Modern Concept Science and Technology 10 New

Approved by the Government of Nepal, Ministry of Education, 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. 10

Published by: Nova Publication Pvt. Ltd. Satungal, Kathmandu Tel.: 01-4313205 www.novapublication.com.np Author: Chinta Mani Panthee Lok Bahadur Thamsuhang Kamal Neupane Edition: Fifth - 2080 Copyright: Chinta Mani Panthee Price : Rs. 670 /– Print Quantity : 10,000 pcs Layout and Design: Zeeta Computer Service Ptv.Ltd. Printed in Nepal 10

PREFACE Modern Concept Science and Technology for grade 10 is written to meet the objectives of the curriculum of class 10 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 10. 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 10. 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 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

1 Scientific Study 1-15 2 Classification of Living Things 16-48 3 Life cycle of Honey Bee 49-63 4 Heredity 64-110 5 Physiological Structure and Life Process 111-144 6 Nature and Environment 145-160 7 Force and Motion 161-185 8 Pressure 186-205 9 Heat Energy 206-227 10 Wave 228-280 11 Electricity and Magnetism 281-303 12 Universe 304-316 13 Information and Communication Technology 317-342 14 Classification of Elements 343-364 15 Chemical Reaction 365-379 16 Some Gases 380-400 17 Metals 401-413 18 Hydrocarbons and Its Compounds 414-433 19 Chemicals Used in Daily Life 434-454 Table of Contents

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 1 Key terms and terminologies of the unit 1. Variables : The factors, traits or conditions that are considered during an experiment are called variables. 2. Independent variable : The variable whose value can be changed by the scientist during his experiment is called independent variable. 3. Dependent variable : The variable whose value depends upon the value of other variables is called dependent variable. 4. Controlled variable : The variable which is kept constant during the experiment is called controlled variable. 5. Physical quantities : The quantities which can be measured by using different kinds of physical devices are called physical quantities. 6. Measurement : Measurement is the comparison of an unknown physical quantity with a known standard quantity of the same kind. 7. Unit : The standard known quantity which is used to measure the unknown quantity of the same kind is called unit. 8. SI units : The General Conference of Weights and Measures held in Paris, France in 1960 introduced a new system of units known as international system of units (SI units). 9. Fundamental quantities : Those physical quantities which are independent of each other are called fundamental physical quantities. 10. Derived quantities : Those physical quantities which are derived from the fundamental physical quantities are called derived physical quantities. 11. Fundamental units : Those units which are independent of each other are called fundamental units. Sequence of Curriculum Issued by CDC  Variables of scientific research: independent variables, dependent variables and controlled variables  Importance of controlled variables  Fundamental and derived units: introduction and examples, units involved in derived units, unitwise analysis of equation UNIT Scientific Study 1 Estimated teaching periods Theory Practical 4 1 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 Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 12. Derived units : Those units which are formed by the combination of two or more fundamental units are called derived units. 13. Unit analysis : Unit analysis is the study of the relationship between physical equations with the help of units of measurement. 14. Principle of homogeneity : The principle of homogeneity states that an equation is unit-wise correct if the units of the various terms on either side of the equation are the same. Introduction Sometimes we feel cold and sometimes we feel hot. Is it cold or hot today? Why does it happen? It may be due to sunlight, climate or weather condition. To know its exact reason, it is necessary to study each factor one by one. It is called scientific study. Scientific study is a systematic way of learning about nature and its phenomena. It involves observation, asking a question, formation of a hypothesis, conducting an experiment, collection of data, analysis of data, drawing conclusion and making a valuable report. Scientific study always depends on well-planned experiment that gives valuable result. Each scientific experiment is affected by several factors. These factors are called variables. Variables The factors, traits or conditions that are considered during an experiment are called variables. For example, temperature, pressure, humidity, duration of light, duration of experiment, height, weight, etc. The result of an experiment is the combined effect of all the governing variables. For example, growth of a plant is affected by light, temperature, humidity, fertilizers, etc. If we want to see the change in the result due to the effect of a variable, we keep all the variables constant except the desired variable. For example, if we want to see the effect of light in the growth of a plant, other variables like temperature, humidity, fertilizers, etc. are kept constant except intensity of light. It means that in an experiment, we cannot study the effect of more than one variable at a time. So we change one variable at a time keeping other variables constant. The experiment should be a fair test in which we change one variable at a time. During the experiment we keep some variables constant. After changing this variable, we get new variable called resultant variable. Based on this fact, variables are divided into three categories. They are: i. Independent variables ii. Dependent variables iii. Controlled variables Independent Variable The variable whose value can be changed by the scientists during their experiment is called independent variable. For example, a scientist is conducting an experiment to MEMORY TIPS Science is a systematic study about any thing in nature and their phenomena. MEMORY TIPS Variables are the factors affecting the experiment. MEMORY TIPS Independent and dependent variables are one each but controlled variables are more than one. MEMORY TIPS The value of an independent variable can be changed continuously in the experiment.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 3 observe the effect of light on the behaviour of moths. For this purpose, he continuously turns a light on and off. In this experiment, amount of light is an independent variable and the reaction of the moth is the dependent variable. Similarly, a boy turns the knob of a tab to fill the bucket with water. Here, turning the knob is an independent variable. Dependent Variable The variable whose value depends upon the value of other variables is called dependent variable. It is tested in the scientific experiment in order to get its values. The dependent variable is obviously ‘dependent’ on the independent variable. In the above experiment, the reaction of moth due to change in amount of light is the dependent variable. Similarly, if we want to see the effect of amount of fertilizer in the growth of a plant, other variables like light, temperature, humidity, altitudes, etc. are kept constant except the use of fertilizer. The different variables when a plant is grown in different amount of a fertilizer. Independent variable Dependent variable Controlled variables Amount of fertilizer Growth of plant Light, Temperature, Humidity, Altitude FACTS WITH REASONS How do you identify the independent and dependent variables? An easy way to think of independent and dependent variables is, while conducting the experiment, the independent variable is always the one that we change, and the dependent variable is that which changes because of independent variable. It means that independent variable is a cause and the dependent variable is an effect. Controlled Variable The variable which is kept constant during the experiment is called controlled variable. The controlled variable is not a part of an experiment but it is important because it can have an effect on the result. If we want to see the effect of temperature in the growth of a plant, other variables like light, fertilizer, humidity, altitudes, air, water etc. are kept constant except the magnitude of temperature. Any given experiment will have numerous control variables. So, it is important for a scientist to try to hold all the variables constant except for the independent variable. Independent variable Dependent variable Controlled variables Amount of temperature Growth of plant Light, Temperature, Humidity, Altitude Importance of the Controlled Variables Although controlled variables may not be measured as they are not recorded, yet they can have a significant effect on the outcome of an experiment. Therefore, the lack of awareness of controlled variables may lead to defective MEMORY TIPS The value of the dependent variable changes due to the effect of independent variable. MEMORY TIPS Independent variable is a cause and dependent variable is an effect. MEMORY TIPS To find out the relation between independent and dependent variable, it is necessary to keep all other variables constant.

4 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur results or what is called “confounding variables”. So, recording controlled variables makes it easier to establish the relationship between the independent and dependent variables. For example, suppose we are trying to determine whether a particular fertilizer has an effect on plant growth or not. Here, the independent variable is the presence or absence of the fertilizer, whereas the dependent variable is the height of the plant or rate of growth. If we do not control the amount of light, for example, we perform some part of the experiment in the summer and some part during the winter, we may not get the exact result. Some more examples of variables S.N. Research Independent variable (what is going to change) Dependent variable (what is going to measure) Controlled variable (what are kept constant) 1. Relation between rate of reaction and surface area Surface area of the reactant Rate of reaction Temperature, pressure, amount of substance, etc. 2. Relation between magnetism and current in a solenoid Amount of current passed Magnetic power of solenoid Number of turns in a coil, thickness of wire, etc. 3. Relation between solubility and temperature Temperature Amount of solute dissolved (solubility) Amount of water, shape and size of container, etc. 4. Relation between heart beat and exercise Rate of exercise Heart beat Type of exercise Some facts about variables 1. For the correct result, we should not change more than one independent variable at a time. 2. In mathematical equation, dependent variable is kept at left hand side and independent variable is kept at right hand side. For example, in distance (s) = velocity (v) × time (t), distance is a dependent variable, time is an independent variable and velocity is a controlled variable. FACTS WITH REASONS Why is independent variable called right variable and dependent variable left variable? This is because, in mathematical equation, dependent variable is kept at left hand side and independent variable is kept at right hand side. 3. If one variable gives two or more effects, then we cannot explain the actual relation between cause and effect. So there should be only one dependent variable at a time. For example, if the air in a flexible container is heated, it increases volume and pressure.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 5 In this situation, it is difficult to explain relation between heat and pressure or heat and volume. 4. In graphic representation, dependent variable is kept in y-axis and independent variable is kept in x-axis. FACTS WITH REASONS Why is independent variable called y-variable and dependent variable x- variable? In graphic representation, dependent variable is kept in y-axis and independent variable is kept in x-axis. So, sometime dependent variable is called as y-variable and independent variable is called as x-variable. Measurement Measurement is an essential process for the accurate description of various quantities. For example, one should know the measurement of the quantity of matter in a body to describe its exact mass. In our daily life, measurement of distance, time and mass is necessary. These measurable quantities are called physical quantities. Thus, the quantities which can be measured by using different kinds of physical devices are called physical quantities. Mass, length, time, volume, force, density, temperature, work, energy, power, speed, etc. are some examples of physical quantities. The process of measurement is basically a comparison process. In order to measure a physical quantity, we assume a certain magnitude of the quantity as a standard called unit. Thus, measurement is the comparison of an unknown physical quantity with a known standard quantity of the same kind. Unit The standard known quantity which is used to measure the unknown quantity of the same kind is called unit. The unit is a fixed quantity. It is used to measure other quantities of the same kind. For example, one unit of length is assumed as the distance between two parallel gold lines on a platinum-iridium rod which is preserved at 0°C and standard atmospheric pressure. It is kept in the international bureau of weight and measures at Sevres, near Paris, France. Classification of Physical Quantities and Units In physics, there are a number of physical quantities to be measured. It is difficult to define a new unit for each of them as well as to remember a large number of new units. Most of the physical quantities are inter-related. For example, velocity is expressed as displacement upon time. So the unit of velocity is expressed in terms of unit of displacement and time. But all the physical quantities MEMORY TIPS Nepal Bureau of Standard and Metrology (NBSM) at Balaju, Kathmandu is the National Standard Body of Nepal. Measuring length Weighing MEMORY TIPS 1 pound = 0.454 kg

6 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur are not independent. Some are independent and others are dependent (derived). On the basis of this fact, the physical quantities are classified as: A) Fundamental physical quantities B) Derived physical quantities A) Fundamental physical quantities Those physical quantities which are independent of each other are called fundamental physical quantities. Length, mass, time, temperature, electric current, amount of substance and luminous intensity are the seven fundamental physical quantities. Other physical quantities can be obtained from them. B) Derived physical quantities Those physical quantities which are derived from the fundamental physical quantities are called derived physical quantities. For example: area, volume, velocity, force, speed, work, power, pressure, etc. i) Area is expressed as the product of length and breadth i.e. Area = length × breadth ii) Volume is expressed as the product of length, breadth and height i.e. Volume = length × breadth × height iii) Density is expressed as mass upon volume i.e. Density = mass volume , etc. FACTS WITH REASONS Velocity is a derived physical quantity. Why? Here, Velocity = displacement time taken = length time taken Velocity is formed by the combination of two fundamental quantities, i.e. length and time. So, it is a derived physical quantity. In order to decide units, neither it is convenient nor necessary to select units independently for all physical quantities. Some units of physical quantities are selected randomly, while the units for other physical quantities are derived from those selected units. Therefore, the units of the physical quantities are divided into two types. They are: a) Fundamental units b) Derived units. a) Fundamental units Those units which are independent of each other are called fundamental units. For examples, metre (m), kilogram (kg), second (s), kelvin (K), etc.There are seven fundamental physical quantities. To measure these seven fundamental physical quantities, there are seven fundamental units. They are metre (m), kilogram (kg), second (s), kelvin (K), ampere (A), candela (Cd) and mole (mol.).

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 7 In SI System, the seven fundamental physical quantities and their units are as follows: S.N Fundamental Quantity SI units SI Symbol 1. Mass kilogram kg 2. Length metre m 3. Time second s 4. Temperature kelvin K 5. Electric current ampere A 6. Amount of substance mole mol. 7. Luminous intensity candela cd SI units also include two supplementary units. These are as follows: S. N. Fundamental Quantities Units (SI) Symbol 1. Angle Radian rad 2. Solid angle Steradian sr b) Derived units There are many units which are expressed in terms of fundamental units. They are called derived units. For example, m2 , m3 , m/s, N, Pa. Thus, those units which are formed by the combination of two or more fundamental units are called derived units. FACTS WITH REASONS The SI unit of velocity is a derived unit. Why? From the definition of velocity, Velocity = displacement time taken Unit of velocity = unit of distance unit of time = m s = m s –1 Here, the unit of velocity (m s-1) can be expressed in terms of metre (m) and second (s). So, it is a derived unit. Unit of force is a derived unit. Why? From the definition of force, Force = Mass × Acceleration or, unit of force = unit of mass × unit of acceleration = kg × m s2 = kg m s –2 Here, the unit of force (N) can be expressed in terms of kilogram (kg), metre (m) and second (s). So, it is a derived unit. Unit of power is a derived unit. Why? Power = work done time = force × displacement time = mass × acceleration × displacement time Unit of power = kg × m s–2 × m s = kg m2 s3 = kg m2 s –3 Thus, the SI unit of power is derived from three fundamental units, namely kilogram (kg), metre (m) and second (s). So, it is a derived unit.

8 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Some derived physical quantities with their units SN. Physical quantities Formulae SI units Symbols Fundamental units involved 1. Area length × breadth square meter m2 m×m 2. Volume length × breadth × height cubic meter m3 m×m×m 3. Density mass / volume kilogram per cubic meter kg/ m3 kg/(m×m×m) 4. Velocity displacement / time meter per second m/s m/s 5. Acceleration change in velocity / time meter per square second m/s2 m/(s×s) 6. Force mass × acceleration newton kgm/s2 , N kg m/(s×s) 7. Work or Energy force × displacement joule J kg×m×m/(s×s) 8. Power work / time joule per second or watt J/s or W kg×m×m/(s×s×s) 9. Pressure force/area newton per square metre or pascal Nm-2or Pa kg/(m×s×s) 10. Momentum mass × velocity kilogram metre per second kg m/s kg×(m/s) 11. Frequency 1/time per second or Hz s-1 or Hz ¹/s Project Work Observe in your surrounding and find out the fundamental and derived units used to measure different physical quantities. Compare with your friend and discuss in the class. Differences between fundamental units and derived units S.N. Fundamental units S.N. Derived units 1. Those units which are independent of each other are called fundamental units. 1. Those units which are formed by the combination of two or more fundamental units are called derived units. 2. They are the units of fundamental physical quantities. 2. They are the units of derived physical quantities. 3. In SI units, there are seven fundamental units. They are m, kg, s, K, A, cd and mol. 3. In SI units, there are many derived units. Examples : m2 , m3 , m/s, N, W, J, etc. Unit-wise analysis of physical equation In the scientific experiment, many physical expression or equations are established. They are used to calculate different physical quantities. These equations can be checked using physical units and dimensions. Based on units, if they are same in left hand side and right hand side, they are called homogenous equations and correct equations. For example, in the equation s = ut + ½ at2 , the units for the L.H.S and R.H.S are the same and it is metre (m). Unit analysis is the study of the relationship between physical equations with the help of units of measurement.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 9 The principle of homogeneity of equations The principle of homogeneity states that an equation is unit-wise correct if the units of the various terms on either side of the equation are same. This principle is helpful because it helps us convert the units from one form to another. To better understand the principle, let us consider the following examples: Solved Numerical 1.1 Check the correctness of physical equation s = ut + 1 2 at2 . In the equation, s is the displacement, u is the initial velocity, v is the final velocity, a is the acceleration and t is the time in which change occurs. Solution: We know that L.H.S = s and R.H.S = ut + 1 2 at2 The units for the L.H.S can be written as s = metre (m) ………..(1) We know that R.H.S is ut + 1 2 at2 , Simply, we can write R.H.S as u × t + a × t2 (Since numerical coefficient does not matter) or, ms-1 × s + ms–2× s2 or, m + m……….…….……..(2) Keeping equation (1) and (2) together, we have, m = m + m From equation (1) and (2), we have L.H.S = R.H.S Hence, by the principle of homogeneity, the given equation is unit-wise correct. Solved Numerical 1.2 Check the correctness of physical equation v2 = u2 + 2as. In the equation, s is the displacement, u is the initial velocity, v is the final velocity, a is the acceleration and t is the time in which change occurs. Solution: We know that L.H.S = v2 and R.H.S = u2 + 2as The units for the L.H.S can be written as v2 = metre2 per second 2 (m2 s-2) ………..(1) We know that R.H.S is u2 + 2as Simply, we can write R.H.S as u2 + a×s (Since numerical coefficient does not matter) or, m2 s-2+ ms-2× m or, m2 s-2+ m2 s-2……….…….……..(2)

10 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Keeping equation (1) and (2) together, we have, m2 s-2 = m2 s-2 + m2 s-2 From equation (1) and (2), we have L.H.S = R.H.S Hence, by the principle of homogeneity, the given equation is unit-wise correct and homogenous. Solved Numerical 1.3 Check the correctness of physical equation v = u + at2 . In the equation, u is the initial velocity, v is the final velocity, a is the acceleration and t is the time in which change occurs. Solution: We know that L.H.S = v and R.H.S = u + at2 The units for the L.H.S can be written as v = metre per second (ms-1) ………..(1) We know that R.H.S is u + at2 Simply, we can write R.H.S as u + a×t2 (Since numerical coefficient does not matter) or, ms- 1 + ms-2 × s2 or, ms-1 + m……….…….……..(2) Keeping equation (1) and (2) together, we have, ms-1 ≠ ms-1+ m From equation (1) and (2), we do not have L.H.S = R.H.S Hence, by the principle of homogeneity, the given equation is unit-wise incorrect and it is non-homogenous. Solved Numerical 1.4 Check the correctness of the physical equation v2 = u2 + 2as2 . Solution: We know that L.H.S = v2 and R.H.S = u2 + 2as2 The units for the L.H.S can be written as v2 = metre2 per second 2 (m2 s-2) ………..(1) We know that R.H.S is u2 + 2as2 Simply, we can write R.H.S as u2 + a×s2 (Since numerical coefficient does not matter) or, m2 s-2+ ms-2× m2 or, m2 s-2+ m3 s-2……….…….……..(2) Keeping equation (1) and (2) together, we have, m2 s-2 ≠ m2 s-2 + m3 s-2 From equation (1) and (2), we do not have L.H.S = R.H.S Hence, by the principle of homogeneity, the given equation is unit-wise incorrect and non-homogenous.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 11 FACTS WITH REASONS Why do we use unit-wise analysis? We use unit-wise analysis to check the reliability of an equation, to derive the relation between physical quantities in physical phenomena and to change units from one system to another. Applications of unit-wise analysis Unit-wise analysis is a fundamental aspect of measurement. It is applied in real-life physics. It is used for following reasons: i. It is used to check the reliability of a physical equation. ii. It is used to derive the relation between physical quantities in physical equation. iii. It is used to change units from one system to another Limitations of unit-wise analysis Some limitations of unit-wise analysis are: i. It doesn’t give information about the equational constant. ii. It doesn’t give information about the coefficient of the equation. iii. It gives no information about whether a physical quantity is a scalar or vector. HOT SKILL HIGHER ORDER THINKING SKILL 1. What is the main thing to distinguish independent and independent variable? The variable whose value can be changed by the scientists during their experiment is called independent variable. Similarly, the variable whose value depends upon the value of other variables is called dependent variable. 2. Is equation P = I2 R acceptable ? Yes, equation P= I2 R is acceptable because the basic units involved in P is kgm2 s-3 and I2 R is also kgm2 s-3 . 3. Mass is called a fundamental physical quantity, why? Mass is called a fundamental physical quantity because it does not depend upon other physical quantities to be expressed. 4. Acceleration is called a derived physical quantity. Why? We know that, acceleration = Change in velocity time taken Here, acceleration is expressed with the help of two fundamental quantities i.e., displacement, and time. Therefore, acceleration is a derived physical quantity. 5. Differentiate between MKS system and the SI units. S.N. MKS system S.N. SI units 1. MKS system is a metric system of measurement. 1. SI units is a revised, redefined and extended version of the MKS system. 2. It involves three fundamental quantities, i.e. length, mass and time. 2. It involves seven fundamental quantities.

12 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 6. Distinguish between dependent and independent variables. S.N. Dependent variables S.N. Independent variables 1. Dependent variables are those that are tested in a scientific experiment to determine their values. 1. The variable that the researcher modifies throughout the experiment is referred to as an independent variable. 2. It depends upon independent variables. 2. It determines the value of dependent variable. 3. It is an effect. 3. It is a cause. 7. Is it possible to add and subtract physical quantities having different basic units No, we can not add and subtract physical quantities having different basic units. It means that only those physical quantities can be added or subtracted which have same units. For example addition or subtraction of 'u' and 'v' is possible because they have same basic units, i.e., ms-1. Similarly, s+at is not possible because 's' has basic unit 'm' and 'at' has basic unit ms-1 . 8. Show that joule is a derived unit. Joule is the SI unit of work. So, work = force × distance = mass × acceleration × distance = kg × m/s2 × m Here, we can see that joule is made up of three fundamental units. They are kilogram, metre and second. Therefore, joule is a derived unit. 9. SI units of units is based on the MKS system of units. How? In the MKS system, only three fundamental quantities, i.e. length, mass and time are considered. Whereas in the SI units, all seven fundamental quantities, i.e. length, mass, time, temperature, luminous intensity, current and amount of substances are considered. It shows that, SI units is the extended version of the MKS system of units. So, SI units is based on the MKS system of units. 10. Can unit-wise analysis tell about the equational constant? What are the other limitations of unit-wise analysis? No, a unit-wise analysis cannot tell about equational constant. Some other limitations of unit-wise analysis are: It cannot tell about equation’s coefficient. It cannot tell if the physical quantity is vector or scalar. 11. Explain the roles that a variable plays in a scientific experiment. The roles that a variable plays in a scientific experiment are: i. Variable is a basic unit of information that is studied during the research. ii. Variable is observed and interpreted in research studies. iii. It is observed and used to relate many variables together to make sense of experiment. iv. It helps in descriptive study of experiment. 12. Is the given equation, v = u + at, homogeneous? Give reason. In this equation v is final velocity, its SI unit is m/s. u is initial velocity, its SI unit is m/s. a is acceleration its SI unit is m/s2. t is time. Its SI unit is second. Now, Left hand side Velocity (v) = m/s Right hand side = u + at = m/s + (m/s²) x s = m/s + m/s Now putting RHS and LHS together m/s = m/s + m/s We have L.H.S = R.H.S. Hence, by the principle of homogeneity, the given equation is unit-wise correct and homogeneous.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 13 13. Nilu wants to observe heat absorb by different colours. For this she brought twelve coloured jugs ( three black, three blue, three white and three red) of equal size. She fill water and put them in the sun light for two hours. After that, she brought a thermometer and measure temperature. Based on this experiment, answer the following questions. i. What are dependent variable, independent variable and controlled variables in this experiment? In this experiment colour is an independent variable, temperature is dependent variable, size of jugs, amount of water and time duration are controlled variables. ii. Why did she brought equal size of jugs and kept them in the sunlight for equal time? In this experiment, she wants to study the relation between colours and heat absorbed (change in temperature). So, size of jugs, amount of water and time duration are kept constant as they are controlled variables. iii. Why did she bring three jugs of each colour? For correct measurement, we should not depend upon only one reading. The mean value of more than one reading gives the correct measurement. For the same purpose Nilu brought three jugs of each colour. 3 STEPS EXERCISE EXERCISE STEP1 1. Select the best answer from the given alternatives. a. What is the name given for the factors, traits or conditions that are considered during an experiment? i. variety ii. variables iii. variation iv. variability b. Which variable can be changed by the scientist during his experiment? i. dependent variable ii. independent variable iii. mixed variable iv. controlled variable c. With the help of units, check the correct one from the given equations. i. s = ut2 + 1 2 at ii. s = ut + 1 2 at, iii. s = ut + 1 2 at2 iv. s2 = ut + 1 2 at2 , d. Based on units, v2 = u2 + 2as is called................... i. homogenous equation ii. non-homologous equation iii. analogous equation iv. variable equation e. Identify the unit analysis for v2 = u2 + 2as i. ms-2 = m2 s-2 + m2 s-2 ii. m2 s = m2 s-2 + m2 s-2 iii. m2 s-2 = m2 s-2 + m2 s iv. m2 s-2 = m2 s-2 + m2 s-2 2. Define the following terms with required examples. a. Variables b. Independent variables c. Dependent variables d. Controlled variables e. Unit f. Fundamental unit g. Derived unit h. Physical quantity

14 Scientific Study Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 3. Answer the following questions in very short. a. What is the independent variable if a scientist is turning bulb on and off to check behaviour of the earthworm? b. What is the type of variable if its magnitude is constant throughout the experiment? c. What are the quantities that can be measured called? d. What is the standard reference quantity of a physical quantity called? e. What type of physical quantity is area? f. Write down the basic units involved in Newton (N), Watt (W), Joule(J) and Pascal (Pa). g. Write down the formula and basic units involved in density, velocity, weight, work, acceleration, force, pressure and speed. STEP2 4. Give reasons. a. The magnitude of kilogram is same all over the world. b. Unit of the temperature is called fundamental unit. c. Unit of work is called derived unit. d. Unit-wise analysis is broadly used to test the physical equation. 5. Differentiate between the following. a. Dependent variables and independent variables b. Controlled variables and dependent variables c. Fundamental units and derived units 6. Answer the following questions in short. a. Examine the physical equation s = u + at where ‘a’ is acceleration, ‘u’ is initial velocity, ‘s’ is distance and ‘t’ is time. b. Is time a physical quantity? Support your answer with a suitable reason. c. What do you mean by principle of homogeneity of equations? d. Write down the applications of unit-wise analysis. e. Explain the limitations of unit-wise analysis. STEP3 7. Answer the following long questions. a. Explain independent variable, dependent variable and controlled variables with examples. b. What kinds of variables are called controlled variables? Write down their importance. c. State principle of homogeneity of equation. Check the correctness of physical equation s = ut + ½ at. d. Write any two differences between fundamental and derived units. Which units are involved in joule and watt? e. Based on units, check whether the following equations are correct or not? i. v2 = u2 + 2as ii. v = u + at iii. s2 = ut + 1 2 at2

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 15 iv. P = mv2 v. P = I²R vi. s = u + at iii. s = ut + 1 2 at2 iv. v = ut + 1 2 at2 f. Alish wants to observe the growth of plants in different fertilizers like urea, compost fertilizer and wooden ash. He brought three vases and kept equal amount of urea, compost fertilizer and wooden ash in each. He sown seeds of same plant and kept them in open place. After germination of seeds, he measured their height each day and maintain record. Based on this experiment answer the following questions. i. What are independent variable, dependent variable and controlled variables in this experiment? ii. Why did he brought vases of equal size and kept equal amount of fertilizers? g. Lokeshwor has a cow farm. He increased the food to one group of cow and kept constant for others. The group that ate more food gave more milk than the others. Enlist dependent and independent variables in this experiment along with their reason. h. Munal says the formula of power P = mv2 and Rohan says P = mv A . Which one is correct? Check using unit-analysis. i. Design an activity where we can identify independent variable, dependent variable and controlled variables. j. Write down the formula and show that the unit analysis of electric resistance (R) is kgm2 A-2s-3. k. Complete the given table using independent variable, dependent variable and controlled variables Experiment Independent variable Dependent variable Controlled variable Relation between distance covered and time taken Relation between hunger and eating time Relation between life time of a battery and number of bulbs used Project Work 1. Visit a local market and observe the instruments used to measure mass, length, and volume and note them on your exercise book. 2. Make a small survey in a limited area to know about the local units of measurement. Visit different families in your locality. Ask the old family members about the system of measurement used in their time and collect information in a table as: Physical quantity Instrument used Local unit Standard unit Relation between the two units

16 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Key terms and terminologies of the unit 1. Classification of organisms: Classification is the act of grouping of organisms on the basis of their similarities and dissimilarities. 2. Taxonomy: Taxonomy is the branch of biology which deals with identification, classification and nomenclature of organisms. 3. Taxon: A taxon is a generally accepted category under which the organisms having similar characteristics are grouped. e.g. kingdom, phylum etc. 4. Genus: Genus represents the group of those organisms that have similar physiology, anatomy and feeding habit. 5. Species: Species represents the organisms that are completely similar to each other and can interbreed to produce a fertile offspring. 6. Epithet: Epithet is the second word of the scientific name of the organism, i.e., species. 7. Unicellular organisms: Organisms which have a single cell in their body to perform life functions are called unicellular organisms. 8. Multicellular organisms: Organisms having more than one cell in their body are known as multicellular organisms. 9. Microscopic organisms: The organisms that are too small to be seen through unaided eyes (naked eyes) are called microscopic organisms. 10. Macroscopic organisms: Macroscopic organisms include those which can be seen with our naked eyes. Sequence of Curriculum Issued by CDC  Classification of living beings: based on five kingdom system  Classification of plant kingdom: features and examples upto division  Sub-division Angiosperm: features and examples of upto class  Classification of animals: features and examples upto phylum  Sub-phylum Vertebrata: features and examples upto class  Relation of evolution with the classification of organisms UNIT Classification of Living Things 2 Estimated teaching period Theory Practical 6 3 Robert Harding Whittaker is an American plant ecologist known for introducing five kingdoms taxonomic classification. He was born on 27th December 1920 and died on 20th October 1980. His work five kingdom system of classification was better to explain the evolutionary relations among the organisms than the two kingdom systems of classifications. Robert Harding Whittaker About the Scientist

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 17 11. Prokaryotes: The organisms that lack a well-organized nucleus and membrane covered structures in their cells are known as prokaryotes. 12. Eukaryotes: The organisms having a well-organized nucleus and membrane bound structures in their cells are known as eukaryotes. 13. Autotrophs: The organisms that can prepare own food by themselves are known as the autotrophs. 14. Heterotrophs: The organisms that cannot prepare own food by themselves are termed as heterotrophs. 15. Saprophytes: The heterotrophs that depend on dead and decayed organic matter are called saprophytes, e.g. mushroom, mucor etc. 16. Parasites: The heterotrophs that live in the body of host organism for their food are known as parasitic organisms, e.g. puccinia, leech, roundworm etc. 17. Algae: Algae are green small thallophytes that are autotrophic in nature. 18. Bryophytes: Bryophytes are the non-flowering (cryptogams) green plants that grow in moist, shady, damp and watery places. 19. Tracheophyta: Tracheophyta is the division which includes vascular plants. 20. Closed circulatory system: Closed circulatory system is a type of circulation in which the blood is transported throughout the body through the blood vessels from and to the heart. 21. Open circulatory system: The circulatory system in which blood is transported directly into the tissues without blood vessels is called open circulatory system. 22. Diploblastic animals: An organism which is developed from two germ layers is called diploblastic animals. 23. Triploblastic animals: The animal developed from three germ layers is called triploblastic animals. 24. Hermaphrodites: The animals that have both male and female sex organs in the same body are called hermaphrodites. Example, earthworm 25. Invertebrates: Invertebrates are the groups of animals which do not have vertebral column in their body. 26. Chordates: Chordates are those animals which bear notochord in some stages of their life. 27. Vertebrates: Vertebrates are those animals that have notochord in their embryonic stage which modifies into backbone or vertebral column. 28. Cold blooded animals: The animals whose body temperature changes according to the surrounding temperature are called cold-blooded animals. Examples, pisces, amphibian and reptiles. 29. Warm blooded animals: The animals whose body temperature does not change according to the surrounding temperature are called warm-blooded animals. Example, birds and mammals. 30. Oviparous animals: Animals that reproduce by laying eggs are called oviparous animals. 31. Viviparous animals: Animals that reproduce by directly giving birth to the young ones are called viviparous animals. 32. Metamorphosis: The process of completion of the life cycle through different distinct stages is called metamorphosis. During complete metamorphosis, insects involve four distinct life stages. They are egg, larva, pupa, and adult.

18 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Introduction Observe the following figures and discuss the given questions (a) (e) (b) (f) (c) (g) (d) (h) a) Can we keep these animals together in a same phylum? b) What are the similarities and differences between pigeon and frog? c) Which of them are invertebrates and vertebrates? Let's observe the estimated total population of different groups of plants and animals found on the earth. We can see that, there are about 5,500 mammals, 10,000 reptiles, 40,000 fishes, 15,000 amphibians, 10,000 birds and 6,755,830 invertebrates in the world. If we examine the names and characteristics of all these species, the variation is so huge that it becomes impossible to study each of them. There is also difficulty of language for the study of these organisms around the world. This problem is solved by grouping the plants and animals on the basis of their similarities and differences into certain types. This is known as classification of plants and animals. Classification of organisms is the act of grouping organisms on the basis of their similarities and dissimilarities. It was first done by Swedish biologist Carolus von Linneaus in the 1750s. Carolus introduced a system known as the Binomial system of Nomenclature in which the plants and animals were given a unique name called the scientific name. The scientific name consists of two Latin words: the first word is called the genus or the generic name and the second one is called the species or specific name or epithet. Today, all known organisms in the world have a universal scientific name that every biologist understands irrespective of his language and country. The system Carolus started is well developed into a branch of biology known as the Taxonomy. Carolus von Linnaeus is known as the father of taxonomy. MEMORY TIPS There are about 8.7 million species of living things in the earth. MEMORY TIPS Taxonomy is the branch of biology which deals with identification, classification and nomenclature of organisms.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 19 FACTS WITH REASONS Carolus von Linnaeus is known as the father of taxonomy, why? Carolus von Linnaeus started the systematization in the classification process through Binomial system of nomenclature for the first time. So, Carolus von Linnaeus is known as the father of taxonomy. Classification Hierarchy Commonly, there are two kinds of organisms: plants and animals. These plants and animals have further types and sub-types. Look at the simple classification of a bird hen: Hen falls under the 5th common level of animals’ type. The types in which hen is classified forms a hierarchy. In this example, there are five groups forming a hierarchy. Each group level of hierarchy is known as a taxon. A taxon is a generally accepted category under which the organisms having similar characteristics are grouped. There are various taxa (pl. of taxon) which form a hierarchy of classification. The classification hierarchy is shown below: Kingdom Phylum Sub-phylum Class Type Animalia Chordata Vertebrata Aves Hen The Five Kingdom System The two kingdom system (Plantae and Animalia) could not distinguish between prokaryotes/ eukaryotes, autotrophs/heterotrophs and unicellular/multicellular. There were many organisms that did not fit in the two kingdom system satisfactorily. Therefore, American Biologist Robert H. Whittaker proposed the five kingdom system, adding three more kingdoms: Monera, Protista and Fungi, in addition to the earlier two kingdoms: plantae and Animalia. The five kingdom system is explained in brief below: 5 Kingdom System Monera Unicellular prokaryotes Plantae Multicellular autotrophic eukaryotes Animalia Multicellular heterotrophic eukaryotics Fungi Non-green uni/ multicellular eukaryotes Protista Unicellular eukaryotes 1. Monera This kingdom includes all types of bacteria (e.g. cyanobacteria or blue-green algae, coccus, bacillus, etc.). They are single-celled microscopic prokaryotes having no nuclear membranes. They are both autotrophic and heterotrophic. Bacteria Coccus Blue-green algae MEMORY TIPS Kingdom monera consists of onecelled organisms, both autotrophs and heterotrophs that are extremely simple in structure.

20 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur 2. Protista This kingdom includes single-celled microscopic eukaryotes. i.e. they contain a well-defined nucleus with membrane bound cellular structures. They have a nuclear membrane and are both autotrophic and heterotrophic. For example, amoeba, paramecium, euglena, dinoflagellates, etc. Their locomotory organs are primitive. 3. Fungi Fungi is the kingdom of non-green eukaryotes. They may be single celled or multi-celled. They cannot prepare food by themselves and are heterotrophic. Hence, they have to depend upon dead and decayed matter for food. Most of the fungi are filamentous and thread-like in structure. Mushroom Yeast Mucor 4. Plantae These are well-developed multicellular organisms. They have a eukaryotic cell and can prepare food by themselves (autotrophic). Plants lying in this kingdom are both higher and lower type. The herbs, shrubs and trees are parts of this kingdom. They have a long life cycle. Their bodies are made up of tissues and organs. 5. Animalia The organisms lying in this kingdom are multicellular, eukaryotic and heterotrophic. They have different forms of habitats. Most of them have well developed tissue, organ and body systems. They swallow their food as a whole and have a digesting column in the body (holozoic in nature). Their cells do not have a cell wall. Dolphin Frog Starfish Amoeba Paramecium Euglena MEMORY TIPS Fungi are useful in our daily life too. The fungus called yeast is used to prepare beer and bread. Similarly, antibiotics are extracted from a fungus called penicillium. Mushroom is a fungus which has several medicinal values. But, some fungus are parasitic too e.g. puccinia, yarshagumba etc. Mango Moss Fern

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 21 FACTS WITH REASONS Why is the five kingdom classification system most accepted? In five kingdom classification system, grouping of diverse organisms is done into five kingdoms. This system groups organisms on the basis of complexity of Cell Structure (Prokaryote or Eukaryote), Complexity of the Organism’s Body (Unicellular or Multicellular and Complex) and Mode of their Nutrition (Photosynthesis, Absorption or Ingestion). So, five kingdom classification is the most accepted system of classification. Kingdom Plantae [Latin: 'planta'- shoot] ACTIVITY 1 Observe the given plants and answer the following questions. (a) (b) (c) (d) i) Name the given plants. ii) Write down the major characteristics of the given plants. The kingdom plantae includes the multicellular, autotrophic eukaryotes. This kingdom contains plants living in all types of habitats. They may vary in shape, size and body features. On the basis of their habitats there are two types of plants: terrestrial and aquatic. All herbs, shrubs, trees, creepers, etc. fall under this category. The plant kingdom is divided into three divisions: i) Division Algae – thalloid colourful plants ii) Division Bryophyta – mosses iii) Division Tracheophyta – plants bearing xylem and phloem i) Division algae [Latin: 'alga'- sea weed] Algae are the wide range of small, thalloid and green plants that are autotrophic in nature. They are mostly seen as green, red, brown, yellow-green, golden and purple patches in the sea, pond, and rivers. They may cover up the entire pond or seacoast that gives a colourful effect to the water. Their bodies are thalloid i.e. cannot be differentiated into roots, stem and leaves. Hence, they are called thallophytes. Their main characteristics are given below: a) Body type: They are both unicellular (e.g. chlamydomonas) and multicellular (e.g. spirogyra) b) Mode of nutrition: They are autotrophic and can prepare food by themselves. Green algae have chlorophyll while other colourful algae may have other colourful pigments too. c) Habitat: Most algae live in the water sources like the pond, lake, sea, etc. by attaching to their bed. Some of them live in moist places too.

22 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur d) Food storage: The algae store their food in the form of a carbohydrate called starch (starch is a common source of foods like rice, wheat, potato etc.). e) Cell wall: They bear cell wall like all other plants. Their cell wall contains cellulose. f) Reproduction: They reproduce both through the vegetative and sexual method. g) Vascular tissues: Absent h) Alternation of generation: Absent Examples: Green algae (e.g. spirogyra, volvox, ulothrix, chlamydomonas, etc.), diatoms (golden brown algae), dinoflagellates (fire algae), rhodophytes (red algae), Laminaria (brown algae), etc. FACTS WITH REASONS Why do some sea-coasts and pond look colourful? In some sea-costs and ponds, there is a growth of various types of algae having different pigments in their cells. So, some sea-coasts and ponds look colourful. Spirogyra Anabaena Chlamydomonas Nostoc Ulothrix Batra Volvox Lamnaria ii) Division Bryophyta [Greek: bryon – moss and phyton - plant] Bryophytes are the flowerless plants (cryptogams) that grow in moist, shady, damp and watery places. They are commonly divided into three groups of plants: liverworts, mosses and hornworts. Mosses form the largest family of bryophytes. Some of their common characteristics are: a) Body type: The body of bryophytes is multicellular. They are both thallus and non-thallus. b) Mode of nutrition: Bryophytes are green plants. They contain chlorophyll and the mode of nutrition is autotrophic. c) Habitat: Most of the bryophytes grow in watery areas. MEMORY TIPS Bryophytes are more advanced than green algae but more primitive than ferns.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 23 FACTS WITH REASONS Bryophytes are called amphibian plants, why? Most of the bryophytes like riccia are found in terrestrial habitat but they depend on water for completion of their sexual reproduction. So, bryophytes are also called amphibian plants. d) Food storage: They store food in the form of starch. e) Cell wall: The cell wall of bryophytes is made up of cellulose. f) Reproduction: They reproduce by both vegetative and sexual method. g) Vascular tissues: Absent h) Alternation of generation:Life cycle of bryophytes is divided into two stages: sporophytic and gametophytic. The sporophytic generation is followed by the gametophytic and vice versa. This is called the alternation of generation. Examples: Moss (e.g. sphagnum, fire moss, funaria etc.), liverworts (e.g. marchantia, riccia, etc.), etc. Marchantia Riccia Irish moss iii) Division Tracheophyta [Greek: 'trakheia' - windpipe and ‘ophyta’ - to produce] Tracheophyta is the division which includes vascular plants. Vascular plants are those which have vascular tissues called xylem and phloem. These tissues conduct food and minerals throughout the plant body. Xylem tissues conduct raw materials from the roots to the leaves while the phloem tissues conduct food prepared in the leaves to all parts of the plant body. The division Tracheophyta is further divided into three sub-divisions: a) Sub-division Pteridophyta : feather like plants Seed lacking plants b) Sub-division Gymnosperms : cone bearing plants Seed bearing plants c) Sub-division Angiosperms : flower, fruit and seed bearing plants Fruit and seed bearing plants FACTS WITH REASONS Plants with xylem and phloem are called vascular plants, why? Xylem and phloem are the vascular bundles in the plants that help in the transportation of water and minerals throughout the body. So, the plants with xylem and phloem are called vascular plants.

24 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Sub-division Pteridophyta [Greek: ‘pteris’ - fern like and ‘phyton’ - plant] Pteridophytes are the most developed non-flowering plants. They do not bear flowers, fruit and seeds. As they are tracheophytes, they bear vascular tissues: xylem and phloem. Some of the characteristics of pteridophytes are given below: a) Habitat: Most pteridophytes grow in open, moist, shady and shadowy places. Some species grow on rocky hillside, banks and cliffs, ponds and some under sunlight. b) Body size and structure: Most pteridophytes are small in structure bearing feather-like leaves called fronds. Some tropical tree ferns can be as tall as 30 m. c) Flower, fruits and seeds: They do not bear flowers, so they do not produce fruits and seeds. d) Mode of nutrition: All pteridophytes are green and bear chlorophyll to produce their own food. Therefore, the mode of nutrition is autotrophic. e) Differentiation: The body of pteridophytes is non-thalloid i.e. divided into roots, stem and leaves. f) Vascular tissues: As pteridophytes are tracheophytes, they bear vascular tissues for food and mineral conduction. g) Reproduction: Pteridophytes do not bear male and female parts in their mature plant body but grow later on in their life cycle. They have both asexual and sexual reproduction systems present in their life cycle. They reproduce asexually by spores. Spores are the numerous tiny structures present in the ventral leaves inside the sorus (spore sac). Likewise, the sexual reproduction occurs afterwards by the union of male and female sex gametes. h) Alternation of generation: The life cycle of pteridophytes is completed in two stages: sporophytic generation (stage of spores) followed by the gametophytic generation (stage of gametes). So, alternation of generation exists. Examples: Fern, Lycopodium, Equisetum or Horsetail, Marsilea etc. Fern Lycopodium Equisetum Selaginella Marsilea FACTS WITH REASONS Why is fern classified in the division tracheophyta and sub-division pteridophyta? Fern consists xylem and phloem which is the characteristic feature of tracheophyta. On the other hand it has feather like leaves which is the characteristic feature of pteridophyta. So, fern is classified in the division tracheophyta and sub-division pteridophyta. MEMORY TIPS Fern is an advanced cryptogam. Its body is differentiated into roots, stem and leaves. MEMORY TIPS Club-moss is more developed than moss because club-moss has vascular bundel but moss do not.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 25 Sub-division: Gymospersms [Greek: 'gymno'-naked and 'sperma'- seed] Gymnosperms are the plants that do not bear fruits but they have naked seeds. Their seeds are not enclosed inside the fruits. That is why they are called naked seeded plants. Their characteristics are given below: a) Habitat: Gymnosperms are terrestrial plants which grow on dry places that receive less rainfall. b) Body size and structure: They are mostly bigger trees with woody parts. Their leaves are needle shaped. c) Flower, fruits and seeds: They do not bear flowers and fruit as they do not have ovary. But they contain seeds. The seeds are naked and not enclosed inside fruits (like in mango) or seed covering (like in paddy). Instead of flowers, they bear woody scales called the cones. The male and female cones help in reproduction. FACTS WITH REASONS The seeds of gymnosperms are not enclosed inside fruits or seed covering, why? Gymnosperms are the plants that do not bear fruits but they have naked seeds. Instead of flowers, they bear woody scales called the cones. They do not have ovary. So, the seeds are naked and not enclosed inside fruits or seed covering. d) Mode of nutrition: All gymnosperms are autotrophic in nature as they are green plants. e) Differentiation: Their bodies are well differentiated into roots, stems and leaves. f) Vascular tissues: All gymnosperms bear vascular bundles. But they are not well developed as in angiosperms. g) Reproduction: Pollination in gymnosperms is caused only by the wind and insects. After pollination, the pollen cells from the male cone fuses with the female cell present in the female cone. Thus, the fertilization occurs. h) Alternation of generation: The sporophytic generation is followed by gametophytic generation and vice versa. Hence, alternation of generation is present. Examples: pine, fir, spruce, deodar, gingko, etc. Cycas Pine Cedar Sub-division: Angiosperms [Greek: 'angion' - coat and 'sperma' - seed] Angiosperms belong to about 300,000 species of the most advanced flowering plants of the Plantae kingdom. They are found both on land and in water and are the most advanced plants. Some of the MEMORY TIPS Gymnosperms grow on dry places. They have long roots to search water, pointed leaves to reduce transpiration and dry scales to prevent loss of water. MEMORY TIPS Pteridophyta have feather like leaves, gymnosperm have needle like leaves and angiosperm flat leaves with veins. MEMORY TIPS Angiosperms are more advanced than gymnosperms. The seeds of angiosperms are enclosed inside fruits or seed covering, whereas gymnosperms do not possess this structure.

26 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur reasons why they are considered the most advanced plants are as follows: i) They have well developed vascular tissues: xylem and phloem. ii) They bear well developed flower, fruit and seed. iii) They are all multicellular, non-thalloid and green plants. iv) Seeds are enclosed inside the fruits and ovules are enclosed inside the ovary of the flowers. v) Flowers are both unisexual and bisexual. vi) Their size ranges from small herbs to large trees. On the basis of the number of leafy parts of a seed (cotyledon), the angiosperms are divided into two major classes: a) Class: Monocotyledon/monocotyledonous/monocot plants b) Class: Dicotyledon/dicotyledonous/dicot plants Monocotyledon: [mono - one] The monocots are those plants which have a single cotyledon or leafy part in their seeds. They are found in various habitats and grow in wide ranges of climates. Their stems and branches are soft and do not contain woody parts. They constitute about 60,000 species. Dicotyledon: [Di - two] The dicotyledons are the plants which bear two cotyledons in their seeds. They mostly are terrestrial plants and have woody stems. There are about 200,000 species of dicots on earth. A short comparison between monocots and dicots along with their characteristics on the basis of various features are given below: Characteristics of monocotyledon and dicotyledon Feature Monocot Dicot Seed The seed bears one cotyledon. The seed bears two cotyledons. Leaf venation Leaf venation is parallel. Leaf venation is reticulate or net-like. Root Root system is fibrous. Root system is tap root or main root. Flower Flower bears petals in multiples of three (trimerous) Flower bears petals in multiples of five or four (tetramerous or pentamerous) Vascular tissues The stems have irregularly scattered vascular bundles The stems have vascular bundles arranged in a ring. MEMORY TIPS Cycas belongs to gymnosperm whereas coconut belongs to angiosperm. So, coconut is more developed plant than cycas as it has closed seed. Monocot seed MEMORY TIPS Fern, cycas, banana, etc. have vascular tissue so, they are kept in division tracheophyta. Dicot seed

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 27 Pollen grain The pollen grains have single opening. Examples: cereals (rice, wheat, etc.), flowers like daffodil, orchid etc., grasses, banana, bamboo, water plants (pistia, lemna, water hyacinth etc.), sugarcane, onion, coconut, etc. The pollen grains have three openings. Examples: tomato, apple, mango, pumpkin, mustard, papaya, gram, rose, soya bean, pea, etc. MEMORY TIPS Monocot flower is identified from its trimerous structure where as dicot flower is identified from its tetramerous or pentamerous structure. Project Work Observe in your surrounding and find out the different plants of angiosperm. Compare with the plants that are collected by your friend. FACTS WITH REASONS The seeds of angiosperms are enclosed inside fruits or seed covering, why? Angiosperms bear flowers with ovule inside an ovary. The ovary changes into fruit and the ovule changes into seed. So, the seeds of angiosperms are enclosed inside fruits or seed covering. Kingdom Animalia [from Latin – animalis meaning ‘having breath and soul’] ACTIVITY 2 Observe the given figures and discuss the following questions. (a) (b) (c) (d) (e) (f) (g) (h) i) Name the kingdom and phylum of these animals. ii) Enlist the major characteristics of these animals Animals are the multicellular, non-green eukaryotes having no cell wall in their cells. They are mostly found in marine water (e.g. seas, oceans), fresh water (e.g. lake, pond, river), deserts, grasslands, jungles etc. The animal kingdom is simply divided into two parts: a) Chordates Chordates are animals which possess a notochord in the embryonic stage of their life. A notochord is a dorsal (towards the back of animal) structure of rod-like cells that runs from head to tail in the embryonic stage. In some animals, the notochord remains same throughout MEMORY TIPS All chordates have blood enclosed in blood vessels, although they may not have blood cells.

28 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur their lifetime (in urochordates and cephalochordates) while in some animals it changes into vertebral column or backbone (in vertebrates: fishes, birds, reptiles, amphibians and mammals). About 3% of animals on earth are chordates. b) Non-chordates These are the animals which do not have notochord in the embryo during their development. Since they do not have notochord, they do not bear a backbone. The non-chordates include the phylum of invertebrates: Porifera, Coelenterata, Platyhelminthes, Nemathelminthes, Annelida, Arthropoda, Mollusca and Echinodermata. They occupy about 97% of all animal species on earth. A chart below illustrates the classification of animals in an understandable manner. Phylum Chordata Sub-phylum: Urochordata Phylum: Porifera e.g. sycon Phylum: Coelenterata e.g. hydra Phylum: Platyhelminthes e.g. tapeworm Phylum: Aschelminthes e.g. round worm Phylum: Annelida e.g. earthworm Phylum: Arthropoda Phylum: Mollusca Phylum: Echinodermata e.g. starfish Sub-phylum: Cephalochordata Class: Pisces e.g. rohu Class: Crustacea e.g. prawn Class: Amphibia e.g. frog Class: Insecta e.g. butterfly Class: Reptilia e.g. snake Class: Myriopoda e.g. millipede Class: Aves e.g. parrot Class: Arachnida e.g. spider Class: Mammalia e.g. human Sub-phylum: Vertebrata Animal Kingdom Group Non-chordata (notochord absent) Group Chordata (notochord present) Sub-phylum: Hemichordata Classification of non-chordates The non-chordates are divided into eight phyla (singular-phylum) altogether which are explained below: 1. Porifera [Greek: 'porus' – pore, 'ferre'– to bear] The poriferons are the most primitive multicellular animals which have pores all over their bodies. They live in both fresh water and marine water but not on land. They are commonly known as the sponges. The general characteristics of poriferons according to their body features are listed below:

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 29 a) Body structure: These animals are rope, ball, vase or tube shaped. b) Special feature: They have numerous small pores in their bodies due to which they are called poriferons. The numerous pores present on their bodies are called ostia (sing. ostium). A large opening is present in their body which helps to excrete out wastes and water called osculum (pl. oscula). c) Locomotion: They remain attached to the substratum and have no complex forms of movement except for few species which move inside water slowly. d) Body organization: Sponges are multicellular organisms that lack true tissues, organs and systems. e) Symmetry: They are both asymmetrical and radially symmetrical. f) Germ layers: They are diploblastic animals with two germ layers in skin: ectoderm and endoderm. g) Segmentation: They are asegmented. h) Reproduction: They reproduce asexually by regeneration and budding and sexually with the help of gametes. i) System: i) Respiratory system: Absent. Breathing of air and take-up of water occurs through ostia. ii) Excretory system: Absent. Excretion takes place through oscula. Examples: spongilla, sycon, grantia, euspongia, etc. Sycon Spongilla Euspongia FACTS WITH REASONS Poriferons are called the simplest multicellular organisms, why? Poriferons are called simplest multicellular organisms because they are just a group of cells and do not have true tissues, organs and systems. 2. Coelenterata [Greek: 'koilos' – hollow, 'enteron' – gut] a) Body structure: They have a hollow branched body. b) Special feature: Coelenterons have a hollow gut inside their bodies. Hence, the name coelenterate is derived from it. The hollow gut in their body is known as true coelom. c) Locomotion: The locomotion takes place with the help of tentacles which are also the organs of defence. d) Body organization: Coelenterates are multicellular organisms with simple tissues. e) Symmetry: They are radially symmetrical. f) Germ layers: They are diploblastic animals with two germ layers in skin: ectoderm and endoderm. g) Segmentation: Asegmented (without segmentation) MEMORY TIPS In Porifera, water along with food and oxygen enters into their body through ostia. Oxygen and food get absorbed by the body whereas remaining things come out from the osculum. This is called water canal system. It is also a kind of digestion.

30 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur h) Digestive tract: They have an incomplete digestive tract. They possess a mouth but no anus. i) Systems: i) Respiratory system: Absent. ii) Reproductive system: They reproduce asexually by budding and sexually with the help of gametes. iii) Excretory system: Excretion takes place through body surface. iv) Nervous system: A network of nerve cells is present. Examples: hydra, jellyfish, sea anemone, coral, rhizostoma etc. Hydra Jelly fish Coral FACTS WITH REASONS Why is hydra called a coelentrate? Hydra is called a coelenterate because it has hollow cavity called coelenteron in it. 3. Platyhelminthes [Greek: 'platys' – flat, 'helminth' – worm] The phylum Platyhelminthes/flatworms are a group of 80% parasitic and 20% free living animals. They have the following characteristics: a) Body structure: The body is flat and long with ribbon, tape or leaf-like structure. b) Special feature: They have a dorsoventrally flat body. So, they are also known as flatworms. c) Locomotion: The locomotion takes place with the help of suckers, hooks or both. These organs are the organs for parasitism. d) Body organization: Coelenterates are multicellular organisms with simple organs. e) Symmetry: They are bilaterally symmetrical. f) Germ layers: They are the first triploblastic animals with three germ layers in skin: ectoderm, mesoderm and endoderm. g) Segmentation: Asegmented h) Sexual orientation: They are bisexual or monoecious or hermaphrodite animals. Male and female sex organs are in the same body. i) Digestive tract: They have an incomplete digestive tract. They have a mouth but no anus. j) Systems: i) Reproductive system: They can only regenerate their injured body parts. Mostly sexual reproduction takes place with the help of gametes. Planaria can reproduce by fragmentation and regeneration. ii) Excretory system: Excretion takes place through protonephridia or flame cells. iii) Nervous system: A bundle of nerves and a nerve cord are present.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 31 Examples: liver fluke, tapeworm, planaria, turbellaria, etc. Tapeworm Liverfluke Planaria FACTS WITH REASONS Why is tapeworm called a hermaphrodite? Male and female sex organs are in the same body of a tapeworm. So, a tapewrom is called a hermaphrodite. 4. Aschelminthes [Greek: 'ascus' – bladder, 'helminth' – worm] The animals belonging to this phylum range from 1 mm to 4 ft in length. They are also called nemathelminthes / nematoda / round worms/bladder worms/unsegmented worms. Some of their characteristics are as follows: a) Body structure: The body is round, slender, tapering and slippery. b) Special feature: They are unsegmented worms with both parasitic and non-parasitic nature. c) Locomotion: The locomotion takes place with the help of thick and tough cuticle. d) Body organization: Nematods have organs developed from tissues. They are multicellular. e) Symmetry: They are bilaterally symmetrical. f) Germ layers: They are triploblastic animals with three germ layers in skin: ectoderm, mesoderm and endoderm. g) Segmentation: These animals are asegmented. h) Digestive tract: They have a complete digestive tract. The food enters from the mouth and excretes out from the anus. i) Sexual orientation: They are unisexual or dioecious animals. Male and female are separate. j) Systems: i) Reproductive system: They reproduce sexually with the help of gametes. ii) Excretory system: Excretion takes place through protonephridia or flame cells. iii) Nervous system: Bundle of nerves and two nerve cords are present. Examples: ascaris, hookworm, pinworm, trichinella etc. male female Ascaris Hookworm Wuchereria

32 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur FACTS WITH REASONS Roundworm is an aschelminth but not annelid, why? Roundworm is called an aschelminth but not annelid because it has unsegmented body. An annelid must have metamerically segmented body which is absent in a roundworm. 5. Annelida [Latin: 'annelus' – ring] Annelida is the phylum of animals with metamerically segmented body. a) Body structure: The body is round, flexible, slender, tapering and slippery. b) Special feature: They are metamerically segmented animals with both parasitic and nonparasitic nature. c) Locomotion: The locomotion takes place with the help of setae (earthworm), parapodia (sandworm) and sucker (leech). d) Body organization: They are multicellular. They have organs developed into few systems. e) Symmetry: They are bilaterally symmetrical. f) Germ layers: These are triploblastic animals with three germ layers in skin: ectoderm, mesoderm and endoderm. g) Segmentation: Their body is metamerically segmented. h) Digestive tract: They have a complete digestive tract. The food enters from the mouth and excretes from the anus. i) Sexual orientation: They are both unisexual (polychaete) and bisexual (earthworm) animals. j) Systems: i) Reproductive system: They reproduce sexually and in some species asexually. ii) Excretory system: Excretion takes place through nephridia or excretory tubes present in their segments. iii) Nervous system : They have a bundle of nerves, two nerve cords and a nerve ring. Examples: earthworm, leech, nereis (sandworm), bobbit worm etc. Earthworm Leech Nereis 6. Arthropoda [Greek: 'arthros' – jointed, 'podos' – feet] Arthropods are bilaterally symmetrical and triploblastic animals which have multiple paired feet. The phylum arthropoda is the largest phylum which includes 84% of all known species of animals. Some of their common features are: a) Special feature: They have jointed appendages (i.e. legs, antennae, mouth parts) due to which they are called arthropods meaning jointed feet in Greek. The body is divided into head, thorax and abdomen and is covered with dry scaly chitinious exoskeleton. They often have sensitive and projected appendage known as antennae. The antennae help

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 33 them in sensing food, prey, weather and their enemies. b) Locomotion: The locomotion takes place with the help of legs, wings or both. c) Symmetry: They are bilaterally symmetrical. d) Germ layers: They are triploblastic animals with three germ layers in skin: ectoderm, mesoderm and endoderm. e) Segmentation: They have segmented body. f) Digestive tract: The digestive tract is complete. The food enters from the mouth and excretes from the anus. g) Sexual orientation: They are generally unisexual. h) Systems: i) Reproductive system: They reproduce sexually. ii) Respiratory system: The respiration takes place through body surface, gills, trachea, book gills or book lungs. iii) Excretory system: Excretion takes place through malphigian tubules and glands. iv) Nervous system: They have a bundle of nerves, two nerve cords and a nerve ring. Examples: prawn, crab, spider, scorpion, centipede, etc. There are four classes in phylum Arthropoda. Which are divided on the basis of the number of legs and habitat.They are: a) Class: Crustacea i) Crustaceans are the aquatic arthropods except for few which are terrestrial (woodlice) and parasitic (fishlice). ii) The body is divided into two parts: cephathorax (fused head and thorax) and abdomen. iii) They have five or more pairs of legs. iv) They bear compound eyes. v) Breathing takes place with the help of gills. Examples: prawn, crab, lobster, woodlice, fish lice, etc. Prawn Crab b) Class: Insecta i) Insects are mostly terrestrial in nature. ii) They have three pairs of legs and one pair of antennae. iii) Breathing takes place with the help of trachea. iv) The body is divided into three parts: head, thorax and abdomen. v) They have compound eyes. Examples: butterfly, housefly, grasshopper, bee, termite, ant, cockroach, wasp, etc.

34 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Mosquito Butterfly FACTS WITH REASONS A mosquito is called an insect, why? A mosquito has three pairs of legs and one pair of antennae which is the characteristic feature of the class insecta. So, a mosquito is called an insect. c) Class: Arachnida i) They are terrestrial in nature. ii) They have four pairs of legs fused together inside their body. iii) Breathing takes place with the help of trachea or book lungs. iv) Antennae and compound eyes are absent. v) The body is divided into cephalothorax and abdomen. Examples: spider, scorpion, tick, mite etc. Scorpion Spider FACTS WITH REASONS Spider is not an insect but an arachnoid, why? Spider possesses four pairs of legs and its body is divided into two parts: cephalothorax and abdomen unlike the body features in insects. So, spider is not an insect but an arachnoid. d) Class: Myriopoda i) They are terrestrial in nature. ii) They have multiple pairs of legs fused together inside their body. Each trunk segment has one or two leg pairs. iii) Breathing takes place with the help of trachea. iv) Simple eyes and antennae are present. v) The body is divided into head and trunk. MEMORY TIPS Most of arachnids are flesh eating predators.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 35 Examples: centipede, millipede, etc. Centipede Millipede The summary of the four classes of the phylum arthropoda is given below for comparison: Feature Crustacea Insecta Myriopoda Arachnida Habitat Mostly aquatic Terrestrial + aerial Terrestrial Terrestrial Body section Cephalothorax and abdomen Head, thorax and abdomen Head and trunk Cephalothorax and abdomen Antennae Two pairs One pair One pair Absent Number of legs Five or more pairs Three pairs Multiple pairs with one or two pairs on each segment Four pairs Presence of wings Absent Present Absent Absent Respiratory organ Gills Trachea Trachea Trachea or book lungs FACTS WITH REASONS Why is the arthropoda largest phylum? Arthropoda is the largest phylum of invertebrates because arthropods have adaptable body which helps them to reproduce more, evolve faster and spread to different habitat. So, they are billions in number and found all over the earth in any climate and habitat. 7. Mollusca [Latin: 'molluscus' – soft] The animals of phylum mollusca have soft-body. They mostly live on land and in water. They are both free living and parasitic. Their salient features are explained below: a) Body structure: The body is soft, flexible and often covered by hard shell. b) Special feature: Their body is divided into three parts: head, visceral mass (with shell) and muscular foot. c) Locomotion: The locomotion takes place with the help of muscular foot or cephalic arms. d) Body organization: They have organs developed into systems and are multicellular. e) Symmetry: They are bilaterally symmetrical. f) Germ layers: They are triploblastic animals with three germ layers in skin: ectoderm, mesoderm and endoderm. g) Segmentation: Their body is unsegmented.

36 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur h) Digestive tract: The digestive tract is complete. The food enters from the mouth and excretes waste from the anus. i) Sexual orientation: They are both unisexual and bisexual animals. j) Systems: i) Reproductive system: They reproduce sexually by internal fertilization. ii) Excretory system: Excretion takes place through metanephridia or excretory ducts. iii) Nervous system: They have a bundle of nerves, two nerve cords and a brain. Examples: octopus (devil fish), snail, slug, squid, sepia (cuttle fish), pila, etc. Snail Octopus Slug Sepia Pila Squid 8. Echinodermata [Greek: 'echinos' – spiny, 'derma' – skin] Echinoderms are exclusively marine animals. So they are not found in Nepal in natural waters. Their body features are given below: a) Body structure: The body is round, star-shaped or cylindrical. b) Special feature: They are exclusively marine organisms with no head. They have water vascular system. Their body is spiny to attack the prey and defend against enemies. c) Locomotion: The locomotion takes place with the help of tube feet. d) Body organization: They have organs developed into systems and are multicellular. e) Symmetry: Their larvae are bilaterally symmetrical while the adults are radially symmetrical. f) Germ layers: They are triploblastic with three germ layers in skin: ectoderm, mesoderm and endoderm. g) Segmentation: Their body is unsegmented. h) Digestive tract: Digestive tract is complete. They possess mouth, stomach, intestine and anus. i) Sexual orientation: They are both unisexual and bisexual animals. j) Systems: i) Reproductive system: They mostly reproduce sexually but are also able to reproduce by regeneration. ii) Excretory system: Excretion takes place through anus. iii) Nervous system: A bundle of nerves arising from a nerve ring is present. Examples: starfish, sea urchin, sea cucumber, brittle star, etc. MEMORY TIPS Starfish (echinoderm), jellyfish (coelenteron), cuttlefish (mollusk), crayfish (arthropod), devilfish (mollusk) and silverfish (arthropod) are not fishes because they are all invertebrates and do not possess backbone.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 37 Starfish Sea urchin Sea cucumber Brittle star Chordates The group chordates include only one phylum: chordata. Phylum Chordata Chordates are those animals which bear notochord in some stages of their life. In sub-phylum Vertebrata, the notochord changes into vertebral column in the adult stage. But in Urochordata and cephalochordata, the notochord remains unchanged throughout their lifetime. Some of the distinguishing features of chordates are: i. Notochord is present at some stage of their life. ii. A dorsal nerve cord is present above the notochord in the embryonic stage. iii. The notochord changes into spinal cord in vertebrates. iv. Pharyngeal gill slits and post anal tail are present in the embryonic stage. v. The circulatory system is closed type vi. They are bilaterally symmetrical and triploblastic animals. Balanoglossus-Hemichordate Herdmania-Urochordate Amphioxus-A Cephalochordate Sub-phylum Vertebrata This sub-phylum includes all the vertebrates. Vertebrates are those animals that have a backbone or vertebral column. The backbone helps to protect the spinal cord enclosed inside it. The common characteristics of sub-phylum vertebrata are as follows: i. The bones and the vertebrae surround the spinal cord. ii. They have a skull that protects their brain. iii. Notochord is present in the earlier stage of their life which converts into spinal cord later. iv. They have an endoskeleton made up of bones and cartilage. v. A dorsal nerve cord is present above the notochord in the embryonic stage. vi. Pharyngeal gill slits and post anal tail are present in the embryonic stage. vii. The circulatory system is closed type.

38 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Project Work Observe in your surrounding and find out the different examples of vertebrata. Write their names and discuss in the class. FACTS WITH REASONS All vertebrates are chordates but all chordates are not vertebrates, why? All vertebrates are chordates but all chordates are not vertebrates because all vertebrates have a notochord in the embryonic stage of their life while all chordates do not possess vertebral column. The sub-phylum Vertebrata is divided into five classes namely: Pisces, Amphibia, Reptilian, Aves and Mammalia. Class Pisces (fishes) (Latin: 'piscis' – a fish) Pisces are the vertebrates that are aquatic and cold-blooded. Their body is specially modified so that they can live in water. Some of their important characteristics are: i) Body is differentiated into head, trunk and tail. Most of them have hard waterproof scales on their body. The body somewhat tapers on both sides making them streamlined. ii) Body temperature changes with the change in the temperature of the surroundings, i.e. they are coldblooded animals. iii) Locomotion takes place with the help of paired fins and tail. iv) Breathing occurs with the help of gills. v) Heart is two chambered (one atrium and one ventricle). vi) Reproduction takes place by laying eggs i.e. they are oviparous. vii) Fertilization is external. Examples: Dog fish, saw fish, great white shark, rohu, katla, sea horse, flying fish, etc. Sea horse Shark Rohu Class Amphibia (Greek: 'Amphi'- dual, 'bios' - life) The amphibians are those creatures that can breathe both on land and inside water. The females lay eggs inside water which hatch and develop gradually into an adult in different stages. Some of its characteristics are: i) Body is differentiated into head and trunk. They have two pairs of limbs with webbed feet for walking and swimming. The skin is moist and doesn’t contain scales. MEMORY TIPS 1. Horse is a mammal and seahorse is a pisces. 2. Pisces and aves have air sacks in their body.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 39 ii) Body temperature changes with the change in the temperature of the surroundings, i.e. they are cold-blooded animals. iii) Locomotion takes place with the help of webbed feet. The limbs are pentadactylated, i.e. with five digits. iv) Breathing occurs with the help of lungs in air, skin in water and gills in tadpole stage. v) Heart is three-chambered (two atria and one ventricle). vi) Reproduction takes place by laying eggs i.e. they are oviparous. Sexes are separate. vii) Fertilization is external. Examples: Frog, toad, salamander, tree frog (hyla), ichthyophis etc. Salamander Toad Frog Ichthyophis FACTS WITH REASONS Why is frog called an amphibian? Frog is called an amphibian because it lives in land but must return in water for fertilization and to keep its skin moist. Amphibians far away from water bodies will die of dehydration. Class Reptilia: (Latin: 'repere or reptum' - to creep or crawl) Reptiles are those creatures that crawl on the ground with their ventral surface. Some of its characteristics are: i) Body is differentiated into head, neck trunk and tail. They have two pairs of limbs with webbed feet for walking and swimming. The skin is dry and contains tough scales. They do not have ear holes. ii) Body temperature changes with the change in the temperature of the surroundings, i.e. they are cold-blooded animals. iii) Locomotion takes place with the help of limbs (except in snakes and lizards like glass lizard) iv) Breathing occurs with the help of lungs. v) Heart is three- chambered except in crocodile which has four chambered heart. vi) Reproduction takes place by laying eggs i.e. they are oviparous. Sexes are separate. vii) Fertilization is internal. Examples: crocodile, tortoise, turtle, wall lizard, garden lizard, snake like Cobra, krait etc. MEMORY TIPS Pisces have two chambered heart, amphibian and reptiles have three chambered heart, similarly aves and mammals have four chambered heart. MEMORY TIPS Crocodiles have four chambered heart but they have dry and tough scales as well as they are coldblooded animal. So, they are reptiles.

40 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Wall lizard Crocodile Turtle Tortoise Snake Class Aves: (Latin: 'avis' - bird) Aves or birds are animals that spend most of the time in air. They are well modified for aerial adaptation. Salient features of aves are: i) Body is differentiated into head, neck trunk and tail. Their forelimbs or wings are modified for flying and hind limbs for walking, grabbing or swimming. They have a toothless beak modified for their feeding habit. ii) Bones are light in weight, air-filled, hollow and reduced. Such bones are known as pneumatic bones. iii) Body temperature does not change with the change in the temperature of the surroundings, i.e. they are warm-blooded animals. iv) Locomotion takes place with the help of wings (in air) and legs (on land). Legs have five digits with claws (pentadactylated). v) Breathing occurs with the help of lungs. vi) Heart is four chambered (two auricles and two ventricles). vii) Reproduction takes place by laying eggs i.e. they are oviparous. Sexes are separate. viii) Fertilization is internal. Examples: parrot, sparrow, pigeon, crow, owl, vulture, eagle, etc. Peacock Ostrich Sparrow Pigeon MEMORY TIPS Pisces and amphibian show external fertilization whereas reptiles, aves and mammals show internal fertilization.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 41 FACTS WITH REASONS Aves are called glorified reptiles, why? Aves are called glorified reptiles because most of the characteristics of aves are similar to reptile which suggests that aves are advanced form of reptiles. Why do birds have hollow bones and streamlined body? Birds have hollow bones that makes them light and the streamlined body helps to reduce friction with air, so that birds can fly easily. Class Mammalia: (Latin: 'mamma' - breast) Mammals are the largest group of vertebrates on earth. They are the most intelligent and advanced creatures. Their chief characteristics are as follows: i) Body is divided into head, neck, trunk and tail (if present). Hairs are present on the body. They have externally projected ears called pinnae. ii) Babies of all mammals suckle the milk of their mothers after birth. iii) Body temperature does not change with change in the temperature of the surroundings, i.e. they are warm-blooded. iv) Locomotion mostly takes place with the help of two pairs of limbs (except in humans). v) Breathing occurs with the help of lungs. vi) Heart is four chambered (two atria and two ventricles). vi) Brain has a distinct region called neocortex. Which is responsible for higher forms of intelligence. vii) Reproduction takes place by giving birth to young ones directly except in monotremes. Sexes are separate. vii) Fertilization is internal. Examples: Human, blue whale, dolphin, bat, kangaroo, duck-billed platypus, etc. Dolphin Kangaroo Monkey Duck-billed platypus Squirrel Bat MEMORY TIPS There are three chief kinds of mammals: monotremes, marsupials and placentals. a. Monotremes are the egg-laying mammals. e.g. platypus, echidna (spiny ant eater), etc. b. Marsupials are the mammals that carry their babies in a pouch. e.g. kangaroo, koala bear, etc. c. Placentals are the mammals that nourish babies in placenta before direct birth. e.g. human, cow, etc. MEMORY TIPS Whale and bat are mammals because they give direct birth and suckle the babies.

42 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Relation of classification of organisms with evolution of life on the earth The grouping of organisms on the basis of their similarities and differences is called classification. In the classification of organisms, the very simple and primitive organisms are kept earlier than the developed organisms. For example, kingdom monera is a group of very simple and primitive organisms than kingdom Protista. Monera are unicellular prokaryotes. Where as protista are unicellular eukaryotes. It means that monera were developed before protista. Similarly, kingdom Protista are simpler than kingdom fungi and so on. In the evolutionary pattern, the simple and primitive organisms were developed before the complex organisms. For example, Pisces having two chambered hearts evolved before amphibian and reptiles with three chambered heart. It shows that the process of evolution and the process of classification of living beings on the earth is the same. In the same way, moving down through each level of classification, the number of species in the group decreases. Two species within the same genus likely share a recent common ancestor in their evolutionary history. It also proves the evolution of life on the earth from simple and primitive to complex one. HOT SKILL HIGHER ORDER THINKING SKILL 1. Fish, cow, cuttlefish, hydra and chicken are kept in same kingdom. Fish, cows, cuttlefish and chicken are kept in same kingdom because all of them are eukaryotic, multicellular, heterotrophic and possess no cell wall. 2. Suppose you found an organism in the meadow. List the way to identify the phylum of that organism. If we see a creature in the meadow, we can identify its phylum by observing its features. For example, i. If it has bones, it is Chordata. ii. If it has a cylindrical, segmented body with many rings, it is an annelida. iii. If it has a cylindrical, unsegmented body, without rings, it is aschelminthes. iv. If it is flat, ribbon-like, it is platyhelminthes. v. If it has a soft muscular body without bones, it isa mollusca. vi. If it is an invertebrate with many appendages, it is Arthropoda. Other phyla are either microscopic that cannot be seen or aquatic that cannot be found in a meadow. 3. Differentiate between jelly fish and cuttle fish. The differences between jelly fish and cuttle fish are: SN Jelly fish SN Cuttlefish 1 It has a coelenteron cavity called coelom. 1 It does not have a coelenteron cavity. 2 Jellyfish have tentacles. 2 Cuttlefish have 8 arms. 3 It belongs to the Phylum Coelenterata.. 3 It belongs to the Phylum Mollusca.. 4. Tabulate the differences between moss and clubmoss. The differences between moss and clubmoss are: MEMORY TIPS Horse is more developed than seahorse, whale is more developed than shark and bat is more developed than bird.

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 43 SN Moss SN Clubmoss 1 It belongs to the division Bryophyta. 1 It belongs to the division Tracheophyta. 2 It is an amphibian plant. 2 It is a terrestrial plant. 3 It does not have a vascular bundle. 3 It has a vascular bundle. 5. Fucus is similar in appearance to Marchantia but it is not a bryophyte. Fucus is similar in appearance to Marchantia but it is not a bryophyte because they do not have leaves and rhizomes. They are algae. 6. Alligators are reptiles despite having four-chambered hearts. Alligators belong to reptiles despite having four-chambered hearts because they are cold-blooded, oviparous crawling creatures with rough scales on their body. 7. Bats and dolphins are different but kept in the same class. Bats and dolphins are different but kept in the same class because both of them are viviparous and suckle milk to babies. 8. Discuss the relation between the classification of organisms and evolution. The classification of organisms and evolution are two branches of biology. These two branches of biology are closely related. They both deal with how living things came to be and how closely are they related. The classification of organisms is based on the similarities between the species. Similar species are kept in the same group whereas dissimilar species are kept in different groups. Whereas evolution studies how an organism slowly and gradually changes over time and develops into new species. 9. What do reptiles and Pisces have in common? Write in three points. The common features between reptiles and Pisces are given below: i. Both reptiles and Pisces are the classes of Vertebrata. ii. They have scales on their body. iii. They are cold-blooded organisms. 10. Study the given diagram and answer the following questions. i. Write the phylum and class of the given organisms. Name : Whale Phylum : Chordata Class : Mammalia Name : Shark Phylum : Chordata Class : Pisces ii. Write similarities and differences between these organisms. Similarities between sharks and whales are: a. Both of them are aquatic. b. Both of them have streamlined bodies. c. Both are carnivorous. d. Both of them locomote by fins. (a) (b)

44 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Differences between sharks and whales are a. Whales are viviparous but sharks are oviparous. b. Whales breathe by lungs but sharks have gills to breathe. c. Whales are warm-blooded but sharks are cold-blooded. d. Whales are mammals but sharks are fish. iii. How do these organisms support evolution? Sharks are fish but whales are mammals. These two different species have adapted to survive in an aquatic ecosystem. Their body despite different anatomy appears the same. For, example, the fins of whales and the fins of shark are anatomically different but appear same and both help to swim. These are analogous organs. These organs suggest that organisms can evolve based on their environment. 3 STEPS EXERCISE EXERCISE STEP1 1. Choose the best answer from the given alternatives. a. Cycas have cones and seeds in them. Which sub-division do they belong to? i. angiosperm ii. tracheophyta iii. gymnosperm iv. monocotyledon b. An organism has multiple pores (ostia) in the body that can collect food and a large pore(osculum) to remove waste. Which phylum does it belong to? i. porifera ii. coelenterata iii. arthropoda iv. protista c. Which of the following has a backbone? i. shellfish ii. fish iii. starfish iv. jelly fish d. Why are fish, cow, cuttlefish, hydra and chicken kept in the same kingdom? i. eukaryotic, multicellular, no cell wall, heterotrophic, locomotion ii. prokaryotic, unicellular, cell wall, locomotion, heterotrophic iii. eukaryotic, multicellular, cell wall, saprophytic, no locomotion iv. eukaryotic, unicellular, no cell wall, heterotrophic, locomotion e. Why does mustard belong to the plant kingdom? i. eukaryotic, multicellular, no cell wall, heterotrophic, locomotion ii. prokaryotic, unicellular, cell wall, locomotion, heterotrophic iii. eukaryotic, multicellular, cell wall, autotrophic, no locomotion iv. eukaryotic, unicellular, no cell wall, heterotrophic, locomotion f. Why does pine belong to the gymnosperm? i. needle-like leaf, naked seed, rough bark ii. needle-like leaf, enclosed seed, rough bark iii. flat and broad leaf, enclosed seed iv. narrow leaf, parallel venation, spongy stem

Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur Modern Concept Science & Technology - 10 45 2. Define the following. a. Classification of organisms b. Two kingdom system c. Five kingdom system d. Tracheophyta e. Autotrophs f. Heterotrophs g. Parasites n. Saprophytes o. Hermaphrodite p. Unisexual s. Alternation of generation t. Vascular bundles u. Reticulate venation v. Parallel venation w. Notochord 3. Answer the following questions in very short. a. Where are sponges found? Can they travel? b. What is a group of individuals with identical anatomy and can interbreed called? c. Write the function of ostia and osculum. d. What is the mode of nutrition of sycon, liver fluke and earthworm? e. Where are Ascaris and arthropods found? f. What is the external skeleton of arthropods made up of? g. What helps arthropods to sense? h. What is the mantle? i. What helps molluscs in locomotion? j. What does it mean by bilaterally symmetrical? k. How do molluscs notice external threats and hide inside the mantle? l. Which of the five kingdoms have a cell wall? m. Which division of the plant kingdom does plants with vascular bundles belong to? n. How many divisions are there in a plant kingdom? o. Which class of plants have petals in the multiples of 3 in the flower? p. How many chambers are there in the heart of each class of vertebrates? q. Which class of animals suckle milk to babies? r. Which class of aquatic animals have air bladders in them? s. Who introduced the five-kingdom system? t. Name two mammals that lay eggs. u. What makes a fern a tracheophyte? v. What are non-green thallophytes called? w. What are green thallophytes called?

46 cl aS Sification of living t HingS Approved by the Curriculum Development Centre, Sanothimi, Bhaktapur STEP2 4. Give reason a. Angiosperms have fruit but gymnosperms do not. b. Bryophytes are called amphibian plants. c. Potato plant is too different from banyan tree but kept in same sub-division angiosperm. d. Spider is kept in Arthropoda. e. Dolphins and whales are called mammals even though they are like fishes. f. Lycopodium is more developed than Marchantia. g. Horse tail and mucor are not kept in the same kingdom. h. Frog is called a cold-blooded animal. i. Classification of living things is necessary. j. Carlous Linnaeus is the father of taxonomy. k. Two kingdom system is replaced by five kingdom system of classification. l. Cyanobacteria belong to Monera. m. Amoeba belongs to the kingdom protista. n. Echinodermata have spines on the body surface. o. Humans belong to chordate. p. Roundworm has long and cylindrical body but it does not belong to annelida. 5. Differentiate between the following. a. Ant and spider b. Two-kingdom system and five-kingdom system of classification c. Bird and bat d. Bryophyta and pteridophyta e. Neem tree and Pine tree f. Monocot and dicot g. Chordates and non-chordates h. Protista and porifera i. Platyhelminthes and aschelminthes j. Annelida and roundworm k. Mollusca and Echinodermata l. Reptiles and birds m. Labeo and star fish n. Shark and whale 6. Answer the following questions in short. a. Make a chart of the animal kingdom including the chordates and the non-chordates.