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Enhancement of Food Production Class 12 Biology Chapter 11 Questions And Answers Maharashtra Board

Class 12 | Biology Maharashtra Board Textbook Solutions

20 Apr 2026

Enhancement of Food Production Class 12 Biology Chapter 11 Questions And Answers Maharashtra Board

Q. 1. Multiple Choice Questions. 1. Antibiotic Chloromycetin is obtained from …………………a. Streptomyces erythreusb. Penicillium chrysogenumc. Streptomyces venezuelaed. Streptomyces griseus Answer. (c) Streptomyces venezuelae 2. Removal of large pieces of floating debris, oily substances, etc. during sewage treatment is called …………….a. primary treatmentb. secondary treatmentc. final treatmentd. amplification Answer. (a) primary treatment 3. Which one of the following is free living bacterial biofertilizer?a. Azotobacterb. Rhizobiumc. Nostocd. Bacillus thuringiensis Answer. (a) Azotobacter 4. Most commonly used substrate for industrial production of beer is ………………….(a) barley(b) wheat(c) corn(d) sugarcane molasses Answer. (a) barley 5. Ethanol is commercially produced through a particular species of …………..a. Aspergillusb. Saccharomycesc. Clostridiumd. Trichoderma Answer. (b) Saccharomyces 6. One of the free-living anaerobic nitrogen- fixers is ………………….(a) Azotobacter(b) Beijerinckia(c) Rhodospirillum(d) Rhizobiu Answer. (c) Rhodospirillum 7. Microorganisms also help in production of food like ………………….(a) bread(b) alcoholic beverages(c) vegetables(d) pulses Answer. (a) bread 8. MOET technique is used for ………………….(a) production of hybrids(b) inbreeding(c) outbreeding(d) outcrossing Answer. (a) production of hybrids 9. Mule is the outcome of ………………….(a) inbreeding(b) artificial insemination(c) interspecific hybridization(d) outbreeding Answer. (c) interspecific hybridization Q. 2. Very Short Answer Questions: 1. What does make idlies puffy ? Answer. During preparation of idlis, rice and black gram flour is fermented by air borne Leuconostoc and Streptococcus bacteria. CO2 produced during fermentation makes them puffy. 2. Name any two bacterial biofertilizers. Answer. Rhizobium, Frankia, Pseudomonas striata, Bacillus polymyxa, Agrobacterium, Microccocus, Azotobacter, Costridium, Beijerinkia, Klebsiella. 3. What is the microbial source of vitamin B12? Answer. The microbial source of vitamin B12 is Pseudomonas denitrificans. 4. What is the microbial source of enzyme Invertase? Answer. The microbial source of enzyme invertase is Saccharomyces cerevisiae. 5. Milk start to coagulate when Lactic Acid Bacteria (LAB) is added to warm milk as a starter. Mention any two other benefits of LAB. Answer. Lactic Acid Bacteria (LAB) check the growth of disease causing microbes and produce vitamin B. 6. Name the enzyme produced by Streptococcus bacterium. Explain importance in medical sciences. Answer. The enzyme produced by Streptococcus spp. is streptokinase. It is used as a ‘clot buster’ for clearing blood clots in the blood vessels in heart patients. 7. What is breed? Answer. Breed is a group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc. 8. Define estuary. Answer. Estuary is a place where river meets the sea. 9. What is shellac? Answer. Shellac is the pure form of lac obtained by washing and filtering. Q. 3. Short Answer Questions. 1. Many microbes are used at home during preparation of food items. Comment on such useful ones with examples. Answer. 2. What is biogas? Write in brief about the production process. Answer. Biogas is a mixture of methane CH4 (50-60%), CO2 (30-40%), H2S (0-3%) and other gases (CO, N2, H2) in traces. Biogas production process:a. A typical biogas plant consists of digester (made up of concrete bricks and cement or steel and is partly buried in the soil) and gas holder (a cylindrical gas tank to collect gases).b. Raw materials like cow dung is mixed with water in equal proportion to make slurry which is fed into the digester’ through a side opening (charge pit). Anaerobic digestion involves following processes:i. Hydrolysis or solubilization:Anaerobic hydrolyzing bacteria like Clostridium and Pseudomonas hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids. ii. Acidogenesis:Facultative and obligate anaerobic, acidogenic bacteria convert simple organic substances into acids like formic acid, acetic acid, H2 and CO2 iii. Methanogenesis:Anaerobic methanogenic bacteria like Methanobacterium, Methanococcus convert acetate, H2 and CO2 into Methane, CO2 and H2O and other products.12 mol CH3COOH → 12CH4 + 12CO2 4mol H.COOH → CH4 + 3CO2 + 2H2O CO2 + 4H2 → CH4 + 2H2O 3. Write a note on biocontrol agents. Answer. (1) Biocontrol agents are the organisms like (bacteria, fungi, viruses and protozoans) act which are employed for controlling pathogens, pests and weeds. (2) They cause the disease to the pest or compete or kill them. (3) The use of biocontrol measures greatly reduces use of toxic chemicals and pesticides that are harmful to human beings and also pollute our environment. (4) Biocontrol agents and their hosts. (5) Some examples: 4. Name any two enzymes and antibiotics with their microbial source. Answer. 5. Write priciples of farm management. Answer. The principles of farm management are as follows: 6. Give economic importance of fishery. Answer. Economic importance of fisheries is as follows: 7. Enlist the species of honey bee mentioning their specific uses. Answer. (1) The four species of honey bees commonly found in India : Apis dorsata (rock bee, or wild bee), Apis jlorea (little bee), Apis mellifera (European bee) and Apis indica (Indian bee). (2) Uses: 8. What are A, B, C and D in the table given below : Answer. A : Penicillium chrysogenumB : Vinegar (Acetic acid)C : FungusD : Sachharomyces cerevisiae var. ellipsoidis Q. 4. Long Answer Questions. 1. Explain the process of sewage water treatment before it can be discharged into natural bodies. Why this treatment is essential? Answer. Sewage treatment includes following steps:(1) Preliminary Treatment: (2) Primary treatment (physical treatment): (3) Secondary treatment (biological treatment): (4) Tertiary treatment: 2. Write a note on lac culture. Answer. 3. Describe various methods of fish preservation. Answer. The different methods of fish preservation are as follows: 4. Give an account of poultry diseases. Answer. Various poultry diseases are as follows: 5. Give an account of mutation breeding with examples. Answer. 6. Describe briefly various steps of plant breeding methods. Answer. The main steps of the plant breeding program (Hybridization) are as follows: (1) Collection of variability: (2) Evaluation and selection of parents: (3) Hybridization: (4) Selection and Testing of Superior Recombinants: (5) Testing, release and commercialization of new cultivars:

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Transport and Communication Class 9 Geography Chapter 11 Questions And Answers Maharashtra Board

Class 9 Social Science Maharashtra Board Textbook Solutions

30 Mar 2026

Transport and Communication Class 9 Geography Chapter 11 Questions And Answers Maharashtra Board

1. Differentiate between: (A) Railways and roadways Answer. Basis Railways Roadways (1) Carrying Capacity Carrying capacity is more Carrying capacity is limited (2) Distance Suitable for long distances Suitable for short distance (3) Door to door service Railway does not provide door to door service. Roadways provide door to door service. (4) Traffic There is no problem of traffic jam on railways. There is a problem of traffic jam on roadways. (5) Pollution Railways do not create a problem of air pollution. Roadways create a problem of air pollution. (B) Transportation and communication Answer. Basis Transportation Communication (1) Meaning Transportation is the movement of humans, animals and goods from one location to another. Communication is the exchange of information, ideas and messages by speaking, writing or some other medium. (2) Means It is done through railways, roadways, waterways, airways and pipelines. It is done through telephones, mobiles, video-conferencing, email and post etc. (3) Threats The threats like a traffic jams, accidents, noise pollution, air pollution are associated with transportation. The threats like technical issues, cyber crimes, etc. are associated with the communication. (C) Conventional and modern means of communication. Answer. Basis Conventional means of Communication Modem means of Communication (1) Meaning The means of communication – used since olden times – conventional means of communication. The means of communication – used in modern times – modern means of communication. (2) Examples Letter, newspapers, radio, television. Mobile phone, internet, etc. (3) Interaction May not facilitate the direct interaction between – sender and receivers of information. Facilitates the direct interaction between – sender and the receivers of information. 2. Answer in detail : (1) ‘Newspapers are used for communication’. Explain the statement. Answer. Thus, newspapers are used for communication. (2) Explain how T.V. is a cheap means of communication. Answer. Thus, TV is a cheap means of communication. (3) What types of communications can be done through mobiles ? Answer. 3. Name them on the basis of the given information: (1) Five cities with airways services in Maharashtra Answer. Mumbai, Pune, Nagpur, Kolhapur, Aurangabad, Nashik and Nanded. (2) Services available in post offices Answer. (3) National Highways near your area Answer. (4) Ports along the coast of Maharashtra Answer. 4. Identify the relation and match the columns making a chain Group ‘A’ Group ‘B’ Group ‘C’ (1) Postal services Roadways Speed post (2) Shivneri World network of connected computers Exchange of information (3) Internet Conventional means of communication Comfortable journey (4) RoRo transport Railways Energy, time and labour saving Answer. Group ‘A’ Group ‘B’ Group ‘C’ (1) Postal services Conventional means of communication Speed post. (2) Shivneri Roadways Comfortable journey. (3) Internet World network of connected computers Exchange of information. (4) RoRo transport Railways Energy, time and labour saving.

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Maharashtra Board

23 Feb 2026

Reflection of Light Class 9 Science Chapter 11 Questions And Answers Maharashtra Board

1. Answer the following questions. a. Explain the difference between a plane mirror, a concave mirror and a convex mirror with respect to the type and size of the images produced. Answer. Plane mirror Concave mirror Convex mirror Type of image Virtual and Erect Virtual (erect) as well as Real (inverted) Virtual and Erect Size of image Same size Diminished, Same size and magnified Diminished b. Describe the positions of the source of light with respect to a concave mirror in 1.Torch light 2.Projector lamp 3.Floodlight Answer. (a) Torch light: The source of light is placed at the focus.(b) Projector lamp : The source of light is placed at the centre of curvature.(c) Flood light : The source of light is placed just beyond the centre of curvature. c. Why are concave mirrors used in solar devices? Answer. d. Why are the mirrors fitted on the outside of cars convex? Answer. e. Why does obtaining the image of the sun on a paper with the help of a concave mirror burn the paper ? Answer. f. If a spherical mirror breaks, what type of mirrors are the individual pieces? Answer. 2. What sign conventions are used for reflection from a spherical mirror? Answer. According to the Cartesian sign convention, the pole of the mirror is taken as the origin. The principal axis is taken as the X-axis of the frame of reference. The sign conventions are as follows. 3. Draw ray diagrams for the cases of images obtained in concave mirrors as described in the table on page 122. Answer. (a) A ray diagram for object at infinity for a concave mirror. Image position Nature of image At focus Real, inverted and point image (b) A ray diagram for object beyond centre of curvature for a concave mirror. An object beyond centre of curvature for a concave mirror Image position Nature of image Between the centre of curvature and focus. Real, inverted and diminished. (c) A ray diagram for object at the centre of curvature for a concave mirror. Object at centre of Curva fu re be a concave mirror. Image position Nature of image At the centre of curvature. Real, inverted and same size (d) A ray diagram for object between F and C for a concave mirror. Object between F & C for a concave mirror Image position Nature of image Beyond the centre of curvature. Real, inverted and magnified. (e) A ray diagram for object at focus for a concave mirror. Object at focus for a concave mirror. Image position Nature of image At infinity. Real, inverted and highly magnified. (f) A ray diagram for object between pole and focus for a concave mirror. Image position Nature of image Behind the mirror. Virtual, erect and magnified. 4. Which type of mirrors are used in the following?Periscope, floodlights, shaving mirror, kaleidoscope, street lights, head lamps of a car. Answer. Objects Type of Mirror Periscope Plane mirror Floodlights Concave mirror Shaving mirror Concave mirror Kaleidoscope Plane mirror Street lights Convex mirror Head lamps of car Concave mirror 5. Solve the following examples a. An object of height 7 cm is kept at a distance of 25 cm in front of a concave mirror. The focal length of the mirror is 15 cm. At what distance from the mirror should a screen be kept so as to get a clear image? What will be the size and nature of the image? (Answer: 37.5 cm and 10.5 cm. Image is real) Answer. Object size (h1) = 7 cmObject distance (u) = -25 cmFocal length (f) = -15cmTo find: Image distance (u) = ?Image size (h2) = ? The screen should be kept 373 cm in front of the mirror. The image is real. The height of the image is 10.5 cm, it is an inverted and enlarged image. b. A convex mirror has a focal length of 18 cm. The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror? (Answer: 18 cm) Answer. Image size (h2) = 1/2 h1Focal length (f) = 18 cmTo find: Object distance (u) ? The object is placed in front of the convex mirror at a distance of 18 cm. c. A 10 cm long stick is kept in front of a concave mirror having focal length of 10 cm in such a way that the end of the stick closest to the pole is at a distance of 20 cm. What will be the length of the image? (Answer: 10 cm) Answer. Given: Object size (h1) = 10 cmObject distance (u) = -20 cmFocal length (f) = -10 cm The height of the image is 10 cm and it is a real and inverted image. 6. Three mirrors are created from a single sphere. Which of the following pole, centre of curvature, radius of curvature, principal axis – will be common to them and which will not be common? Answer.

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Maharashtra Board

23 Feb 2026

Information Communication Technology (ICT) Class 9 Science Chapter 10 Questions And Answers Maharashtra Board

1. Fill in the blanks to complete the statements. Justify the statements. a. While working with a computer we can read the information stored in its memory and perform other actions in …………… memory. Answer. Internal or Primary. Reason : For the Central Processing Unit ( CPU ) to process the program instructions and data, these must be loaded into the computer’s internal memory. b. While presenting pictures and videos about the works of scientists, we can use ………….. Answer. A presentation software / Microsoft PowerPoint. Reason : A presentation software ( e.g., PowerPoint ) allows images as well as videos to be placed on a slide. c. To draw graphs based on the quantitative information obtained in an experiment, one uses ….. Answer. A spreadsheet program / Microsoft Excel. Reason : A spreadsheet program ( e.g., Excel ) has facilities for graphical representation of data as a graph or a chart. d. The first generation computers used to shut down because of ……. Answer. Excessive heat. Reason : First generation computers were built using valves. Valves consumed lot of electricity and generated lot of heat. The heat caused frequent burn-out of the valves which stopped the computers from working. e. A computer will not work unless ….…. is supplied to it. Answer. Electric power. Reason : A computer is an electronic device that needs electrical power to work. 2. Answer the following questions. a. Explain the role and importance of information communication in science and technology. Answer. b. Which application software in the computer system did you find useful while studying science, and how ? Answer. c. How does a computer work ? Answer. Input unit Processor Output Unit All types of information/ data is entered into the computer through this unit. Generally, a keyboard is used to enter data or information Processing Unit(1) Memory unit(2) Control unit(3) ALU unit The result/solution/ answer is eventually sent to the output unit. Generally, a screen/monitor or printer is used as an output unit. d. What precautions should be taken while using various types of software on the computer ? Answer. e. Which are the various devices used in information communication ? How are they used in the context of science ? Answer. 3. Using a spreadsheet, draw graphs between distance and time, using the information about the movements of Amar, Akbar and Anthony given in the table on page 4 , in the lesson on Laws of Motion. What precautions will you take while drawing the graph? Answer. Choice of Axes: Always plot Time on the X-axis (independent variable) and Distance on the Y-axis (dependent variable). Scale Selection: Choose a scale that allows the graph to cover most of the sheet/area. For example, if the time is in 30-minute increments, let 1 cm = 30 mins. Origin (0,0): Ensure your graph starts from the origin if the data indicates they started from rest at time zero. Point Plotting: Mark the points accurately. In a spreadsheet, double-check that the “Data Range” is correct so the lines don’t get swapped. Nature of the Line: * For Amar and Anthony, the graph should be a straight line passing through the origin (indicating constant speed). Labeling: Don’t forget to label the axes with their respective units (e.g., Time in min/hr and Distance in km). 4. Explain the differences between the different generations of computers. How did science contribute to these developments ? Answer. Generation: 1stTime Period: 1946 – 1956Development: Vacuum Tubes Characteristics: Generation: 2ndTime Period: 1956 – 1963Development: TransistorsCharacteristics: Generation: 3rdTime Period: 1963 -1971Development: ICCharacteristics: Generation: 4thTime Period: 1971 – 2010Development: Microprocessor Characteristics: Generation: 5thTime Period: 2010 – Till DateDevelopment: Artificial Intelligence (AI) Characteristics: 1st Generation computers occupied the entire room, but due to advancement in science and technology, today’s computer fits into our pockets. Initially computers needed a specific language to interact but today we use voice recognition for the same. In these ways, science has contributed in making the computers faster, smaller, cheaper and much more useful. 5. What devices will you use to share with others the knowledge that you have ? Answer. Devices like radios, televisions, pendrives, computers, laptops, mobiles, landlines, hard drives, CDs, memory cards help us in sharing our knowledge with others. 6. Using information communication technology, prepare powerpoint presentations on at least three topics in your textbook. Make a flowchart of the steps you used while making these presentations. Answer. (1) Gather important points on a topic. (2) Plan the coverage of the topic, i.e., what to say, how much to say, and how to say it. (3) Write down the content of each slide in the correct sequence, for about 10 to 12 slides. (4) Search for relevant diagrams / pictures using a web browser, download and save them in an appropriate folder. (5) Use Home  New Slide to insert slides with appropriate placeholders ( e.g., text, table, picture, video, etc. ) (6) Use the Design tab to select the theme, colours and font for the slides. (7) Use the Animations tab for slide transitions and for animating slide objects. Suggested topics :(1) Scientists appearing in your textbook(2) Classification of plants ( Chapter 6 )(3) Bio-geochemical, Carbon, Oxygen and Nitrogen cycles ( Chapter 7 )(4) Reflection of light ( Chapter 11 ). 7. Which technical difficulties did you face while using the computer? What did you do to overcome them? Answer.

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Class 8 | Science | Chapter 11 | Human Body and Organ System | Exercise Solution | Maharashtra Board

Class 8 | Science | Textbook Solutions | Maharashtra Board

20 Feb 2025

Class 8 | Science | Chapter 11 | Human Body and Organ System | Exercise Solution | Maharashtra Board

1. Find out my partner. Group ‘A’ Group ‘B’ 1. Heartbeats a. 350 ml 2. RBC b. 7.4 3. WBC c. 37° C 4. Blood donation d. 72 per min 5. Normal body temperature e. 50 – 60 lakh/mm3 6. pH of oxygenated blood f. 5000 – 6000 per mm3 Answer: Group ‘A’ Group ‘B’ 1. Heartbeats d. 72 per min 2. RBC e. 50 – 60 lakh/mm3 3. WBC f. 5000 – 6000 per mm3 4. Blood donation a. 350 ml 5. Normal body temperature c. 37° C 6. pH of oxygenated blood b. 7.4 2. Complete the following table. Question a. Answer: 3. Draw neat and labeled diagrams. a. Respiratory system.Answer: b. Internal structure of heart.Answer: 4. Explain with reasons. a. Human blood is red coloured.Answer:The red colour of human blood is due to hemoglobin which is a red coloured conjugated protein with iron that is present on the red blood cells. Therefore, it looks red. b. Upward and downward movement of diaphragm occurs consecutively.Answer:The breathing movements are possible due to contraction and relaxation of the diaphragm. The rib muscles also help in these movements. When the ribs rise and diaphragm is lowered at the same time, then there is a decrease in pressure on lungs. This causes movement of air into the lungs at the time of inhalation. On the other hand, when ribs come back to their normal position and diaphragm is risen, then pressure on the lungs increases. This causes movement of the air out of the body through the nose in the form of exhalation. These movements are possible only due to consecutive upward and downward movement of the diaphragm. c. Blood donation is considered to be superior of all donations.Answer:Blood cannot be manufactured by any artificial chemical process. The only way to obtain blood is by donations of blood from a live donor. Blood is needed at times of emergency. The life of person can be saved if timely blood transfusion is given to the needy victim or a patient. Since such donation can save a valuable human life, it is called superior of all donations. d. Person with ‘O’ blood group is considered as ‘universal donor’.Answer:Person with ‘O’ blood group does not have any antigen on his/her RBCs. The ‘O’ type blood thus cannot cause clotting reactions in the body of the recipients. Such persons with ‘O’ blood group can donate blood to any person having any blood group therefore they are considered as ‘universal donor’. e. Food must have limited amount of salts.Answer:More salt in diet means more sodium ions. These extra sodium salts cause rise in blood pressure. Such condition is called hypertension. This condition can be dangerous and fatal in some cases. Therefore, one must keep control over sodium content of the food. 5. Answer the following questions in your own words. a. Explain the functional correlation of circulatory system with respiratory, digestive and excretory system.Answer:1. Three systems viz. respiratory, digestive and circulatory always work in coordination.2. Digestive system helps in breaking down complex food molecules into simple soluble nutrients at the end of the digestion process.3. The soluble nutrients are absorbed in the circulating blood in the villi of the intestine.4. The blood carries these nutrients to each cell during its circulation.5. The respiratory system helps the oxygen from the air to be absorbed in the blood.6. This process takes place in alveolus present in lungs. The oxygen is absorbed in the blood and through haemoglobin it is taken to every cell of the body. At the same time the unwanted carbon dioxide produced in each cell is given out in a process of gaseous exchange.7. The soluble nutrients, and chiefly glucose is metabolized with the help of oxygen-producing energy. Thus, all the three systems bring about coordinated functions to keep the body alive. b. Explain the structure and function of human blood.Answer:I. Structure, i.e. components of the human blood: Human blood is a fluid connective tissue consisting of blood plasma and blood corpuscles suspended in it. 1. Plasma: Plasma is the fluid part of the blood which is pale yellow in colour. It is slightly alkaline in nature. It has 90-92% water, 6-8 % proteins and 1-2 % inorganic salts.It contains proteins such as albumin, globulin, fibrinogen, etc. There are inorganic ions such as Ca, Na and K. 2. Blood cells:a. Blood cells are mainly of three types, viz. RBCs, WBCs and blood platelets. They are produced in the red bone marrow.b. RBCs are small, circular and enucleated cells. They are full of haemoglobin which is essential in transporting oxygen. RBCs are red blood cells which are 50 to 60 lakh per cubic millimetre. Their life span is 100 to 127 days.c. WBCs are large, nucleated and colourless. They are of five subtypes, viz. neutrophils, basophils, eosinophils, monocytes and lymphocytes. They are 5 to 10 thousands per millimetre of blood.d. Platelets are very small disc-shaped blood cells which are 2.5 to 4 lakh per cubic millimetre of blood. II. Function of human blood: 1. Transport functions: 2. Protection: Antibodies are produced in the blood and they protect the body from microbes and other harmful particles.3. Thermoregulation: Body temperature is maintained constant at 37 °C by vasodilation and vasoconstriction.4. Maintaining the balance of minerals like Na, K in the body.5. If bleeding occurs at the injury, platelets and a protein called fibrinogen of the blood form a clot and seal the injury.6. Functions of blood cells: c. Explain the importance and need of blood donation.Answer:Blood can never be synthesized artificially. There is no substitute for natural blood. Every healthy person possesses about 5 litres of blood in his or her body. In case of haemorrhage i.e. blood loss, the blood volume may reduce which can result into threat to life. Moreover, the loss of blood should be immediately taken care of, otherwise it may cost the life. Therefore blood transfusion is very crucial in case of victims of accidents, patients of surgeries or mothers who suffer from

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Class 7 | Science | Textbook Solutions | Maharashtra Board

8 Jul 2024

Class 7 | Science | Chapter 11 | Cell Structure and Micro-Organisms | Maharashtra Board | Solution

1. Answer the following questions. a. What is a cell?Answer:The cell is the fundamental, structural and functional unit of living organism. b. Name the different organelles in a cell.Answer:The nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids, chloroplasts are the different organelles in a cell. c. What are micro-organisms?Answer:The organisms which cannot be seen with our eyes but can only be observed under a microscope are called micro-organisms. d. Which are the different types of micro-organisms?Answer:Algae, fungi, bacteria, protozoa and viruses are various types of micro-organism. Some are unicellular and others are multicellular. Some of them are useful and some are harmful. 2. Fill in the blanks with the proper word. a. The organelle called the ……………. is present in the plant cells only.Answer:chloroplasts b. Garbage is converted into ……….. by microorganisms.Answer:fertilizer c. In the cell, photosynthesis is carried out with the help of …………… .Answer:chloroplast d. An electron microscope is necessary for the study of ……………… .Answer:micro-organism e. The process of preparing their own food in presence of sunlight and chloroplast by plants cells is known as ……….. .Answer:photosynthesis. 3. What is the difference between us? a. Plant cell and animal cell.Answer: Plant cell Animal cell 1. Plant cell has cell wall. 1. Cell wall is absent in animal cell. 2. Plant cell has definite shape due to presence of cell wall. 2. Animal cell do not have definite shape. 3. Plant cell has one big vacuole. 3. Animal cells have many small vacuoles. 4. Plant cell has chloroplast so they produce their own food. 4. Animal cells do not have chloroplast, so they cannot produce their own food. 5. Plant cell has plastids. 5. Plastids are absent in animal cell. 6. Centrosomes are absent in plant cell. 6. Centrosomes are present near the nucleus. 7. Lysosomes are absent in plant cell. 7. Lysosomes are present in animal cell. b. Prokaryotic cell and Eukaryotic cellAnswer: Prokaryotic cell Eukaryotic cell 1. No well defined nucleus. 1. Well defined nucleus with a nuclear membrane 2. Ribosomes are small. 2. Ribosomes are large. 3. A single length of DNA is present. 3. Several lengths of genetic materials (DNA) is present. 4. No other cell organelles are present. 4. Several organelles like mitochondria, chloroplasts, etc. are present. 5. Examples: Bacteria, blue green algae 5. Examples: Euglena, Amoeba, all plant and animal cells 4. Sketch and describe in your on words, the plant cell and animal cell. Answer:There are two types of cell-animal cells and plant cells. These cells contain various types of membrane beyond cell-organelles. Plant cells have a definite shape due to the presence of cell wall. Besides, unlike animal cells, plant cells contain single large vacuole. All these cells are known as eukaryotic cells. It cell has four main parts: the cell wall, cell membrane, cytoplasm and cell organelles.1. Cell wall: The cell wall is the outermost covering of a cell. It is present only in plant cells. 2. Plasma membrane: The plasma membrane, also called the cell membrane, is a kind of thin covering, (a) It is extremely delicate and flexible, (b) It is the outermost covering of animal cells. 3. Cytoplasm: The liquid part in the cell, present around the nucleus is called cytoplasm, (a) It occupies the space between the plasma membrane and nucleus, (b) Cell organelles are scattered in the cytoplasm. 4. Cell organelles: These mainly include the nucleus, endoplasmic reticulum, Golgi bodies, lysosomes, mitochondria, vacuoles, plastids etc. Plant cells contain chloroplasts.(a) The nucleus is the most important organelle of the cell, (b) There is a porous double membrane around it. (c) The nucleus controls all functions of the cell, (d) The endoplasmic reticulum is a sprawling net-like organelle. Its function is to make necessary changes in the proteins produced by ribosomes and send them to the Golgi bodies, (e) Golgi bodies are made up of several flat sacs. Their function is the proper distribution of proteins. (f) Mitochondria and plastids are organelles with double outer coverings, (g) As mitochondria produce energy, they are called the powerhouses of the cell, (h) The chloroplasts in plant cells carry out the function of photosynthesis, (i) Vacuoles help to throw out waste products of the cell, (j) Vacuoles in animal cells are small whereas there is only one large vacuole in a plant cell. 5. Explain the uses and the harmful effects of micro-organisms. Answer:Micro-organisms which are helpful are called useful micro-organisms.Uses:1. Micro-organisms present in nodules of leguminous plants, convert atmospheric nitrogen into its compounds and these compounds help to increase the soil fertility and protein content in the soil. 2. Some micro-organisms are useful in process of fermentation, making the food easily digestible and more nutritious. For producing milk products like butter, buttermilk, cheese, paneer, etc. 3. Microbes present in soil, dung etc. decompose garbage and convert into manure of best quality and surrounding is kept clean. 4. Microbes are also useful for sewage disposal. They help in decomposition of organic compounds in it.5. Microbes are used in production of vaccines. 6. Microbes are also used in processes like tanning of skin, production of ropes and strings, from agave.7. Some microbes use oil for their growth. Such microbes are used to clear a layer of oil floating on the surface of an ocean or lake formed due to leak or spill. 8. Farm waste, human urine and faeces, wet garbage etc. is collected and used in a biogas plant to produce biogas and fertilizer. Harmful effects:1. Disease producing micro-organisms are called pathogens, they are harmful micro-organisms. 2. Fungus grows on moist food, and microbes release enterotoxins into the food. Such toxins spoil the foods. Eating such spoiled food causes food poisoning i.e. loose motions and vomiting. 3. Pathogens may be present in water bodies contaminated with sewage, and dirt from surroundings, in food with flies sitting on it. If such contaminated food or water is consumed, we may fall ill with diseases like amoebiasis, typhoid, cholera, hepatitis, gastro, etc. 4. Pathogens are released in the air by

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