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Ecosystems and Energy flow Class 12 Biology Chapter 14 Questions And Answers Maharashtra Board

Class 12 | Biology Maharashtra Board Textbook Solutions

22 Apr 2026

Ecosystems and Energy flow Class 12 Biology Chapter 14 Questions And Answers Maharashtra Board

Q. 1. Multiple choice questions 1. Which one of the following has the largest population in a food chain?a. Producersb. Primary consumersc. Secondary consumersd. Decomposers Answer. (a) Producers 2. The second trophic level in a lake is ……………………(a) Phytoplankton(b) Zooplankton(c) Benthos(d) Fishes Answer. (b) Zooplankton 3. Secondary consumers are …………………….(a) Herbivores(b) Producers(c) Carnivores(d) Autotrophs Answer. (c) Carnivores 4. What is the % of photosynthetically active radiation in the incident solar radiation?(a) 100%(b) 50%(c) 1-5%(d) 2-10% Answer. (b) 50% 5. Give the term used to express a community in its final stage of succession?a. End communityb. Final communityc. Climax communityd. Dark community Answer. (c) Climax community 6. After landslide which of the following type of succession occurs?(a) Primary(b) Secondary(c) Tertiary(d) Climax Answer. (a) Primary 7. Which of the following is most often a limiting factor of the primary productivity in any ecosystem?(a) Carbon(b) Nitrogen(c) Phosphorus(d) Sulphur Answer. (c) Phosphorus Q. 2. Very short answer question. 1. Give an example of ecosystem which shows inverted pyramid of numbers. Answer. Number of insects dependent on a single tree, is an example of ecosystem having inverted pyramid of numbers. 2. Give an example of ecosystem which shows inverted pyramid of biomass. Answer. Oceanic ecosystem has inverted pyramid of biomass. 3. Which mineral acts as limiting factor for productivity in an aquatic ecosystem. Answer. Phosphorus acts as limiting factor for productivity in an aquatic ecosystem. 4. Name the reservoir and sink of carbon in carbon cycle. Answer. Atmosphere is the reservoir of carbon cycle, while fossil fuels embedded in ocean and oceanic waters are the sink of carbon in carbon cycle. Q. 3. Short answer questions. 1. Distinguish between upright and inverted pyramid of biomass Answer. Upright pyramid Inverted pyramid 1. In upright pyramid, the number and biomass of the organisms which are at first trophic level of producers is high. 1. In inverted pyramid, the number and biomass of organisms at first trophic levels of producers is lowest. 2. The biomass goes on decreasing at each trophic level. 2. The biomass foes on increasing at each trophic level. 3. The base of the pyramid is always in large number of producers. 3. The base of pyramid is always in small numbers of producers. 4. Pyramid is always upright. 4. Pyramid is always inverted. 2. Distinguish between Food chain and Food web. Answer. Food chain Food web 1. Food chain is the linear sequence of organisms for feeding purpose. 1. Food web is interconnections between many small food chains. 2. In food chain the flow of energy is through a single straight pathway from the lower trophic level to the higher trophic level. 2. In food web, the energy flow is interconnected through numerous food chains in the ecosystem. 3. In a food chain, members present at higher trophic level feeds on only single type of organisms. 3. In a food web, one organism can feed on multiple types of organisms. 4. Energy flow can be easily calculated in food chain. 4. Energy flow is difficult to calculate in a food web. 5. In food chain there is increased instability due to increasing number of separate and confined food chains. 5. In food web there is increased stability due to the presence of the complex food chains. 6. The whole food chain gets affected even if one group of an organism is disturbed. 6. The food web does not get disturbed by the removal of one group of organisms. 7. Member of higher trophic level depends or feed upon the single type of organisms of the lower trophic level. 7. The members of higher trophic level depend or feed upon many different types of the organism of the lower trophic level. 8. Food chain consists of only 4-6 trophic levels of different species. 8. Food web contains numerous trophic levels and also of different populations of species. 9. Competition is seen in members of same trophic level. 9. Competition is seen in members of same as well as different trophic levels. 10. Food chains are of two types:1. Grazing food chain 2. Detritus food chain. 10. In food web there are no types Q. 4. Long answer questions. 1. Define ecological pyramids and describe with examples, pyramids of number and biomass. Answer. 1. Ecological Pyramids : Ecological Pyramids are the representation of relationships between different components of ecosystem at successive trophic levels. 2. Pyramid of numbers: 3. Pyramid of biomass:(1) Pyramid of biomass are constructed by taking into consideration the different biomass in every successive trophic level.(2) Pyramid of biomass in seas in inverted as the biomass of fishes is more than the biomass of phytoplankton. 2. What is primary productivity? Give brief description of factors that affect primary productivity. Answer. (1) Primary Productivity : The rate of generation of biomass in an ecosystem which is expressed in units of mass per unit surface (or volume) per unit time, for instance grams per square metre per day (g/m²/day) is called primary productivity. (2) Primary productivity is described as gross primary productivity (GPP) and net primary productivity (NPP). (3) The rate of production of organic matter during photosynthesis is called gross primary productivity of an ecosystem. Of this the amount of energy lost through respiration of plants is called respiratory losses. (4) Gross primary productivity minus respiratory losses gives the net primary productivity (NPP). (5) Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores, carnivores and decomposers). (6) Factors affecting primary productivity: Gross primary productivity (GPP) depends on the following factors: 3. Define decomposition and describe the processes and products of decomposition. Answer. 4. Write important features of a sedimentary cycle in an ecosystem. Answer. 5. Discribe carbon cycle and add a note on the impact of human activities on carbon cycle. Answer. I. Carbon cycle:(1) The entire carbon cycle has following basic processes viz. Photosynthesis, Respiration, Decomposition, Sedimentation and Combustion. (2) Carbon is an important element as it forms 49% of the dry weight of all organisms. 71% of global

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Substances in Common Use Class 9 Science Chapter 14 Questions And Answers Maharashtra Board

Class 9 Science Maharashtra Board Textbook Solutions

25 Feb 2026

Substances in Common Use Class 9 Science Chapter 14 Questions And Answers Maharashtra Board

1. Fill in the blanks. a. The number of molecules of water of crystallization in washing soda is ………….b. The chemical name of baking soda is ………….c. …………. is used in treatment of hyperthyroidism.d. The chemical name of Teflon is …………. Answer. a. 10b. Sodium bicarbonatec. Iodine -123d. Polytetra fluoroethylene (C2F4)n 2. Match the pairs Group A Group B 1. Saturated brine a. sodium metal freed 2. Fused salt b. basic salt 3. CaOCl2 c. crystallization of salt 4. NaHCO3 d. oxidation of colour Answer. (1 – c)(2 – a)(3 – d)(4 – b) 3. Write answers to the following a. What is meant by radioactivity ? Answer. b. When is the nucleus said to be unstable ? Answer. c. Which diseases are caused by artificial food colours ? Answer. Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours. d. Where in the industrial field is radioactivity used ? Answer. Industrial field Radiography Measurement of thickness, density and level Luminescent paint and radio luminescence: Use in Ceramic articles: e. Write down properties of teflon. Answer. Properties of teflon : f. What type of colours will you use to celebrate ecofriendly Rang Panchami? Why? Answer. g. Why has the use of methods like Teflon coating become more common? Answer. The use of methods like Teflon coating became more common because of following properties of teflon: 4. Give a scientific explanation a. Bleaching powder has the odour of chlorine. Answer. b. The hard water of a well becomes soft on adding washing soda to it. Answer. c. Soap forms a precipitate in hard water. Answer. d. The particles of powder are given an electric charge while spraying them to form the powder coating. Answer. e. The aluminium article is used as an anode in the anodising process. Answer. f. When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path. Answer. (i) When the radiation coming out from certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path. This is because the radiation coming out from radioactive substance are of three types Alpha rays, Beta rays and Gamma rays. (ii) The rays which get deviated slightly towards negatively charged plate are called alpha rays. They get deviated towards negatively charged plate because they are made of positively charged particles, called as alpha particles (He++). (iii) The rays which get deviated substantially towards the positively charged plate are called beta rays. They get deviated towards a positively charged plate because they are made of negatively charged particles called as beta particles (e-). (iv) The rays which do not deviate at all are called gamma rays. They are uncharged electromagnetic radiation. Hence, marks are found at three places on the photographic plate. g. A certain type of ceramic tiles are fixed on the outer layer of a space shuttle. Answer. (i) Each shuttle is covered by more than 24,000 of the six- by six-inch advance ceramic tiles. This tiles withstand high temperatures without decomposing. They are brittle, water-resistant and electrical insulator. Most of the tiles are made of silica fibres, which are produced from high-grade sand (SiO2). (ii) Silica is an excellent insulator because it transports heat slowly. When the outer portion of a tile gets hot, the heat takes a long time to work its way down through the rest of the tile to the shuttle’s skin. The tiles keep the orbiter’s aluminium skin at 350 degrees or less. (iii) The silica fibers are mixed with water and chemicals, and the mixture is poured into molds, which are zapped in microwave ovens at 2,350°C to fuse the silica fibres. Tiles are too brittle to attach to the orbiter directly. (iv) The shuttle’s skin contracts slightly while in orbit, then expands during re-entry. (v) In addition, the stresses of launch and re-entry cause the skin to flex and bend. Such motions could easily crack the tiles or shake them off. To keep them in place, workers glue the tiles to flexible felt-like pads, then glue the pads to the orbiter. 5. Write answers to the following a. Write about artificial food colours, the substances used in them and their harmful effects. Answer. (a) Artificial food colour and substances in them. (b) Harmful effects of artificial food colours b. What is meant by water of crystallization? Give examples of salts with water of crystallization, and their uses. Answer. The exact number of water molecules which are chemically bonded to a molecule of a salt within a hydrated crystalline compound is called as water of crystallization are: Some substances in our daily use which contain water of crystallization are: Uses of these salts are as given below:(i) Alum (Potash alum – K2SO4.Al2(SO4)3.24H2O) (ii) Borax (Na2B4O7.10H2O) (iii) Epsom salt (Magnesium sulphate MgSO4.7H2O) (iv) Barium chloride (BaCl2.2H2O) (v) Sodium sulphate (Glauber’s salt Na2SO4.10H2O) (vi) Blue vitriol (Copper sulphate CuSO4.5H2O) c. Write briefly about the three methods of electrolysis of sodium chloride. Answer. 6. Write the uses.a. Anodizing b. Powder coating c. Radioactive substances d. Ceramic Answer. (a) Anodizing : Anodizing is done on aluminum cooking utensils like griddles and cookers. (b) Powder coating : Powder coating is done on iron objects to prevent rusting. Also, on Plastic and Medium density fibre (MDF) board, to make them highly durable, hard and attractive. (c) Radioactive substances:(I) Industrial field:(i) Industrial Radiography : Internal cracks and voids in cast iron articles and iron solder can be. detected with the help of gamma rays. For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera. This technique is used for detecting flaws in metal work. (ii) Measurement of thickness, density and level: It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness. In the manufacturing process, a radioactive substance

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Class 8 | Science | Textbook Solutions | Maharashtra Board

20 Feb 2025

Class 8 | Science | Chapter 14 | Measurement and Effect Of Heat | Exercise Solution | Maharashtra Board

1. A. Whom should I pair with? Group ‘A’ Group ‘B’ 1. Temperature of a healthy human body a. 296 K 2. Boiling point of water b. 98.6 °F 3. Room temperature c. 0°C 4. Freezing point of water d. 212 °F Answer: Group ‘A’ Group ‘B’ 1. Temperature of a healthy human body b. 98.6 °F 2. Boiling point of water d. 212 °F 3. Room temperature a. 296 K 4. Freezing point of water c. 0°C 1.B. Who is telling the truth? a. The temperature of a substance is measured in joule.Answer:False. (The temperature of a substance is measured in °C or °F or K.) b. Heat flows from an object at higher temperature to an object at lower temperature.Answer:True. c. The joule is the unit of heat.Answer:True. d. Objects contract on heating.Answer:False. (In general, objects expand on heating. There are some exceptions to this, you will learn about them in Standard X.) e. Atoms of a solid are free.Answer:False. (Atoms of a solid are bound to each other due to the forces acting between them.) f. The average kinetic energy of atoms in a hot object is less than the average kinetic energy of atoms in a cold object.Answer:False. (The average kinetic energy of atoms in a hot object is more than the average kinetic energy of atoms in a cold object.) 1.C. You will find if you search. a. A thermometer is used to measure ……………. .Answer:A thermometer is used to measure temperature. b. The apparatus used to measure heat is called a ………… .Answer:The apparatus used to measure heat is called a calorimeter. c. Temperature is the measure of the …………. kinetic energy of the atoms in a substance.Answer:Temperature is the measure of the average kinetic energy of the atoms in a substance. d. The heat contained in a substance is the measure of the ………….. kinetic energy of the atoms in the substance.Answer:The heat contained in a substance is the measure of the total kinetic energy of the atoms in the substance. 2. Nishigandha kept a vessel containing all the ingredients for making tea in a solar cooker. Shivani kept a similar vessel on a stove. Whose tea will be ready first and why? Answer:Shivani’s tea will be ready first.Reason: In a given time, the amount of heat received by the vessel on a stove is far greater than that received by the vessel kept in a solar cooker. 3. Write brief answers. a. Describe a clinical thermometer. How does it differ from the thermometer used in a laboratory?Answer:A clinical thermometer has a narrow stem and a long bulb filled with mercury (or alcohol). There is a small constriction in the stem above the bulb. When the bulb of the thermometer is held in the armpit or the mouth of a patient, the mercury (or alcohol) in the bulb rises in the stem. When it is taken out of the patient’s body, the small constriction does not allow the mercury (or alcohol) from the stem to retreat into the bulb. Thus, this arrangement enables us to read the temperature of the patient’s body at ease after the removal of the thermometer from his body. The clinical thermometer is graduated from 35 °C to 42 °C (or from 95 °F to 108 °F). At 37 °C (98.6 °F), there is a red arrow mark which indicates the temperature of a healthy person. The thermometer used in a laboratory has wider range and does not have constriction like a clinical thermometer. b. What is the difference between heat and temperature?Answer:Heat is related to the total kinetic energy of the atoms in a substance while temperature is related to the average kinetic energy of the atoms in the substance. Heat flows from a body at higher temperature to a body at lower temperature. Thus, temperature is a quantity that determines the direction of flow of heat. It is a quantitative measure of the degree of hotness or coldness of a body. Higher temperature does not mean higher heat content. Suppose a vessel A contains 2 litres of water at 90 °C and a vessel B contains 100 ml of water at 91 °C. Then the heat content of water in A is greater than that of water in B, but the temperature of water in B is higher than that of water in A. Units of heat:Heat is usually expressed in calorie, kilocalorie and joule. It can also be expressed in erg as heat is a form of energy. c. Explain the construction of a calorimeter. Draw the necessary figure.Answer: Figure shows the construction of a calorimeter. Like a thermo flask, a calorimeter has two vessels. The inner vessel, made of copper, is (practically) thermally isolated from the surroundings. The outer vessel is made of wood and is covered with a heat resistant lid. The lid has two holes, one for the thermometer and the other for the stirrer. The inner and outer surfaces of the inner vessel are polished for minimizing exchange of heat with the surroundings by radiation. A heat resistant ring covers the inner vessel. d. Explain why rails have gaps at specific distances.Answer:The rails expand in summer due to increase in the temperature of the atmosphere. Also, they expand due to rise in temperature caused by the friction between the rails and the wheels of the running train. If there is no gap between successive rails of a railway line, the rails would bend due to expansion. This bending and twisting of the rails would cause accidents. Hence, a gap is kept between successive rails of a railway line to make provision for their expansion in summer. Do you know: Have you seen rails? They are not continuous. A small gap is kept between them at regular intervals. This is shown in the figure. This is kept to accommodate the change in the length of the rails with change in temperature. If this gap is not kept, then the rail will get distorted due to expansion in summer

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Class 7 | Science | Textbook Solutions | Maharashtra Board

8 Jul 2024

Class 7 | Science | Chapter 14 | Elements, Compound and Mixtures | Maharashtra Board | Solution

1. Who are my companions? Group A Group B 1. Stainless steel a. Non-metal 2. Silver b. Compound 3. Bhajani mixture for milling c. Mixture 4. Salt d. Element 5. Coal e. Alloy 6. Hydrogen f. Metal Answer: Group ‘A’ Group B’ 1. Stainless steel e. Alloy 2. Silver f. Metal 3. Bhajani mixture for milling c. Mixture 4. Salt b. Compound 5. Coal a. Non-metal 6. Hydrogen d. Element 2. Write the names of elements from the following symbols:Zn, Cd, Xe, Br, Ti, Cu, Fe, Si, Ir, Pt. Answer: Symbol Element Zn Zinc Cd Cadmium Xe Xenon Br Bromine Ti Titanium Cu Copper Fe Iron Si Silicon Ir Iridium Pt Platinum 3. What are the molecular formulae of the following compounds?(Hydrochloric acid, Sulphuric acid, Sodium chloride, Glucose, Methane) Answer: 4. Give scientific reasons: a. Buttermilk is churned to get butter.Answer: b. In Chromatography the ingredients of a mixture rise up to a limited height when water rises up to the upper end of the paper.Answer:In Chromatography two properties of substances are used, (a) They are the stability of the substances in the solvent that moves up. The ability of the substance to stick to the stationary filter paper, (b) So all the components of the mixture do not rise all the way to the upper end of the filter paper but remain behind at limited heights. c. A wet cloth is wrapped around a water storage container in summer.Answer:A wet cloth will absorb the heat from the surroundings and it will keep the water in the container, cool for a longer time. 5. Explain the difference. a. Metals and Non-metalsAnswer: Metals Non-metals 1. Metals are good conductors of heat and electricity. 1. Non-metals are poor conductors of heat and electricity. 2. Metals are solids at room temperature except for mercury. 2. Non-metals exists in all three states. 3. Metals are lustrous, (shiny) 3. Non-metals are not lustrous, (dull appearance) except graphite. 4. Metals are malleable (can be hammered into sheets) 4. Non-metals are brittle, not malleable. 5. Metals are ductile, can be drawn into wire. 5. Non-metals are not ductile. 6. Metals are very hard and strong. 6. Non-metals are brittle, will break down into pieces except diamond. b. Mixture and CompoundAnswer: Mixture Compound 1. The different substances are not chemically joined together to form a mixture but mixed physically. 1. A compound is formed when two or more elements chemically combine together e.g. H2O → chemical formula of water. 2. Each substance in the mixture retains its own properties 2. Compound has fixed properties. 3. Mixtures are impure substances. 3. Compounds are pure substances. 4. Substances from the mixture can easily be separated by physical methods. 4. The constituents of a compound can be separated only by chemical methods. 5. The constituents of a mixture are present in varying proportions. 5. The constituents of a compound are present in fixed proportion. c. Atoms and MoleculesAnswer: Atoms Molecules 1. An atom is the fundamental part of matter. 1. A molecule is a group of chemically bonded atoms. 2. Atoms are basic building blocks of matter. 2. Molecule is the smallest unit of a chemical compound 3. It is foundation of molecules. 3. It is foundation of chemical compound. d. Separation by distillation and Separation by separating funnelAnswer: Separation by distillation Separation by separating funnel 1. Distillation is used for purification of impure liquids, for separating liquid and solids (Separation of mixture containing two miscible liquids) e.g. to separate salt and water from saltwater. 1. This procedure is used for separating two liquids e.g. separating oil and water, (two immiscible liquids) 6. Write answers to the following questions in your own words. a. How are the components of mixture separated by simple methods?Answer:1. Component of mixtures are separated by straining, filtering, sifting, picking, sorting, winnowing, combing with a magnet and sublimation.2. In a mixture, the constituent substances do not lose their identity, they can be separated easily by physical methods.a. Sedimentation: (i) It is a process of separating an insoluble solid from a liquid in which it is suspended, by allowing it to settle to the bottom of the container, e.g. Muddy water contains heavier particles like sand and soil, (ii) Leave this muddy water undisturbed for some time, (iii) The heavier soil and sand particles settle down and the clear upper water is poured out by decantation. b. Filtration: It is used for separating insoluble solids from a liquid, e.g. mixture of chalk and water is poured through a filter paper in a funnel while the water gets collected in the beaker below, chalk is retained in the filter paper. c. Evaporation: It is used for recovering dissolved solid substances from solutions by evaporation e.g. sugar can be recovered from sugar-water. d. Distillation: It is a process of heating a solution containing soluble solids to form vapours of the liquid and then cooling the vapours to get the liquid back. e.g. A mixture of common salt and water is taken in distillation flask and heated. Steam rises up and comes out into condenser. e. Sublimation: It is a process in which some solids on heating are transformed directly to vapour without passing through the liquid state, (i) It is used to separate a mixture of solids. The vapours are cooled separately, (ii) Used to separate ammonium chloride, iodine, camphor and sulphur from any mixture. f. Magnetic separation: A mixture with iron fillings as one of the components can be separated using magnet to attract the iron particles away from the mixture. b. Which elements (metals, non-metals) compounds and mixtures do we use in our day to day life?Answer:Elements – non-metal Elements – metals Compounds: Mixtures: c. In everyday life, where and for what purpose do we use centrifugation?Answer:Centrifugation: It is a process which involves application of centrifugal force.1. It is used in industrial and laboratory settings. It is used for separation of fluids, gas or liquid based on density. In centrifugation mixture is separated through spinning and the

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