Blog

Study tips that actually help

Real strategies from real teachers and toppers. New post every week.

Biodiversity, Conservation and Environmental Issues Class 12 Biology Chapter 15 Questions And Answers Maharashtra Board

Class 12 | Biology Maharashtra Board Textbook Solutions

22 Apr 2026

Biodiversity, Conservation and Environmental Issues Class 12 Biology Chapter 15 Questions And Answers Maharashtra Board

Q. 1. Choose the correct option 1. Observe the graph and select correct option. (a) Line A represents, S = CA²(b) Line B represents, log C = log A + Z log S(c) Line A represents, S = CAZ(d) Line B represents, log S = log Z + C log A Answer. (c) Line A represents, S = CAZ 2. Select odd one out on the basis of Ex situ conservation.a. Zoological parkb. Tissue culturec. Sacred grovesd. Cryopreservation Answer. (a) Zoological park 3. Which of the following factors will favour species diversity?(a) Invasive species(b) Glaciation(c) Forest canopy(d) Co-extinction Answer. (a) Invasive species 4. The term “terror of Bengal’ is used for(a) algal bloom(b) water hyacinth(c) increased BOD(d) eutrophication Answer. (b) water hyacinth 5. CFC are air polluting agents which are produced by ______.a. Diesel trucksb. Jet planesc. Rice fieldsd. Industries Answer. (b) Jet planes Q. 2. Very short answer type questions. 1. Give two examples of biodegradable materials released from sugar industry. Answer. 2. Name any two modern techniques of protection of endangered species. Answer. 3. Where was ozone hole discovered? Answer. Ozone hole was discovered in Antarctica. 4. Give one example of natural pollutant. Answer. Volcanic ash is a natural pollutant. 5. What do you understand by EW category of living being? Answer. A species which becomes extinct in the wild (EW) is called EW category, their members are seen only in captivity or as a naturalized population outside its historic range due to massive habitat loss. Q. 3. Short answer type questions. 1. Dandiya raas is not allowed after 10.00 pm. Why? Answer. Dandiya raas involves blaring loudspeakers which cause noise pollution. It is undesired loud sound which could be hazardous for ears and general health. In India, the Air (Prevention and Control of Pollution) Act 1981, Amendment 1987, includes noise as an air pollutant. As per law noise after 10 pm is not allowed as many people may be resting. Therefore, Dandiya Raas is not allowed after 10 pm. 2. Tropical regions exhibit species richness as compared to polar regions. Justify. Answer. 3. How does genetic diversity affect sustenance of a species? Answer. 4. Is green house effect boon or bane? Give your opinion. Answer. (1) The natural greenhouse effect is good, it is a boon but human enhanced greenhouse effect is a bane. (2) In the absence of an atmosphere, Earth’s surface temperature would be about -18 °C, or 0 °F, which is too cold for sustaining life. (3) Earth is habitable because of the natural greenhouse effect. Heating of Earth’s atmosphere due to the presence of greenhouse gases such as water vapour, carbon dioxide (CO2), methane (CH4) and oxides of nitrogen (NO2). (4) Greenhouse gases have just the right molecular structure to absorb infrared radiation that the Earth emits. It re-emits most of that infrared energy in all directions, warming the atmosphere to its comfortable average temperature of 15 °C (60 °F). So, the greenhouse effect was a boon in olden days before industrialization and invention of automobiles. (5) However, due to human impact, the proportion of greenhouse gases has increased tremendously causing global warming. Thus, now greenhouse effect has become a bane. 5. How does CO cause giddiness and exhaustion? Answer. Effects of Carbon monoxide: 6. Name two types of particulate pollutants found in air. Add a note on ill effects of the same on human health. Answer. I. Types of gaseous pollutants include CO2, CO, SO2, NO, NO2, etc.(1) Carbon dioxide : It is a greenhouse gas. It is produced in excess due to human activities such as burning of fossil fuels. It is also rising due to increasing deforestation. The natural cycle of Carbon dioxide is disturbed due to human interference. Otherwise, the process of photosynthesis can balance CO2 : O2 ratio of the air. Aeroplane traffic such as a jet plane also emits lots of CO2. (2) Carbon monoxide (CO) : CO is produced due to incomplete combustion of fuels. It is a toxic gas. Vehicular exhausts produce lot of CO. II. Types of particulate pollutants are mist, dust, fume and smoke particles, smog, pesticides, heavy metals and radioactive elements, etc.(1) Dust are fine particles which enter the respiratory passage and can cause damage to delicate tissues in the lungs. Various processes such as construction work, demolition of buildings and traffic can cause dust pollution. There are natural causes of release of dust too, through wind or volcanic eruption. (2) Smoke and smog are worst type of particulate air pollutants which can cause many respiratory problems like emphysema or asthma. Q. 4. Long answer type questions. 1. Montreal protocol is an essential step. Why is it so? Answer. 2. Name any 2 personalities who have contributed to control deforestation in our country. Elaborate on importance of their work. Answer. Two personalities who have contributed to control deforestation in our country are:Saalumara Thimmakka from Karnataka and Moirangthem Loiya from Manipur.1. Saalumara Thimmakka : 2. Moirangthem Loiya : 3. How BS emission standards changed over time? Why is it essential? Answer. 4. During large public gatherings like Pandharpur vari mobile toilets are deployed by the government. Explain how this organic waste is disposed. Answer. 5. How Indian culture and traditions helped in bio-diversity conservation? Give importance of conservation in terms of utilitarian reasons. Answer. In Indian culture and traditions in different religions, biodiversity is protected and conserved. Few examples of worship of animals and plants can be given here. Conservation in terms of utilitarian reasons:The conservation of biodiversity can be done in utilitarian way or for ethical reasons. Utilitarian reasons are further classified into narrowly utilitarian and broadly utilitarian reasons: I. Narrowly utilitarian reasons: II. Broadly utilitarian reasons: III. Taking all these aspects in consideration, conservation of biodiversity becomes essential. Therefore, to protect and conserve our rich biodiversity on the planet, we have to remember all the utilitarian reasons.

Read article

Maharashtra Board

25 Feb 2026

Life Processes in Living Organisms Class 9 Science Chapter 15 Questions And Answers Maharashtra Board

1. Match the pairs and explain. Answer. (1 – b),(2 – c),(3 – a),(4 – e) 2. Complete the paragraph. The milk was on the stove. Rasika was engrossed watching television. She smelled something burning. She ran towards the kitchen. The milk was boiling over. She held the vessel with her bare hands but, screaming, she let it go at once. This activity was controlled by ……………….. cells. Special ends of ……………….. in these cells collected the information, from where it was transferred to the ……………….. and then towards the terminal end of the ……………….. The chemicals produced at the terminal end passed through the minute space i.e. ………………. . In this way, ……………….. were conducted in the body and the process of ……………….. was completed by conducting the impulses from ……………….. to ……………… (Nerve, muscle cell, impulse, dendrite, synapse, axon, reflex action, cell body) Answer. Nerve, dendrite, cell body, axon, synapse, impulses, reflex action, nerve, muscle cell. 3. Write notes on Root pressure, Transpiration, Nerve cell, Human brain, Reflex action Answer. 1. Root pressure (1) The pressure created in the root cells is called a root pressure. Root cells are in contact with water and minerals in the soil. But the concentration inside the cells and the concentration in the surrounding soil is different from each other and thus there is concentration gradient created. (2) Due to concentration gradient, the water and minerals from the surrounding areas enter in the root cells. (3) Due to this, the root cells become turgid and exert pressure on the adjacent cells. (4) Due to root pressure, the water and minerals enter the xylem present in the roots. To reduce this difference in concentration they are continuously pushed forward. This continuous movement creates a water column that is continuously pushed ahead. (5) The pressure exerted by the root cells thus is sufficient to lift the water up in small shrubs and small trees. 2. Transpiration (1) There are stomata on the leaves of the plants. Through these opening the excess of water is thrown out in the form of water vapours. This process is called transpiration. (2) There are two guard cells around the opening of stomata. They have an external membrane. They control the opening and closing of the stomata. (3) Also some amount of water is lost due to evaporation from the leaves. (4) As a result, water level in the epidermal layer of the leaf decreases. (5) To compensate this loss, more water is brought to the leaves through the xylem. (6) Transpiration thus helps in absorption of water and minerals and their distribution to all parts of the plant. (7) Root pressure pushes the water up during the night time. 3. Nerve cell (1) Neurons or nerve cells are structural and functional units of the nervous system that carry impulses from one place to other. (2) Neuron has the ability to generate and conduct electrochemical impulses. (3) Every neuron has three main parts, viz. cyton or cell body, axon and dendrites. Dendrites pick up the electrochemical signals produced. (4) These signals are transferred to cyton and from cyton they are sent to axons. From axon of one neuron, the impulse is then given to dendrites of next neuron. 4. Human brain (1) Human brain is highly evolved organ. It is the main controlling centre of nervous system. It is the part of the central nervous system. It is very well protected inside the cranium or cranial cavity. (2) The brain is enclosed by meninges which are protective coverings. There are hollow ventricles inside the brain which are filled up with cerebrospinal fluid. This fluid is protective and nourishing in function. The average weight of adult human brain is about 1300 – 1400 grams and there are approximately 100 billion neurons in the brain. (3) There are three main parts of the brain, viz. Cerebrum, cerebellum and medulla oblongata. 5. Reflex action (1) Reflex action is an immediate and involuntary response given to a stimulus from the environment. (2) The reflex action is so spontaneous that it does not require thinking or control by our brain. (3) Reflex actions are not controlled by brain. But the control and coordination is maintained by the reflex actions by which the load on the brain isreduced. They are of survival value as a person is saved from a dangerous situations due to reflex actions. (4) The path of reflex action is as follows : This is also known as reflex arc. Sense organs Sensory neurons -> Towards the spinal cord -> Coordination neuron -> Motor neuron-> Muscle or gland. 4. Name the hormones of the following endocrine glands and the function of each. Pituitary, Thyroid, Adrenal, Thymus, Testis, Ovary. Answer. Hormone Function (i) Growth hormone Stimulates growth of bones. (ii) Adrenocorticotropic hormone Stimulates adrenal gland. (iii) Thyroid-stimulating hormone Stimulates thyroid gland. (iv) Prolactin Stimulates milk production. (v) Follicle-stimulating hormone Controls growth of gonads. (vi) Luteinizing hormone Controls menstrual cycle and ovulation. (vii) Oxytocin Contracts uterus during parturition. (viii) Antidiuretic hormone Regulates water-level in the body. 2. Thyroid Hormone Function (i) Thyroxine Controls growth of body and metabolic activities. (ii) Calcitonin Controls calcium metabolism and calcium level in blood. 3. Adrenal Hormone Function (i) Adrenalin and nor-adrenalin Controls behaviour during crisis and emotional situation. (ii) Corticosteroid Maintains balance of Na+ and K+ and stimulates metabolism. 4. Thymus Hormone Function Thymosin Control the cells which give rise to immunity. 5. Testis Hormone Function Testosterone Stimulates growth of secondary sexual characteristics like beard, mustache, hoarse voice etc. in men. 6. Ovary Hormone Function (i) Oestrogen Stimulates growth of the endometrium. Stimulates growth of secondary sexual characteristics in women. (ii) Progesterone Prepares the endometrium for conception and maintains pregnancy. 5. Draw and label the diagrams. Human endocrine glands, Human brain, Nephron, Nerve cell, Human excretory system. Answer. 1. Human endocrine glands 2. Human brain 3. Nephron 4. Nerve cell 5. Human excretory system 6. Answer the following. a. Explain chemical co-ordination in humans and give the names and

Read article

Class 8 | Science | Textbook Solutions | Maharashtra Board

20 Feb 2025

Class 8 | Science | Chapter 15 | Sound | Exercise Solution | Maharashtra Board

1. Fill in the blank with appropriate word: a. The region in a sound wave, with higher pressure and density is called ………….. and that with low pressure and density is called ……….. .Answer:The region in a sound wave, with higher pressure and density is called compression and that with low pressure and density is called rarefaction. b. Medium is …………… for generation of sound.Answer:Medium is needed (or necessary) for generation of sound. c. The total number of compressions and rarefactions produced per second in a sound wave is 1000. The frequency of the sound wave is ………… .Answer:The total number of compressions and rarefactions produced per second in a sound wave is 1000. The frequency of the sound wave is 500 Hz.[Note: Total number: 100. ∴ 500 compressions and 500 rarefactions are produced per second.] d. Different sound notes have different ………………. .Answer:Different sound notes have different frequencies. e. In a loudspeaker, …………… energy is converted into ………….. energy.Answer:In a loudspeaker, mechanical energy is converted into sound energy. 2. Give scientific reasons: a. It is essential to change the tension in the vocal cords, as we produce different sound notes from our larynx.Answer:Different sound notes correspond to different frequencies. The frequency of sound depends on the tension in the vocal cords. Hence, it is essential to change the tension in the vocal cords, as we produce different sound notes our larynx. b. Astronauts on the moon cannot hear each other directly.Answer:Two astronauts on the moon talking to each other directly, will be unable to listen to each other, even if they are very close to each other. The moon does not have atmosphere. Since there is no medium which is necessary for generation and propagation of sound, between the astronauts, direct sound propagation between them is not possible. Therefore, the astronauts use some technology like the one used in our cell-phones to communicate with each other. The waves used in cell-phone do not need any medium for propagation. c. As the sound wave propagates from one place to the other in air, the air itself is not required to move from one place to the other.Answer:Propagation of sound through air occurs due to energy transfer by vibrating air molecules in one region to those in the adjacent region away from the source. The molecules simply vibrate about their mean positions. Hence, the air itself is not required to move from one place to the other. 3. How are different sound notes generated in musical instruments like guitar, which uses strings for sound generation, and flute, which uses blown air for sound generation? Answer:1. Guitar: It is a string based, flat- backed instrument. It has usually six strings, the strings are plucked or strummed with the fingers or a small piece of plastic, wood, etc. It has a flat sounding board with a circular sound hole in the centre. Also it has a fretted fingerboard. Its frequency range is more than three octaves. The frequency of vibration of the string is changed by changing the tension in the string or changing the vibrating length of the string. As the tension is increased, the frequency increases. As the vibrating length is increased, the frequency decreases. This is how different sound notes are generated.[Note: The acoustic guitar has hollow body and six or twelve strings while the electric guitar usually has solid body and six strings. The electric bass guitar has four strings.] 2. Flute: It is a wind instrument where air is blown against the edge or rim of the blowing hole. The frequency of the sound produced depends upon the length of the vibrating air column in the tube. The greater the length of the vibrating air column, the less is the frequency of the sound produced. This is how different sound notes are produced. The flute has six or seven or eight holes to generate sounds of different frequencies. Different notes can be generated also by changing the way of air-blowing. 4. How is sound produced in the human larynx and a loudspeaker? Answer:1. Sound production in the human larynx:In the humans, sound is produced in the voice box called the larynx. It is located at the upper end of the windpipe. Two vocal cords (chords) are stretched across it with a narrow slit between them for the passage of air (Fig. 15.5). When the lungs force air through the slit, the cords start vibrating. The frequency of the sound produced depends upon the length and thickness of the cords, and the tension in the chords. The frequency increases with the increase in tension and the more the length or the thickness of the cord, the less is the frequency. Muscles attached to the cords can make the cords tight (more tension) or loose (less tension). 2. Sound produced in a loudspeaker:Figure shows the internal construction of a loudspeaker. Here, a coil is wound around a permanent magnet. The conical screen of the loudspeaker is attached to the coil. When a current is passed through the coil, a magnetic field is produced. Its interaction with the permanent magnet results in the back and forth motion of the coil. The frequency and the amplitude of the motion of the coil depends on the variation in the current through the coil. As the coil moves, the conical screen also moves back and forth. The vibrations of the screen produce sound waves in air. Very loud sound can be produced by changing the current.[Note: If you gently touch the vibrating screen, you can feel the vibrations.] 5. Explain the experiment, with a neat diagram, to prove the following:‘Sound needs a material medium for propagation.’ Answer: Figure shows part of the set up used in this experiment. What is not shown is the electric circuit in which the electric bell is connected. A vacuum tight bell jar contains an electric bell connected to a power supply through the lid of the jar. The jar is placed on a smooth horizontal surface such as that of glass. Initially the vacuum pump is off and

Read article

Class 7 | Science | Textbook Solutions | Maharashtra Board

8 Jul 2024

Class 7 | Science | Chapter 15 | Material We Use | Maharashtra Board | Solution

1. Fill appropriate terms in the blanks:(white cement, soap, detergent, wearing of bones, tooth decay, hard, soft, portiand, fatty acid) a. The substance that helps water to remove dirt from the surface of material is called …………… .Answer:soap b. Fluoride is used in toothpaste to prevent …………… .Answer:tooth decay c. Soap is a salt of …………… and sodium hydroxide.Answer:fatty acid d. Synthetic detergents can be used in …………… water as well.Answer:hard e. For construction purposes …………… Cement is the most commonly used cement.Answer:white cement 2. Write answers to the following questions. a. How does the use of a detergent help to clean soiled clothes?Answer: b. How will you check with the help of soap powder whether water is hard?Answer: c. What are the important ingredients of a tooth paste and what is the function of each?Answer: d. What are the ingredients of cement?Answer: e. What will happen if cement is not used in making concrete?Answer: f. Make a list of detergents, that you use. Answer: There are two types of detergents that we use, (a) Natural (b) Man-made detergents. g. What should be expected from a detergent for delicate garments?Answer: h. What is meant by surface activity? Name three chemicals responsible for the surface activity of various detergents.Answer: 3. What are the similarities and differences between: a. Natural detergents and Man-made detergentsAnswer: Natural detergents Man-made detergents 1. Soap nut (ritha) and soap pod (shikekai) are the natural detergents. 1. Soap is man-made detergent soft soap and hard soap. 2. Natural detergents do not have harmful effect on human skin or on silk or woollen clothes. 2. Soap has effect on skin and cloth because it has chemicals in it. 3. Soap nut, soap pod contain a chemical saponin. 3. Soap has acid in it, soap is sodium and potassium salt of fatty acids. 4. It is naturally available. 4. It is man made using chemicals and oil. b. Soap and Synthetic detergentsAnswer: Soap Synthetic detergents 1. Soap is man-made detergent, it is in use since ancient times. 1. Synthetic detergent have taken the place of soap. 2. Soap loses its cleansing property in hard water it does not give lather. 2. Synthetic detergent can be used in hard water also. 3. Soap was prepared by using animal fat and wood ash. 3. Synthetic detergent are obtained by subjecting fats, kerosene to various chemical processes. 4. Variety of soaps are available, soft soap for bathing, hard soap for washing, cleaning. 4. Variety of synthetic detergents are available – Ariel, Surf Excel, etc. c. Bath soap and Soap for washing clothesAnswer: Bath soap Soap for washing clothes 1. Soft soap is used for bathing. 1. Hard soap is used for washing clothes. 2. Soft soap is potassium salt is fatty acids. 2. Hard soap is sodium salt of fatty acid. 3. Soft soap dissolves more easily readily in water. 3. Hard soap do not dissolve easily in water. 4. Now a days many perfumes, moisturizes are mixed to make it more attractive and useful. 4. In this type of soap now a days germicides, anti foaming agents are mixed to make it more useful. d. Modern cement and Ancient cementAnswer: Modem cement Ancient cement 1. Cement manufactured from 60% lime, silica 25% and alumina 5%. the rest is iron oxide and gypsum. 1. Romans used to make aqueous cement by mixing volcanic ash in moistened lime. It was very durable. 2. It is the most commonly used cement for Construction work. 2. It is Roman cement volcanic ash prevent cracks from spreading. 3. It is called Portland Cement. 3. It is called Aqueous Cement. 4. Explain why – a. Soap cannot be used in hard water.Answer: b. Oil does not mix in water. However, oil and water become homogenous if a sufficient quantity of detergent is added.Answer: c. Synthetic detergents are superior to soap.Answer: d. Often coloured spots are formed on clothes during washing.Answer: e. Tobacco masheri should not be used for cleaning teeth.Answer:

Read article