202110201-APEX-STUDENT-WORKBOOK-BIOLOGY-G08-PART1

Biology Workbook_8_P_1.pdf 1 17-10-2019 19:36:45 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Table of Contents 1 15 1 WHAT IS SCIENCE 35 2 CELL – THE BASIC UNIT OF LIFE 64 3 STORY OF MICROORGANISMS 87 4 REPRODUCTION IN ANIMALS 107 5 ATTAINING THE AGE OF ADOLESCENCE 108 PROJECT BASED QUESTIONS ADDENDUM: ADDITIONAL AS-BASED PRACTICE QUESTIONS TABLE OF CONTENTS

1. WHAT IS SCIENCE SESSION 1 INTRODUCTION AND WHY WE STUDY SCIENCE 1.1 Mind Map 1.2 Terminology i. Observational science – is theoretical, experimental and applied research related to oceanic, atmospheric, and terrestrial sciences to provide a better description of the world around us. ii. Experimental science – refers to testing under controlled conditions for demonstrating a known truth, examine the validity of a hypothesis, or to determine the efficacy of something previously untried. iii. Ecologists – are concerned with the ecosystems as a whole, the abundance and distribution of organisms, and their relationship with their environment. iv. Geologists – are scientists who study the solid and liquid matter that constitutes the earth as well as the processes and history behind its formation and shape. SESSION 1. INTRODUCTION AND WHY WE STUDY SCIENCE 1

v. Astrophysicists – employ the principles of physics and chemistry to ascertain the nature of the heavenly bodies, rather than their positions or motions in space. vi. Climatologists – analyze climate patterns to provide an understanding of the condi- tions of a particular area, and help the citizens of that area adapt to their surroundings. vii. Nuclear physicists – study the subatomic particles in the nucleus of an atom to be able to harness nuclear energy, examine medicinal properties of nuclear radiation or to document the breakdown of radioactive nuclear particles. viii. Geneticists – are biologists who study genetics, the science of genes, heredity, and variation of organisms. ix. Chemists – are scientists who research and experiment with the properties of chemi- cal substances. x. Physicists – are scientists who specialize in physics research spanning all length scales: from sub–atomic particles of which all ordinary matter is made (particle physics) to the behavior of the material universe as a whole (cosmology). xi. Individual perspective – research undertaken for personal growth in terms of accumu- lation of knowledge, fame or money xii. Societal perspective – research undertaken or technological innovation for the better- ment of the society as a whole. xiii. Economic development – is the sustained, concerted actions of communities and policy makers that improve the standard of living and economic health of locality. 1.3 Key Concepts i. Science is the organized study of natural world, based on facts learned through ex- periments and observations. ii. The fundamental step of scientific thinking is questioning which helps to think beyond the box. iii. An astrophysicist, a chemist, a biologist, all observe nature to understand how it works, in the broadest sense. iv. The word science is derived from Latin, “scientia” means knowledge. v. The scientist collects information to test new ideas or to disapprove or modify the old theories/ideas. vi. Nation funds scientist to improve the life of people and economic development. vii. Society supports science because of simple curiosity, satisfaction and enlightenment that comes from knowledge of the world around us. viii. The scientific theories are modified along with the time as old ideas are questioned and new evidences are discovered. SESSION 1. INTRODUCTION AND WHY WE STUDY SCIENCE 2

SESSION 2 SCIENTIFIC METHOD 2.1 Mind Map Scientific Method 2.2 Terminology i. Investigation – is a formal or systematic examination or research. ii. Planning an experiment – involves thinking about and organizing the activities required to achieve a desired goal. SESSION 2. SCIENTIFIC METHOD 3

iii. Conducting experiment – involves carrying out an experiment following the steps writ- ten or planned for experiment and observing and recording the changes carefully. iv. Conclusion – analysing the data collected during experimentation and reaching a judgement or decision based on reasoning. v. Communication – includes representing the results of an experiment as a lab report, oral presentation, science fair display board or as a research publication. vi. Control – is a sample in science experiments that remains the same throughout the experiment in order to receive accurate results. vii. Variables – are characteristics, numbers, or quantities that increase or decrease over time, or take different values in different situations. viii. Prediction – is a statement about what will or might happen in the future. ix. Inference – is a conclusion reached on the basis of evidence and reasoning. 2.3 Key Concepts i. Scientist follows scientific method which is a body of techniques for investigating phe- nomena, acquiring new knowledge to plan and conduct a study. ii. Scientific methods follows the followings steps a. Observe and ask a question b. Form a hypothesis c. Plan an experiment d. Conduct the experiment e. Draw conclusions and communicate results iii. Hypothesis is a possible answer made on the basis of limited evidence that can be tested. iv. Process skills is a thinking tool which scientists use to find an answer to a question or do an experiment. SESSION 2. SCIENTIFIC METHOD 4

SESSION 3 READING, WRITING AND SAFETY 3.1 Mind Map 3.2 Terminology i. Endemic species – is the one that is only found in a particular region and nowhere else in the world. ii. Ecosystem – is a community of living organisms in conjunction with the non-living components of their environment (like air, water and mineral soil), interacting as a system. iii. Biosphere – is the biological component of all earth systems, including lithosphere, hydrosphere, atmosphere and other “spheres”, together with the dead organic matter produced by them. SESSION 3. READING, WRITING AND SAFETY 5

iv. Abiotic factors – are non–living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. v. Producers – also called autotrophs, they are organisms that can make their own en- ergy through biochemical processes, that involve chemical reactions. vi. Consumers – also called heterotrophs, they are organisms of an ecological food chain that receive energy by consuming other organisms. vii. Decomposers – are organisms such as bacteria and fungi that break down the organic matter in the dead bodies of plants and animals into simple nutrients. viii. Filament – a conducting wire or thread with a high melting point, forming part of an electric bulb which is heated by electric current. ix. Fuse – Also known as circuit breaker, it interrupts the flow of electricity in case of high voltage. x. Data analysis – is a process of inspecting, cleaning, transforming, and modeling data with the goal of discovering useful information, suggesting conclusions, and supporting de- cision–making. xi. Interpreting data – is the process of assigning meaning to the collected information and determining the conclusions, significance, and implications of the findings. xii. Safety measures – are activities and precautions taken to improve safety, i.e. reduce risk related to human health. 3.3 Key Concepts i. Before reading - think, look for vocabulary words, say the definition to yourself, and use the word in a sentence. ii. During reading – find the main idea in the first paragraph, find details in the next para- graph that support the main idea, check understanding of the concept by answering questions given at the end of the section. iii. After reading – summarise what you have read, study the photos and illustrations. iv. Writing can be done in four ways: a) Narrative Writing b) Expressive Writing c) Per- suasive Writing and d) Informative Writing. v. As the scientists collect data they make accurate measurements using instruments such as thermometer, clocks, timers, rules, a spring scale and balance. They use beakers and other containers to measure liquids. vi. Scientists collect, organise, display and interpret data as they do investigations. vii. One must follow safety measures while conducting investigations or experiments such as: a) Understanding safety symbols, b) Keeping work area clean, c) Informing teacher in case of spill, break or a cut, d) Keeping eyes safe by wearing safety goggles when directed, e) Being careful while using electrical appliances and f) Washing hands after the experiment. SESSION 3. READING, WRITING AND SAFETY 6

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 1.1 ] (i) What is Science? 2. Fill in the blanks. [Refer to Session 1.1 ] (ii) is the primary or fundamental step in scientific thinking. (iii) are the organized ways followed by a scientist to plan and conduct a study. 3. Answer the following questions in one sentence. [Refer to Session 1.2 ] (iv) Saket collects seashells on his visit to the beach. He wants to classify those shells. Can you help him by giving him two criteria on which he can classify those shells? (v) What are variables? CHAPTER 1. WHAT IS SCIENCE 7

4. Fill in the blanks. [Refer to Session 1.2 ] (vi) is a statement about an expected outcome of an experiment. (vii) By observing the growth of seeds or seedlings in soil, one can know both the of soil and their in different soils. 5. Match the following. Column B [(Session 1.3)] Column A a. Salinity b. White tiger i. Producer c. Paddy ii. Consumer d. Humans iii. Decomposer e. Bacteria iv. Endangered species v. Abiotic component 6. Fill in the blanks. [Refer to Session 1.3 ] (viii) Blue green algae is an example of . (ix) Due to extremes of temperature, the species composition of a desert ecosystem are much and . (x) Bacteria is an example of . CHAPTER 1. WHAT IS SCIENCE 8

Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 1.1)] Why do we need to study science? 8. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] How Arvind uses process skills to investigate working nature of light switch in his bedroom? Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 1.3)] What is the sequential order you need to follow to discover things? AS2-Asking questions and making hypothesis Short Answer Type Questions 10. Answer the following questions in 3-4 sentences. (i) [(Session 1.1)] A scientist made a new discovery but did not communicate his findings. Did he do the right thing? Justify your answer. AS3-Experimentation and field investigation Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 1.2)] Devise an experiment to find out the cause of change in shape and size of rocks? CHAPTER 1. WHAT IS SCIENCE 9

Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 1.3)] What are the steps involved in an attempt to solve a problem by scien- tific method? AS4-Information skills and projects Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 1.2)] In an experiment to survey the milk producing areas in India, Mohan interpreted his data as follows. Observe his data and answer the given questions. i. What do his findings tell about the total number of milk producing states in India? ii. Which are the greatest milk producing areas in the country? CHAPTER 1. WHAT IS SCIENCE 10

iii. Which is the lowest milk producing state of the country as per Mohan’s findings? iv. What does the finding suggest about impact of milk production on economy of India? v. Is such a finding important for future development of the country? vi. How can this finding benefit society? AS5-Communication through drawing and model making Very Short Answer Type Questions 14. Answer the following questions in one sentence. (i) [Refer to Session 1.3 ] The above picture shows pie chart. How pie charts are useful in science experiments or investigation? Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 1.2)] Rita made a model of a glowing tree but the tree did not glow. Demon- strate a scientific method for investigating her problem with the help of a flowchart. CHAPTER 1. WHAT IS SCIENCE 11

AS6-Appreciation and aesthetic sense, Values Very Short Answer Type Questions 16. Answer the following questions in one sentence. [Refer to Session 1.1 ] (i) Whom can you appreciate for developing new chemical substances with potential technological applications? Short Answer Type Questions 17. Answer the following questions in 3-4 sentences. (i) [(Session 1.1)] How do you appreciate the fact that science has changed our life? Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) A: Bulb, wires, and batteries have to be connected with each other to make the bulb glow. R: Switch can interrupt the flow of electricity and turns off the bulb. (A) Assertion is correct and reason explains assertion. (B) Both assertion and reason are correct but reason does not explain assertion. (C) Assertion is correct but reason is wrong. (D) Assertion is wrong but reason is correct. (ii) One who observes rate of chemical reaction is a (A) physicist (B) botanist (C) chemist (D) microbiologist CHAPTER 1. WHAT IS SCIENCE 12

(iii) The word science comes from the Latin word . (A) cento (B) scenic (C) essentia (D) scientia (iv) These are the organised ways in which scientists plan and conduct their study. (A) Process skills (B) Scientific methods (C) Data interpretation (D) Drawing conclusion (v) Which of these describe a hypothesis? (A) A possible answer (B) Conclusion of experiment (C) Recorded data (D) Question asked to conduct an experiment (vi) These are the factors that can affect the outcome of an investigation (A) scientific methods (B) process skills (C) results (D) variables (vii) Writing letters on important issues of science is an example of this type of writing. (A) Narrative writing (B) Expressive writing (C) Persuasive writing (D) Informative writing (viii) Which of these does not classify as a safety measure while conducting science experiment? (A) Pulling up long hair (B) Not tasting any test compound CHAPTER 1. WHAT IS SCIENCE 13

(C) Keeping the experiment space clean (D) Accurately displaying the results (ix) Giving information about how to conduct an experiment is an example of this type of writing. (A) Persuasive writing (B) Expressive writing (C) Narrative writing (D) Informative writing AS4-Information skills and projects 19. Choose the correct answer. (x) Read the statement below and choose the branch of science it defines. (AS4) ”Science is a way of discovering what’s in the universe” (A) Biological Science (B) Chemical Science (C) Physical Science (D) Earth Science AS5-Communication through drawing and model making 20. Choose the correct answer. (xi) What is the girl doing in above picture? (B) Eating (A) Drinking (D) Planting (C) Measuring CHAPTER 1. WHAT IS SCIENCE 14

2. CELL – THE BASIC UNIT OF LIFE SESSION 1 INTRODUCTION AND DISCOVERY OF THE CELL 1.1 Mind Map SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL 15

1.2 Terminology i. Cell – is the smallest structural and functional unit of an organism. ii. Cell membrane – Also called plasma membrane, it is a very thin membrane, composed of lipids and proteins that surrounds the cytoplasm of a cell and controls the passage of substances into and out of the cell. iii. Cell wall – is the protective, semi–permeable outer layer of a plant cell and certain algae, bacteria and fungi but characteristically absent in animal cells. iv. Nucleus – is a dense organelle present in most eukaryotic cells, which is typically a single rounded structure bounded by a double membrane, containing the genetic material. v. Unicellular – refers to organism consisting of a single cell. vi. Multicellular – refers to organism composed of many cells. vii. Organ – is a part of an organism which is typically self contained and has a specific vital function. viii. Organelles – are differentiated structures within a cell, such as a mitochondrion, vac- uole or chloroplast that perform a specific function. SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL 16

1.3 Key Concepts i. Robert Hooke, a British scientist discovered cell in 1665. He observed small cavities like structures in the section of cork and called them as ‘cell’, which means “small room” in Latin. ii. Cell membrane is the boundary of the animal cell which gives a shape to the cell and selectively allows substances to pass through it, in or out of the cell. iii. Cell wall which is present only in plants cells give rigidity to the cell. iv. A dense round body which is present more or less at the center of the cell is called nucleus. v. Robert Brown discovered the nucleus in 1831 while observing the epidermis of orchid leaves. vi. Cytoplasm is a jelly like substance between the nucleus and the cell membrane. It contains membrane–bound structures called cell organelles, as well as more complex chemicals. 1.4 Conceptual Understanding Q1. Who discovered the cell for the first time? [Refer to TB page 24 Q1] A. Robert Hooke, an English scientist discovered the cell for the first time while observing thin slices of cork. Q2. How will you prepare a slide without drying quickly? [Refer to TB page 24 Q4] A. Preparation of slide : i. The glass slide selected for slide preparation must be washed well and wiped dry with a clean cloth. ii. Put a drop of water with the help of a needle. Cover the specimen with cover slip. Dry out excess water around the cover slip with filter paper or blotting paper. iii. A drop of glycerine is added to the water, if the slide is to be kept for longer time. Glycerine saves the material from drying out. SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL 17

Q3. Correct the statements if necessary and rewrite. [Refer to TB page 24 Q6] (a) Cell wall is essential in plant cells. (b) Nucleus controls cell activity. (c) Unicellular organisms perform all life processes like respiration, excretion, growth and reproduction. (d) To observe nucleus and organelles clearly, staining is not necessary. A. (a) Cell wall is essential in plant cells. True (b) Nucleus controls cell activity. True (c) Unicellular organisms perform all life processes like respiration, excretion, growth and reproduction. True (d) To observe nucleus and organelles clearly, staining is not necessary. False. To observe nucleus and organelles clearly, staining is necessary. Q4. Describe the structure of nucleus. Explain the functions of nucleus. [Refer to TB page 24 Q7, Q8] A. i. Nucleus is the most important and crucial organelle that controls all the activities of the cell. It was first discovered by Robert Brown in 1831. ii. It may be spherical in shape occupying 10 to 15% of the cell volume. It may be present in the middle region of the cell. iii. The ground matrix of the nucleus is called nucleoplasm. It contains two important structures, the nucleolus and the chromosomes. iv. Nucleus is bounded by a membrane called nuclear membrane or nuclear envelope. This consists of two unit membranes made up of lipoproteins. Functions of Nucleus: i. The nucleus is the control centre of the cell as it controls all its activities. ii. The nucleus is a membrane–enclosed organelle found in eukaryotic cells. iii. The nucleus contains the genetic material of the cell in the form of chromosomes. iv. The main function of the nucleus is cell division, regulating cell metabolism and controlling protein synthesis. SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL 18

1.5 Communication Through Drawing and Model Making Q1. Make sketches of animal and plant cells which you observe under microscope. [Refer to TB page 24 Q15] A. Animal Cell Plant Cell 19 SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL

1.6 Appreciation and Aesthetic Sense, Values Q1. Ameer said “Bigger onion has larger cells when compared to the cells of smaller onions”. Do you agree with his statement or not? Explain why. [Refer to TB page 24 Q16] A. i. The statement made by Ameer is incorrect as both the bigger onion and smaller onion have cells with similar structure and shape. ii. The size of organism does not affect the size or shape of the cell. iii. However, number of cells is more in a bigger organism. So bigger onion has more number of cells as compared to a smaller onion. 1.7 Application to Daily Life, Concern to Bio Diversity Q1. Deepak said “A plant cannot stand erect without cell wall in its cell”. Support this state- ment. [Refer to TB page 24 Q18] A. Yes, Deepak’s statement is correct. A plant cannot stand erect without cell wall in its cells because: i. The cell wall provides mechanical strength to the cell. ii. The cell wall is tough and hard so it can prevent excess swelling. iii. The cell wall provides shape and limited plasticity to the plant. iv. The cell wall helps the plant in maintaining turgor pressure due to uptake of water which contributes to the stiffness of plant. SESSION 1. INTRODUCTION AND DISCOVERY OF THE CELL 20

SESSION 2 DIVERSITY IN CELLS 2.1 Mind Map 2.2 Terminology i. Pseudopodia – is a temporary projection of the cytoplasm of certain cells (Amoeba) useful for movement and feeding. ii. Life processes – Movement, respiration, sensitivity, growth, reproduction, excretion and nutrition are the life processes that are common to all living beings. iii. Staining – is the artificial coloration of a substance to facilitate examination of tissues, microorganisms, or other cells under the microscope. iv. Magnification – is the process of enlarging something only in appearance, not in physical size. SESSION 2. DIVERSITY IN CELLS 21

2.3 Key Concepts i. Unicellular organism are single celled organism capable of performing all the life pro- cesses like obtaining food, respiration, excretion, growth, and reproduction. ii. Cell exhibits a variety of shape and sizes which is determined by the specific function of the cells. iii. The size of the organism depends on the number of cells and not on the size of the cell. iv. Amoeba has no definite shape. It keeps on changing its shape varying protruding out of its body. These are called Pseudopodia (Pseudo: false, Podia: feet). v. The smallest cell 0.1 to 0.5 micrometers is found in Bacteria. Human nerve cell is nearly about 90 to 100 cm which can be seen with naked eye. 2.4 Conceptual Understanding Q1. Name the factors on which shape of the cell depends? [Refer to TB page 24 Q2] A. The shape of a cell depends upon: (a) The function of the cell, and (b) Its occurrence in the body Q2. Distinguish between unicellular and multicellular organisms. [Refer to TB page 24 Q3] A. Unicellular Organisms Multicellular Organisms i. Organisms like amoeba, i. Multicellular animals from paramoecium and earthworm to elephant are chlamydomonas are single made up of many kinds of celled and are called cells. unicellular organisms (uni = singIe). ii. The single cell performs ii. These cells constitute all the life processes like tissues, tissues make up obtaining food, respiration, the organs which are excretion, growth and organised into organ reproduction. systems like digestive system, respiratory system, etc. Each system performs a specific life process. SESSION 2. DIVERSITY IN CELLS 22

Q3. Deekshith said that “We can’t see cells with unaided eye”. Is the statement true or false? Explain. [Refer to TB page 24 Q5] A. The statement made by Deekshith, that “we can’t see cells with our naked eye” is par- tially true. i. The human eye cannot resolve or discriminate between two points separated by less than 0.1 mm (100 micrometres). ii. Most of the cells are smaller than this and cannot be observed by the naked eye. iii. However, cells like human nerve cells which are long can be seen with naked eye. iv. The ostrich egg is the biggest cell which can be seen with naked eye. Q4. What is difference between cells in onion peel and cells in spinach? [Refer to TB page 24 Q9] A. i. The cells in onion peel are of the same kind and shape. ii. But the cells in spinach are of 4 different types and shapes, each performing a different function: iii. (a) Outer most layers which gives shape and protection to the stem, (b) Inner to outer most layer carry out photosynthesis, (c) Inner to this layer conducts food and water, and (d) Innermost layer at the centre of the young stem which forms a hollow structure in the stem. Q5. Label parts for diagrams given below and identify which one is the plant cell and which one is the animal cell. [Refer to TB page 24 Q10] SESSION 2. DIVERSITY IN CELLS 23

A. A. Nucleus, B. Cytoplasm, C. Cell membrane, D. Vacuole, E. Nucleus, F. Cell wall, G. Cell membrane, H. Cytoplasm, I. Vacuole Since the figure on the right has a cell wall, it is the plant cell and the figure on the left is an animal cell. 2.5 Experimentation and Field Investigation Q1. Get some floating slime from a puddle, pick a small amount of slime and put it on a slide. Separate out one fiber and look at it through microscope. Draw the diagram of what you observed. [Refer to TB page 24 Q13] A. i. The slime of pond water under microscope finds many unicellular plants and ani- mals as shown in the figure. ii. The fibrous one is Spirogyra. It is ribbon shaped and has linear series of cells. iii. It is green in colour, so it can perform photosynthesis. SESSION 2. DIVERSITY IN CELLS 24

2.6 Information Skills and Projects Q1. Collect different kinds of leaves from your surroundings and observe the shapes of the epidermal cells under microscope. Make a table, which contains serial number, name of the leaf, shape of the leaf, shape of the epidermal cells. Do not forget to write specific findings below the table. [Refer to TB page 24 Q14] A. S.No. Name of the Shape of the Shape of the leaf leaf epidermal cells 1 Shoe flower Ovate Barrel shaped 2 Neem Elongated Barrel shaped oval 3 Grass Sword Barrel shaped 2.7 Appreciation and Aesthetic Sense, Values Q1. How do you appreciate the fact that a huge elephant, man and trees are made of cells, which are very small and we can look at them through microscope? [Refer to TB page 24 Q17] A. i. Whether the animal is huge like elephant, man and tree or small like earthworm, cockroach they all are made up of cells. ii. The functions of an organism depends on the functions carried out by its cells. iii. By putting these two statements together we can say that the cell is the basic structural and functional unit of all living organisms. SESSION 2. DIVERSITY IN CELLS 25

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. State true or false. [] [Refer to Session 2.2 ] (i) Cells of onion and blood are of the same shape. 2. Match the following. Column B [(Session 2.2)] Column A i. a. Smooth muscle cell ii. b. White blood cells iii. c. Nerve cell 26 iv. d. Bone cell v. e. Red blood cells CHAPTER 2. CELL –THE BASIC UNIT OF LIFE

3. Match the following. Column B [(Session 2.2)] a. Moves with help of cilia b. Moves with help of flagella Column A c. Moves with help of pseudopodia i. Amoeba d. W.B.C ii. Paramoecium e. Nerve cell iii. Euglena iv. Dendrite v. Monocyte 4. Fill in the blanks. [Refer to Session 2.2 ] (ii) The human kidney and liver cell is in size. (iii) Size of the cell is determined by its . (iv) cell has no definite shape. (v) is the instrument used to observe microorganisms. (vi) Human cell can be seen with naked eye. (vii) has the largest known cell at present. (viii) is an example of unicellular organism. CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 27

5. Match the following. Column B [(Session 2.1)] a. Saffranin Column A b. Controls the cell c. Present in the cytoplasm i. Cell wall d. Provides rigidity to plant cell ii. Cell membrane e. Permits materials inside and outside of iii. Nucleus iv. Cell organelles cell v. Stain 6. Answer the following questions in one sentence. [Refer to Session 2.1 ] (ix) Who discovered nucleus in orchid leaves? (x) Who was the first person to see living bodies under microscope? (xi) What is its function of cell wall? 7. Fill in the blanks. in 1665. [Refer to Session 2.1 ] prevents the material on slide from drying (xii) Cells were first observed by (xiii) Addition of (dehydration). CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 28

(xiv) gives rigidity and strength to plants. (xv) The jelly like substance present between the nucleus and the cell membrane iscalled as . (xvi) are the pores through which the leaves exchange the gases. (xvii) All the activities of the cell are controlled by . (xviii) The major component of cell wall is . (xix) and are present within the nucleus. (xx) Cytoplasm contains membrane bound structures called . Short Answer Type Questions 8. Answer the following questions in 3-4 sentences. (i) [(Session 2.2)] Does amoeba have a definite shape? (ii) [(Session 2.2)] Is size of the cell related to its function? If yes, explain with an exam- ple? Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 2.1)] Cells are the “basic structural units of living organism” is this statement correct? If yes give reasons. CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 29

AS2-Asking questions and making hypothesis Short Answer Type Questions 10. Answer the following questions in 3-4 sentences. (i) [(Session 2.2)] What questions will you ask when you meet a haematologist to know more about blood cells? AS3-Experimentation and field investigation Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 2.1)] What is the use of cover slip while preparing slide? Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 2.1)] Write the procedure to observe the cheek cells under the microscope. AS4-Information skills and projects Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 2.2)] Find out information on size of cells given below and fill the table. CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 30

Sl.No Name of organism Size of the cell 1. Ostrich 2. 3. Mycoplasma 4. 5 Human Egg 6 7 Unicellular Alga 8 Human Kidney Human nerve cell Root hair cell Chloroplasts AS5-Communication through drawing and model making 31 Very Short Answer Type Questions 14. Answer the following questions in one sentence. [Refer to Session 2.2 ] (i) Draw a simple diagram of Human RBC. Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 2.2)] Make sketches of (a) Amoeba (b) Nerve cell CHAPTER 2. CELL –THE BASIC UNIT OF LIFE

AS6-Appreciation and aesthetic sense, Values Very Short Answer Type Questions 16. Answer the following questions in one sentence. [Refer to Session 2.1 ] (i) Whom can you appreciate for observing living cells for the first time? Short Answer Type Questions 17. Answer the following questions in 3-4 sentences. (i) [(Session 2.1)] How would you appreciate the presence of nucleus in a cell? Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) He observed the cell for the first time in cork of oak tree under a magnifying device. (A) Robert Hooke (B) Robert Brown (C)Charles Darwin (D) Leeuwenhoek (ii) I form the boundary of the cell. Who am I? (A) Cell membrane (B) Nucleus (C) Cytoplasm (D) Endoplasmic Reticulum CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 32

(iii) What is considered to be the structural and functional unit of living body? (A) Cell (B) Organ (C) Cell organelle (D) Nucleus (iv) This means “A little room” in Latin. (B) Cavity (A) Cell (D) Vacuole (C) Cork (v) Which of these are present only in a plant cell? (A) Cell wall and Chloroplast (B) Cell membrane and Cytoplasm (C)Cytoplasm and Mitochondria (D) Cell membrane and Nucleus (vi) Neutrophils are a type of which of these cells? (A) Red blood cells (B) White blood cells (C)Nerve cells (D)Muscle cells (vii) Which of these length conversions are correct? (A) 1 micrometre = 100 nm (B) 1 micrometre = 10 nm (C)1 micrometre = 10000 nm (D)1 micrometre = 1000 nm (viii) Locomotion and nutrition in amoeba occurs with the help of which of these? (A) Pseudopodia (B) Flagella (C) Cilia (D) Fins CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 33

(ix) This has the largest cell. (B) Nerve cell (A) Egg of ostrich (D) Bacteria (C) Amoeba AS4-Information skills and projects 19. Choose the correct answer. (x) Out of the given species which will have greatest number of cell? Amoeba, Elephant, Mice, Onion (A) Onion (B) Amoeba (C) Elephant (D) Mice AS5-Communication through drawing and model making 20. Choose the correct answer. (xi) Which instrument is shown in the above picture? (A) Periscope (B) Telescope (C) Microscope (D) Kaleidoscope CHAPTER 2. CELL –THE BASIC UNIT OF LIFE 34

3. STORY OF MICROORGANISMS - 1 SESSION 1 DISCOVERY AND GROUPS OF MICROORGANISMS 1.1 Mind Map 1.2 Terminology i. Microscope – is an optical instrument used for viewing very small objects, such as mineral samples or animal or plant cells, typically magnified several hundred times. ii. Bacteria – are single–celled microorganisms with no nucleus and membrane–bound organelles that can exist either as free–living organisms or as parasites. iii. Fungi – are single–celled or multicellular organisms possessing cell wall made up of chitin. iv. Protozoans – are parasitic single–celled organisms that can divide only within a host organism (Eg. Malaria is caused by the protozoan Plasmodium). v. Algae – are simple, non–flowering, and typically aquatic plants of a large assemblage that includes the seaweeds and many single–celled forms. vi. Discovery – is the act of detecting something new, or something “old” that had been unknown. vii. Invention – is the act of inventing something, typically a process or device. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 35

1.3 Key Concepts i. Antonie van Leeuwenhoek (1678) was the first person to discover the presence of microorganisms. He called them “animalcules”. ii. Organisms which are very minute and can be seen only with the help of microscope are called microorganisms. iii. The major groups of microorganisms are bacteria, fungi, protozoa, and algae. Certain arthropods called micro arthropods are also too small to be viewed with the naked eye. iv. Viruses are special type of microorganisms, interlinked between living and non–living organisms. They behave like non–living things when they are outside a living cell, but reproduce when they are inside living host cells. 1.4 Conceptual Understanding Q1. Which organisms are interlinked between living and non–living organisms? Why do you think so? [Refer to TB page 35 Q1] A. i. Viruses are special organisms which are interlinked between living and non–living organisms. ii. They behave like non–living things when they are outside the living cell, but they behave like living organisms in host cells. iii. Since they exist in both living and non living forms in nature, they form an interlink between both life forms. Q2. What are microorganisms? Where do you find them? [Refer to TB page 35 Q2] A. i. Minute organisms in our surrounding which can’t be seen with our naked eye but can be seen only with the help of microscope are called microorganisms. ii. Microorganisms are present everywhere around us in air, water, and in the soil. iii. Eg. bacteria, virus, fungi etc. Q3. What type of microorganisms we can observe in pond water? [Refer to TB page 35 Q3] SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 36

A. The microorganisms which are observed in pond water are bacteria, algae, protozoans etc. Q4. Whether microorganisms are useful or harmful? How explain. [Refer to TB page 35 Q4] A. Microorganisms can be both useful and harmful. Microorganisms are useful, because: i. Some bacteria are useful in food processing. Eg. Lactobacillus responsible for curd formation, yeast added to dough during bread preparation etc. ii. They are useful as bio–pesticides to kill pests. iii. Several bacteria help in the process of sewage treatment. iv. Some are used in making medicines such as antibiotics and vaccines. Microorganisms are harmful, because: i. They cause dreadful diseases. ii. They spoil the food causing food poisoning. iii. They block water pipes. Q5. Why cooked food spoil soon but not uncooked food? Give your reasons. [Refer to TB page 35 Q6] A. i. Raw or uncooked food has enzymes protecting them from environment. ii. During heating, these enzymes get destroyed. iii. The bacteria that are naturally covering the food to give protection are also dam- aged. iv. Thus once the food is cooked, its half life is shortened and it becomes an easy target for many bacteria leading to its spoilage. Q6. How human actions can cause death of useful bacteria and fungi? What will happen if it continues? [Refer to TB page 35 Q5] A. i. Using a wide variety of antibiotics with broad range also kills the useful bacteria in the body. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 37

ii. Using enormous amounts of chemical fertilizers and pesticides and insecticides during crop production kills the useful soil bacteria. iii. Vigorous heat treatment of food material results in death of bacteria which helps in food digestion. iv. Some skin bacteria living on our skin protects it from getting fungal infections. Repeatedly washing hands with soap lead to a loss of such bacteria. v. If the microorganisms are eliminated like this, it would lead to drastic effects on human and plant health. 1.5 Asking Questions and Making Hypothesis Q1. What questions would you like to ask your teacher to know about different shapes of Bacteria. [Refer to TB page 35 Q7] A. I would ask the following questions regarding shape of bacteria: i. Do all bacteria have same shape? ii. Why different bacteria have different shapes? iii. In how many shapes do bacteria appear in nature? iv. Do bacteria having same shapes are similar to each other? Q2. What will happen if you add buttermilk to chilled milk? [Refer to TB page 35 Q8] A. The milk will become butter milk over a period of time due to the action of the bac- terium Lactobacillus. 1.6 Experimentation and Field Investigation Q1. How do you observe the Lactobacillus bacterium ? [Refer to TB page 35 Q7] A. i. Take one or two drops of buttermilk on a slide, spread it on the slide. ii. Heat it slightly on a lamp for 3–4 seconds. iii. Add a few drops of crystal violet on it. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 38

iv. After 30 to 60 seconds, wash the slide gently with water to remove excess stain by carefully blotting with a blotting sheet at the corner of the slide. v. Observe the slide under a compound microscope. vi. We will find several rod–like structures. These are Lactobacilli. 1.7 Information Skills and Projects Q1. Visit any bakery or milk chilling center near your school with the help of your teacher or parents. Learn about some techniques for culture and usage of some microorganisms and prepare a note on them. [Refer to TB page 35 Q8] A. On visiting a local bakery, the following information was obtained about the usage of yeast in making bread: i. The most fundamental biological process in bread making is fermentation, initiated and sustained by the life activities of a unicellular microscopic yeast cell. ii. Baker’s yeast, also known as Saccharomyces cerevisiae is actually a member of the mushroom family. iii. It is a biological leavening agent (the leavening agent incorporates gas bubbles into the dough) and possesses basic attributes of all living things such as respiration and reproduction. iv. Its role in bread making is to convert sugars to carbon dioxide gas and thus leaven the dough. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 39

v. Yeast is the little “artisan” who creates the internal cellular structure of bread. vi. Yeast fermentation is also involved in the maturation of dough and taste enhance- ment in alcohol, wine, beer and acetic acid. We were also informed about several other species of microorganisms used in food processing. i. Many species of fungus Candida sps. are used for making sour dough bread, cheese and chocolates. ii. Some species of fungus Aspergillus sps. are used in adding flavour to tea and coffee. 1.8 Communication Through Drawing and Model Making Q1. Observe some permanent slides of microorganisms in your school lab with help of a microscope. Draw its pictures. [Refer to TB page 35 Q9] A. Spirogyra Amoeba 40 SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS

Paramoecium Aspergillus Q2. Prepare a model of any microorganism. And write a note on them. [Refer to TB page 35 Q10] A. i. I prepared a Chlamydomonas model on thermocol sheet. ii. I took a thermocol sheet and drew an oval shaped structure. iii. I cut it from the sheet, and painted it green in colour. iv. In the middle of oval, I put a round big red button. v. At the top of the oval, I put two wires. vi. In this model green colour indicates –chloroplast, red button –nucleus and wires –flagella. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 41

Chlamydomonas is a unicellular green algae found all over the world, in soil, fresh water, oceans, and even in snow on mountain tops. It is autotrophic and prepares its food by the process of photosynthesis. It may reproduce asexually by fission or sexually by fusing in pairs with other individuals to form a zygote and eventually give rise to new individuals passing through series of developmental changes like zygospore formation. 1.9 Application to Daily Life, Concern to Bio Diversity Q1. Why should we clean our hands with soap before eating? [Refer to TB page 35 Q11] A. i. Our hands acquire so many bacteria while doing work. ii. If we don’t wash our hands before eating, they may enter our body. iii. This could lead to harmful illness. iv. Soaps contain antibacterial agents that kill bacteria. v. So washing of hands with soap is necessary before eating. SESSION 1. DISCOVERY AND GROUPS OF MICROORGANISMS 42

3. STORY OF MICROORGANISMS - 2 SESSION 1 MICROORGANISMS AS FRIENDS 1.1 Mind Map 1.2 Terminology i. Lactobacillus – is a rod–shaped bacterium which produces lactic acid from the fer- mentation of carbohydrates and aids in curd formation. ii. Penicillium – is a blue mould that grows commonly on food, is added to some cheeses and used to produce the antibiotic penicillin. iii. Sterilization – is the removal of all microorganisms and other pathogens from an object or surface by treating it with chemicals or subjecting it to high heat or radiation. iv. Vaccination – refers to administration of antigenic material (a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a pathogen. SESSION 1. MICROORGANISMS AS FRIENDS 43

v. Bacillus thuringiensis – is name of a bacterium which is used as bio pesticide. It produces a toxin which kills pests on plants or crops. 1.3 Key Concepts i. Milk is converted into curd/buttermilk by a bacterium called Lactobacillus. ii. Yeast produces carbon dioxide during the process of fermentation to increase the volume of dough and make it spongy in nature. iii. Sugars are converted into alcohol by yeast. This process is known as fermentation and is used on a large scale in the production of alcohol, wine, beer and acetic acid. iv. Antibiotics are antibacterial drug used to treat diseases like typhoid, gonorrhoea and prevent infections like Septicemia. v. Penicillin is an antibiotic produced by the fungus Penicillium notatum. Penicillin was dis- covered by Dr. Alexander Fleming in 1929. vi. Vaccines are the weakened disease–causing microorganisms which are injected into our bodies. The word vaccine comes from ‘vaca’ which means cow. vii. Microorganisms like Rhizobium, Nostoc, Anabena, Azotobacter, etc., help to fix atmo- spheric nitrogen.in the plants. viii. The microorganisms like fungi and bacteria present in the soil degrade biological wastes in the soil into simple and smaller compounds, some of which are essential for plants. 1.4 Conceptual Understanding Q1. How do vaccines work in our body? [Refer to TB page 49 Q1] A. i. Vaccines protect us from diseases over a long period of time. ii. As vaccine contains only killed or weakened microorganisms they can’t cause the disease but stimulate the body to produce antibodies. iii. So when the disease causing microorganism enters our body, the antibodies al- ready present in our body fight and eliminate them and the disease is controlled. Q2. What are the differences between antibiotics and vaccines? [Refer to TB page 49 Q2] SESSION 1. MICROORGANISMS AS FRIENDS 44

A. Antibiotics Vaccines i. Antibiotics help in curing i. Vaccines are used before many diseases like typhoid, the symptoms as preventive gonorrhea, tuberculosis etc. medicines. ii. Antibiotics consist of ii. Weakened or killed some microorganisms that strains of disease causing prevent growth and infection microorganisms are by some other group of introduced to our body as microorganisms. For Eg. vaccines. They produce The fungal strain Penicillium antibodies in our body and prevents the growth of in case of infection by that bacteria. particular strain, the antibodies combat and kill the causative microbes. iii. Penicillin, tetracycline, iii. Polio vaccine, smallpox streptomycin, erythromycin vaccine, Rabies vaccine, etc. are important BCG vaccine are some antibiotics. examples of vaccines. Q3. Invention of penicillin protected the world from deaths during the first world war. Explain. [Refer to TB page 49 Q3] A. i. Penicillin was invented by Dr. Alexander Fleming who was an army doctor during the First World War. ii. Penicillin kills and prevents the growth of disease–causing bacteria. iii. Thus, its invention prevented many injured soldiers from dying of their wounds dur- ing the first world war. SESSION 1. MICROORGANISMS AS FRIENDS 45

1.5 Experimentation and Field Investigation Q1. Take three bowls and mark as A, B, C. Pour lukewarm milk in bowl A, hot milk in bowl B and cold milk in bowl C. Add one tea spoon of curd or buttermilk in the three bowls and stir them slightly. Cover the bowls with lids. Keep the bowls undisturbed for 5 to 6 hours. In which bowl is the milk turned into curd? Give your reasons. [Refer to TB page 49 Q4] A. i. In bowl A with lukewarm milk, milk was converted to curd because the warmth helped the bacteria to grow and hence, the milk got converted into curd. ii. In bowl B, the milk was hot, so the bacteria either died or became inactive. So they could not undergo reproduction and thus the milk in bowl B was not converted into curd. iii. In bowl C, the milk was cold. Since the bacteria cannot reproduce in cold conditions and become inactive, so no curd was formed. 1.6 Information Skills and Projects Q1. Collect more information about scientists who invented and discovered other facts re- lated to microorganisms. How did these discoveries help mankind? Make a chart pre- sentation and paste it on your classroom wall magazine. [Refer to TB page 49 Q5] A. i. Students can collect information on various scientists or microbiologists related to the discovery and effects of microrganisms. For example Antonie Van Leeuven- hoek, Lazzaro Spallanzani, Robert Koch and Louis Pasteur. ii. The following links can be used for gearing up information. a. https://explorable.com/ discovery – of – bacteria b. study.com/academy/lesson/alexander–fleming– discovery –contributions– facts .html c. https://en.wikipedia.org/wiki/Microorganism Q2. Make an album of scientists and their discoveries related to microorganisms. [Refer to TB page 49 Q6] SESSION 1. MICROORGANISMS AS FRIENDS 46

A. Hint: Follow the link–http://www.thefamouspeople.com/microbiologists.php for detailed information. 1.7 Appreciation and Aesthetic Sense, Values Q1. How do you appreciate Edward Jenner’s experiment? [Refer to TB page 49 Q9] A. i. Edward Jenner was the first person to give a vaccine against smallpox. He ob- served that the milkmaids who developed cowpox, did not develop smallpox even on exposure. ii. So he took some fluid from a cowpox pustule and inoculated in an 8–year old boy. The boy did not get smallpox and the vaccine for smallpox was discovered. iii. Edward Jenner’s attempts and experiments lead to the idea and method of vac- cination which is a useful method of preventing many dreadful diseases in the present times as well. Q2. “Prevention is better than cure.” Comment. [Refer to TB page 49 Q11] A. Once infected, the body becomes weak. Hospitalization and medicines also affect our health adversely. Therefore, it is always a better and safer practice to get vaccinated against diseases that have vaccines against them to protect ourselves. Q3. Jeevan said that “If there are no microorganisms, earth will remain with wastes”. Will you agree with this statement? Why? [Refer to TB page 49 Q13] A. Yes, I agree with this statement, because: i. Microorganisms present in the soil, air, and water act upon wastes around us and decompose them. ii. Thus microorganisms help us in cleaning environment. iii. If microorganisms were absent, decomposition would not take place, and earth would be filled with dead bodies, garbage and plant and animal remains, making it uninhabitable. SESSION 1. MICROORGANISMS AS FRIENDS 47

Q4. Pranavi is suffering from a serious illness. Doctor prescribed antibiotics for five days. After three days of usage she stopped taking antibiotics. Is it right or not? Discuss. [Refer to TB page 49 Q14] A. i. No, it is not right to stop antibiotic before completing the prescribed course. ii. If all the disease–causing bacteria present in Pranavi’s body will not be killed, there will be a chance of development of resistant strains to that particular antibiotic. iii. This could be very dangerous as in future, that strain of bacteria may not be killed by that antibiotic. iv. The resultant bacteria will be more dangerous and it will get more difficult to pre- vent and cure disease caused by this bacteria in the future. 1.8 Application to Daily Life, Concern to Bio Diversity Q1. One medical store owner is giving antibiotics to his customer who is suffering with fever without doctor’s prescription. But customer’s daughter Malathi is telling her father not to take antibiotics without doctor’s prescription. Whom do you support and why? [Refer to TB page 49 Q16] A. i. We support the customer’s daughter. One should not use antibiotics without doc- tor’s prescription. ii. Unnecessary use of antibiotics leads to killing of useful internal bacteria and blood cells. iii. Moreover, it also increases the resistance power of the bacteria to the drug and the drug may not affect the bacteria in future. SESSION 1. MICROORGANISMS AS FRIENDS 48