Secondary Biology Student's Book 1 (South Sudan) PDF

1 South Sudan South Sudan...

1 South Sudan South Sudan 1 Secondary Secondary Biology Student’s Book Biology Secondary Biology has been written and developed by Ministry of General Student’s Book Education and Instruction, Government of South Sudan in conjunction with Subjects experts. This course book provides a fun and practical approach to the subject of Biology, and at the same time imparting life long skills to the students. The book comprehensively covers the Secondary 1 syllabus as developed by Ministry of General Education and Instruction. Each year comprises of a Student’s Book and Teacher’s Guide The Student’s Books provide: Full coverage of the national syllabus. A strong grounding in the basics of Biology. Clear presentation and explanation of learning points. A wide variety of practice exercises, often showing how Biology can be applied to real-life situations. It provides opportunities for collaboration through group work activities. Stimulating illustrations. All the courses in this secondary series were developed by the Ministry of General Education and Instruction, Republic of South Sudan. The books have been designed to meet the secondary school syllabus, and at the same time equiping the students with skills to fit in the modern day global society. This Book is the Property of the Ministry of General Funded by: Funded by: Education and Instruction. This Book is the Property of the This Book is not for sale. Ministry of General Education Any book found on sale, either in print or electronic and Instruction. form, will be confiscated and the seller prosecuted. This Book is not for sale.  How to take care of your books. Do’s 1. Please cover with plastic or paper. (old newspaper or magazines) 2. Please make sure you have clean hands before you use your book. 3. Always use a book marker do not fold the pages. 4. If the book is damaged please repair it as quickly as possible. 5. Be careful who you lend your schoolbook to. 6. Please keep the book in a dry place. 7. When you lose your book please report it immediately to your teache Don’ts 1. Do not write on the book cover or inside pages. 2. Do not cut pictures out of the book. 3. Do not tear pages out of the book. 4. Do not leave the book open and face down. 5. Do not use pens, pencils or something thick as a book mark. 6. Do not force your book into your schoolbag when it is full. 7. Do not use your book as an umbrella for the sun or rain. 8. Do not use your book as a seat.  SECONDARY South Sudan 1 Biology Student’s Book 1 © 2018,THE REPUBLIC OF SOUTH SUDAN, MINISTRY OF GENERAL EDUCATION AND INSTRUCTION. All rights reserved. No part of this book may be reproduced by any means graphic, electronic, mechanical, photocopying, taping, storage and retrieval system without prior written permission of the Copyright Holder.Pictures, illustrations and links to third party websites are provided in good faith, for information and education purposes only This book is the property of the Ministry of Funded by: General Education and Instruction. THIS BOOK IS NOT FOR SALE. FOREWORD I am delighted to present to you this textbook, which is developed by the Ministry of General Education and Instruction based on the new South Sudan National Curriculum. The National Curriculum is a learner-centered curriculum that aims to meet the needs and aspirations of the new nation. In particular, it aims to develop (a) Good citizens; (b) successful lifelong learners; (c) creative, active and productive individuals; and (d) Environmentally responsible members of our society. This textbook, like many others, has been designed to contribute to achievement of these noble aims. It has been revised thoroughly by our Subject Panels, is deemed to be fit for the purpose and has been recommended to me for approval. Therefore, I hereby grant my approval. This textbook shall be used to facilitate learning for learners in all schools of the Republic of South Sudan, except international schools, with effect from 4th February, 2019. I am deeply grateful to the staff of the Ministry of General Education and Instruction, especially Mr Michael Lopuke Lotyam Longolio, the Undersecretary of the Ministry, the staff of the Curriculum Development Centre, under the supervision of Mr Omot Okony Olok, the Director General for Quality Assurance and Standards, the Subject Panelists, the Curriculum Foundation (UK), under the able leadership of Dr Brian Male, for providing professional guidance throughout the process of the development of National Curriculum and school textbooks for the Republic of South Sudan since 2013. I wish to thank UNICEF South Sudan for managing the project funded by the Global Partnership in Education so well and funding the development of the National Curriculum and the new textbooks. I am equally grateful for the support provided by Mr Tony Calderbank, the former Country Director of the British Council, South Sudan; Sir Richard Arden, Senior Education Advisor of DfID, South Sudan. I thank Longhorn and Mountain Top publishers in Kenya for working closely with the Ministry, the Subject Panels, UNICEF and the Curriculum Foundation UK to write the new textbooks. Finally, I thank the former Ministers of Education, Hon. Joseph Ukel Abango and Hon. Dr John Gai Nyuot Yoh, for supporting me, in my previous role as the Undersecretary of the Ministry, to lead the Technical Committee to develop and complete the consultations on the new National Curriculum Framework by 29 November 2013. The Ministry of General Education and Instruction, Republic of South Sudan, is most grateful to all these key stakeholders for their overwhelming support to the design and development of this historic South Sudan National Curriculum. This historic reform in South Sudan’s education system is intended to benefit the people of South Sudan, especially the children and youth and the future generations. It shall enhance the quality of education in the country to promote peace, justice, liberty and prosperity for all. I urge all Teachers to put this textbook to good use. May God bless South Sudan. May He help our Teachers to inspire, educate and transform the lives of all the children and youth of South Sudan. Deng Deng Hoc Yai, (Hon.) Minister of General Education and Instruction, Republic of South Sudan ii  Table of Contents Unit 1: Diversity of Living Things.......................................................... 1 1.1 Definition of Biology and its branches.........................................2 1.2 Importance of studying Biology.....................................................3 1.3 Characteristics of living things........................................................5 1.4 Various life forms of organisms.......................................................7 1.5 Classification of organisms and its importance....................... 10 1.6 Taxonomy hierachy of classification...................................................13 1.7 The binomial system.................................................................................16 1.8 Dichotomous key............................................................................. 19 Unit 2: The Cell..................................................................................... 25 2.1 Definition of the cell....................................................................... 26 2.2 Magnifying instruments................................................................. 27 2.3 Parts and functions of a light microscope................................. 29 2.4 Structure of plant and animal cells............................................. 38 2.5 Functions of parts of plant cell and animal cell....................... 42 2.6 Specialised plant cells...................................................................... 48 2.7 Levels of organisation in multicellular organisms................... 53 2.8 Organ and organ systems............................................................. 55 Unit 3: Movement of substances into and out of cells...................... 63 3.1 Structure and properties of the cell membrane....................... 63 3.2 Diffusion............................................................................................. 64 3.3 Osmosis.............................................................................................. 69 3.4 Solute, Solution and Solvents........................................................ 70 3.5 Water relations in plants and animal cells............................... 74 3.6 Active transport............................................................................... 80 Glossary............................................................................................................................ 86 Appendix I........................................................................................................................... 91 Appendix II.......................................................................................................................... 93 iii iv  Unit Diversity of Living Things 1 Learning outcomes Knowledge and Skills Attitudes understanding Understand the Investigate how living things can Appreciate diversity of living be grouped according to their the variety of things. similarities and differences. organisms. Identify different kinds of Show curiosity organisms using taxonomic keys. about the existence of Collect insects using nets organisms and (sweep net), jam jar / sunk into the importance of soil, pooters and plankton net. sustaining diversity (conservation). Develop simple keys to classify and investigate living things Thinking critically. according to their similarities (Dichotomous key). Sharing views and opinions. Critical observation and recording skills. Cooperating with others. Introduction Look around you. Name some living things that you can see. Where do they live? How do they move? How about feeding? Now look at this picture. Fig 1.1:Biodiversity in the forest Which animals can you see in Fig 1.1 above? What are the animals doing? What does this tell you about how organisms interact? 1 When you look around, you see many My environment, my life! organisms. Some are big while others are small. Some are visible to your When collecting specimens, avoid naked eyes while others are invisible. An uprooting plants or killing animals example is bacteria. There are millions collected. Make sure you release the of bacteria in the air. Some bacteria are animals back to their habitat. found in soil while others are inside our The word ‘biology’ comes from two bodies yet we cannot see them. Fish and crocodile are examples of visible Greek words:“Bio” – which means ‘life’ organisms found in water. The many and “Logos” – which means ‘study of’. plants and animals around you make up Therefore, Biology is the science that part of the living environment. This unit deals with the study of life and living entails the study of all living things and things. Living things are also known as the role they play in the environment. organisms. Branches of biology 1.1 Definition of Biology Like a tree, biology is divided into many and its branches branches. Can you name some of them? Activity 1.1: Collecting Activity 1.2: Playing a game of organisms and examining their naming branches of Biology characteristics In pairs In groups Write names of the various 1. Go to the field and collect branches of Biology in manila these things: small animals like paper then cut them out. earthworms, ants, termites and insects like grasshoppers, What to do: cockroaches, etc. Also, collect 1. Hold up one name of branches pieces of stone, sticks and grass. of Biology. 2. Give the grasshopper some grass. 2. Let your partner say what the What happens? branch is about. 3. Touch the insect or earthworm 3. Share your work with other using a stick. What happens? Do members of the class. the same to the stone. What 4. Repeat this until you finish all the happens? From the results of the branches of Biology. experiments, between the stone and the small animal, which one is a living thing? Why? 4. Relate the results of these experiments to the study of Biology. 2  The facts 1.2 Importance of studying Biology The two main branches of Biology are: Activity 1.3: What role does Biology Zoology - the study of animals. play in our lives? Let us find out. Botany - the study of plants. Discussion corner Other common branches of Biology In pairs include: a) Genetics- the study of genes and 1. What do you think would happen if: inheritance. (a) We did not understand how b) Ecology - the study of the our bodies work? interaction of organisms with each (b) Doctors were not there? other and with their environment. (c) Research on new drugs and c) Anatomy - the study of vaccines was not carried out? organisms and their structure. (d) We did not understand how d) Microbiology - the study of various organisms interact micro-organisms. with one another and with the e) Physiology - the study of how surrounding environment? cells function. (e) Scavengers, bacteria and fungi f) Biochemistry – the study of the did not feed on dead animals chemical processes that take place and plants. in the body of a living thing. (f) Yeast was not used in bread Assuming each of the leaves in the tree and during fermentation. below is a branch of biology; draw it in (g) We did not have plants to your notebook and fill the gaps. carry out photosynthesis. (h) We did not have domesticated animals and wild animals. csi 2. List down in your notebook some net Ge jobs or professions that require Biochemistry knowledge of Biology. Refer to the chart provided by your teacher. y atom The facts An The following are some reasons why Zo ol og the study of Biology is important in our y society today. 1. Biology helps us to understand Biology our bodies. We are able to know how our bodies work and how they are affected by what we eat, the air Fig 1.2: Branches of Biology 3  we breathe, and our surrounding 3. The study of Biology helps environment.This can help prevent, nu t r i t i o n i s t s c o m e u p w i t h cure and even eliminate diseases. approriate diets for our various 2. The study of Biology helps us body needs. in treating and preventing 4. Biology helps us to understand diseases. the science of exercise. The Here, research is done to invent new knowledge of anatomy enables drugs and to even come up with athletes to understand how the better vaccines. body functions. This helps athletes to create methods of training that Further activity 1. Study the following chart carefully. 2. Come up with a table on the applications of biology based on the chart. 3. Compare your work with the other class members. A C Applications of Biology in life B D E 4  enable them to become more Activity 1.4 proficient. 5. Biology helps us to understand our In groups environment.Through Biology, we 1. Go to the field for a nature walk. are able to appreciate the wide 2. Collect a few things from the range of organisms around us.These environment. Such things may organisms affect us and we affect include stones, pieces of wood, them as well. This knowledge helps insects such as grasshoppers, us to realise the need to conserve butterflies, ants, termites and the environment. branches of plants, leaves or roots. 6. As a subject, Biology guides us 3. Bring the things you have on the best farming practices and collected to class. thereby ensuring food security. 4. Observe them in detail using a Through biotechnology, we are hand lens noting the presence of: able to develop high yielding crops a) Breathing structures. and animals. Disease and drought b) Movement structures such as resistant plants and animals are also legs, wings, among others. developed. c) Feeding structures, such as 7. Biology is a career subject. Some mouth parts among others. careers linked to Biology include 5. Discuss with your partner, how the medicine, pharmacy and veterinary animals use the above structures among others. With these careers, for. we are able to earn a living and take care of our families. 6. How about the things that do not have these structures? How do My environment, my life! they survive? Are they living? We should always strive to conserve the environment in whatever we do. My environment, my life! We should avoid polluting the When collecting specimen, avoid environment, destroying plants and uprooting whole plants or killing the killing animals! animals collected. Always use a pair of forceps when handling stinging insects. 1.3 Characteristics of living things What would you look out for if you The facts wanted to distinguish between things For an organism to be described as that are living and things that are not living, it must be able to carry out some living? processes, which are essential for life. The processes constitute the 5 characteristics of living things. They 5. Respiration - this is the process include: whereby an organism produces 1. Movement - this is the ability of energy by breaking down food organisms to change position of substances. Oxygen is taken in the whole body (like in animals) alongside the food while carbon or even parts of the body (like in dioxide, water and energy get plants) where leaves or branches released. This process is preceded that move. by gaseous exchange which is the 2. Reproduction - this is the ability of process by which living things take in organisms to make new individuals oxygen and release carbon dioxide. of their kind. It can be through sexual or asexual means. CO2 3. Growth - this is the irreversible O2 CO increase in size and dry mass of a 2 CO2 living organism. Growth can occur in three forms: cells of the organism CO2 can become bigger, they can increase O2 their number or both. Fig 1.4 Gaseous exchange 6. Excretion - this is the process whereby organisms remove toxic waste products from the body. The toxic wastes come from Fig 1.3 Growth of a chick metabolism (the chemical reactions occurring inside the body). Note: Plants grow throughout their Plants use old leaves, fruits and lives while animals stop growing at flowers to get rid of wastes while some point. animals use the excretory system. The four main excretory organs are 4. Sensitivity (or Irritability) - this the skin, kidneys, lungs and liver. is the ability of an organism to detect 7. Nutrition (Feeding) - this involves or sense changes in its surrounding taking food into the body to provide environment and then respond to energy as well as bring about growth them. These changes are known as and repair of worn out tissues. In stimuli (singular – stimulus). For green plants, photosynthesis occurs example, plants respond to sunlight to produce food while animals eat by growing its leaves towards it. plants, other animals or both in Animals respond to touch, sound order to survive. and chemicals among others. 6  1.4 Various life forms of organisms Activity 1.5 In groups Materials Pond water, light microscope, methyl blue dye, microscope slide. 1. Collect some pond water or stagnant water from your locality. 2 Bring the water to the laboratory. Fig 1.5 Animals feeding Put a drop on a microscope slide Things that possess these characteristics then add methyl blue dye. are living things. Things that do not 3. Observe the slide through low possess these characteristics are non- power objective using a light living things. Plants and animals are microscope. living things. Objects like stones, desks, pens and pieces of wood among others are non-living things. Work to do 1. Read the above points then come up with summarised notes on characteristics of living things. 2. Create a table on the differences Using a microscope to observe a specimen between living and non-living things. What can you see? 4. Now, use high power objective lens to observe the specimen. Self Test 1.1 5. Draw the organisms you saw in 1. Justify why a motor vehicle moves your note book. but it is not considered a living thing. Activity 1.6 2. Plants and animals are both living In groups things. Show how they differ in Materials terms of: Sweep net, small pooter, pitfall i) Growth trap, hand lens, specimen bottles, ii) Movement net, jam among others. iii) Nutrition 3. Which characteristics are not What to do exclusive to living organisms 1. Go for a nature walk in the only? nearby forest. 7 2. During the nature walk, use The facts the pooter and the sweep net to collect various insects such The findings in Activities 1.5 and 1.6 as butterflies, grasshopper, above show that living things exist in cockroaches, pond snails various life forms. Some are very tiny that among others. they cannot be seen using naked eye. 3. Use a small pitfall trap to trap We have to use lenses like microscopes insects and other arthropods as in order to see them. In most cases these may bite and cause injury such animals are made up of a single or infection. 4. Put all the collected animals in cell. They are known as unicellular specimen bottles. organisms. Examples of unicellular 5. Observe other big animals in the organisms include amoeba, paramecium, forest such as zebras, ostriches, euglena ‘trypanosoma’ bacteria among giraffes among others. others. 6. Back in class, obser ve the specimens you collected using a hand lens as shown below. Draw the animals in your note book. amoeba paramecium Usingahandlenstoobserveaspecimen 7. Also, make a sketch of some of the big animals you observed during the nature walk. euglena Study Questions 1. Can you see any similarities and differences among the animals you drew? List them down in a table. 2. What does this tell you about living organisms in general? trypanosoma Fig 1.6: Examples of unicellular organisms 8 Other animals are made up of more Other big animals such as elephant, than one cell. They are multicellular giraffe, lion, ostrich, gazelle and human organisms. Examples of multicellular beings. Most plants are also multicellular organisms include a variety of insects organisms. such as butterflies, grasshoppers, cockroaches, pond snails and spider. fish grasshopper butterfly tortoise cockroach lion snail spider ostrich Fig 1.7: Examples of multicellular Fig 1.8: Examples of big multicellular organisms oganisms 9  Self Test 1.2 Activity 1.7 1. Distinguish between unicellular and In pairs multicellular organisms using a table. 1. Think about the various life forms (a) Paramecium given in Figures 1.6, 1.7 and 1.8 (b) Amoeba above. You can also watch the (c) Fungi videolink: https://www.youtube. 2. Which organisms in this list is com/watch?v=BVpWQcLZzIY (a) the most primitive? ________ 2. Now, study the evolutionary tree below. Based on your answers (b) the most complex? ________ in question 1 above, fill the gaps (Centipede, blue-reen algae, maize in the Figure with the organisms. plant) You may add more from you own 3. Draw and label research. (a) Euglena (b) pond snail 1.5 Classification of organisms and its importance Animals Activity 1.8 In groups Evolutionary Tree 1. Look at the photograph below. It 3. Make conclusions about how shows inside a supermarket. organisms are related. Write short notes and share with other class members. The facts Does your evolution tree in activity 1.7 above, look like this? Bacteria Plants Fungi Fish Arrangement of goods inside a supermarket. Mammals With your friend, identify the order in Animals Birds which things are arranged. Why do you Reptiles think such arrangement is necessary? Amphibians What will happen if the items were not Fig 1.9 Evolutionary tree of organisms properly arranged? 10 2. Now, look at the picture below. Which organisms can you see? Name them. What does this show you about the nature of organisms in various habitats? Fig 1.10: Carolus Linnaeus Activity 1.9 In groups 1. You are provided with a mixture of seeds that include: maize, beans, groundnuts, peas, rice, wheat and millet.Try to count each seed in the mixture. Biodiversity in a forest. What challenges did you face 3. Do you think it will be better if the while counting each seed in the organisms are put in some forms mixture? of groups? Why? The facts Different habitats have millions of organisms hence the need for grouping organisms for ease of identification and study. Scientists previously grouped Mixed seeds organisms using artificial means. For 2. Now, separate the seeds into example: individual groups say maize alone, If the organisms were useful or beans alone, etc as shown below. harmful to human beings. If the organisms were edible or not. If the organisms lived on land, water or air. However, such features could not form meaningful groups for study. A scientist called Carl Von Linne’ (Carolus Linnaeus), in 1753 introduced a modern way of classifying organisms. Sorted seeds 11 3. Try counting the maize and the bean Provides plenty Provides only seeds separately. of useful limited Is it now easier to count the information information separated seeds? Why is this the case? Activity 1.10 In groups The facts 1. Take a walk outside the classroom Therefore there are two types of and collect different types of living classification. organisms. Caution! Some organisms can sting! Natural classification Others can bite! Therefore do not Artificial classification use your bare hands to handle such organisms. Use protective gloves. Natural classification is based on the 2. Take the collected organisms back natural order or common ancestors that to class for study. is supposed to exist and that is informed 3. Put the organisms into various by science e.g. the cat family. Artificial groups. classification on the other hand is You can use these features; based on superficial characteristics, Number of legs imaginations or human uses e.g parasites Presence of wings or pests. Presence of antennae What covers the body, etc 4. Share your findings with the rest of Work to do the class. Based on the descriptions above, come up with a table showing the differences Importance of classification b e t we e n n a t u r a l a n d a r t i f i c i a l The facts classification methods. Did your table look like this? There are about 1.8 million species of known organisms. It is also believed that Table 1.1 Comparison beween natural there could be many more undiscovered and artifical classification methods species in the forest ecosystems and in Natural Artificial deep seas. Many Only puts into 1. Classification puts information in an characteristics are consideration a organised manner to avoid chaos considered few characteristics and confusion among scientists. Members of a Members are 2. It enables scientists to place group are similar not similar organisms in their correct groups in hereditary in hereditary for ease of study. patterns patterns 3. It allows scientists to better Stable and most M ay c h a n g e a s understand the phylogenetic modern method knowledge about relationships among organisms i.e of classification organisms changes how organisms are interrelated. 12  (Organisms that have more common My heritage my pride! characteristics are more closely related). Our language reflects who we are as a 4. Classification allows scientists to identify, group and properly name a people. It is our nation’s identity. Always newly discovered organism. be proud of your language. Self Test 1.3 1. What is classification? Activity: 1.12: Categorising 2. Distinguish between artificial and people according to their natural classification. addresses 3. Describe classification as proposed In groups by carolus Linnaeus. 1. With the help of your teacher, 4. State the importance of classifying estimate the number of people in organisms. each administrative unit in South Sudan. 1.6 Taxonomy hierachy of 2. Note down the administrative unit classification in column A and corresponding total number of people in column Activity 1.11: Discussion corner B as indicated in the table below. In groups Table 1.2: Number of people in an 1. Give the names of the animals administrative unit below in your native language. Administrative Total number of (i) Cow (ii) Cat unit (A) people (B) (iii) Elephant (iv) Lion State 2. Do you think people from other County parts of the world can recognise Payam the names you gave in 1 above? Boma 3. What impact do you think this Village will have on the study of living Home organisms? Study questions The facts 1. Which of the administrative units has: It is sometimes difficult to identify living (a) The largest number of things using local names. This is because people? of the existence of several local languages. (b) The smallest number of To assist scientists from different parts people? of the world to communicate, one 2. What do you think is the scientific name is given. importance of this manual of This creates no confusion as to grouping of people? which organism is being referred to. 3. Talk to your friend about this, Scientific names rarely change. then compare with hierachy of Scientific names are written in the classifications. same language around the world. 13  Table 1.3 : Relating order of taxa to The facts address information When grouping organisms, it is necessary Administrative Classification to have an organised order.This enables unit group organisms to be identified easily State Kingdom depending on the level of classification they are placed. Different levels of County classification in which organisms are Payam placed form a taxonomic unit. Each Boma taxonomic unit is referred to as a Village taxon (plural taxa). The order in which Home the taxa are arranged starting from the highest to the lowest is taxonomic hierarchy of classification. The facts Kingdom From your work above, The country has the highest number of people just like the Phylum/division kingdom which has the largest number of organisms. On the other hand, the village Class has the lowest number of people which corresponds to the species level in the Order classification hierachy. Family Therefore, organisms placed in the same kingdom share fewer basic features Genus as compared to those at species level. For example, all multicellular organisms Species possessing chlorophyll and synthesise organic food substance are placed Fig 1.11: Taxonomic Hierarchy of classification in Kingdom Plantae, those that are This hierarchical order corresponds multicellular but feed on already made to the address information in Table 1.2. organic food substances are placed in In Activity 1.12 above we can relate Kingdom animalia. the order of the taxa to the address Kingdom is the taxon with more information. members and it is split further into phyla (singular-phylum) or division (when referring to plants). Phylum or Work to do division is further split into classes, In the following table, write the correct classes into order, order into family, classification against the address family into genus and finally genus into information. The first one has been species. done for you. As you progress from Kingdom to the lower levels of classification; the features shared by the organisms become more, while the number of organisms become 14 fewer. As such, species being the lowest 3. Now observe the external features level of classification comprises of of the organisms you had placed closely related organisms that share in Kingdom Animalia. The external many characteristics. features of these animals will A species can therefore be defined enable you to place them either in as a group of organisms which can the same group or different groups. naturally interbreed to give rise to a 4. Look at the organisms below. viable offspring. Activity 1.13: How can organisms be placed into various taxa? In groups Your teacher will provide you with the following: Laboratory rat or rabbit Housefly, butterfly, grasshopper Grass, bean plant, maize plant among others. 1. Try to group these organisms into their respective kingdoms. Rabbit Cite the features that you used to place the above organisms in the various groups. 2. Observe keenly the roots and leaves of the plants. The features of these parts will enable you to place the two plants either in the same group or different groups. In your opinion, do you think grass, maize and bean plants can be placed in the same group or taxa. Explain why. Hint: Housefly Consider the types of roots below. (a) Observe the body of the animals. Is it covered with fur, hair, feathers or wings? Name other animals that have hair, fur, feathers or wings on their bodies. (b) Go further and check on the presence and number of legs on the organisms. Can they be placed in the same Grass Bean plant group? Give reasons why. 15  My environment, my life! Observable features can be external or internal. External physical features Collect only specimen you need. Do of organisms are mainly used to put not harm the organisms nor pollute organisms into different taxonomic unit. the environment. These features include number of legs, number of eyes, types of leaves, among others. Organisms that are closely related have more common features The facts and are therefore grouped together. Those that are distantly related have The most commonly used criteria for less common features and are grouped classification of organisms is use of separately. Study table 1.4 below. observable features. Summarise the features that were used to rank the organisms. Table 1.4: Some organisms classified up to species level Taxon Maize Bean Human being Domestic cat Kingdom Plantae Plantae Animalia Animalia Phylum/ Angiospermatophyta Angiospermatophyta Chordata Chordata Division Class Monocotyledonae Dicotyledonae Mammalia Mammalia Order Poales Rosales Primates Carnivora Family Poaceae Leguminosae Hominidae Felidae Genus Zea Phaseolus Homo Felis Species mays vulgaris sapiens Catus 1.7 The binomial system Do a presentation to the rest of the class on your findings above. Activity 1.14 Research activity In groups Discuss these questions with your 1. Find out from your parents or friends. guardian about the source and 1. Are there students with similar meaning of your name. names? How do you identify them? 2. Ask about the meaning of the 2. Are the students with similar names of your siblings. names related? 3. Are there students known by their 3. Share your findings with the rest nicknames? How did they acquire of the class members. them? 4. How do you name children in your community? Do their names have meanings? 16 Activity 1.15: Reading The facts In pairs Read the following story then Naming of organisms is called discuss the study question. nomenclature. The system of Do you remember the long lost naming organisms whereby an cousin you were looking for? You organism is given two scientific names have finally located the house where is called Binomial nomenclature. this cousin lives. However, you have The two names represent the Genus been told that your cousin is at and the Species of the organism. This school. To assist you find your cousin system of naming is conventional i.e. the teacher tells you that there are five learners with the same name as it is accepted and is used by scientists your cousin’s first name. all over the world irrespective of their The teacher assisting you asks you language used. if your cousin is tall or short. You Rules of Binomial Nomenclature say tall.You are told that of the five 1. The genus name is written first learners, who share your cousin’s followed by the species name. first name, three are tall. 2. The genus name always starts with The teacher asks you if your cousin a capital letter.The species name has a light skin complexion or dark is written in small letters. skin complexion.You say dark skin 3. T h e t wo n a m e s s h o u l d b e complexion.You are told that of the u n d e r l i n e d s e p a r a t e ly i f three tall learners, two are dark- skinned. handwritten. If typed, they should be in Italics. The teacher then asks you if your Table 1.5 gives scientific names of some cousin has straight or curly hair. You common organisms. say that your cousin has curly hair. The teacher then says that your Table 1.5: Scientific names of some cousin is in Secondary 3 East. The common organisms teacher then goes to fetch your Organism Scientific name cousin of whom you are pleased to Human being Homo sapiens see again after a long time. Cow Bos taurus Study Question Domestic dog Canis familiaris What characteristics did you follow Domestic cat Felis Catus to find your lost cousin? Write Maize Zea mays them down. Beans Phaseolus vulgaris Banana Musa acuminata Sweet potatoes Ipomoea batatas 17 Work to do Carry out research on scientific common plants and animals in your community. Come up with a table like the one above. Self Test 1.4 1. Arrange the following classification units in an ascending order Genus, family, order, phylum, kingdom, class, species 2. Study the table below and answer the questions that follow. Taxon Human Lion Wolf Domestic Domestic being dog cat Phylum Chordata Chordata Chordata Chordata Chordata Class Mammalia Mammalia Mammalia Mammalia Mammalia Order Primates Carnivora Carnivora Carnivora Carnivora Family Hominidae Felidae Canidae Canidae Felidae Genus Homo Panthera Canis Canis Felis Species sapiens leo lupus familiaris Catus (a) Which organism in the table is closely related to the domestic dog? Give a reason for your answer. (b) Which organism in the table is most distantly related to the domestic cat? Give a reason for your answer. (c) Which organism in the table is closely related to the wolf? Give a reason for your answer. 3. Opi is a scientist who came across an organism in Jonglei forest that had not been described before. He listed the features of the organism as follows: Has fur on its body. Feeds on flesh. Has a tail. (a) Suggest a name for the organism from the table in question. (b) To what kingdom would the organism be placed? (c) Which animal(s) in the table above is closely related to the organism and why? 18 1.8 Dichotomous key Table 1.6: Observable features of organisms The term dichotomous comes from Organism Unique features the word “dichotomy” which means divided into two parts. A dichotomous Fish Presence of scales key is a set of instructions used to Presence of fins identify unknown organisms. To be able to identify organisms, observable features Grasshopper are used.This key uses two variations in Snail description of a characteristic or feature for identification. The key is used to Millipede identify and place new or unknown Rabbit organisms into specific taxonomic units Chicken or groups. The organisms can then be named. 3. Use the unique features you have recorded in your table to create Activity 1.16 pairs of contrasting features that will enable you to split the In pairs organisms into two large groups. Materials: Hand lens We are all equal! Fish (in a bottle containing water) As human beings, we should Grasshoppers (in a specimen appreciate not only our similarities bottle) but also our differences! Snails Millipedes Rabbits (caged) The facts Chicken (caged) The observable structural features of Pair of forceps organisms can be used to come up with What to do a numerical identification key. Such 1. Observe each of the specimens key can be used to identify unknown provided carefully. Note down organisms. the unique structural observable A dichotomous key is one of such features in a table like the one shown below. keys used in identifying organisms. It (Use a hand lens if you cannot see provides a written set of choices, each the features clearly.) having two contrasting statements. These statements lead to a group of organisms and eventually to the name of the organism. Scientists therefore use this key to identify unknown organisms. 19 The key normally begins with general the organism. characteristics and lead to more If an organism falls into one category specific characteristics. You are therefore indicated in the dichotomous key, expected to compare the characteristics you go to the next step indicated. you see in the unknown organism You do this until you arrive at a step against an appropriate statement of the that identifies your specimen at the dichotomous key in order to identify correctly indicated taxonomic level. Activity 1.17: Constructing a dichotomous key using plant specimen In groups 1. Collect these leaf specimens from your school compound or the surroundings. A B C D E 2. Use this figure to construct a dichotomous key as shown below. 20 3. Observe the leaves carefully. (You may also use a hand lens if there is need). 4. List down the major characteristics of all the five leaves. For instance: Type of leaf Type of apex Type of venation Arrangement of leaflets 5. Fill the gaps in the table below based on your observation. Type of leaf Type of venation Type of apex Leaf A Leaf B Leaf C Leaf D Leaf E 6. Summarise each characteristic of the leaves into two variations as shown in the following table. Table 1.7 Variation of characteristics Characteristic Variations in the characteristic Type of leaf Simple leaf Compound leaf Type of venation Network venation Parallel venation Type of apex Pointed tip Rounded tip Arrangement of leaflets Pinnate Digitate 7. Starting with one characteristic of the leaves, group the leaves into two groups according to the two variations of that characteristic. Assign the number “1” to the first characteristic. For example, type of leaf: 1 – To the two variations, assign the letters (a) and (b). For example, simple leaf (a), compound leaf (b). 8. In the two groups of leaves obtained, further sort them out using a different characteristic. Then re-group them into two new groups each according to variations in that characteristic. For example, sort out the leaves according to the arrangement of leaflets on the stalk i.e. those with digitate arrangement and those with pinnate arrangement. Assign the number 2 to the new characteristic. For example, arrangement of leaflets – 2 21  Work to do The facts Read through the information in the Did your dichotomous key in Activity key above then come up with steps 1.17 above look like this? that will lead to identification of the 1. Compound or simple leaf leaves above. 1. (a) Compound leaf (leaf divided Compare your steps with those in the into leaflets………….go to 2 Table below. (b) Simple leaf (leaf not divided into leaflets)…..…….go to 3 Table 1.8: Steps of identification 2. Arrangement of leaflets A 1b, 3b,4b Orange 2. (a) Digitate arrangement of leaflets (leaflets attached at the tip of B 1b,3a Maize the leaf)………..E (Cassava) C 1b,3b,4a Cabbage (b) Pinnate arrangement of leaflets D 1a,2b Eucalyptus (leaflets attached at several points on stalk)………D E 1a,2a Cassava (Eucalyptus) 3. Arrangement of leaf veins Activity 1.18: How can we 3. (a) Parallel venation (veins running construct a dichotomous key from main stalk to the tip of using animal specimens? the leaf (apex) i.e. parallel to In pairs each other off a central vein. Materials …...B (Maize) Specimen bottles 3. (b) Network venation (veins Forceps branched out from the midrib Sweep nets or central point…..….go to 4 Labels 4. Overall leaf shape Chloroform or ethanol 4. (a) Leaf round-shaped………...C Petri-dishes or tin covers ( Cabbage) Hand lens (b) L e a f n o t ro u n d - s h a p e d ……….........….. A ( Orange) What to do Note 1. Collect small animals from grass, The numbers 1, 2, 3 and 4 in the tree trunks, small bushes and key represent the characteristic flying insects, using the items indicated in the tree. above. The letters (a) and (b) represent two 2. Transfer the animals into a jar variations in each characteristic. containing cotton wool soaked The phrase “go to” indicates in either chloroform or ethanol. the characteristic into which the 3. Once the animals are dead, specified leaves are to be further transfer them into the petri- grouped. For example, in 1 (a) dishes. compound leaf.........go to 2, indicates Caution: that the compound leaves are Do not touch harmful animals like grouped further into two according centipedes, spiders or scorpions to the arrangement of leaflets (2) i.e. with your bare hands. digitate (a) and pinnate (b). 22  Do not directly breathe in the Now, study the following chloroform from the killer jar. The dichotomous key. chemical should only be handled 1. a) Has four legs.......... Frog by the teacher. b) Has no four legs........... 4. Use a hand lens to observe the Go to 2 specimens and note down the 2. a) Has feathers..........Eagle. external features of the animals. b) Has no feathers.............. 5. Use a flow diagram to group the Go to 3 organisms you have collected in 3. a) Has fins............. Tilapia the activity above. b) Has no fins.......... Snake. 6. Which steps did you use to (i) Draw a flow diagram to group the organisms. represent the information. 7. Write them down. (ii) Show the steps that you can use to identify the organisms in the photographs. A.................. B.................. My environment, my life! C.................. D................. Collect only the number of specimen you need – so as not to cause an imbalance in the  Check Your Progress 1 ecosystem. Do not kill the organisms unnecessarily during the collection 1. The study of Biology is important and study. Return the organisms to to the society. Which problems can their natural habitats if possible. it help us solve? Do not destroy the natural habitat of the organisms during collection 2. You are provided with a stone, show of specimens. that it is not a living thing. 3. Narot is interested in the study of Self Test 1.5 chemical processes that take place 1. You are provided with the in the body of living organisms. photographs below representing Suggest branches of Biology that organisms in the Kingdom she should be conversant with. Animalia. Examine the specimens carefully. 4. A student wrote the scientific name of blackjack as bidens Pilosa. a) Identify the mistakes that the student made. b) Identify the genus name for A. B. blackjack? 5. During a school excursion in a forested area, some students came across an organism. The organism was small, with a whitish soft body. C. D. 23  An argument broke out among 8. Construct a dichotomous key for the students as to whether the the animals below. organism was a plant or not. (a) Giving reasons, suggest the Kingdom where the organism belongs. (b) What is the economic impor- tance of the Kingdom where the T organism belongs to? P 6. Which statement below does not describe a bacteria? A. All live in colonies. B. They have nuclear materials. C. All live singly. D. Cellwall is surrounded by a tough coat. Q R 7. What is the importance of scientific names for organisms? U S 24  Unit The Cell 2 Learning outcomes Knowledge and Skills Attitudes understanding Understand Able to observe the Appreciate the structure of structures of the shape of a cell under a the cell. cell, organization microscope. and functions. Show curiosity and wonder Prepare slides and about the existence of perform simple microscopic units of life. experiments with plant tissues for example. Appreciate the microscope. Use a microscope. Think creatively about the cell as unit of life. Co-operating with others. Accuracy, systematic, ethical and patient. Introduction Bodies of all living organisms are made up of tiny microscopic units. These units collectively carry out processes that make the organism a living entity. These microscopic units are known as cells. Eyepiece Barrel Focusing screw Objective Fig. 2.1: Robert Hooke Fig. 2.2: Robert Hooke's Microscope Cells were first described in the year 1665 by a biologist, Robert Hooke. He did this using the microscope shown above. He came up with the cell theory which 25 describes the properties of a cell. This We are all equal! unit will enable you to appreciate the importance of cells in an organism. We should learn to live in peace and harmony among ourselves. 2.1 Definition of the cell We should understand and appreciate each other’s culture Activity 2.1: Discussion corner and traditions as well. As a class Read the following story then The facts answer the questions that follow. Just as the family is the basic unit In our society, the family is considered in the society so are the cells in as the basic unit. It consists of a man, our bodies. Plants and animals have a woman and children. This forms complex structures that are all made the nuclear family. The family forms of cells. The cells are modified to the basic social organisation, unit of perform various functions. any society. The cell is the basic unit of life. Some When the family is strong, the organisms are made up of only one cell society is strong. From the nuclear and are referred to as unicellular or family we get the extended family single-celled organisms. They include that comprises uncles, aunts, cousins, amoeba and paramecium. Others are grandparents among others. made up of many cells and are referred This forms a large pool of relatives. to as multicellular organisms. They This large pool of relatives makes include human beings, pine tree, locust, a clan. Clans form tribes and tribes housefly among others. Therefore, make a nation of people who share the cell is the structural unit of a common heritage and culture. an organism. Cells can be likened to Nations make the world that we live building blocks that are put together in. to form a house. Study Questions 1. What lessons can you learn from the above article? 2. Draw a tree diagram to illustrate the societal structure. 3. A broken family leads to a broken society. Explain. 4. Without the family there is no society. True or false? Fig. 2.3: Building blocks of a house 26 Many chemical processes take place 2. Use your naked eyes to examine in the cell. These processes keep the the insects. organism alive and functioning. Can you draw diagrams of For this reason, the cell is also referred their mouth parts? to as the functional unit of the 3. Examine the slices of bread with organism. Therefore, the cell is the mould. structural and functional unit of any living thing. Can you see the moulds clearly? Characteristics of a cell 4. Examine the leaves carefully. It is microscopic. Leaves have tiny holes called It is membrane bound. stomata. Can you see them? It has structures that are sites for chemical reactions called organelles. One of the methods of studying living It has the ability to divide (replicate) things is by observing them closely and since it contains the genetic material. accurately. However, there are certain organisms and structures, which are 2.2 Magnifying instruments too small to be seen by the unaided eye. In order to see such organisms Activity 2.2: Examining and structures clearly, a microscope specimens with naked eye or a hand lens is used. Why should this In pairs be the case? 1. Collect the following from your To magnify is to make something look local environment: bigger. Can you imagine instances in (i) Various insects life when you have to make certain (ii) Plant leaves things look bigger? What is often (iii) Slices of bread having mould. used? Look at the pictures below. A. B. C Can you name them? Where are they often used? Why? What would happen if the instruments never existed? Most objects for study in Biology are very small to be seen by the naked eye. 27 Therefore magnifying instruments are 3. View the leaf specimen with one needed. eye. Features of a hand lens 4. Draw the image of the leaf You have used a hand lens in the previous specimen that you can see. unit. In this Unit, we shall investigate 5. Calculate the magnification of hand lenses in more detail. A hand your drawing. lens is also called a magnifying glass. It is a simple optical instrument used for magnifying objects in a scientific The facts study. A hand lens is made of a convex lens mounted on a frame. The frame is usually made of wood, metal or plastic. When an image appears bigger than the object when observed through Frame the hand lens, the object is said to be magnified. Biconvex To determine magnification, you lens measure the length of the object and Handle the length of your drawing. You then calculate magnification using the Fig. 2.4: Hand lens formula below. Magnification Length of the drawing = Activity 2.3: Determining (mg) Length of the object magnification using a hand lens For example: In pairs Materials Hand lens × 2.5 Various leaves or insects 1. Hold a hand lens about three 2 cm leaf A 5 cm leaf B inches from your eyes. Keep your head up. Fig. 2.5: Determining leaf magnification 2. Using your hand, slowly bring If you had a leaf that is 2 cm in length the leaf specimen to be viewed and made a drawing of the leaf that is towards the lens until the image 5 cm in length, the magnification would is in focus as illustrated below. be: Magnification Length of the drawing (mg) = Length of the object 5 cm = 2.5; hence Mg = ×2.5 2 cm Note: Always indicate the magnification below the diagram by writing ×2.5. Using a hand lens to observe a leaf 28 Note: Some hand lenses have their 2.3 Parts and functions of magnification written on their frame. a light microscope Share with your friend why is it A light microscope uses light rays and important to calculate magnification. a system of lenses to magnify images Care of the hand lens of small objects. Have you ever come For the hand lens to last for long, it has across a microscope? How does it look to be cared for. Hand lens is made of like? a glass part which can gather dust or break if it falls down. Activity 2.5: Observing parts of a microscope and how to use it Activity 2.4: Discussion corner In groups In groups 1. Hold the arm of the microscope 1. In your study group, discuss with one hand. ways of caring for a hand lens. 2. Place your other hand at the 2. Why is this important? base of the microscope. 3. Compare your findings with the 3. Lift the microscope while facts below. holding its base when transferring The facts the microscope from one The hand lens should be stored in place to another. a dry place where the lens cannot break or get scratched. The hand lens should be cleaned by use of a special soft tissue. Handle the hand lens with care to avoid breaking the lens. Self Test 2.1 How a microscope should be carried 1. A student used a hand lens to observe an ant. The actual 4. Place the microscope on the length of the ant was 0.6 cm. bench in front of you.The handle On observing, the ant was should be towards you. Make 6.8 cm long. Calculate the sure that the microscope is not magnification. at the edge of the bench. 2. Identify circumstances where a 5. O b s e r ve t h e m i c ro s c o p e hand lens can be used to observe carefully. Can you name the features of a big organism. parts. 6. List all the parts you are able 29  to identify. Take note of the adjusting the coarse adjustment following: knob until the print is visible.Very The eye piece Mirror slowly use the fine adjustment Stage Knobs knob to bring the print into sharp Lenses focus. 7. Look into the eyepiece lens. 12. With your group member What do you observe? Adjust discuss what you think would the mirror below the stage so be the function of each part that light coming through the of the microscope you have window falls on it and reflects identified.Why is it called a light it into the microscope stage. microscope. The facts A microscope is an instrument that is used to observe cells which are too small to be seen by the eye unaided. There are different types of microscopes. The most commonly Using a microscope to observe a specimen used one is the light microscope. It is 8. Cut out a piece of newspaper called light microscope because it uses print, and place it on the stage. light to illuminate the specimen. Other Hold it down with the clips.What examples of microscopes include do you observe? Can you read electron microscope and compound the print on the newspaper? microscope. 9. Rotate the revolving nosepiece until the low power objective lens Money matters! clicks into position. The microscope is a very delicate and 10. Lower the low power objective expensiveinstrument.Therefore,enough lens using the coarse adjustment care has to be taken when handling it. knob. View all this from the side of the microscope. 11. Look into the eyepiece and keep 30 Fig 2.6 shows the parts of a light microscope.The functions of the various parts are given in Table 2.1 below. Eyepiece lens Eyepiece Coarse adjustment knob Body tube Fine adjustment knob Revolving nosepiece Objective lens Limb or arm Stage Condenser Hinge screw Diaphragm Mirror Base Fig. 2.6: Light microscope Table 2.1: Parts of the microscope and their functions Part Description Use/ function Eyepiece Uppermost part of the Magnifies the object under study. microscope. Enables one to look through to It is made up of lenses fixed observe the specimen. in a tube-like structure. Body tube Holds the eyepiece on Supports the eyepiece and objective (barrel) the upper side and the lens. revolving nose piece on In some microscopes it moves up and the lower side. down lifting and lowering objective lenses over the specimen. Coarse Big rotating knob on the Used for rough (initial) focusing. adjustment side of the arm. knob 31  Fine adjustment Small rotating knob on the Used to bring the object into sharp knob side of the arm. focus. Used in final focusing. Revolving Rotating part attached on Used to select the objective lenses by nosepiece the underside of the body placing the objective lenses in line with tube. the eyepiece and specimen on stage. Part that holds objective lenses. Objective lens Lenses attached to Magnifies the object. revolving nose piece. They Low power ×4-5 are of three types: Medium power ×10 Low, medium and high High power ×60 or more power lenses. Stage Flat surface below the Holds the slide during observation. objective lens where Holds slides in place. specimen are placed. Has clips for holding slide. Has small hole at the centre to allow light from the condenser to pass to the object. Has clips to hold the slides. Condenser Made of lenses placed It concentrates the light reflected by below the stage. the mirror to the specimen on stage. Diaphragm Made of many small holes It regulates the amount of light of different sizes. passing from the light source through the microscope. Base Flat surface on which the It supports the microscope and all its microscope 'sits'. other parts. Arm It is the curved part of the It is the part we hold when using or microscope. carrying the microscope. Other equipment used with a microscope on it. If dirty a slide is wiped by use include: of a lens tissue. Microscope slides – these are Cover slips – small and thin square rectangular pieces of glass on pieces of glass used to cover the which the specimen is placed. The specimen placed on the slide. They slide should always be cleaned prevent the specimen from drying. before a specimen can be placed 32  Mounting needle Cover (a) (b) Slide Fig. 2.9: Cells seen under (a) high power and (b) low power Fig. 2.7: Slides and cover slips Steps to follow when using a light Lens paper– special type of tissue microscope paper used to wipe the lenses and slides. 1. Place the microscope on a bench, always in an upright position, with its arm towards you. Do not place The facts it in bright sunlight to avoid too much light getting to the eye. The field of view is the circular 2. Use the iris diaphragm to increase space in the microscope in which the or decrease the amount of light image of the specimen is observed. It getting into the microscope from varies according to the magnification the light source. If the light is too at which the specimen is viewed. much, it will be difficult to see Under low magnification power, the details of the specimen. field of view is wider than under high 3. Carefully mount the specimen on magnification power. the microscope slide and cover it with a cover slip. Your teacher will diameter of the provide the specimen or help you field of view to prepare one. 4. Place the microscope slide on the stage so that the specimen is in the middle of the hole on the stage. Fig. 2.8: Field of view Gently lower the stage clips to hold the slide in place. If 25 plant cells are to be viewed under 5. Watch the slide from the side, and a microscope, all may be seen under use the coarse adjustment knob to low power magnification, but only 10 lower the body tube (or raise the of these may be seen at high power stage). Do this carefully until the magnification. This is because at lower end of the objective lens is about 2 magnification, the cells are magnified mm above the cover slip. The lens less hence appear smaller. Under high should not touch the cover slip. power, the magnification is greater and 6. Look through the eyepiece lens. the cells appear larger. As such, fewer Keep both eyes open when looking cells are seen under high power. through the eyepiece. 33 7. Turn the coarse adjustment knob the ways of handling and caring for a slowly upwards, to raise the microscope are discussed below. body tube. This is to increase the 1. Keep the lenses clean by carefully distance between the slide and the wiping them with special lens tissue. objective lens in order to focus the Do not use water or tissue paper specimen. When focusing, do not nor touch the lenses with your move the body tube downwards. fingers or allow them to get wet. The objective lens could crush the 2. Never focus downwards when slide and both may be damaged. your eyes are looking through the 8. To examine the specimen under eye-piece lens. You could break high power, rotate the nosepiece slides and damage the objective till the high power objective clicks lens. into position. Be careful that the 3. Hold the microscope with your two objective lens does not touch the hands. One holding the arm and the cover slip. other the base when moving it from 9. You may need to turn the fine one place to another. adjustment knob slightly to get a 4. To avoid straining your eyes, learn better focus of the specimen. to keep both eyes open when 10. Never use the coarse adjustment looking through the eyepiece. knob to focus specimens under high 5. Always cover the specimen with a power objective.This is because the coverslip and make sure the slides high power objective is too near the and coverslips are clean. slide. It could damage the slide and 6. Avoid tilting the microscope when the objective lens. you have a wet preparation on the Care of the microscope slide as it could run off. 7. Always keep the stage of the A microscope is a very delicate and microscope clean and dry. expensive instrument. Utmost care should be taken when handling it. Storing the microscope It is important to store the microscope Activity 2.6: Discussion corner well after use. Follow the procedure In groups below to prepare the microscope for 1. Discuss how to care, handle and storage. store a light microscope. 1. Rotate the nosepiece to have 2. Compare your work with other the microscope under low power groups. o b j e c t i ve. N eve r s t o re t h e microscope under high power 3. Now, read the facts below. Did objective lens. you get it right? 2. Raise the body tube (or lower the stage) with the coarse adjustment knob so that the lenses cannot The facts strike the stage accidentally. 3. Clean the oil immersion lens with The microscope requires special care xylene. during handling and storage. Some of 4. Clean all lenses with lens paper. 34 5. Turn off the light if using an electric Biological drawings microscope. You will be required to look at a large 6. Cover the microscope with its number of specimens during this cover. If there is no cover, improvise course. You are much more likely to one to prevent accumulation of remember them if you draw them. dust. Drawing a specimen requires you to 7. Pick up the microscope by its arm pay attention to detail so that you can with one hand, support it under re-create it on the sheet. While doing the base with the other hand and return it to its storage box or this, your brain is recording these cabinet. same features in such a way that you can recall them if necessary. Self Test 2.2 Activity 2.7: Observing prepared 1. Arrange the following steps of slides using a light microscope setting up a microscope with a slide for viewing into the correct In groups sequence. Materials (a) Select the medium objective lens (×10) or the low power Light microscope of the two objective lenses. Prepared slides Turn the coarse focusing Procedure knob to bring this lens as close to the slide as possible. 1. Set the microscope on a bench. (b) With the part of the 2. Follow the steps as already specimen to be examined in learnt. the centre of the field of view, 3. Observe the prepared