a technological revolution. It has changed our world. With the Internet, communication is so easy and cheap that the entire world is like a small village. The Internet has helped education, business, industries, entertainment industries, communication, transportation, banking, space exploration and many other fields. However, the Internet cannot be accessed easily. To be connected to the Internet we need to buy services from Internet service providers (ISP). It is a company that sells Internet facilities to common people and business customers. ISP helps in internet access, internet transit, domain name registration, In service provider (INSP), web hosting etc. When we buy an Internet package from any Internet service provider, they visit our house and install a router, special networking etc. They let us rent that equipment. They give us the user name and password of an account. We have to pay them periodically for Internet service. Some common internet service providers in Nepal are CGNET, World link, Vianet, Subisu, classic tech etc. MEMORY TIPS ISP charges a fee for installing the connection and for maintaining it. Fig 2.13 : CGNET, World link, vianet, subisu, classic tech

Modern Concept Science and Technology – 8 25 Internet was available to public since 1980 through World Wide Web (WWW). Telenet is the world's first internet service provider. It was launched in 1974. Mercantile company was the first internet service provider in Nepal. Internet was first introduced in Nepal in 1994. Importance of ISP are: i. It helps in webhosting. ii. It prevents malware from attacking its users. iii. It provides IP address to us. iv. It provides internet to us. FACTS WITH REASONS Why do most ISPs install fibre Internet over wireless Internet? Most Internet service providers prefer fibre Internet over wireless Internet because it offers faster Internet speed over longer distances. There is no packet loss through fibre. ACTIVITY 8 Install the mobile application of your Internet service providers. Learn to open a ticket to deal with problems with Internet in your house. 2.3 Social Networking Site Introduction The Internet connects us all. The Internet itself cannot connect people. The Internet is used by various websites to create a platform where people stay connected. Some websites such as Facebook, Instagram, TikTok, YouTube, Wikipedia, Twitter, etc. allow people to share information. People can share photos, videos, text, ideas etc. Such websites are called social networking sites. The Online platform where people can stay connected and create a social relationship with people of similar interests or careers is called social networking site (SNS). There are varieties of social networking sites. These sites can be accessed from smart-phones, iPhones, Macs, tablets, laptops, desktops etc. Based on the nature of the site, it may allow sharing texts, posts, photos, videos, diary and information. Some of them allow us to directly communicate with other people through text messages, audio calls and video calls. SNS allow us to create and maintain social and professional relationships. They help us to keep in touch with people who live very far away. It removes the obligation to meet the other party personally for minor tasks. The website of government offices, national organizations, international organizations, social organizations and schools are also social networking sites. Importance of Social Networking 1. Strong medium: It is a powerful platform where people can express their opinion, communicate, access information, launch social, educational or political campaign etc. 2. Brand development: It is a platform where varieties of business organizations, educational organizations or social organizations can promote their companies, business etc. MEMORY TIPS More than 4.2 billion people use mobile phones to access social networking sites.

26 Information and Communication Technology 3. Costumer interaction: Consumers can learn about various products of various companies. They can interact with companies through social networking. Fig 2.14: Youtube Fig 2.15: Facebook Fig 2.16: Instagram FACTS WITH REASONS Why should we follow computer ethics while accessing social networking sites? We should follow computer ethics while accessing social networking sites so that we would not hurt each other through the Internet. ACTIVITY 9 Open a website of your school and download the school calendar or any other notice. For example: The website of the school gives us space for interaction between ex-students, active students, parents and teachers. We can obtain information on various activities, programs, exam schedules, holiday notices and much other useful information on the school website. We can view or download school calendar, photos, videos, exam routines and notices from the website of the school. Wikipedia is a source of information. It is a free Online encyclopedia. It uses simple English words and grammar so that even children can understand it. Similarly,Twitter is another social networking site. People post tweets in it. The tweet may be their idea, photos, videos, links and texts. It helps people to communicate and stay connected. SMS is another service provided by telephone companies, Internet and mobiles. It stands for Short Messages Services. We can use it to send short text messages to one or multiple receivers. Zoom, skype, messenger and Viber can be used for video conferences. Fig 2.17 : Wikipedia Fig 2.19 : twitter Fig 2.18 : skype MEMORY TIPS Zoom can be used for online classes and webinars.

Modern Concept Science and Technology – 8 27 FACTS WITH REASONS Social networking sites are useful tools for education sector. Social networking sites are useful tools for education sector because they provide different ways that can be used to create classrooms and share information. They connect students, parents and teachers. ACTIVITY 10 Organize a video conference on any application such as zoom or Google meet etc. Practice using these applications. In short, the importance of social networking sites can be summarized as: i. It helps to stay connected with family members and relatives. ii. Business companies can connect with customers. iii. We can stay connected to our friends. iv. It helps to make audio calls and video calls. v. It helps to collect information from various websites. vi. It helps to learn about other people, companies or events. Disadvantage of social networking sites 1. Cyber bullying: Since person do not need to directly face other people, the rate of bullying increases in social networking sites. 2. Fake accounts: Many people, hackers, terrorists etc. make fake accounts in social networking sites and use it to bully others or hack others for evil purposes. 3. Confidential information leak: Since people unknowingly upload information, use passwords and sometimes hackers use malware to steal information, SNS is hurting us by leaking private information. Blogging website The blog is an informational website similar to social networking sites. The act of publishing information on a certain topic, often an informal diary-style text post is called blogging. In blogs, the most recent post appears at the top of the web-page. Usually, a blog contains text, images, web pages and hyper-links. However recently most of the blog contains videos. They are called vlogs. A blog is a regularly updated website. It is used for personal use. Business companies also use a blog to advertise themselves, take care of customers etc. Blog nowadays usually means the creation of certain content and sharing on social media. Many people make vlogs and share them on Facebook, Instagram, TikTok and YouTube. How to make a blog? i. Select hosting company. Choose a hosting package and create a hosting account. ii. Press ‘get started now’. Follow the lead. iii. Install the Word-press application. Fig 2.20 : wordpress

28 Information and Communication Technology iv. My sites > Create site > start building under Word-press option. v. Enter Admin information. vi. Log in and choose a theme. ACTIVITY 11 Make a blog about your classroom. FACTS WITH REASONS A blog is very important for business companies. A blog is very important for business companies because it connects companies with customers. Customers can learn about company products and facilities. 2.4 Introduction of Cyber-crime, Computer Ethics, Cyber Law and Internet Security Cyber-crime The computers and Internet are very useful tools. It has helped humans in many fields. However, it can be weaponized too. Some people use it to harm others. The use of a computer to harm other people is called cyber-crime. Hackers and terrorists use it to do illegal activities. Some common types of cybercrime are: 1. Identity theft: The act of stealing personal and financial information to commit fraud is called identity theft. 2. Cyber terrorism: The act of using internet and computers to hurt a person, company or the government is called cyber terrorism. 3. Cyber bullying: the act of using computer and internet to hurt a person and harassment them is called cyber bullying. 4. Hacking: The act of using virus, malware, worms etc. to steal information, hack ICT tools, cameras etc. is called hacking. 5. Defamation: Some people use computer and internet to defame other people or companies. Safety measures from cyber-crime: i. We should never open random emails. ii. We should ignore random websites. iii. We should back up our information every day. iv. We should keep antiviruses, windows defender and firewall updated. v. We should remember our user-name and password. We should not auto-save passwords on devices. Computer ethics As we discussed above computers can be used to harm others. The hardware and software of the computer can be used to steal information. It is illegal. Many people are found bullying others on social networking sites, which is a crime. To make the Internet a safe place for everyone, everyone must be responsible. All of us should follow certain moral standards. The

Modern Concept Science and Technology – 8 29 set of moral standards that rules the use of computers is called computer ethics. It is a psychological concept. It protects us from online cyberattacks. It deals with copyright, privacy etc. Some of the common computer ethics are: i. Computers should never be used to harm others. ii. We should never disturb other people’s computer work. iii. We should never use a computer to steal others’ information. iv. We should never peek at other people’s files. v. We should not use pirated versions of software. vi. We should not use any computer or computer applications without permission. vii. We should think about consequences when we do anything on the computer and the Internet. FACTS WITH REASONS We should not use pirated versions of applications. We should not use pirated versions of applications because they may contain viruses, malware and worms that will harm our computers. Using pirated copies is also considered cyber-crime. ACTIVITY 12 Research on cyber-bullying. Check if any activity you are doing is cyber-bullying or any other cyber-crime. Avoid doing cyber-crime. Cyber laws Cyber law has a great importance in today’s world because lots of things are digitized nowadays. E-business, e-commerce, e-banking etc. are common nowadays. Online shopping is growing popular. Even though lots of us follow computer ethics, many abuse computers to harm others. Cyber-bullying, phishing, stealing information, hacking banks, hacking government websites etc. are some cyber-crimes that can happen around us. To protect us from cyber-crimes, cyber-law is necessary. The law which is used to stop cyber-crime and abuses is called cyber law. If someone breaks cyber law, we can take action against them. Cyberlaw allows us to punish them and get compensation. Cyber act in Nepal Nepal police used to regulate cyber-crimes by using Electronic Transactions Act 2063. According to section 9 of Electronic Transactions Act, i. If a person is found damaging any computer systems or data or pirating soft-wares, s/he is jailed for 3 years or is fined 2 lakhs or both. MEMORY TIPS Computer ethics is a part of practical philosophy. Fig 2.22 : cyber laws

30 Information and Communication Technology ii. If a person posts illegal contents, s/he is jailed for five years or fined 1 lakh or both. iii. If a person uses computer to fraud, s/he s/he is jailed for 2 years or is fined 1lakhs or both. Internet security The Internet can be very useful to us and very harmful at the same time. We can access information throughout the world. However, there is a chance that our private information will be leaked. Phishing, malware, worms, trojan and viruses are common threats in cyberspace. So, there are rules and methods to counter cyber-crimes.The rules and measures to stop attacks over the Internet are called Internet security. It keeps away hackers and cyberthieves from stealing sensitive information. Software such as firewall, email security and Microsoft defender is popular software that provides Internet security. Fig 2.23 : email security Fig 2.24 : firewall Fig 2.25 : antivirus FACTS WITH REASONS We should install a firewall on our computers. We should install a firewall on our computers to protect our computers from unwanted traffic, hackers and malware. It provides Internet security. ACTIVITY 13 Install software that provides Internet security on your computers and mobile phones. Some of the common risk of internet security are spams, worms, botnets, website spoofing, ransomware, phishing, malware and IoT hacking. Computers along with the Internet are widely used to access social networking sites. Certain websites can be stealing our private information. Fake websites that look identical to the real one is launched by hackers. It is called website spoofing. They steal user-names and passwords. With the stolen data they can steal money, digital property, copy right etc. MEMORY TIPS Email is the number one way to send malware. Fig 2.21: to represent cyber crimes

Modern Concept Science and Technology – 8 31 Sometimes cyber criminals steal very important data of companies or people. Then they blackmail companies to pay a huge sum of money. It is called ransomware. Sometimes malware comes along with emails. Those malware steal information from customers of the bank, military information etc. Then hackers use that information to damage the reputation of the company, military, people and government. It is called phishing scams. Malware is harmful software that allows hackers to access our computers. It can also physically damage our computers. It can spread the virus, damage operating software, corrupt files and steal our private information. Various devices such as mobiles, tablets, Macs etc. are connected to the Internet. We use these tools to access various websites and applications. They auto-save our user-names and passwords. This information is collected and exchanged by various devices and companies secretly. It is called the Internet of Things (IoT) hacking. Spam: Spam are harmful emails. It can install harmful software in our computers or mobiles. Computer worms: Computer worms are malwares that self-replicate and infect other computers while hiding in original infected computer. Botnet: Botnet is a group of internet-connected devices that can steal data, send spam and hack cameras. FACTS WITH REASONS It is not wise to insert personal information on random websites. It is not wise to insert personal information on random websites because they can steal our information and use it against us. They may steal our money, blackmail us, damage our prestige etc. ACTIVITY 14 Open your computer. Go to start menu > all programs > windows security > run scan. Does your computer find any malicious files? Some Internet security precautions i. We should never read spam emails. ii. We should disregard and remove random websites. iii. Every day, we should back up our information. iv. We should maintain updated antivirus, Windows Defender, and firewall software. v. We should remember our login credentials. We should not save passwords automatically on gadgets. vi. We should use safe and trusted browser. vii. We should use multiple security measures while accessing websites, ICT tools. We can use passwords, lock patterns, finger print, face scan etc. viii. We can use email security by encrypting emails to protect it from email virus, worms, phishing etc. MEMORY TIPS Phishing scams are the most common type of cybercrime.

32 Information and Communication Technology 2.5 Introduction of Robotics and Virtual Reality Robotics Some machines are programmed to do certain works automatically. They are programmable by a computer. Some of them can be controlled by remotes. Most robots are machines that are made to do particular work such as break rocks, dig mines etc. Some robots are made to mimic humans. For example, Ping Pong Playing Robot, Jia Jia, Sophia etc. Sophia is the most sophisticated humanoid robot. She is given citizenship in Saudi Arabia. The programmable machine that can perform a series of complex works automatically is called a robot. The microscopic robots are called nanorobots. The production of robots is possible due to the combined effort of engineering and computer science. The process to design, construct, operate and using robots is called robotics. Some interrelated fields of science that helps in robotics are computer engineering, software engineering, mathematics, electronics, electrical engineering, mechanical engineering, mechatronic etc. Robotic Process Automation (RPA) can observe and imitate humans and helps us to do automated works. Use of robots Robots are widely used to work in the mines. The mines are hot, and filled with carbon dioxide. It is a dangerous place for humans. A robot can go and work there without any problem. Robots are allowed for space exploration. For example, Perseverance is a robot that is navigating Mars. Robots also dive into the bottom of the sea. Military robots help in the war zone to supply medicines, carry wounded people etc. Robots also help in the industry to make complex machines, vehicles etc. Medical operating robots help doctors to perform surgery. Fig 2.26: robots working on mines Fig 2.17: robots helping in surgery Fig 2.28: robots helping in military FACTS WITH REASONS Robots are used in space travel. Robots are used in space travel because as they are non-living, they are less vulnerable to threats present in space than humans. Space travel is impossible for humans until to this date. ACTIVITY 15 Research on very simple robotics. Make a very simple model of a robot. MEMORY TIPS Robot farmers are programmed to plant seeds, weed, water and spray without the help of a human.

Modern Concept Science and Technology – 8 33 Merits and demerits of robots Since robots are non-living things, they can help us to do dangerous works such as mining, space travel, deep sea navigation, complex surgery etc. However, the growing use of robots in various fields of society is increasing unemployment. Robots work for free and do not die. Robots can work fast, accurately and conveniently. Robots do not complain. So, industries use robots instead of humans. As a result, people are losing their job. Robots help in cooking, hospitality, medical fields, education and research. However, terrorists and militaries can program robots to use weapons and bombs. It can be used as a machine of war to kill people. Virtual reality It is a computer-simulated world. It is either similar or completely different from the real world. Virtual reality is used to create a digital world where a person can dive in and interact with people and objects. The technology uses virtual reality headsets or multi-projected environments to produce a virtual world. The use of computer modeling and simulation that allows a person to interact with a three-dimensional computer-generated environment is called virtual reality. Fig 2.29: VR sets Fig 2.30: VR world It can simulate realistic images, sound and other physical aspects. There is a small screen in the VR headset before the eyes. Virtual reality is widely used in the fields of entertainment. It is particularly used by movie industries and video games. FACTS WITH REASONS VR is being used by militaries to practise their missions. VR is being used by militaries to practice their missions because it can easily create an almost real world. It is cheaper and more convenient than engaging in the real world. ACTIVITY 16 Search information on virtual reality and robotics on the Internet and write a short report on it. Fig 2.31: Ueaponised robots MEMORY TIPS VR technology is now being used in health care to treat depression and anxiety.

34 Information and Communication Technology Companies such as meta are using VR technology to create a digital world called metaverse. We can use VR technology for virtual busies meetings, school meetings, perform group activities and do practical work together with friends from our own homes. It is also used in medical science to treat depression. VR is used by military to treat people who has post-traumatic stress disorder (PSTD). It can be used to access educational materials for students. Such as digital planetarium where students can explore virtual solar system. Athletes and sportsman can practice in a virtual world. Doctors and dentists can practice surgeries in virtual samples. Merits and demerits of VR Virtual reality connects people together. It is effective means of communication. Continuous use of VR may cause headaches, nausea and eyestrain. 2.6 Artificial Intelligence and Cloud Computing Artificial intelligence As we all know Google search allows us to search for almost any information. If we observe very carefully, we can notice that Google will search links based on our previous search history and preferences. They remember our choices and interests. If two people stay in the same place and scroll down their own Facebook, what are the chances that the same content is displayed on their mobile? If two different people open YouTube, will same content be available on their homepage? No, the contents on Facebook, Instagram, TikTok, YouTube etc. are personalized. The contents displayed are based on the preference, history and interest of the particular user. So how is it possible? How do YouTube, Google, Facebook, and TikTok know our interests and preferences? They know it because they are monitoring us. They are using powerful supercomputers with advanced artificial intelligence. The software that can mimic human intelligece, critical thinking and problem-solving ability in the machine is called artificial intelligence. The AI can track our preferences. AI can use deep learning and machine learning. They use algorithms to solve problems. AI can think rationally and take action to achieve a particular goal. They are almost like living beings. AI could be weak if it can do only one simple task. Similarly, artificial general intelligence is as capable as human beings and Artificial super intelligence is far too intelligence than humans. Merits and demerits of AI The objective of an AI is to focus on computer-enhanced learning, critical thinking, reasoning, and perception. AI is used in medicine, education, transportation, research, Fig 2.31: AI MEMORY TIPS AI pets are available. They act like real pet animals. MEMORY TIPS The banks are the companies that use cloud computing the most.

Modern Concept Science and Technology – 8 35 diagnosis of disease etc. AI is also able to create art and poem nowadays. Sophia is a social humanoid AI robot. She can think, chat, make a joke, tell poems, feel happy or be sad too. Alexa and Siri are chatbots with AI. Tesla is an electric car with AI. Despite the usefulness of AI, many people fear that AI can harm society. AI can use deep fake. Millions of people lose their job every year to a robot and AI. AI can be weaponised to harm people. Use of AI 1. AI is widely used in the study of outer space. 2. AI helps to diagnose diseases, find cure and suggest best treatment methods and develop vaccine. 3. AI is widely used in sports. Some of them work as referee in football competition or play chess against us. 4. AI helps business organizations to analyze stock, provide customer service and suggest business plans. 5. Social networking sites uses AI to make it user friendly. 6. It can also use cloud computing to store information. 7. Robotics and AI are used combined to make powerful robots. 8. AI is very useful in education. 9. AI robots help in agriculture. FACTS WITH REASONS Why does Google use artificial intelligence? Google uses an AI system to monitor our preferences and improve the search results for us. Why do big business companies use artificial intelligence? Big business companies use artificial intelligence because AI can select the best possible channel for a company with the highest chance of success. ACTIVITY 17 Creativity is unique to humans. We can create art, music and poems. Can AI do this? Research. Cloud computing If we have a Gmail account, we can use 15 GB of cloud storage for free. When we turn on the backup service. Our photos, videos and contacts are automatically saved in our G-drive and Google photos. Now let’s try to learn its meaning. It means if the Internet is available, we can store information in Google Drive. Such a facility is called clod computing. The delivery of various services, data storage facilities, access to servers and databases, networking and software through the Internet is called cloud computing. Fig 2.32: google drive Fig 2.33: one drive

36 Information and Communication Technology Cloud computing is very important for people, schools and businesses as well. It is safer to store files in a remote database than save them on the hard disk of our computer. FACTS WITH REASONS It is wise to save documents in cloud storage. It is wise to save documents in cloud storage because they will be preserved in clouds so that we can access them from any device. Data is not lost even if the device is destroyed. Importance of cloud computing It is low cost. It does not consume the space. It increases productivity, speed and efficiency of work. It is secure. It can back up phone contacts, photos, videos and other files in cloud storage. We can download information from the cloud on any other device. It can be used from anywhere in the world. Disadvantages of cloud computing Since all of the information is stored on the internet, there is a chance of cyber-crime. If the main server is damaged due to a natural disaster, data may be lost forever. FACTS WITH REASONS Cloud computing is useless without Internet. Cloud computing is useless without Internet because if there is no Internet, we can neither upload nor download our files. We cannot even use it. ACTIVITY 18 Click a photo from your smart-phone. Upload it in Google photos or other cloud computing software. Then download that photo to your computer from the cloud. [Do not use USB data cable, memory card, blue tooth etc. to transfer file] HOT SKILL HIGHER ORDER THINKING SKILL 1. What is the collection of multiple web pages under the same domain called? The collection of multiple web pages under the same domain is called a website. 2. Mention the use of VR in health care. The VR is used in health care to treat depression, assist in surgery and train new doctors. 3. Why is fibre connection better to access Internet on the computers? The fibre connection is better to access internet on the computer because it provides higher bandwidth, faster speed and reliability. 4. Differentiate between printer and scanner. The differences between printer and scanner are:

Modern Concept Science and Technology – 8 37 SN Printer SN Scanner 1 It converts digital copies into hard copies. 1. It converts hard copies into soft copies. 2. It is an output device. 2. It is an input device. 5. Let’s suppose we have recently opened an account on social networking sites. What are our responsibilities while using it? What kind of activities on social networking sites can be considered cyber-crime? What should we be aware of? If we have a social networking site account, we have the following responsibilities: i. We should not use it to post hurtful text, pictures or videos. ii. We should not bully others over the Internet. iii. We should not make any digital footprint that can be harmful in future. iv. We should not spend a lot of time over it. Following activities on social networking sites can be called cyber-crime: i. Bullying others on posts and comments. ii. Sharing links of malware and virus. We should be aware of the following things while using social networking sites. i. We should not share user name and password with others. ii. We should never enter user name and password on an insecure website. 6. Nowadays single device can work as a printer, photocopier and scanner. If your parents got you a printer, how would you photocopy your birth certificate? Even though I got printer, it can still do photocopy. I can use it to photocopy my birth certificate in following ways: i. First of all, I will power on the device and feed paper to it. ii. Lift the top cover and put the birth certificate face down and close it. iii. Then I will press copy, select number of copies to be made and then press start. The birth certificate will be photocopied. 7. Artificial Intelligence is a new technology. It is heavily impacting our society already. Lets find out their positive and negative impacts on the society. The positive impacts of the artificial intelligence are: Artificial intelligence is a new technology. It is being used by large corporations to make business plans for them. It is used by traffic police to observe the traffic and reduce traffic accidents. It helps doctors in surgery. AI such as Siri of the apple company and Alexa of the Amazon company act as personal assistant to the people. They help to access digital world. Artificial intelligence also helps in navigation of satellites. AI also have some negative impacts. Some of them are: After all AI are built by humans, it can have built-in bias either accidentally or intentionally. Programmers can hack it and use it for cyber crime. It can be easily weaponized so it could be used as weapon for mass destruction.

38 Information and Communication Technology 3 STEPS EXERCISE EXERCISE STEP1 1. Select the best answer from the given alternatives. a. Why do ATMs need an internet connection? i. To download money. ii. To check the bank account. iii. To print the money. iv. To record the video of user. b. We should handle toner of photocopier very carefully. Why? i. It is expensive. ii. It has fine powder that causes a respiratory problem. iii. It will not print. iv. It is slippery. c. Which tool is used to make a soft copy of the photos? i. Photocopier ii. Printer iii. Scanner iv. ATM d. What is the reason for using a wireless router in homes? i. Its signal is blocked by a thick wall. ii. Its signal is blocked by metal plates. iii. Its signal is absorbed by an aquarium. iv. It can connect Internet to mobile phones. e. Why is it not wise to surf random websites on the internet? i. It installs viruses, YouTube, antivirus and firewall in our computer. ii. It steals information, and steals hard disk from our computer. iii. It consumes more data packages. iv. It installs viruses, malware and worms on our computers. 2. Write True for the correct and False for the incorrect statements. a. ATM of some banks allows withdrawing cash in foreign counties too. b. Advanced ATMs can do complex transactions such as balance transfers check deposits and bill payments. c. The inkjet printers print very fast but low-quality prints. d. The hypertext documents on the World Wide Web are called websites. e. A blog contains text, images, webpages and hyperlinks. 3. Fill in the blanks using a suitable word. surgery computer ethics website spoofing blogging robots a. The act of publishing information on a certain topic, often an informal diary-style text post is called ………... b. Fake websites that look identical to the real one launched by hackers is called .....………...

Modern Concept Science and Technology – 8 39 c. The set of moral standards that rules the use of computers is called ………... d. The production of ………… is possible due to the combined effort of engineering and computer science. e. The medical operating robots help doctors to perform ………... 4. Answer the following questions in very short. a. What types of ink are used in photocopiers and printers? b. In which format a scanned document can be stored? c. What happens to the Internet speed if multiple devices are connected to it? d. Which language is used to write a web page? e. What is a regularly updated website called? STEP2 5. Give reasons a. We are asked not to wear masks and helmet while using ATMs. b. We should immediately notify the bank if someone steals our debit card. c. We should not block the air vent of a photocopier. d. Routers are not placed near water, metal and thick wall. e. TV setup box is connected to the router. f. Internet service providers are a necessary component of information and communication technology. g. Search engines are very useful software. h. Most people are on social networking sites. i. Downloading copyright movies, songs etc. without paying is called cyber-crime. j. Most industries use robots instead of humans in risky jobs. k. Artificial intelligence can make a negative impact on society. l. Business companies and banks use cloud computing. 6. Differentiate between the following. i. Photocopier and scanner ii. Scanner and printer iii. ATM and router iv. Router and TV setup box v. Internet service provider and website vi. Blog and social networking sites vii. Search engine and websites viii. Virtual reality and cloud computing ix. Robots and Artificial intelligence 7. Answer the following in short. a. Write a short note on the Internet service provider. b. Define the website. c. What is a seach engine? How is it used? d. What is an SNS? What is it used for? e. How can we protect ourselves from cyber-criminals?

40 Information and Communication Technology f. Write a short note on Internet security. g. Robots are a boon as well as a curse. Justify. h. What are the disadvantages of cloud computing? i. What is a TV setup box? What is it used for? j. Write a short note on the printer. STEP3 8. Answer the following questions. a. The Internet has revolutionized Information and Communication. Justify with any three examples. b. Define information and communication tools. How does it make our daily life easier? Discuss. c. What is an ATM? Mention its parts and uses. d. What is a photocopier? What is it used for? e. Define scanner. Let’s suppose we need to scan and email our birth certificate. How can we do it? f. What is a router? What are the precautions while installing a router? g. What is a blog? How can we make a blog? Describe the process. h. What is a social networking site? Is it beneficial to society? Enlist those benefits. i. Most people spend many hours each day on social networking sites. Does it have any negative effect on humans? Enlist them. j. How do social networking sites help in education? k. What is cyber-crime? Ramesh hacked the school’s website to steal question papers of class tests. Is it cyber-crime? What other activities are considered cyber-crime? Make a list. l. How do cyber-criminals attack our computers? m. What is computer ethics? Monalika downloaded a music video which had a copyright on torrent. Is it an ethical way to use computers and the Internet? What are the ethical ways to use the computer? Make list. n. What is cyber law? How does it protect us? o. What are robots and robotics? Mention its uses. p. What is virtual reality? How is it useful to us? q. Stephen Hawking cautioned against AI. What might be the reason? What possible threats does AI possess to humanity? r. What do you mean by cloud computing? How is it beneficial to individuals and companies? s. Neharika was using a VR headset for a while. She complains that she got a headache. Is it because of VR? What other health hazards are caused by VR? Discuss. t. What do you mean by artificial intelligence? Artificial intelligence is an amazing technology. Support the statement by showing its uses.

Modern Concept Science and Technology – 8 41 Living Beings and Their Structures Unit 3 Introduction Cells are the building blocks of life. Each living body is made up of cells. A cell is made of cell membranes, cell walls, cytoplasm, mitochondria, nucleus and many other cell organelles. Each of them works together to keep the cell alive. The cells of the same origin form tissues. The tissues work together to make organs. Organs make systems and systems make multicellular organisms. They can be plants or animals or fungi. However, some organisms are microscopic. They are very small and can be observed through a microscope only. They are called microorganisms. They can be Monera, Protista, Fungi or viruses. Microorganisms are an essential component of the ecosystem. They help to regulate the ecosystem, recycle minerals, produce food and synthesize oxygen. They are also responsible for infection, diseases and food spoilage. Sanitation, antibiotics and antivirals can prevent diseases from such organisms. We can prevent food spoilage by canning, frying, freezing, salting and sweetening. This unit is divided into the following two subunits : Ribosome Cytoplasm Microtubules Centrioles Nucleus Nucleolus Golgi apparatus Mitochondrion Cell membrane Smooth ER Endoplasmic reticulum (ER) Lysosome Pinocytotic vesicle Cell wall Cell membrane Golgi apparatus Chloroplast Vacuole membrane Raphide crystal Druse crystal Mitochondria Cytoplasm Large central vacuole Rough (ER) Nucleus Nucleolus Endoplasmic reticulum (ER) Ribosome Animal cell Plant cell

42 The Cell Sequence of Curriculum Issued by CDC  Cell organelles of plant cells and animal cells  Function of cell organelles  Differences between plant cells and animal cells  Interrelationship among cells, tissues and organs in the human body UNIT The Cell 3.1 Estimated teaching periods Theory Practical 5 1 Robert Hooke is popular for discovering cells. He was born in England on 18th July 1635 and died on 3rd March 1703. He was a physicist and biologist. He proposed Hooke’s law. He was an expert in microscopy. He discovered and coined the term cell. He studied at Wadham College, Oxford. About the Scientist Key terms and terminologies of the unit 1. Cell : A cell is the structural and functional unit of life. 2. Prokaryotic cell : The cell that lacks an organized nucleus and other membrane bound cell organelles is called prokaryotic cell. 3. Eukaryotic cell : The cell that has well organized nucleus and membrane bound cell organelles is called eukaryotic cell. 4. Unicellular organisms : Those organisms which are made up of a single cell are called unicellular organisms. 5. Multicellular organisms: Those organisms which are made up of more than one cells are called multi-cellular organisms. 6. Cell wall : Cell wall is the outermost tough covering of a plant cell. 7. Cell membrane : Cell membrane or plasma membrane is the semi-permeable membrane that surrounds the cytoplasm. 8. Cytoplasm : Cytoplasm is the substance that is present between the nucleus and the plasma membrane. 9. Mitochondria : Mitochondria are the rod or oval shaped cell organelles which produce energy in the cell. 10. Nucleus : Nucleus is a round cell organelle which controls the overall activities of a cell. It is also called brain of the cell. Robert Hooke

Modern Concept Science and Technology – 8 43 11. Vacuoles : Vacuoles are the single-membrane cell organelles that store essential materials and wastes. 12. Plastid : Plastids are the double layered cell organelles that store food, give colour to the petals and produce food. 13. Endoplasmic reticulum : Endoplasmic reticulum is the branching tubules and flattened sacs that extend throughout the cytoplasm. 14. Ribosomes : Ribosomes are the small granular structures which are the site of protein synthesis. 15. Lysosomes : Lysosomes are the membrane-bound sacs that contain digestive enzymes. 16. Chloroplasts : The green plastids present in plant cells are called chloroplasts. 17. Plasmodesmata : Plasmodesmata are the pores in the cell wall that help to transport substances from one cell to the another cell. 18. Tissue : The group of large number of specialized cells with a common origin, similar structure and function is called tissue. 19. Organ : Organ is a group tissues working together for a particular function. 20. System : A system is a group of specialized organs working together to achieve a major physiological function. Introduction The body of living organisms is made up of tiny building blocks called cells. Cells are the basic unit of life. They are responsible for performing living activities in organisms such as growth, reproduction, excretion, etc. A single cell contains all the vital structures and substances for their independent function. The body of living organism as a whole is the sum of activities of all the cells. Hence, cell is called structural and functional unit of life. The word ‘cell’ was first coined by an English scientist named Robert Hooke in 1665 A.D. When he observed thin slice of wooden cork under his own crude microscope. He noticed the rows of tiny boxes that are made up the dead wood’s tissue and named a box as cell. Antonie van Leeuwenhoek invented an advanced microscope during the same time and observed, drew and described various cellular living forms. Later in 1839, German botanist Matthias Jakob Schleiden and German zoologist Theodor Schwann proposed that all living beings are made up of cells. Fig 3.1 : A compound microscope

44 The Cell FACTS WITH REASONS The cell is called the structural and functional unit of life. Cell is called the structural and functional unit of life because the structure of an organism depends upon the number of cells. Also, everything performed by an organism is the outcome of the work done by the cells. Prokaryotic and Eukaryotic Cells On the basis of structure and composition, cells are divided into two major categories. They are Prokaryotic cell and Eukaryotic cell. Fig 3.2 : Prokaryotic cell Fig 3.3 : Eukaryotic cell The cell that lacks an organized nucleus and other membrane bound cell organelles is called Prokaryotic cell. Such cells are only found in Bacteria and Archaea. The cell that has a well-organized nucleus and membrane bounded cell organelles is called eukaryotic cell. Cells of plants and animals are the examples of eukaryotic cells. FACTS WITH REASONS The bacteria are called prokaryotes. Bacteria are called prokaryotes because they do not have an organized nucleus and membrane bound cell organelles. Cell Shape, Size and Number Prokaryotic cells are rod like, spherical or spiral in shape. They are the tiniest cells and ranges from 0.0001 to 0.003 mm in diameter. Eukaryotic cells also have different shapes like irregular (amoeba), oval, circular, spherical (animals) or hexagonal (plants). Eukaryotic cells are typically about ten to hundred times larger than the prokaryotic cells. Mycoplasma, a smallest prokaryotic cell, has a diameter of about 0.0001mm. Similarly, an ostrich egg is the largest eukaryotic cell measuring about 15 cm long and 13 cm wide. Likewise, a nerve cell of Giraffe is the longest cell which measures about 3m in length. 3.1.1 Detailed Structure of a Typical Cell Cells differ in shape, size and functions. But, most of the cells contain some basic living structures inside them known as cell organelles. These cell organelles have specific structure MEMORY TIPS 1. Mycoplasma is the smallest cell. 2. Egg of ostrich is the largest cell. 3. Nerve cell in the neck of giraffe is the longest cell.

Modern Concept Science and Technology – 8 45 and functions. Some of the important cell organelles are discussed below. Ribosome Cytoplasm Microtubules Centrioles Nucleus Nucleolus Golgi apparatus Mitochondrion Cell membrane Smooth ER Endoplasmic reticulum (ER) Lysosome Pinocytotic vesicle Cell wall Cell membrane Golgi apparatus Chloroplast Vacuole membrane Raphide crystal Druse crystal Mitochondria Cytoplasm Large central vacuole Rough (ER) Nucleus Nucleolus Endoplasmic reticulum (ER) Ribosome Fig 3.4 : Animal cell Fig 3.5 : Plant cell a. Cell wall Cell wall is the outermost tough covering of a plant cell. It is absent in animal cell. Cell wall is mainly composed of non-living materials called cellulose. Cell wall maintains rigidity of the cell. It is a permeable membrane. Plasmodesmata are the pores present in the cell wall that help to transport substances from one cell to the another cell. Functions i. Cell wall protects the cell from external injuries. ii. It maintains the shape and size of the cell. iii. It helps in transporting substances in and out of the cell. b. Cell membrane or Plasma membrane Cell membrane or plasma membrane is the semi-permeable membrane that surrounds the cell. It is made up of phospholipids and proteins. It acts as a first and outer covering in an animal cell. But in plant cell, it is the second covering present inner to the cell wall. It is a thin and elastic membrane with numerous pores on it. Cell membrane allows only selective substances to pass in and out of the cell. So, it is also called a semi-permeable membrane. Functions i. It acts as a protective covering of a cell. ii. It helps in the selective transport of chemical substances in an out of the cell. iii. It also helps in communication among the cells in animals. Differences between cell wall and cell membrane S.N. Cell wall S.N. Cell membrane 1 Cell wall is made up of cellulose. 1 Cell membrane is made up of lipid and protein. 2 Cell wall is dead and it is permeable. 2 Cell membrane is living and it is semi-permeable.

46 The Cell c. Cytoplasm Cytoplasm is the fluid-like substance that is present between the nucleus and the plasma membrane. Cell organelles float freely in the cytoplasmic fluid. It is made up of lipids, proteins, minerals and water. Proteins in cytoplasm are also called the cytoskeleton as they maintain the shape of the cell. Functions i. Cytoplasm maintains the turgidity of the cell. ii. It forms the skeleton of the cellular body. iii. It anchors different cell organelles in it. iv. It distributes nutrients and enzymes within the cell organelles. d. Mitochondria Mitochondria are the rod or oval shaped cell organelles that produce and store energy in the cell. They are found distributed in the cytoplasm. All cells need energy to perform their functions. In most of the cells, energy is produced in the mitochondria. Without mitochondria, energy cannot be produced from the food we eat. A process called respiration occurs in mitochondria. Respiration is the process by which energy is produced by utilizing food and oxygen in the cell. The inner membranes of the mitochondria have finger like projections where respiration occurs. This produces energy in the cell in the form of a chemical called adenosine triphosphate (ATP). So, mitochondria is also called the powerhouse of a cell. Functions i. Mitochondria produces energy needed for various cellular activities. ii. They also involve in synthesis of smaller units of proteins called amino acids. FACTS WITH REASONS The mitochondria are called the powerhouse of the cell. Mitochondria are called the powerhouse of the cell because they perform cellular respiration to release energy and store it. e. Nucleus Nucleus is a double layered round cell organelle. It contains nuclear membrane, chromatin fibres, nucleolus and nucleoplasm. Nuclear membrane is the outermost covering of the nucleus. A dark spot inside the nucleus is called nucleolus. In a plant cell, nucleus lies at the periphery of the cell membrane. But, in animal cell, nucleus lies at the centre of the cell. Fig 3.6 : Mitochondria Chromatin network Nuclear membrane Necleoplasm Nucleolus Nuclear pore Fig 3.7 : Structure of nucleus