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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.

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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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Organisms and Populations Class 12 Biology Chapter 13 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
21 Apr 2026

Organisms and Populations Class 12 Biology Chapter 13 Questions And Answers Maharashtra Board

Q. 1. Multiple choice questions 1. Which factor of an ecosystem includes plants, animals and microorganisms?(a) Biotic factor(b) Abiotic factor(c) Direct factor(d) Indirect factor Answer. (a) Biotic factor 2. An assembladge of individuals of different species living in the same habitat and having functional interactions is …………….a. Biotic communityb. Ecological nichec. Populationd. Ecosystem Answer. (a) Biotic community 3. Association between sea anemone and Hermit crab in gastropod shell is that of ………………..(a) Mutualism(b) Commensalism(c) Parasitism(d) Amensalism Answer. (b) Commensalism 4. Select the statement which explains best parasitism.a. One species is benefited.b. Both the species are benefited.c. One species is benefited, other is not affected.d. One species is benefited, other is harmed. Answer. (d) One species is benefited, other is harmed. 5. Growth of bacteria in a newlly innoculated agar plate shows …………….a. exponential growthb. logistic growthc. Verhulst-Pearl logistic growthd. zero growt Answer. (c) Verhulst-Pearl logistic growth Q. 2. Very short answer questions. 1. Define the following terms : a. Commensalism Answer. The interaction between two species in which one species gets benefits and the other is neither harmed nor benefited is called commensalism. b. Parasitism Answer. The interaction between two species in which one parasitic species derives benefit from the other host species by harming it is called parasitism. c. Camouflage Answer. Camouflage is the disguising colouration or behaviour to merge with the surrounding so that prey or predator can remain hidden. 2. Give one example for each : a. Mutualism Answer. Lichen is composed of alga (cyanobacteria) and fungus. They cannot survive independently. Their association is mutualistic alga synthesises food by photosynthesis and fungus does the absorption of moisture. b. Interspecific competition Answer. Leopard and lion competing for a same prey. Sheep and cow competing for grazing in the same land. 3. Name the type of association: a. Clown fish and sea anemone Answer. Commensalism b. Crow feeding the hatchling of Koel Answer. Brood parasitism c. Humming birds and host flowering plants Answer. Mutualism 4. What is the ecological process behind the biological control method of managing with pest insects? Answer. Protocooperation: Q. 3. Short answer questions. 1. How is the dormancy of seeds different from hibernation in animals? Answer. In dormancy seed is not showing any metabolic activities. It can come back to life if and only if it gets suitable moisture and sunlight. Hibernation is suspended state, in which metabolic reactions do take place but at a very reduced pace. Animal arouses on its own after the winter sleep is over. This arousal is spontaneous and depends upon the ambient temperature. Dormant seed does not show such change unless it is planted or thrown in to moist place. 2. If a marine fish is placed in a fresh water aquarium, will it be able to survive? Give reason. Answer. Marine fish has its own osmoregulation which is different from the osmoregulation seen in fresh water fish. In marine water, the ambient salinity is more than the concentration of ions in the body. But in fresh water reverse is the case. Therefore, marine fish has different machinery to cope up with high saline environment. Therefore, it cannot survive in fresh water as its osmoregulation is not possible in less saline waters. 3. Name important defense mechanisms in plants against herbivores. Answer. Some important defence mechanisms in plants against herbivores are thorns, toxic chemicals, secondary metabolites, etc. Herbivores feed on plants and thus they are predators for the vegetations.Plants therefore have evolved variety of morphological and chemical defences against herbivores, which are as follows :  1. Thorns : Thorns seen in Cactus or Acacia make the plant inedible and thus this is the most common morphological means of defence. 2. Toxic chemicals : Many plants produce and store chemicals that are toxic and unpalatable, affecting feeding herbivores. When these secretions are consumed, they inhibit feeding or digestions in the predator, disrupt reproduction, or even kill it. 3. Secondary metabolites : Plants like Calotropis produce highly poisonous cardiac glycosides which can act toxic to the grazers. A wide variety of chemical substances such as nicotine, caffeine, quinine, strychnine, opium, etc. are secondary metabolites produced by plants which act as defences against grazers and browsers. 4. An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree? Answer. 5. Distinguish between the following: a. Hibernation and Aestivation Answer. Hibernation Aestivation 1. Hibernation is winter sleep shown by some warm-blooded and some cold-blooded animals. 1. Aestivation is the type of summer sleep, shown by cold-blooded animals. 2. It is for the whole winter. 2. It is of short duration. 3. The animals look out for the warmer place to enter into hibernation. 3. Animals search for the moist, shady and cool place to sleep. 4. Metabolic activities of hibernators slowdown in this dormant stage. 4. Metabolic activities of aestivators remain low during aestivation period. 5. Hibernation helps in maintaining the body temperature and prevents any internal body damage due to low temperatures.E.g. Bats, birds, mammals, insects, etc. show hibernation. 5. Aestivation helps in maintaining the body temperature by avoiding the excessive water loss and thus prevents any internal body damaged due to high temperatures.E.g. Bees, snails, earthworms, salamanders, frogs, earthworms, crocodiles, tortoise, etc. show aestivation. b. Ectotherms and Endotherms Answer. Ectotherms Endotherms 1. Ectotherms do not have ability to generate heat in the body. 1. Endotherms possess the ability to generate their own body heat. 2. Ectotherms depend on the environmental sources to heat their bodies. E.g sunlight. 2. Endotherms do not depend upon outside sources to generate heat. 3. Most ectotherms are confined to warmer parts of the world. 3. Endotherms inhabit coldest parts of the earth. 4. Body temperature of ectotherms fluctuate according to ambient temperature. 4. Body temperatures of endotherms remain constant and do not show fluctuations as per ambient temperatures. 5. Metabolic rate of ectotherms is low.E.g. Amphibians and reptiles. 5. Metabolic rate of endotherms is high.E.g. Mammals and birds c. Parasitism and Mutualism Answer. Parasitism Mutualism 1. Parasitism is the

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Biotechnology Class 12 Biology Chapter 12 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
21 Apr 2026

Biotechnology Class 12 Biology Chapter 12 Questions And Answers Maharashtra Board

Q. 1. Choose the correct option 1. The bacterium which causes a plant disease called crown gall is …………….b. Helicobacter pyloric. Agrobacterium tumifaciensd. Thermophilus aquaticuse. Bacillus thuringienesis Answer. (b) Agrobacterium tumifaciens 2. The enzyme nuclease hydrolyses …………… of polynucleotide chain of DNA.a. hydrogen bondsb. phosphodiester bondsc. glycosidic bondsd. peptide bonds Answer. (b) phosphodiester bonds 3. In vitro amplification of DNA or RNA segment is known as ……………a. chromatographyb. southern blottingc. polymerase chain reactiond. gel electrophoresis Answer. (c) polymerase chain reaction 4. Which of the following is the correct recognition sequence of restriction enzyme hind III.(a) 5′ —A-A-G-C-T-T— 3′3′ —T-T-C-G-A-A—5′(b) 5′ — G-A-A-T-T-C—3′3′ — C-T-T-A-A-G—5′(c) 5′ — C-G-A-T-T-C—3′3′ — G-C-T-A-A-G—5′(d) 5′ — G-G-C-C—3′3′ — C-C-G-G—5′ Answer. (a) 5’ —A-A-G-C-T-T—3’3’ —T-T-C-G-A-A—5’ 5. Recombinant protein ……………… is used to dissolve blood clots present in the body.a. insulinb. tissue plasminogen activatorc. relaxind. erythropoietin Answer. (b) tissue plasminogen activator 6. Recognition sequence of restriction enzymes are generally ……………….. nucleotide long.(a) 2 to 4(b) 4 to 8(c) 8 to 10(d) 14 to 18 Answer. (b) 4 to 8 Q. 2. Very short answer type questions. 1. Name the vector which is used in protuction of human insulin through recombinent DNA technology. Answer. PBR 322 2. Which cells from Langerhans of pancreas do produce a peptide hormone insulin? Answer.  β-cells of islets of Langerhans of pancreas produce a peptide hormone insulin. 3. Give the role of Ca++ ions in the transfer of recombinant vector into bacterial host cell. Answer. Ca++ ions promotes binding of plasmid DNA to lipo polysaccharides on bacterial cell surface. Then plasmid can enter the cell on heat shock. 4. Expand the following acronyms which are used in the field of protechnology.i. YAC ii. RE iii. dNTP iv. PCR v. GMO vi. MAC Answer. 5. Fill in the blanks and complete the chart. Answer. GMO Purpose (i) Bt cotton Insect resistance (ii) Flavr savr Tomato Delay the softening of tomato during ripening (iii) Golden rice Rich in vitamin A (iv) Holstein cow High milk productivity Q. 3. Short answer type questions. 1. Explain the properties of a good and ideal cloning vector for rDNA technology. Answer. Desired characteristics of ideal cloning vector are as follows: 2. A PCR machine can rise temperature up to 100 °C but after that it is not able to lower the temperature below 70 °C automatically. Which step of PCR will be hampered first in this faulty machine? Explain why? Answer. 3. In the process of r-DNA technology, if two separate restriction enzymes are used to cut vector and donor DNA then which problem will arise in the formation of r-DNA or chimeric DNA? Explain. Answer. In the process of r-DNA technology, if two separate restriction enzymes are used to cut vector and donor DNA, then it will result in fragments with different sticky ends which will not be complementary to each other. 4. Match and write the pairs. Answer. Recombinent protein Its use in or for (1) Platelet derived growth factor (g) Atherosclerosis (2) a-antitrypsin (e) Emphysema (3) Relaxin (f) Parturition (4) Eryhthropoietin (a) Anemia (5) Factor VIII (c) Haemophilia A (6) DNA ase (b) Cystic fibrosis Q. 4. Long answer type questions. 1. Define and explain terms. i. Biopiracy Answer. Following are the examples of biopiracy:(a) Patenting of Neem (Azadirachta indica): (b) Patenting of Basmati: (c) Haldi (Turmeric) Biopiracy: ii. Biopatent Answer. This patent was not granted by Indian government. Such a patent is considered morally unacceptable and fundamentally unequitable. Such patents would pose a threat to global food security as financially powerful corporations would acquire monopoly over biotechnological process. iii. Bioethics Answer. Ethical aspects pertaining to the use of biotechnology are: 2. Explain the steps in process of rDNA technology with suitable diagrams. Answer. The steps involved in gene cloning are as follows:(1) Isolation of DNA (gene) from the donor organism: (2) Insertion of desired foreign gene into a cloning vector (vehicle DNA): (3) Transfer of r-DNA into suitable competent host or cloning organism: (4) Selection of the transformed host cell: (5) Multiplication of transformed host cell: (6) Expression of gene to obtain desired product. Then desired products like enzymes, antibiotiocs etc. separated and purified through down stream processing using bioreactors. 3. Explain the gene therapy. Give two methods of the same. Answer. Gene therapy is the treatment of genetic disorders by replacing, altering or supplementing a gene that is absent or abnormal and whose absence or abnormality is responsible for the disease.Types of gene therapy:(a) Germ line gene therapy: (b) Somatic cell gene therapy: 4. How are the transgenic mice used in cancer research? Answer. 5. Give the steps in PCR or polymerase chain reaction with suitable diagrams. Answer. (1) The DNA segment and excess of two primer molecules, four types of dNTPs, the thermostable DNA polymerase are mixed together in ‘eppendorf tube’. (2) One PCR cycle is of 3-4 minutes duration and it involves following steps: (3) In an automatic thermal cycler, the above three steps are automatically repeated 20-30 times.(4) Thus, at the end of ‘n’ cycles 2n copies of DNA segments, get synthesized. 6. What is a vaccine? Give advantages of oral vaccines or edible vaccines. Answer. 7. Enlist different types of restriction enzymes commonly used in rDNA technology? Write on their role. Answer. 8. Enlist and write in breif about the different biological tools required in rDNA technology. Answer. The biological tools used in r-DNA technology are various enzymes, cloning vectors and competent hosts.(1) Enzymes: (2) Vectors: (3) Competent host cells:

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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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Human Health and Diseases Class 12 Biology Chapter 10 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
18 Apr 2026

Human Health and Diseases Class 12 Biology Chapter 10 Questions And Answers Maharashtra Board

Q. 1. Multiple Choice Questions. 1. Which of the following is NOT caused by unsterilized needles?a. Elephantiasisb. AIDSc. Malariad. Hepatitis B Answer. (a) Elephantiasis 2. Opium derivative is …………………(a) Codeine(b) Caffeine(c) Heroin(d) Psilocybin Answer. (c) Heroin 3. The stimulant present in tea is …………………(a) tannin(b) cocaine(C) caffeine(d) crack Answer. (c) caffeine 4. Which of the following is caused by smoking?a. Liver cirrhosisb. Pulmonary tuberculosisc. Emphysemad. Malaria Answer. (c) Emphysema 5. An antibody is …………………(a) molecuic that binds specifically an antigen(b) WBC which invades bacteria(c) secretion of mammalian RBC(d) cellular component of blood Answer. (a) molecule that binds specifically an antigen 6. The antiviral proteins released by a virus-infected cell are called …………………(a) histamines(b) interferons(c) pyrogens(d) allergens Answer. (b) interferons 7. Both B-cells and T-cells are derived from ………………..a. lymph nodesb. thymus glandsc. liverd. stem cells in bone marrow Answer. (b) thymus glands 8. Which of the following diseases can be contracted by droplet infection?(a) Malaria(b) Chicken pox(c) Pneumonia(d) Rabies Answer. (c) Pneumonia 9. Confirmatory test used for detecting HIV infection is …………………(a) ELISA(b) Western blot(c) Widal test(d) Eastern blot Answer. (b) Western blot 10. Elephantiasis is caused by …………………(a) W. barterofti(b) P. vivax(c) Bedbug(d) Elephant Answer. (a) W. bancrofti 11. Innate immunity is provided by …………………(a) phagocytes(b) antibody(c) T-lymphocytes(d) B-lymphocytes Answer. (c) T-lymphocytes Q. 2. Very Short Answer Questions 1. What is the source of cocaine ? Answer. Source of cocaine is coca plant – Erythroxylum coca. 2. Name one disease caused by smoking? Answer. Emphysema. (Damaged and enlarged lungs causing breathlessness) 3. Which cells stimulate B-cells to form antibodies? Answer. Helper T-cells stimulate B-cells to form antibodies. 4. What does the abbreviation AIDS stand for? Answer. AIDS stands for Acquired Immuno Deficiency Syndrome. 5. Name the causative agent of typhoid fever? Answer. Salmonella typhi 6. What is Rh factor? Answer. Antigen ‘D’ present on the surface of RBCs is known as Rh factor. 7. What is schizont? Answer. Schizont is a ring-like form produced from merozoites inside the erythrocytes of human beings, infected by Plasmodium, which again forms new merozoites. 8. Name the addicting component found in tobacco. Answer. Nicotine 9. Name the pathogen causing Malaria. Answer. Plasmodium vivax 10. Name the vector of Filariasis. Answer. Female Culex mosquito 11. Give the name of the causative agent of ringworm. Answer. Trichophyton 12. Define health. Answer. Health is defined as the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. Q. 3. Short Answer Questions: 1. What are acquired diseases? Answer. Diseases which are developed after the birth of an individual are called acquired diseases. These are of two types, viz. (a) Communicable or infectious diseases and (b) Non- communicable or Non-infectious diseases. Communicable or infectious diseases are transmitted from infected person to another healthy person either directly or indirectly. They are caused due to pathogens like viruses, bacteria, fungi, helminth worms, etc. Non-communicable or Non-infectious diseases cannot be transmitted from infected person to another healthy one either directly or indirectly. 2. Differentiate between antigen and antibody. Answer. Antigen Antibody 1. Antigens are foreign proteins which are capable of producing infection. 1. Antibodies are immunoglobulins produced by the body to act against the antigens. 2. The structure of antigens is variable dependent upon the type of pathogen. 2. The structure of antibody is Y-shaped. 3. The antigen is the ‘non-self’ molecule. 3. The antibody is ‘self’ molecule. 4. The antigens have epitope sites which bind with the antibody molecule. 4. The antibodies have paratope sites which bind with the antigen molecule. 3. Name the infective stage of Plasmodium. Give any two symptoms of malaria. Answer. SporozoiteI. Symptoms of malaria: II. Spread / Transmission of malaria: 4. Explain the mode of infection and cause of elephantiasis. Answer. Mode of infection, i.e. transmission: 5. Why is smoking a bad habit? Answer. 6. What do the abbreviations AIIMS and CMIS denote? Answer. AMIS is Antibody-mediated immune system or humoral immunity and CMIS is cell- mediated immune system. 7. What is a carcinogen? Name one chemical carcinogen with its target tissue. Answer. 8. Distinguish between active immunity and passive immunity. Answer. Active immunity Passive immunity 1. Active immunity is produced in response to entry of pathogens and their antigenic stimuli. 1. Passive immunity is produced due to antibodies that are transferred to the body. 2. Active immunity is the long lasting immunity. 2. Passive immunity is short-lived immunity. 3. In active immunity, the body produces its own antibodies. 3. In passive immunity, antibodies are given to the body from outside. 4. Natural acquired active immunity is obtained due to infections by pathogens. 4. Natural acquired passive immunity is obtained through antibodies of mother transmitted- to baby by placenta or colostrum. 5. Artificial acquired active immunity is obtained through vaccinations. These vaccines contain dead or live but attenuated pathogens. 5. Artificial acquired passive immunity is also obtained through vaccinations, but here the vaccines contain the readymade antibodies which are prepared with the help of other animals such as horses. Q. 4. Short Answer Questions 1. Differentiate between B-cells and T-cells. Answer. B-cells T-cells. 1. B-cells are type of lymphocyte whose origin is in bone marrow but maturation is in blood. 1. T-cells are type of lymphocytes which originate in bone marrow but maturation occurs in thymus. 2. B-cells Eire type of lymphocytes which are involved in humoral mediated immunity. 2. T-cells are type of lymphocytes which are involved in cell-mediated immunity. 3. 20% of lymphocytes present in the blood are B-cells. 3. 80% of lymphocytes present in the blood are T-cells. 4. Two types of B-cells are Memory cells and Plasma cells. 4. T-cells are of following subtypes : Cytotoxic T-cells, helper T-cells, suppressor T-cells. 5. They are involved in antibody mediated immunity. (AMI) 5. They are involved in cell-mediated immunity (CMI). 6. B-cells produced antibodies with which they fight against pathogens. 6. T-cells do not produce antibodies. 7. B-cells have membrane bound immunoglobulins located on the surface. 7. There is a presence of T cell

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Control and Coordination Class 12 Biology Chapter 9 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
15 Apr 2026

Control and Coordination Class 12 Biology Chapter 9 Questions And Answers Maharashtra Board

Q. 1. Multiple choice questions. 1. The nervous system of mammals uses both electrical and chemical means to send signals via neurons. Which part of the neuron receives impulse?(a) Axon(b) Dendron(c) Nodes of Ranvier(d) Neurilemma Answer. (b) Dendron 2. ……………. is a neurotransmitter.(a) ADH(b) Acetyl CoA(c) Acetyl choline(d) Inositol Answer. (c) Acetyl choline 3. The supporting cells that produce myelin sheath in the PNS are ______.a. Oligodendrocytesb. Satellite cellsc. Astrocytesd. Schwann cells Answer. (d) Schwann cells 4. A collection of neuron cell bodies located outside the CNS is called …………….(a) tract(b) nucleus(c) nerve(d) ganglion Answer. (d) ganglion 5. Receptors for protein hormones are located …………….(a) in cytoplasm(b) on cell surface(c) in nucleus(d) on Golgi complex Answer. (b) on cell surface 6. If parathyroid glands of a man are removed, the specific result will be ——a. onset of agingb. disturbance of  Ca++c. onset of myxoedemad. elevation of blood pressure Answer. (b) disturbance of Ca++ 7. Hormone thyroxine, adrenaline and non¬adrenaline are formed from ……………(a) Glycine(b) Arginine(c) Ornithine(d) Tyrosine Answer. (d) Tyrosine 8. Pheromones are chemical messengers produced by animals and released outside the body. The odour of these substance affects …………….(a) skin colour(b) excretion(c) digestion(d) behaviour Answer. (d) behaviour 9. Which one of the following is a set of discrete endocrine glands?a. Salivary, thyroid, adrenal, ovaryb. Adrenal, testis, ovary, liverc. Pituitary, thyroid, adrenal, thymusd. pituitary, pancreas, adrenal, thymus Answer. (c) Pituitary, thyroid, adrenal, thymus 10. After ovulation, Graafian follicle changes intoa. Corpus luteumb. Corpus albicansc. Corpus spongiosumd. Corpus callosum Answer. (a) corpus luteum 11. Which one of the following pair correctly matches a hormone with a disease resulting from its deficiency?a. Parathyroid hormone – Diabetes insipidusb. Leutinising hormone – Diabetes mellitusc. Insulin – Hyperglycemiad. Thyroxine – Tetany Answer. (c) Insulin – Hyperglycaemia 12. ……………. is in direct contact of brain in humans.(a) Cranium(b) Dura mater(c) Arachnoid(d) Pia mater Answer. (d) Pia mater Q. 2. Very very short answer questions. 1. What is the function of red nucleus? Answer. Red nucleus plays an important role in controlling posture and muscle tone, modifying some motor activities and motor coordination. 2. What is the importance of corpora quadrigemina? Answer. Corpora quadrigemina consists of 4 solid rounded structures, viz. superior and inferior colliculi. Superior colliculi control visual reflexes while inferior colliculi control auditory reflexes. 3. What does the cerebellum of brain control? Answer. Cerebellum of brain is an important centre which maintains equilibrium of body, posture, balancing orientation, moderation of voluntary movements and maintenance of muscle tone. 4. Name the three ear ossicles. Answer. Malleus [hammer], incus [anvil] and stapes [stirrup]. 5. Name the anti abortion hormone. Answer. Progesterone. 6. Name an organ which acts as temporary endocrine gland. Answer. Placenta. Corpus luteum in ovary. 7. Name the type of hormones which bind to the DNA and alter the gene expression. Answer. Steroid hormones. 8. What is the cause of abnormal elongation of long bones of arms and legs and of lower jaw. Answer. Hypersecretion of growth hormones in adults causes abnormal elongation of long bones of arms and legs and of lower jaw i.e. acromegaly. 9. Name the hormone secreted by the pineal gland. Answer. Melatonin. 10. Which endocrine gland plays important, role in improving immunity? Answer. The endocrine gland, thymus plays an important role in improving immunity. Q. 3. Match the organism with the type of nervous system found in them Column A Column B (1) Neurons (a) Earthworm (2) Ladder type (b) Hydra (3) Ganglion (c) Flatworm (4) Nerve net (d) Human Answer. olumn A Column B (1) Neurons (d) Human (2) Ladder type (c) Flatworm (3) Ganglion (a) Earthworm (4) Nerve net (b) Hydra Q. 4. Very short answer questions. 1. Describe the endocrine role of islets of Langerhans. Answer. Endocrine cells of pancreas form groups of cells called Islets of Langerhans. There are four kinds of cells in islets of Langerhans which secrete hormones. 2. Mention the function of testosterone? Answer. Testosterone is a steroid sex hormone secreted by testes and cortex of adrenal glands. It controls the secondary sexual characters in males. 3. Give symptoms of the disease caused by hyposecretion of ADH. Answer. Polydipsia, i.e. frequent thirst and polyuria, i.e. frequent urination are the symptoms of the disease caused by hyposecretion of ADH. Q. 5. Short answer questions 1. Rakesh got hurt on his head when he fell down from his motorbike. Which inner membranes must have protected his brain? What other roles do they have to play? Answer. 2. Give reason – Injury to medulla oblongata may prove fatal. Answer. 3. Distinguish between the sympathetic and parasympathetic nervous system on the basis of the effect they have on: a. Heart beat b. Urinary Bladder Answer. Sympathetic Nervous System Parasympathetic Nervous System (1) Heartbeat Increases Decreases (2) Urinary bladder Relaxes and stores urine Contracts causing micturition 4. While holding a tea cup Mr. Kothari’s hands rattle. Which disorder he may be suffering from and what is the reason for this? Answer. 5. List the properties of the nerve fibres. Answer. 6. How does the tongue detect the sensation of taste? Answer. 7. State the site of production and function of Secretin, Gastrin and Cholecystokinin. Answer. Hormone Site of production Functions 1. Secretin Duodenal mucosa Stimulates secretion of pancreatic juice and bile from pancreas and liver respectively. 2. Gastrin Gastric mucosa Stimulates gastric glands to secrete gastric juice. 3. Cholecystokinin Duodenal mucosa Stimulates pancreas and gall bladder to release pancreatic enzymes and bile respectively. 8. An adult patient suffers from low heart rate, low metabolic rate and low body temperature. He also lacks alertness, intelligence and initiative. What can be this disease? What can be its cause and care? Answer. 9. Where is the pituitary gland located? Enlist the hormones secreted by anterior pituitary. Answer. The pituitary gland is attached to hypothalamus on the ventral surface of brain. It is lodged in a bony depression called sella turcica of sphenoid bone.For names of hormones: Gonadotropins- 10. Explain how the adrenal medulla and sympathetic nervous system function as a

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Respiration and Circulation Class 12 Biology Chapter 8 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
15 Apr 2026

Respiration and Circulation Class 12 Biology Chapter 8 Questions And Answers Maharashtra Board

Q. 1. Choose the correct alternatives from those given below and complete the statements. 1. The muscular structure that separates the thoracic and abdominal cavity is …………………..(a) pleura(b) diaphragm(c) trachea(d) epithelium Answer. (b) diaphragm 2. What is the minimum number of plasma membrane that oxygen has to diffuse across to pass from air in the alveolus to haemoglobin inside a R.B.C.?(a) two(b) three(c) four(d) five Answer. (a) two 3. …………………. is a sound producing organ.(a) Larynx(b) Pharynx(c) Tonsils(d) Trachea Answer. (a) Larynx 4. The maximum volume of gas that is inhaled during breathing in addition to T.V. is …………………..(a) residual volume(b) IRV(c) GRV.(d) vital capacity Answer. (b) IRV 5. ……………. muscles contract when the external intercostal muscles contracta. Internal abdominalb. Jawc. Muscles in bronchial wallsd. Diaphragm Answer. (d) Diaphragm 6. Movement of cytoplasm in unicellular organisms is called …………………..(a) diffusion(b) cyclosis(c) circulation(d) thrombosis Answer. (b) cyclosis 7. Which of the following animals do not have closed circulation?(a) Earthworm(b) Rabbit(c) Butterfly(d) Shark Answer. (c) Butterfly 8. Diapedesis is performed by …………………..(a) erythrocytes(b) thrombocytes(c) adipocytes(d) leucocytes Answer. (d) leucocytes 9. Pacemaker of heart is …………………..(a) SA node(b) AV node(c) His bundle(d) Purkinje fibers Answer. (a) SA node 10. Which of the following is without nucleus?(a) Red blood corpuscle(b) Neutrophil(c) Basophil(d) Lymphocyte Answer. (a) Red blood corpuscle 11. Cockroach shows which kind of circulatory system?(a) Open(b) Closed(c) Lymphatic(d) Double Answer. (a) Open 12. Diapedesis can be seen in …………………..(a) RBCl(b) WBC(c) Platelet(d) neuron Answer. (b) WBC 13. Opening of inferior vena cava is guarded by ______.a. bicuspid valveb. tricuspid valvec. Eustachian valved. Thebesian valve Answer. (c) Eustachian valve 14. …………………. wave in ECG represent atrial depolarization.(a) P(b) QRS complex(c) Q(d) T Answer. (a) P 15. The fluid seen in the intercellular spaces in Human is …………………..(a) blood(b) lymph(c) interstitial fluid(d) water Answer. (b) lymph Q. 2. Match the Respiratory surface to the organism in which it is found. Respiratory surface Organism (1) Plasma membrane (a) Insect (2) Lungs (b) Salamander (3) External gills (c) Bird (4) Internal gills (d) Amoeba (5) Trachea (e) Fish Answer. Respiratory surface Organism (1) Plasma membrane (d) Amoeba (2) Lungs (c) Bird (3) External gills (b) Salamander (4) Internal gills (e) Fish (5) Trachea (a) Insect Q. 3. Very short answer questions. 1. Why does trachea have ‘C’ shaped rings of cartilage? Answer. Trachea is supported by ‘C’-shaped rings of J cartilage which prevent it from collapsing and always keep it open. 2. Why is respiration in insect called direct respiration? Answer. Respiration in insect is called direct because tracheal tubes exchange O2 and CO2 directly with the haemocoel which then exchange them with tissues. 3. Why is gas exchange very rapid at alveolar level. Answer. Gas exchange is very rapid at alveolar level because numerous alveoli (about 700 millions) in the lungs provide large surface area for gaseous exchange. 4. Name the organ which prevents the following the entry of food into the trachea while eating. Answer. Epiglottis prevents the entry of food into trachea while eating. Q. 4. Short answer questions. 1. Why is it advantageous to breathe through the nose than through the mouth? Answer. Breathing through nose is better than breathing through the mouth because of the following reasons: 2. Identify the incorrect statement and correct it,a. A respiratory surface area should have a large surface area.b. A respiratory surface area should be kept dry.c. A respiratory surface area should be thin, may be 1mm or less. Answer. Statement (a) and statement (c) are correct whereas statement (b) is incorrect. A respiratory surface area should be kept moist, is the correct statement. 3. Given below are the characteristics of some modified respiratory movement. Identify them. a. Spasmodic contraction of muscles of expiration and forceful expulsion of air through nose and mouth. Answer. Sneezing b. An inspiration followed by many short convulsive expiration accompanied by facial expression. Answer. Laughing, Crying. 4. Write a note on blood plasma. Answer. 5. Explain blood clotting in short. Answer. 6. Describe pericardium. Answer. 7. Describe valves of human heart. Answer. Human heart has following main valves: 8. What is role of papillary muscles and chordae tendinae in human heart? Answer. 9. Explain in brief the factors affecting blood pressure. Answer. Q. 5. Give scientific reason. 1. Closed circulation is more efficient than open circulation. Answer. 2. Human heart is called as myogenic and autorhythmic. Answer. 3. Person who has undergone heart transplant needs lifetime supply of immunosupressants. Answer. a. Immunosuppressants are the drugs that reduce the level of immune activity and the risk of rejection of foreign bodies such as transplant organs. b. After transplantation, there is a risk of graft rejection as the body may recognize the transplanted organ/tissue as foreign and may trigger an immune response thereby damaging the transplanted organ. Therefore, the heart recipient has to rely upon lifetime supply of immunosuppressants. 4. Arteries are thicker than veins. Answer. 5. Left ventricle is thick than all other chambers of heart. Answer. Q. 6. Distinguish between : 1. Open and closed circulation. Answer. Open circulation Closed circulation 1. In open circulation, blood flows through large open spaces and channels called lacunae and haemocoels among the tissues. 1. In closed circulation, blood flows through a network of blood vessels all over the body. 2. Tissues are in direct contact with the blood. 2. Blood does not come in direct contact with tissue. 3. Blood flows with low pressure and usually does not contain any respiratory pigment like haemoglobin. 3. Blood flows with high pressure and contains respiratory pigment like haemoglobin. 4. Exchange of material takes place directly between blood and cells or tissues of the body. 4. Exchange of material takes place between blood and body tissues through an intermediate fluid called lymph. 5. Volume of blood flowing through a tissue cannot be controlled as blood flows out in open space. 5. Volume of blood can be regulated by the contraction and relaxation of the smooth muscles of the blood vessels. 6. Open circulatory system is found in arthropods

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Plant Growth and Mineral Nutrition Class 12 Biology Chapter 7 Questions And Answers Maharashtra Board
Class 12 | Biology Maharashtra Board Textbook Solutions
14 Apr 2026

Plant Growth and Mineral Nutrition Class 12 Biology Chapter 7 Questions And Answers Maharashtra Board

Q. 1. Multiple choice questions. 1. Which of the hormones can replace vernalization?a. Auxinb. Cytokininc. Gibberellinsd. Ethylene Answer. (c) Gibberellins 2. The principle pathway of water translocation in angiosperms is ……….a. Sieve cellsb. Sieve tube elementsc. Xylemd. Xylem and phloem Answer. (c) Xylem 3. Abscisic acid controls ………………a. cell divisionb. leaf fall and dormancyc. shoot elongationd. cell elongation and wall formation Answer. (b) leaf fall and dormancy 4. Which is employed for artificial ripening of banana fruits?(a) Auxin(b) Ethylene(c) Cytokinin(d) Gibberellin Answer. (b) Ethylene 5. Which of the following is required for stimulation of flowering in the plants?a. Adequate oxygenb. Definite photoperiodc. Adequate waterd. Water and minerals Answer. (b) Definite photoperiod 6. For short day plants, the critical period is ………………..(a) light(b) dark/night(c) UV rays(d) Both (a) and (c) Answer. (b) dark/night 7. Which of the following is day neutral plant?a. Tomatob. Cottonc. Sunflowerd. Soybean Answer. (d) Soybean 8. Essential macroelements are …………a. manufactured during photosynthesisb. produced by enzymesc. absorbed from soild. produced by growth hormone Answer. (c) absorbed from soil 9. Function of Zinc is …………….a. closing of stomatab. biosynthesis of 3-IAAc. synthesis of chlorophylld. oxidation of carbohydrates Answer. (b) biosynthesis of 3-IAA 10. Necrosis means ……………a. yellow spots on the leavesb. death of tissuec. darkening of green colour in leavesd. wilting of leaves Answer. (b) death of tissue 11. Conversion of nitrates to nitrogen is called …………………a. ammonificationb. nitrificationc. nitrogen fixationd. denitrification Answer. (d) denitrification 12. How many molecules of ATP are required to fix one molecule of nitrogen?(a) 12(b) 20(c) 6(d) 16 Answer. (d) 16 Q. 2. Very Short Answer Questions : 1. Enlist the phases of growth in plants? Answer. The three phases of growth are phase of cell division, phase of cell enlargement and phase of cell maturation. 2. Give the full form of IAA? Answer. Full form is Indole Acetic Acid. 3. What does it mean by ‘open growth’? Answer. In plants the growth is indeterminate and takes place throughout the life at specific regions having meristems. 4. Which is the plant stress hormone? Answer. Abscisic acid 5. What is denitrification? Answer. Anaerobic bacteria can convert nitrates of soil back into nitrogen gas. That process performed by denitrifying bacteria is denitrification. 6. Name the bacteria responsible for conversion of nitrite to nitrate. Answer. Nitrobacter. 7. What is role of gibberellin in rosette plants? Answer. In rosette plants like beet and cabbage, bolting, i.e. elongation of internodes before flowering is observed due to effect of gibberellins. 8. Define vernalization. Answer. The response of plant to the influence of low temperature on flowering in plants is called vernalization. 9. Define photoperiodism. Answer. The response of plant to the influence of light for initiation of flowering is known as photoperiodism. 10. What is grand period of growth? Answer. There are three phases of growth and the total time required for all phases to occur is called grand period of growth. Q. 3. Short Answer Questions : 1. Write a short note on : a. Differentiation Answer. b. Redifferentiation Answer. 2. Differentiate between Arithmetic and Geometric growth. Answer. Arithmetic growth Geometric growth 1. In arithmetic growth only one daughter cell continues to divide, while the other undergoes differentiation and maturation. 1. In geometric growth both the daughter cells continue to divide and redivide again and again. 2. Rate of growth is constant. 2 Rate growth is initially slow but later on rapid rate. 3. Linear curve is obtained. 3. Exponential curve is obtained. 4. Mathematical expression isLt = Lo + rt whereLt = length of time ‘t’Lo = Length at time zerort = growth rate, t = time of growth 4. Mathematical expression isWt = Woe rt where,Wt = final size,Wo = initial size, r = growth rate, t = time of growth E = base of natural logarithm 5. e.g. Elongation of root 5. e.g. Divisions of zygote during embryo development. 3. Enlist the role and deficiency symptoms of : a. Nitrogen Answer. Role : Constituent of proteins as amino acids, nucleic acids, vitamins, hormones, coenzymes, ATP and chlorophyll molecule.Deficiency symptoms : stunted growth and chlorosis. b. Phosphorus Answer. Role : Constituent of cell membrane, certain proteins, nucleic acids and nucleotides, required for all phosphorylation reactions.Deficiency symptoms : Poor growth, leaves dull green c. Potassium Answer. Role : Determination of anion – cation balance in cell, necessary for protein synthesis, involved in formation of cell membrane, opening and closing of stomata, activates enzymes, helps in maintenance of turgidity of cells.Deficiency symptom : Yellow edges in leaves, premature death. 4. What is short day plant? Give any two examples. Answer. The plants which flower when the day length or light period is shorter than the critical photoperiod are called short day plants or SDPSDPs usually flower during winter and late summer.Examples – Dahlia, Aster, Tobacco, Chrysanthemum, Soybean (Glycine max) and Cocklebur (Xanthium). 5. What is vernalization? Give its significance. Answer. A low temperature or chilling treatment that induces early flowering in plants is known as vernalization. Significance: Q. 4. Long Answer Questions : 1. Explain sigmoid growth curve with the help of diagram. Answer. 2. Describe the types of plants on the basis of photoperiod required, with the help of suitable examples. Answer. 1. Short day plants : Plants that flower under short day length conditions are called short day plants. Plants such as Dahlia, Xanthium, Soybean, Aster, Tobacco and Chrysanthemum are short day plants or SDR. Short day plants require a long uninterrupted dark period for flowering. Therefore, they are also called long night plants. 2. Long day plants : Plants that flower only when they are exposed to light period longer than their critical photoperiod are called long day plants or LDP Long day plants require a short dark or night period for flowering. Hence, they are also called short night plants. Plants such as radish, spinach, wheat, poppy, cabbage, pea, sugar beet, etc. are long day plants. 3. Day neutral plants : Plants in which the flowering is not affected by the day length period are called day neutral plants or

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