Q1.During the lifetime of an entity accounting produce financial statements in accordance with which basic accounting concept: (a) Conservation (b) Matching (c) Accounting period (d) None of the aboveAnswer
Answer: (c) Accounting period
Q2.When information about two difference enterprises have been prepared presented in a similar manner the information exhibits the characteristic of: (a) Verifiability (b) Relevance (c) Reliability (d) None of the aboveAnswer
Answer: (d) None of the above
Q3.concept that a business enterprise will not be sold or liquidated in the near future is known as : (a) Going concern (b) Economic entity (c) Monetary unit (d) None of the aboveAnswer
Answer: (a) Going concern
Q4.The primary qualities that make accounting information useful for decision-making are (a) Relevance and freedom from bias (b) Reliability and comparability (c) Comparability and consistency (d) None of the aboveAnswer
Answer: (b) Reliability and comparability
Fill in the blank with correct word: Q1.Recognition of expenses in the same period as associated revenues is called ………………. concept.
Answer: Matching
Q2.The accounting concept that refers to the tendency of accountants to resolve uncertainty and doubt in favour of understating assets and revenues and overstating liabilities and expenses is known as ………………….
Answer: Conservatism
Q3.Revenue is generally recognised at the point of sale denotes the concept of ………………….
Answer: Revenue Realisation
Q4.The ………………… concept requires that the same accounting method should be used from one accounting period to the next.
Answer: Consistency
Q5.The ……………….. concept requires that accounting transaction should be free from the bias of accountants and others.
Q1.Which of the following is not a business transaction? (a) Bought furniture of Rs. 10,000 for business (b) Paid for salaries of employees Rs. 5,000 (c) Paid sons fees from her personal bank account Rs. 20,000 (d) Paid sons fees from the business Rs. 2,000
Answer: (c) Paid sons fees from her personal bank account Rs. 20,000
Q2.Deepti wants to buy a building for her business today. Which of the following is the relevant data for his decision? (a) Similar business acquired the required building in 2000 for Rs. 10,00,000 (b) Building cost details of 2003 (c) Building cost details of 1998 (d) Similar building cost in August, 2005 Rs. 25,00,000Answer
Answer: (a) Similar business acquired the required building in 2000 for Rs. 10,00,000
Q3.Which is the last step of accounting as a process of information? (a) Recording of data in the books of accounts (b) Preparation of summaries in the form of financial statements (c) Communication of information (d) Analysis and interpretation of informationAnswer
Answer: (c) Communication of information
Q4.Which qualitative characteristics of accounting information is reflected when accounting information is clearly presented? (a) Understandability (b) Relevance (c) Comparability (d) ReliabilityAnswer
Answer: (a) Understandability
Q5.Use of common unit of measurement and common format of reporting promotes (a) Comparability (b) Understandability (c) Relevance (d) ReliabilityAnswer
Answer: (a) Comparability
Complete the following sentences with appropriate words
Q1.Information in financial reports’is based on ……………. transactions.
Answer: economic
Q2.Internal users are the ……………… of the business entity.
Answer: management/employees
Q3.A ………………. would most likely use an entities financial report to determine whether or not the business entity is eligible for a loan.
Answer: creditor
Q4.The Internet has assisted in decreasing the ………………… in issuing financial reports to users.Answer
Answer: time-gap
Q5.………………….. users are groups outside the business entity, who uses the information to make decisions about the business entity.Answer
Answer: external
Q6.Information is said to be relevant if it is ……………….Answer
Answer: free from bias
Q7.he process of accounting starts with …………….. and ends with ……………….Answer
Answer: identifying the transactions, communicating information
Q8.Accounting measures the business transactions in terms of ……………….. units.
Answer: monetary
Q9.Identified and measured economic events should be recording in ……………….. order.
In This Post we are providing Chapter- 16 ENVIRONMENTAL ISSUES NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON ENVIRONMENTAL ISSUES
Question 1. Define pollution. Compare the biodegradable and non-biodegradable pollutants. Answer: Pollution: “Environmental pollution is an unfavorable alteration of our surroundings largely as a by-product of man’s actions through direct or indirect effects of changes in energy patterns, radiation levels, chemical and physical conditions and abundance of organisms.”
Differences between biodegradable and non-biodegradable pollutants:
Biodegradable Pollutants
Non-biodegradable Pollutants
1. These wastes can be broken down into harmless substances naturally.
1. These cannot be broken down into harmless substances naturally.
2. The disposal of biodegradable wastes is easy and therefore, maintains balance in the ecosystem. Example. Cattle dung
2. Their disposal is not easy and is a problem. Example. D.D.T., plastics.
Question 2. What is air pollution? List various air pollutants. Answer: Air pollution: The release of harmful materials into the air is called air or atmospheric pollution. It is the degradation of air quality and atmospheric conditions.
Air pollutants include gaseous materials, suspended particles, and radioactive substances. 1. The gaseous pollutants of the air come from combustion in motor vehicles and industries. These include CO, C02, NO, N02, S02, S03, hydrocarbons, fluorides, and photochemical oxidants such as peroxyacetyl nitrate (PAN), ozone (03), and aldehydes. PAN is a secondary pollutant formed in the air by the interaction between nitrogen oxides and hydrocarbons in the presence of sunlight. It is more toxic than the primary pollutants. An increase in toxicity by the reaction among pollutants is called synergism.
2. The particulate contaminants of air also come from industries and automobiles. These include fly-ash, soot, metal dust, cotton fibers, asbestos, fibers, lead, aerosols (chlorofluorocarbons or CFCs), polychlorinated biphenyls (PCBs), tobacco smoke, smog, pollen, spores, cysts, and bacteria. (in) Radioactive substances released by nuclear explosions and war explosives are also very harmful air pollutants.
Question 3. Define a pollutant. How many types of pollutants are there? Answer: Pollutant: It is a substance (e.g. dust, smoke), chemical (e.g. S02), or factor (e.g. heat, noise) that on release into the environment has an actual or potentially adverse effect on human interests. A pollutant can also be defined as a constituent in the wrong amount, at the wrong place, or at the wrong time.
Question 4. What measures do you suggest to control pollution from automobile exhaust? Answer: Control of pollution from automobile exhaust:
Efficient engines can reduce the number of unburnt hydrocarbons from vehicuLar emissions.
Use of cataLytic converters to convert harmful gases to harmless.
Use of good quality fuel.
Unleaded petroL can reduce the amount of lead in the exhaust.
The use of CNG (compressed natural gas) Lowers the toxic contaminants in the exhaust.
Question 5. Blends of polyblend and bitumen, when used, help to increase road life by a factor of three. What is the reason? Answer: Polyblend is a fine powder of recycled modified plastic. The binding property due to increased cohesion and enhanced water-repelling property of plastic makes the road last longer besides giving added strength to withstand more loads.
This is because:
Plastic increases the melting point of the bitumen which would prevent it from melting in India’s hot and extremely humid climate, where temperature frequently crosses 45°C.
Rainwater will not seep through because of the plastic in the tar.
Question 6. “Indiscriminate human activities have strengthened the greenhouse effect resulting in Global Warming.” Give the relative contribution of various Greenhouse Gases in the form of a pie chart and explain the rate of the energy of sunlight reaching the earth’s surface contributing towards Global Warming. (CBSE Sample Paper 2020) Answer: a) (b) Rate of the energy of sunlight:
Clouds and gases reflect one-fourth of incoming solar radiations.
Some of the energy is absorbed by clouds and gases.
Thus only half of the solar energy falls on the surface of the earth.
The small amount of energy is reflected back.
Earth surface re-emits heat in the form of infrared radiations.
The major fraction of solar energy is absorbed by atmospheric gases.
Question 7. How does a scrubber function? Answer: Scrubber: A scrubber can remove gases like sulfur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime. Water dissolves gases and lime reacts with sulfur dioxide to form a precipitate of calcium sulfate or sulfite.
Question 8. Discuss the causes and effects of global warming. Answer: Global warming: The increase in global mean temperature due to the enhanced greenhouse effect is called global warming.
Effects of global warming: 1. Effect on weather and climate. (а) The average temperature of the earth may increase by 1.4° to 5.8°C by the year 2100. (б) Winter precipitation may decrease at lower altitudes. (c) Frequency of droughts, floods may increase. (d) Climatic change is a threat to human health in tropical and subtropical countries.
2. Sea level change. Sea level had been raised by 1 to 2 mm per year during the 20th century. It is predicted that by the year 2100, the global mean sea level can increase up to 0.88 m over the 1990 level. Global warming may contribute to sea-level rise due to the thermal expansion of the ocean.
3. Effect on a range of species distribution. Vegetation may extend 250-600 km poleward with a global rise in temperature by 2 to 5°C during the 21st century.
4. Effect on food production. Increased temperature will cause an eruption of plant diseases and pests and vast growth of weeds.
Question 9. Show the relative contribution of greenhouse gases to total global warming. Answer: Greenhouse gases: The relative contribution of various greenhouse gases to total Global warming.
Question 10. Make a chart illustrating the kinds of water pollutants. Answer: Classification of water pollutants:
In This Post we are providing Chapter- 13 ORGANISMS AND POPULATIONS NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON ORGANISMS AND POPULATIONS
1. How does the shape of age pyramid reflect the growth status of a population? Ans.Shape of pyramids reflects growth statusof the population (a) growing (b) Stable (c) declining.
2. Darwin showed that even a slow growing animal like elephant could reach enormous number in absence of checks. With the help of your understanding of growth models, explain when is this possible? Why is this notion unrealistic? Ans. Possible if the growth model is Exponential, i.e., having unlimited resources. Its an unrealistic situation because resources are limited. Hence, it follows logistic growth model.
3. How will you measure population density in following cases? (i) fish in a lake (ii) tiger census in a national park (iii) single huge banyan tree with large canopy . Ans. (i) fish caught per trap. (ii) number per unit area (iii) percentage cover in biomass.
4. Species facing competition might evolve mechanism that promotes coexistence rather than exclusion. Justify this statement in light of Gause’s competitive exclusion principle, citing suitable examples. Ans.State Gause’s competitive exclusion principle.Mechanisms is resource partitioning. E.g., experiment of Mac Arthur on Warblers (Refer page 325, NCERT book, Biology – XII).
5.Describe the specific adaptation of xerophytes with respect to root system, stem & leaves. Ans. i) ADAPTATIONS INROOTS :- Xerophytes have well developed & extensively branched long rootsystem. While some perennial xerophytes of succulent nature possess extensive but shallow root system.They can absorb water from dew drops & small rain droplets. ii) ADAPTATION IN STEM:- stems of woody xerophytes are comparatively stunted hard & rigid. Theymay be covered with thick e.g. Acacia main stem & branches may occur as think, fleshy, flattened & greenmodified structure called phylloclade. iii) ADAPTATION IN LEAVES:- Leaves are usually short sized which decreases the chances of gettingover – heated when exposed to solar radiation & thus by reducing rate of transpiration. Leaves ofssxerophytes are usually thick, fleshy green & leathery which are known to store water.
6.List the important characteristics of a population & Explain? Ans.A population has following four major characteristics :- i) Population Density :- The size of a population in relation to a definite unit of space is termed aspopulation density. The maximum limit of density depends upon energy flow in an ecosystem, nutritionalstatus of trophic level & metabolic equilibrium. Population density can be mathematically calculatedas : D=N/atD=N/at ii) Birth Rate / Natality :- The birth rate or natality denotes the produced number of new individuals byany natural method in per unit time. The birth can be expressed lay formula B=NntB=Nnt iii) Death Rate / Mortality :- It refers to death rate of individuals in the population. It is expressed in asnumber of individual dying in a given period.Death Rate = no of death in population Timeno of death in population Time iv) Carrying Capacity:- Each habitat or ecosystem has a certain space which can accommodate a finitenumber of organisms depending on its size & productivity. This is called carrying capacity
7.Describe the specific adaptations of hydrophytes with respect to roots, stem & leaves? Ans. i) ADAPTATIONS IN ROOTS:- Root system is feebly developed &unbranched some floating plants orsubmerged plants lack roots Root hairs are absent except rooted floating hydrophyte. True root caps areabsent. ii) ADAPTATIONS IN STEM :- In submerged hydrophytes, stems are long slender & flexible whereas inthe free – floating hydrophytes stem are modified as thick, stout, stoloniferous& occur horizontal onwater surface. iii) ADAPTATIONS IN LEAVES:- Leaves are thin, long, ribbon shapes submerged forms. In free floatingplants, the petioles of leaves show indefinite power of growth.
8.Name& explain the bind of interaction in the following. i) Algae & fungi in ii) Head louse & humans iii) Hermit crab & sea anemone. Ans. i) Algae & fungi in lichens :- Lichens shows an intimate mutualistic interaction in with both fungushelps in absorption of nutrients & provides protection, while algae or cyanobacterium prepares the food. ii) Head louse & humans:- Head louse shows ectoparasitism on humans in which head louse is gettingnutrition from human body & is thus benefited while human beings are harmed. iii) Hermit crab & sea anemone:- Hermit crab & sea anemone shows commensalism as hermit crab isbenefited because it gets protection from predators which stays away from stinging tentacles of the seaanemone.
9.Mention the different defense mechanism to reduce the impact of predation? Ans.plant species evolved various defense mechanism to reduce impact of predation :- i) Certain insect species & frogs have camouflage or cryptic colouration to avoid detection by their predators. ii)Some animals like monarch butterfly are highly distasteful to their predators because they accumulate a certain chemical by feeding on poisonous weeds during its caterpillar stage. iii)Some prey are poisonous & hence are avoided by predators . iv)Plants have evolved certain morphological, or chemical defense mechanism against herbivores e.g. thorns in bougainvillea. v)plants also produce certain chemicals which functions as :-
They make animal feel sick.
They may inhibit them from feeding.
They may interfere with digestion.
They may directly kill them.
10.Mutualism often involves co-evolution of mutualists. Describe taking the example of animal plant (wasp-fig) relationship. Ans.Plants need the help of animals for pollination their flowers & dispersing their seeds. Animals obviously have to be paid fees for the services that plants expect from them. Plants offer rewards or fees in the form of seed dispersers “plant – animal interactions often involve co-evolution of the mutualists that is, the evolution of the flower & its pollinator species can be pollinated only by its partner wasp species & no other species. The female wasp uses the fruit not only as an oviposition site but uses the developing seeds within the fruit for nourishing its larvae. The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites. In return for the favors of pollination the fig offers the wasp some of its developing seeds as food for the developing wasp larvae.
In This Post we are providing Chapter- 14 ECOSYSTEM NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON ECOSYSTEM
Question 1. What is an ecosystem? Write its main components. Answer: Ecosystem. A stable, self-supporting ecological unit resulting from an interaction between a biotic community (living organisms) and its abiotic environment is called an ecosystem.
An ecosystem comprises two main components:
biotic including plants, animals, and microorganisms and
abiotic mainly including substratum, water, minerals, temperature, carbon dioxide, and oxygen. It must also receive a constant supply of energy (light).
Question 2. Briefly describe the biotic components of an ecosystem. Answer: Biotic components: Of an ecosystem’s biotic components, the plants are producers as they introduce food materials and energy into the living world. The animals are consumers because they get food and energy by consuming plants directly thus called primary consumers (herbivores); secondary/ tertiary consumers (carnivores) obtain energy and food indirectly from plants, and microorganisms are decomposers for they flourish by breaking dead organic matter to simple substances that are returned to environment for reuse by plants.
In an ecosystem, nutrients are used again and again in a cyclic manner, whereas energy trapped from sunlight is lost as heat.
Question 3. Give an account of factors affecting the rate of decomposition. Answer: Factors affecting decomposition:
The upper layer of soil is the main site of decomposition processes in the ecosystem.
The rate of decomposition of detritus is affected by climatic factors and the chemical quality of detritus.
Temperature and soil moisture affect the activities of root microbes.
The chemical quality of detritus is determined by the relative proportion of water-soluble substances, polyphenols, lignin, and nitrogen.
Question 4. List the important differences between producers and decomposers. Answer: Differences between producers and decomposers:
Producers
Decomposers
(i) These are organisms that synthesize their own food by the process of photosynthesis. These are also called autotrophs.
(i) These organisms feed on the dead bodies of plants and animals.
(ii) They convert the raw materials in the earth and water into carbohydrates which give them food.
(ii) They enrich the earth with raw materials trapped in dead bodies of plants and animals.
(iii) They are dependent on decomposers for soil nutrients.
(iii) They are dependent on plants and animals for their food.
Question 5. Explain the terms standing crop, biomass, and standing state. Or State what does a standing crop of a trophic level represent? (CBSE Outside Delhi 2013) Answer: Standing crop: Each trophic level has a certain mass of living material at a particular time called the standing crop. Biomass. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area. The biomass of a species is expressed in terms of fresh or dry weight. Measurement of biomass in terms of dry weight is more accurate as the moisture content of biomass fluctuates greatly.
Standing State: Organisms need a constant supply of nutrients to grow, reproduce and regulate various body functions. The amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, etc. present in the soil at any given time, is referred to as the standing state. It varies in different kinds of ecosystems and also on a seasonal basis.
Question 6. Give a diagrammatic representation of trophic levels in an ecosystem. Answer: Diagrammatic representation of trophic levels in an ecosystem.
Question 7. Sometimes due to biotic/abiotic factors, the climax remains in a particular serai stage (pre-climax) without reaching climax. Do you agree with this statement? If yes give a suitable example. Answer: Sometimes pre-climax stage remains in a particular serai stage without reaching the climax because during ecological succession any change in abiotic and biotic components may affect the particular serai stage, leading to the pre-climax stage before the climax is achieved.
This type of condition occurs in the presence of seeds and other propagules. This secondarily based area may be invaded by moss or exotic weeds thus exhibiting succession seriously and the climax community is never regenerated.
Question 8. Explain the meaning of the food web and illustrate with a ray diagram. Answer: Food web. In nature, the food chains are not strictly linear, but are interrelated and interconnected with one another. Generally, the various food chains in a community are so interlinked as to form a sort of web. As a result, one animal may be a link in more than one food chain.
A network of food chains in a community is referred to as a food web. A food web may have all or some of the three types of food chains, i.e. detritus, predator, and parasitic. The food webs become more complicated because of the variability of taste and preference, availability and compulsion, and several other factors at each level. For example, tigers normally do not eat fish or crab, but they are forced to feed on them in the Sundarbans.
Question 9. Starting from a bare rock or a site of volcanic eruption, trace the organisms that participate in the process of succession. Or Describe the process of succession on a base rock. (CBSE 2012) Answer:
Simple organisms appear first of all on such an exposed site as lichens. Lichens make conditions suitable for mosses (bryophytes).
Gradually a variety of complex organisms join the community. Stages of biotic succession.
Finally, large plants, trees, etc. appeared. It can be illustrated that lichens are pioneers, followed by mosses, annual grasses, perennial herbs, shrubs, and finally trees along with their characteristic animal populations.
Question 10. How does succession differ in terrestrial and aquatic systems? Give salient points. (CBSE Delhi 2019) Answer: Differences between terrestrial and aquatic succession:
Succession on land/rock
Succession In Water
1. lichens and mosses are the pioneer community.
1. Phytoplankton is a pioneer community.
2. Soil is formed by the action of lichens.
2. Waterbodies are prone to silting due to soil erosion.
3. There is a deficiency of water.
3. Water is abundant.
4. The various stages are crustose lichen stage, foliose lichen stage, moss stage, herb stage, shrub stage, and forest stage.
4. The various stages are the plankton stage, floating stage, rooted stage, swamp stage, woodland stage, and forest stage.
In This Post we are providing Chapter- 15 BIODIVERSITY AND CONSERVATION NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON BIODIVERSITY AND CONSERVATION
1. Hot spots are the regions of exceptionally high biodiversity . But they have become regions of accidental habitat loss too. Name the three hot spots of our country. Why are they called ‘Hot spot’? Ans. Western Ghats and Sri lanka; Indo-Burma; Himalaya called ¡¥biodiversity hot spots¡¦ as they show (i) High level of species richness (ii) High degree of
2. Study the diagram of the earth given below . Give the name of the pattern of biodiversity therein. Suggest any two reasons for this type of occurance. Ans. Latitudinal gradients (i) More solar energy available in tropics, more productivity. (ii) Tropical environments are less seasonal, so more predictable.
3. What is so special about tropics that might account for their greater biological diversity? Ans.a) Speciation is a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitude have remained relatively undisturbed for million of years and thus had long evolutionary time for species diversification b) Tropical environment are less seasonal, more const ant and predictable c) More solar energy awailable in the tropics contributing to high productivity leading to greater diversity .
4.What do you mean by biodiversity? What are the different types of Biodiversity? Ans. Biodiversity can be defined as the totality of genes species & ecosystem of a given region. Three important components of Biodiversity are:- i) Genetic Biodiversity:- It refers to the diversity of genes within a species, Greater the genetic diversity amongorganisms of a species. More sustenance it has against environmental perteburations whereas geneticallyuniform populations are highly prone to diseases or harsh environment ii) Species Biodiversity:- It refers to variety of species within a region. It has two important measures :- a) Species richness:- i.e. number of species per unit area. b) Species evenness:- i.e. abundance with which each species is represented in an area. iii) Ecosystem Biodiversity:- It refers to variation of habitats, community types & abiotic environment present in an area. It is further of three types:- a) αα – diversity- It refers to number of species in a given community. b) ββ– diversity – biodiversity which appears in range of communities due to replacement ofspecies with change in community is called ββ– diversity. c) γγ– diversity – It refers to diversity of habitats over the total geographical area.
5.What do you mean by latitudinal gradient? What could be the possible reasons for diversity between tropic & temperate region? Ans. Latitudinal gradient in diversity means that species diversity usually decreases as we move away fromequator towards the poles, Tropic area of latitudinal range 23.50c harbor more species than temperate orpolar area. Three hypothesis have been proposed to explain this difference:- i) Speciation is a function of time, which temperate regions were subjected to frequent glaciations in the past,the tropics have remain unchanged & hence evolved more species diversity. ii) As compared to temperate region, tropical environment are less seasonal, relatively more constant &predictable; such constant environment have promotes niche specialization & greater species diversity. iii) There is more solar radiation avail able in tropical region this contributes directly to greater productivity &indirectly to greater species diversity.
6.Why is it necessary to conserve biodiversity? Ans.The reasons for conserving biodiversity can be grouped into three categories. i) Narrow utilitarian reasons:- Human beings derive a number of economic benefits like food, fibre,firewood, industrial product & medicinal products. ii) Broad utilitarian reasons:- Biodiversity plays a major role in providing ecosystem services like :- a) production of oxygen b) Pollination of flowers, without which seeds or fruits are not produced. c) Aesthetic pleasures like bird watching, watching spring flowers, walking through thick forest, workingup to bulbul’s song etc. iii) Ethical reasons :- Every species has an intrinsic value even if it is not of any economic value to us-wehave a moral duty to care for their well-being & pass on the biological legacy in a proper from to ourfuture generation.
7.What is the relation between species richness & area? What is the significance of slope of regression? Ans.Alexander Von Humboldt has observed that within a region, species richness increased withincrease explored area but only upto a limit thus the relationship between species richness & area for anumber of taxa is found to be a rectangular hyperbola. On a log scale, the relation ship becomes linear & is described layequation Log S = log C + Z log A The values of slope of regression are identical regardless of the taxonomic group or the region. When such analysis is made among very large areas, the slope ofregression would be much steeper.
8.What are the different approaches for biodiversity conservation in India? Ans.There are two major approaches for conservation of biodiversity:- i) In-situconservation :- It is the process of protecting the endangered species of plant or animal in thenatural habitat lay either protecting or cleaning up the habitat or by defending species from predators Itincludes:- a) Biosphere Reserves:- There are 425 biosphere reserve in the world of which 14 are in India. Hotspotshave been identified for maximum protection to endemic or endangered species. b) National park or wildlife Sanctuaries:- India has about 90 national parks & 448 wildlife sanctuaries. c) Sacred forests:- These are undisturbed forests without any human intervention & are surrounded by highly degraded landscapes. ii) Ex- situ Conservation:- It is the process of protecting the endangered species of plants or animals by removing it from threatened habitat & placing them under care of humans. It includes :- a) Botanical garden, zoological park and arboreta are conventional methods of ex-situ conservation b) Cryopreservation to the storage of materials at ultra low temperature either by rapid cooling or by gradual cooling & simultaneous dehydration at low temperature.
9.Give an account of Biodiversity in India? Ans.India is one of the 10th mega biodiversity countries of the world because of the presence of variety ofclimatic conditions prevailing on different ecological habitat ranging from tropical, subtropical,temperate, So far as biodiversity of India is concerned, it comprises about 47,000 plants & 81,000 animalspecies. India occupies 2-4% of total land area of would but in terms of biodiversity, India contributeabout 10-35% of global diversity. A large number of species is native of India. About 5000 species of flowering plants belonging to 141genera& 47 families had a birth in India. There are 62% of amphibian species& 50% of lizards endemicto our country with large number in Western Ghats. India is an origin place of 166 species of crop plants& 320 species of wild relatives of cultivated crop. India is rich in marine biodiversity lying along coastlineof 7500 km. There are two hotspots located in India out of 25 in would – These are Western Ghats&Eastern Himalayas.
10.What is the significance of Biodiversity to Human beings? Ans.Biodiversity provide numerous direct or indirect services to human beings. These are- i) Source of food & improved varieties:- Biodiversity directly or indirectly adds as the source of food,cloth& shelter. ii) Fats & Oils:- A variety of plants are used to extract different kinds of oils. iii) Fibres:- A variety of plants eg. cotton, hemp, jute are chief sources of fibres. iv) Resins:- Resins are sticky exudation of plants. v) Gums, Timber, Paper, Tannins, Dyes:- Plants species provide variety of useful products eg. gums,raisins, dyes, similarly animal species provide leather, fur, honey, silk, pearl etc. vi) Drugs & Medicines:- Hiving organism also contain number of therapeutically useful substances. vii) Stability of Ecosystem:- The food web, food chain energy flow in various tropic level & biochemicalcycles occurs in natural ways without any hindrance if there is proper availability of diversified species viii) Aesthetic, Scientific & Recreational values :- Indian people grow many plants because they regardthem as sacred.
In This Post we are providing Chapter- 10 MICROBES IN HUMAN WELFARE NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON MICROBES IN HUMAN WELFARE
Question 1.
Name the toxin produced by B. Thuringiensis. Answer: ∝-exotoxin, β-exotoxin, γ-exotoxin, and louse factor
(ii) Nitrogen fixers are available on a commercial basis in the market? Also, name the beneficial crop and microbes used in the following table.
Product
Microbe used
Beneficial crop
1. NitraginTM
(A)
Soybean
2. Rhizocote
Rhizobium
(B)
3. Nodosit
Rhizobium
(C)
Answer: A. Rhizobium B. Legume C. Legume
(iii) Expand BOD and COD Answer: BOD- Biological Oxygen Demand COD- Chemical Oxygen Demand
Question 2. By a flow chart showing the stages in anaerobic digestion during the production of biogas. Answer:
Stages in Anaerobic Digestion during biogas formation
Question 3. Given below is a list of six microorganisms. State their usefulness to humans. (i) Nucleopolyhedrovirus (ii) Saccharomyces cerevisiae (iii) Monascus Purpureus (iv) Trichoderma polypore (v) Penicillium Notatum (vi) Propionibacterium shamanic. Answer:
Name of Micro-organisms
Uses
(i) Nucleopolyhedrovirus
Used in biocontrol of insects
(ii) Saccharomyces cerevisiae
Bread making, Ethanol making
(iii) Monascus Purpureus
Produces Statin used as blood cholesterol-lowering agent
(iv) Trichoderma polypore
Preparation of cyclosporin having antifungal, anti-inflammatory, immuno-suppressive properties
(v) Penicillium Notatum
Production of antibiotic, Penicillin
(vi) Propionibacterium shamanic
Preparation of large-holed swiss cheese.
Question 4. Explain the different steps involved in the secondary treatment of sewage. (CBSE Sample paper 2018—19) Or Secondary treatment of sewage is also called biological treatment. Justify this statement and explain the process. (CBSE 2018) Answer:
Secondary treatment of sewage is a biological process that employs the heterotrophic bacteria naturally present in the sewage.
The effluent from the primary treatment is passed into large aeration tanks, where it is constantly agitated and the air is pumped into it.
This allows the rapid growth of aerobic microbes into ‘floes’ which consume the organic matter of the sewage and reduce the biological oxygen demand (BOD). The greater is the BOD of wastewater, the more is its polluting potential.
When the BOD of sewage is reduced significantly, the effluent is passed into a settling tank, where the ‘floes’ are allowed to sediment forming the activated sludge.
A small part of the activated sludge is pumped back into the aeration tanks.
The remaining major part of the sludge is pumped into anaerobic sludge digesters, where the anaerobic bacteria digest the bacteria and fungi in the sludge-producing methane, hydrogen sulfide, and carbon dioxide, i. e. biogas. This is why secondary treatment of sewage is also called biological treatment.
The effluent after secondary treatment is released into water-bodies like streams or rivers.
Question 5. Microbes can be used to decrease the use of chemical fertilizers. Explain how this can be accomplished. (CBSE Delhi 2019) Answer:
Rhizobium bacteria present in the root nodules of leguminous plants (pea family) forms a symbiotic association and fixes atmospheric nitrogen into organic forms as nitrates/nitrites which are used by the plant as nutrient.
Free-living bacteria in the soil Azospirillum and Azotobacter can fix atmospheric nitrogen thus enriching the nitrogen content of the soil.
Many members of the genus Glomus (Fungi) form mycorrhizal symbiotic associations with higher plants. In these, the fungal symbiont absorbs phosphorus from soil and passes it to the plant.
Question 6. Organic farmers prefer biological control of diseases and pests to the use of chemicals for the same purpose. Justify. Answer: Chemical methods often kill both useful and harmful living beings indiscriminately. The organic farmer holds the view that the eradication of the creatures that are often described as pests is not only possible but also undesirable, for without them the beneficial predatory and parasitic insects which depend upon them as food or hosts would not be able to survive. Thus, the use of biocontrol measures will greatly reduce our dependence on toxic chemicals and pesticides.
(ii) Give an example of a bacterium, a fungus, and an insect that are used as biocontrol agents. (CBSE 2018) Answer: Insects = Ladybird and Dragonflies. Bacteria = Bacillus thuringiensis. Fungus = Trichoderma
Question 7. The three microbes are listed below. Name the product produced by each one of them and mention their use. (i) Aspergillus niger (ii) Trichoderma polypore (iii) Monascus Purpureus (CBSE Delhi 2018C) Or (i) A patient had suffered myocardial infarction and clots were found in his blood vessels. Name a ‘clot buster’ that can be used to dissolve clots and the microorganism from which it is obtained. (ii) A woman had just undergone a kidney transplant. A bioactive molecular drug is administered to oppose kidney rejection by the body. What is the bioactive molecule? Name the microbe from which this is extracted. (iii) What do doctors prescribe to lower the blood cholesterol level in patients with high blood cholesterol? Name the source organism from which this drug can be obtained. Answer: (i) Aspergillus niger produces citric acid. Citric acid is used as a flavoring agent and as a food preservative. (ii) Trichoderma Polysporum produces a bioactive molecule cyclosporin A. It is used as an immunosuppressive agent in organ transplant patients. (iii) Monascus Purpureus produces statins. Statins are capable of competitive inhibition of enzymes required for cholesterol synthesis. Hence, it is used as blood cholesterol-lowering agents. Or (i) Streptokinase-‘Clot buster’ can be used to dissolve clots. It is obtained from the bacteria Streptococcus. (ii) The bioactive molecule is Cyclosporin A which is used as an immunosuppressive agent in organ transplantation. It is produced by the fungus Trichoderma Polysporum. (iii) Doctors prescribe Statins to lower blood cholesterol. It is obtained from the fungus Monascus Purpureus.
Question 8. Baculoviruses are good examples of biocontrol agents. Justify giving reasons. (CBSE Delhi 2018C) Answer: Baculoviruses kill insects and other arthropods, hence they are used as biocontrol agents especially Nucleopolyhedrovirus.
Reasons for their use:
These viruses are species-specific and have narrow spectrum insecticidal applications.
They do not harm non-target organisms like other harmless insects, birds, animals, etc.
It is very useful in integrated pest management programs or treatment of ecologically sensitive areas.
Question 20. Describe the primary and secondary treatment of domestic sewage before it is released for reuse. (CBSE, 2014) Answer: Treatment of domestic sewage. The municipal wastewaters are treated in Effluent Treatment Plant (ETP) prior to disposal in water bodies.
It consists of 3 steps: primary, secondary, and tertiary. 1. Primary treatment. It includes physical processes, such as sedimentation, floatation, shredding (fragmenting and filtering). These processes remove most of the large debris.
2. Secondary treatment. It is a biological method. Activated sludge method. Sewage, after primary treatment, is pumped into aeration tanks or oxidation ponds. Here, it is mixed with air and sludge containing algae and bacteria. Bacteria consume organic matter. The process results in the release of C02 and the formation of sludge or biosolid. Algae produce oxygen for the bacteria. The water, which is now almost clear of organic matter, is chlorinated to kill microorganisms.
3. Tertiary treatment. It involves. removal of nitrates and phosphates. The water, after the above treatment, is then released. It can be reused.
Question 9. Explain biological control of pests and plant pathogens with examples. Answer: The very familiar beetle with red and black markings the Ladybird, and Dragonflies are useful to get rid of aphids and mosquitoes, respectively.
Role of Bacillus Thuringinesis: Bt Coming to microbial biocontrol agents that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus thuringiensis (often written as Bt). These are available in sachets of dried spores which are mixed with water and sprayed onto vulnerable plants such as Brassica and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed.
The bacterial disease will kill the caterpillars, but leave other insects unharmed. Because of the development of the methods of genetic engineering in the last decade or so, scientists have introduced B. thuringiensis toxin genes into plants. Such plants are resistant to attack by insect pests. Bt-cotton is one such example which is being cultivated in some states of our country.
Biological control of plant pathogens: A biological control developed for use in the treatment of plant disease is the fungus Trichoderma. Trichoderma sp. are free-living fungi that are very common in soil and root ecosystems. They are effective biocontrol agents of several plant pathogens.
Baculoviruses are pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications.
They have been shown to have no negative impacts on plants, mammals, birds, fish, or even on non-target insects. This is especially desirable when beneficial insects are being conserved to aid in an overall IPM (integrated pest management) program, or when an ecologically sensitive area is being treated.
Question 22. How do biofertilizers enrich the soil? Answer: Biofertilizers play a vital role to solve the problems of soil fertility and soil productivity.
Anabaena azollae, a cyanobacterium, lives in symbiotic association with the free-floating water fern, Azolla. The symbiotic system Azolla-Anabaena complex is known to contribute 40-60 mg N ha-1 per rice crop. In addition to this, cyanobacteria add organic matter, secretes growth-promoting substances like auxins and vitamins, mobilizes insoluble phosphate, and thus improves the physical and chemical nature of the soil.
Rhizobium Leguminoserum and Azospirillum fix atmospheric nitrogen as nitrates and nitrites.
Mycorrhizae formed by an association of bacteria and roots of higher plants increase soil fertility.
Question 10. Discuss the role of Microbes as Biofertilizers. (CBSE Delhi 2011, 2015, 2019) Answer: Role of microbes as biofertilizers: Bacteria, cyanobacteria, and fungi (mycorrhiza) are the three groups of organisms used as biofertilizers. 1. Bacteria: (a) Symbiotic bacteria Rhizobium. (b) Free-living bacteria Azospirillum and Azotobacter. (c) They fix the atmospheric nitrogen and enrich soil nutrients.
2. Cyanobacteria, e.g. Anabaena, Nostoc, Aulosira, Oscillatoria, etc. (a) They function as biofertilizers by fixing atmospheric nitrogen and (b) Increasing the organic matter of the soil through their photosynthetic activity.
3. Fungi/mycorrhizae: (a) Fungi form a symbiotic association with roots of higher plants (mycorrhizae), e.g. Glomus. (b) The fungus absorbs phosphorus and passes it on to the plant. (c) Other benefits of mycorrhizae are :
resistance to root-borne pathogens.
tolerance to salinity.
tolerance to drought.
the overall increase in the plant growth and development
In This Post we are providing Chapter-11 BIOTECHNOLOGY: PRINCIPLES AND PROCESSESS NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERTMOST IMPORTANT QUESTIONS ON BIOTECHNOLOGY: PRINCIPLES AND PROCESSESS
1. Observe the given sequence of nitrogenous bases on a DNA fragment and answer the following question 5´ – CAGAATTCTTA – 3´ 3´ – GTCTTAAGAAT – 5´ (a) Name a restriction enzme which can recognise this DNA sequence. (b) Write the sequence after digestion. (c) Why are the ends generated after digestion called sticky ends? Ans. (a) EcoRI (c) These are named sticky ends, because they form hydrogen bonds with their complementary cut parts.
2. A selectable marker is used in the section of recombinants on the basis of their ability to produce colour in presence of chromogenic substrate. (a) Mention the name of mechanism involved. (b) Which enzyme is involved in production of colour? (c) How is it advantageous over using antibiotic resistant gene as a selectable marker? Ans. (a) Insertional inactivation (b) b-galactosidase. (c) Selection of recombinants due to inactivation of antibiotics requires simultaneous plating on two plates having different antibiotics.
3.Mention the important properties which a good vector must possess? Ans.The important properties which a good vector must possess are :- i) Size :- The vector must have small size so that it is easier to purify & isolate. ii) Origin of replication :- This is a sequence of base pairs where replication starts. Any piece of DNA linked to this sequence can be made to replicate within its host cell & thus, controls the copy number of linked DNA. iii) Selectable Marker :- A marker is a gene which helps in selecting those host cells which contain the vector & eliminating the non – transformants Common Selectable marker include gene encoding resistance to antibiotics. iv) Cloning Sites :- The vector Should have a few or at least one unique recognition site to link the foreign / alien DNA. Presence of a particular recognition site enables the particular restriction enzyme to cut the vector.
4.Describe any three vectors less method of introducing the rDNA into a competent host cell? Ans. i) Transformation :- In order to force bacteria to take up the plasmid, the bacterial cell must first be made competent to take up DNA. This is done by treating them with specific concentration of divalent cationeg. Ca2+ which increases the efficiency with which DNA enters the bacterium through pores in its cell wall Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them at 420 C& then putting them back into ice. This enables the bacteria to take up the recombinant DNA. ii) Microinjection :- recombinant DNA is directly injected into the nucleus of an animal cell using a micro – needle of tip with diameter (~ 4mm) iii) Biolistics / Gene gun :- cells are bombarded with high velocity micro – particles of gold or tungsten coated with DNA.
5.Why is Agrobacterium mediated genetic transformation described as Natural Genetic engineering in plants? Ans.Agrobacterium tumefacien, anatural pathogen of Several dicot plants is able to deliver a piece of DNA known as “t – DNA” to transform normal plant cell into a tumor & direct gene transfer transform tumor cells to produce chemicals required by pathogen . The tumor inducing (Ti) plasmid of Agrobacterium tumefacien has now been modified into a cloning vector which is no more pathogenic to plant but is still able to use the mechanism to deliver genes of our interest into a variety of plants Since Agrobacterium tumefacien has the natural ability to donate a part of its DNA to the plant during infection. This property of Agrobacterium is exploited and a gene of interest is ligated into T-DNA so that it automatically gets transformed into plant cell thus, Agrobacterium tumefacien is known as “Natural Genetic Engineer” of plants.
6.Mention the important tools required for genetic engineering technology? Ans.The process of genetic engineering is accomplished only when we have following key tools :- a)Restriction enzymes:- Restriction enzymes are a group of endonucleases which cut the DNA at Specific position anywhere in its length. Each restriction endonuclease functions by inspecting the length of DNA & binds to DNA at the recognition Sequence. b)Cloning Vector:- The DNA molecule which carry the desired DNA Segment of an organism & transfer it to cell or DNA of another organism is called cloning vector. c)Desired foreign DNA:- The segment of DNA containing genes having desired characters & which are being transferred into genome of another cell with the help of vector is called foreign DNA.
7. In the given figure, one cycle of polymerase chain reaction (PCR) is shown- (a) Name the steps A, B and C. (b) Give the purpose of each of these steps. (c) State the contribution of bacterium Thermus aquaticus in this process. Ans. (a) Denaturation Heat denatures DNA to separate complementary strands. (b) Annealing : Primers hybridises to the denatured DNA strands. (c) Extension : Extension of primers resulting in synthesis of copies of target DNA sequence. Enzyme Tag polymerase is isolated from the bacterium Thermusaquaticus. This enzyme induces denaturation of double stranded DNA at high temperature.
8.Describe the various steps involved in Recombinant DNA technology with the help of a well labeled. Diagram? Ans. i) Identification of DNA with desirable Genes:- Other molecules in the target cell can beremovedby appropriate treatment & purified DNA ultimately precipitates out after addition ofchilled ethanol. ii) Cutting the DNA at specific location :- After having cut the source DNA as well as vector DNA with Specific restriction enzyme, the cut out “gene of interest” from the source DNA & the cut vector with space are mixed & ligase is added. iii)Insertion of Recombinant DNA into host cell :- Recipient cells after making them competent to receive takes up DNA in its surrounding. Recombinant DNA is introduced into suitable host cell by vector – based or vector – less method. iv)Selection & Screening :- If a recombinant DNA bearing gene for resistance to an antibiotic is trAns.ferred into E-coli the host – cell become trAns.formed into ampicillin – resistant cells. Due to this amp gene one is able to select a trAns.formed cell in the presence of ampicillin. This amp r gene is called selectable marker. v)Obtaining the foreign Gene product :- After having cloned the gene of interest & having optimized the conditions to induce expression of the target protein, one has to consider producing it on large scale.
9.Expand PCR? Describe the different Steps involved in this technique? Ans. PCR stands for polymerase chain reaction.It is a technique for amplification of gene of interest or to obtain multiple copies of DNA of interest. The PCR requires primers, taq polymerase, target sequence, DNA sample &deoxyribonucleotides. PCR includes number of cycles for amplifying DNA of interest invitro. Each cycle has three steps :- a)DENATURATION:- The first step is denaturation of SNA sample in a reaction mixture to 940 c. During this step, DNA strand gets separated. b)RENATURATION / ANNEALING:- The temperature is allowed to cool down to 500c to allow two oligo-nucleotide primers to anneal to complementary sequence in DNA molecule. c)EXTENSION:- The temperature is raised to 750c. At this temperature, taq – polymerase initiates DNA Synthesis at 3-OH end of primer.
10.What are Restriction enzyme? Why do bacteria have these restriction enzymes. Show diagrammatically a restriction enzyme its recognition & the product it produces? Ans. Restriction enzymes are endonucleases which recognize a specific sequence within DNA and cut the DNA within that sequence at a specific point. In bacteria, these restriction enzymes operates modification restriction system which modifies & cuts the foreign DNA entering into the bacterial cell& thus, provides immunity to bacterial cell. Name of Restriction enzyme- EcoRI Substrate DNA on which it acts
In This Post we are providing Chapter- 12 BIOTECHNOLOGY AND ITS APPLICATION NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter
NCERTMOST IMPORTANT QUESTIONS ON BIOTECHNOLOGY AND ITS APPLICATION
1.Describe how nematode – resistant transgenic plants have been obtained? Ans.A nematode Meloidogyne incognita infects tobacco plant &reduces its yield. The specific genes fromparasite are introduced into plant using Agrobacterium. The genes are introduced in such a way that bothsense& Antisense RNA are produced. Since these two RNAs are complementary, they form a doublestranded RNA (ds RNA). This neutralizes the specific RNA of nematode by a process called RNAinterference as a result, the parasite cannot live in transgenic host & plant is protected from the pest.
2.What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit? Ans.The soil bacterium Bacillus thuringiensis produces crystal proteins called cry proteins that are toxicto larvae of insects like tobacco budworm, beetles & mosquitoes. The cry proteins exist as inactiveprotoxin& gets converted into active toxin when ingested lay the insect, as the alkaline pH of gutSolublises the crystal. The activated toxia binds to surface of epithelial cells ofmidgut& create pores thiscauseslysis of cells leading to death of insects.The genes encoding this protein are isolated from bacterium & incorporated into crop-plant to make them insect – resistant.
3.Write an account on the production of human insulin in transgenic organisms. Ans. Human insulin consists of two short polypeptide chains: chain A & B linked by disulfide bonds.Insulin is secreted as prohormone which has to be processed before it becomes a mature & functionalhormone. The prohormone contains another polypeptides called C-peptide which is removed during maturation.Using genetic engineering, the two DNA sequences coding for chains A & B of human insulin areintroduced into plasmid of E – coli – to produce insulin. The two chains produced are extracted &combinedby creating disulfide bridges.
4.Compare & contrast the advantages & disadvantage of production of Genetically modified organisms? Ans. ADVANTAGES OF PRODUCING GMOS.
GM crops produce desired phenotypic traits in crop plants.
The genes responsible for production of specific proteins are inserted into GM crops. These crops then produce that specific protein.
Transgenic crops synthesizes new end product of specific biochemical pathway.
These crops also help in preventing expression of existing native Gene.
DISADVANTAGES OF PRODUCING GMOS:
Transgenic crops may endanger wild & native species.
GM crops may cause health problems by supplying allergens.
GM crops may damage to the natural environment.
5.What is RNA Silencing? How is this strategy used to create pest – resistant plants? Ans.RNA silencing is a technique which involves silencing or disabling of specific mRNA due tocomplementary ds RNA molecule that binds to & prevent translation of mRNA. This strategy is used toprevent infection of roots of tobacco plants lay nematode Meloidegyne incognita. In this strategy, complementary ds RNA is produced against specific mRNA. The source of this complementary RNA couldbe from an infection by viruses having RNA genomes. Using Agrobacterium vector nematode specificgenes were introduced into host plant. The introduction of DNA was such that it produced both sense &anti-dense RNA in the host cell. These two RNA’s being complementary to each other formed a doublestrand RNA that initiated RNAi& thus silenced specific mRNA of the nematode. The consequence wasthat parasite could not survive in transgenic host.
6.What are the steps involved in synthesis of genetically engineered insulin. Ans. Steps involved in Insulin production are :-
for synthesis of Insulin, RNA is extracted from β−β−cells of islets of Langehans of pancreas.
With the help of enzyme Reverse transcriptase, single stranded DNA complementary to mRNA is synthesized second strand of DNA complementary to first is synthesized with enzyme DNA polymerase.
The two strands of copy DNA is joined to plasmid by using an enzyme called terminal transferase.
The two ends of DNA get annealed by enzyme called ligase thus ends of inserted DNA & plasmid are sealed & a new circular plasmid is formed. This is a molecule of recombinant DNA.
This recombinant DNA is then inoculated in a new bacterial cell of E-coli & inserted in a bacterial gene after having cut by restriction enzyme.
After proper expression of genes the bacterial cells of both cultures are lysed with appropriate chemicals. The fragments of insulin are then separated from enzyme by cyanogen bromide.
7. The clinical gene therapy is given to a 4 years old patient for an enzyme which is crucial for the immune system to function. Observe the therapeutical flow chart and give the answer of the following: (a) Complete the missing steps (B) and (D) (b) Identify the disease to be cured. (c) Why the above method is not a complete solution to the problem? (d) Scientists have developed a method to cure this disease permanently. How? Ans. (a) Step (B) : Lymphocytes are grown in culture medium. Step (D) : Infusion of genetically engineered lymphocytes into patients. (b) Adenosine deaminase (ADA) deficiency. (c) As genetically engineered lymphocytes are not immortal, the patient requires periodic infusion of cells. (d) If the gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.
8. In the given figure, Agrobacterium is utilized for the production of a transgenic crop. Explain the steps a, b, c, d and e shown in the figure. Ans. Step (a) Plasmid is removed and cut open with restriction endonuclease. Step (b) Gene of interest is isolated from another organism and amplified using PCR Step (c) New gene is inserted into plasmid Step (d) Plasmid is put back into Agrobacterium Step (e) Agrobacterium based transformation.
9. In the given figure, Form (A) and Form (B) represents different forms of a proteinaceous hormone secreted by pancreas in mammals. (a) What type of bonding is present between chains of this hormone? (b) What are these form (A) and form (B). How these forms differ from each other? (c) Explain how was this hormone produced by Eli Lilly, an American company, using rDNA technology. Ans. (a) Disulphide bonds (b) Form (A) – Proinsulin Form (B) – Mature insulin.Proinsulin contains an extra stretch called C peptide which is absent in mature insulin. (c) Eli Lilly company prepared two DNA sequences corresponding to A and B peptide chains of human insulin and introduced them in plasmid E. coli to produce insulin chains. Chains A and B were producedseparately, extracted and combined by creating disulphide bonds to form insulin.
10.What is Gene therapy – Illustrate using example of Adenosine deaminase deficiency? Ans.Gene therapy is a collection of methods that allows correction of a gene defect. In this method,genes are inserted into the cells & tissues of an individual to correct certain hereditary diseases. Itinvolves delivery of a normal gene into the individual or embryo to replace the defective mutant allele of the gene. Viruses which attack the host cell & introduce genetic material into host are usedas vectors. For example Adenosine deaminase (ADA) deficiency can be cured by bone marrow transplantation in some children but is not curative for Gene therapy, lymphocytes are grown in a culture & functional ADA, cDNA is introduced into these lymphocytes. These lymphocytes are then transferred into body of patient the patient requires infusion of such genetically engineered lymphocytes.
In This Post we are providing Chapter- 8 HUMAN HEALTH AND DISEASE NCERT MOST IMPORTANT QUESTIONS for Class 12 BIOLOGY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERTMOST IMPORTANT QUESTIONS ON HUMAN HEALTH AND DISEASE
1.Describe the ill – effects of drug abuse in males & females. Also mention the preventive measures that is to be taken to reduce such effects. Ans.1) ILL – DEFECTS IN MALES :- acne, increased aggressiveness , mood swing depression reduction of size of testicles, decreased Sperm production, kidney & liver dysfunction, premature baldness. 2) ILL – EFFECTS IN FEMALES :-masculinisation, increased aggressiveness, mood swings, depression abnormal menstrual cycle, excessive hair growth on face & body & deepening of voice. The following measures are need to be taken to prevent such problems :-
EDUCATION & COUNSELLING :- to face problem or stress, to accept failure as part of life & to channelize child’s energy to some health promoting activities.
AVOID UNDUE PEER PRESSURE :- to pressurize a child to perform beyond his capabilities
SEEKING HELP FROM PARENTS &PEERS :- to share the feeling of anxiety & guilty.
SEEKING PROFESSIONAL FOR MEDICAL HELP :- help available in the form of highly qualified psychiatrist, psychologist etc.
2.What is vaccination? What type of immunity is provided by vaccination? Ans.Vaccination is a process of development of immunity with administration of vaccines in the body, here weakened pathogen are infected into the body to produce immunity against a particular pathogen. This pathogen stimulates the body to produce antibodies. The antibodies produced against these antigens would neutralize the pathogenic agent. The vaccine also generates memory B – and T – cells that recognize pathogen quickly on subsequent exposure & overwhelm the invaders with massive production of antibodies. The type of immunity is ACTIVE IMMUNITY. However, if a person is infected with some deadly microbe to which quick immune response is required, we need to directly injected to patient’s body, This type of immunization is called PASSSIVE IMMUNISATION.
3. (i) Differentiate between communicable & non – communicable diseases? (ii) Name the body part & the host in which following events takes place in life cycle of plasmodium. (a) fertilization (b) Development of Gametophyte :- (c) Release of sporozoites :- (d) Asexual Reproduction. Ans. (i) Communicable diseases are caused lay biological agents & can spread from one person to another or one place to another through air, water, physical contact etc. Non – communicable diseases are confined to a person & do not easily spread from one person to another. (ii) (a) in the gut of female anopheles. (b) in RBCS of Human beings. (c) Salivary gland of female anopheles. (d) liver cells of human beings.
4. Answer the following with respect to Caner. (a) How does a cancerous cell differ from a normal cell? (b) Benign tumor is less dangerous than malignant tumor. Why (c) Describe causes of cancer. (d) mention two methods of treatment of the disease. Ans. (a) In normal cells, growth and differentiation is highly controlled and regulated (contact inhibition). The cancerous cells have lost the property of contact inhibition, hence continue to divide giving rise to masses of cells (tumors). (b) The benign tumor remains confined in the organ affected as it is enclosed in a connective tissue sheath and does not enter the metastatic stage. (c) Cancer may be caused due to carcinogens which are physical (radiations), chemicals (Nicotine, Aflatoxin, Cadmium oxide, Asbestos) and biological (viral oncogens). (d) Surgery, radiotherapy, Chemotherapy
5. The pathogen of a disease depends on RBCs of human for grwoth and reproduction. The person with this pathogen suffers with chill and high fever. (a) Identify the disease. (b) Name the pathogen. (c) What is the cause of fever? (d) Represent the life cycle of the pathogen diagrammatically. Ans. (a) Malaria (b) Different species of Plasmodium viz P. vivax, P. Malariae and P. falciparum. (c) Malaria is caused by the toxins (haemozoin) produced in the human body by the malarial parasite. This toxin is released by the rupturing of RBCs. (d) Life cycle of Plasmodium : Fig. 8.1 Page 148, NCERT book, Biology – XII
6. The immune system of a person is supressed. He was found positive for a pathogen in the diagnostic test ELISA. (a) Name the disease, the patient is suffering from. (b) Which pathogen is identified by ELISA test? (c) Which cells of the body are attacked by the pathogen? (d) Suggest preventive measure of the infection. Ans. (i) AIDS (Acquired Immuno Deficiency Syndrome) (ii) HIV (Human Immunodeficiency Virus) (iii) Helper T-cells, macrophages, B-lymphocytes. (iv) Preventive measures : (a) People should be educated about AIDS transmission. (b) Disposable needles and syringes should be used (c) Sexual habits should be changed immediately (d) High-risk groups should be discouraged from donating blood. (e) Routine screening may be done.
7.Discuss the role of lymphoid organs in the immune response. Explain the different types of lymphoid organs giving two examples of each type in humans. Ans.Lymphoid organs are organs where origin or maturation & proliferation of lymphocytes occurs. These lymphoid organs are of two types:- 1.PRIMARY LYMPHOID ORGAN: – where immature lymphocytes differentiate into antigen – sensitive lymphocytes. It includes :- (a)BONEMARROW :– It is the main lymphoid organ present in the thigh region where all types of blood cells including lymphocytes are formed. It provides micro – environment for the development & maturation of B – cells. (b)THYMUS :- It is located beneath the chest bone near heart. It provides microenvironment for the development & maturation of T – lymphocytes. 2.SECONDAR LYMPHOID ORGAN :- They provide the site for interaction of lymphocytes with antigen which then proliferate to become effector cells. It includes. (a)SPLEEN :- It is large bean shaped organ & contains mainly lymphocytes & phagocytes. It acts as a filter of blood by trapping blood – bound micro – organism. (b)LYMPHNODE :- They are small – solid structure located at different points along lymphatic system. It serves to trap antigen which happens to get into lymph & tissue fluid. Antigen trapped in lymph nodes are responsible for activation of lymphocytes,
8.With the help of a well – labelled diagram, Describe the life cycle of malarial parasite. Ans.Malaria is caused by plasmodium vivax. It has two hosts – female anopheles is the vector of plasmodium while the primary host is man where the parasite maintains an amoeboid stage in RBCS & later produces gametophyte. Life cycle of plasmodium involves following steps:-
The sporozoites enters the human body, reach the liver through blood & multiply within the liver cells such liver cells burst & release the parasites into blood.
They attack RBCS, multiply & cause their rupture.
The rupturing of RBCS is associated with the release of a toxin called haemozoin, which is responsible for recurring fever & the chill / shivering.
Gametophytes are developed in RBCS.
When a female anopheles mosquito bites an infected person, these parasites enter the mosquito’s body & undergo further development. These parasites multiply within then in the stomach & develop a cyst.
The cyst produces sporozoites which reach salivary gland of mosquito. When such infected Anopheles sucks blood of a healthy person, it transfers. Sporozoites to repeat amoeboid stage again.
9. What do you mean by “Out – breeding”. What are the different methods employed for out breeding. Ans.Breeding between the unrelated ale & female animals is called Outbreeding. It can be done in following ways:-
OUT CROSS :- The mating of animals within the same breed but do not have any common ancestor on either side of their pedigree for 4-6 generation is called an out cross. It is the best method of breeding of animals that are below average in milk production, growth rate of beef cattle etc.
CROSS–BREEDING :- It is a cross between superior males of one breed & Superior females of another breed. It allows the desirable qualities of two different breeds to be combined & are used for commercial production eg .Hisardale, a new breed of sheep is developed by crossing bikaneri ewes & Marino rams.
INTERSPECIFIC HYBRIDISATION :- male & female animals of two different related species are mated so, that progeny may combine desirable features of both parents eg. mule is produced by crossly donkey & a female house.
10. What is somatic hybridization – Explain the steps involved in the production of somatic hybrids? Ans.Somatic hybridization is the process of fusing protoplasts of somatic cells derived from two different varieties or species of a plant on a suitable nutrient culture medium under sterile condition. One example of somatic hybrid is topato produced by fusion of protoplast of tomato & potato. Somatic hybridization involves the following steps:-
Isolation of protoplast from two different varieties of plants – each having a desirable character,
Fusion of cytoplasm of two protoplast results in coalescence of cytoplasm. The nuclei of two protoplasts may or may not fuse together even after fusion of cytoplasm, fusion of protoplast requires a suitable agent called fusogeneg. PEG or polyethylene glycol.
Under favourable conditions, hybrid protoplast synthesise new cell wall around it. Hybrid cell functions as a single cell & then undergo sustained division to form callus.
The regenerated callus is transferred to a new culture plates containing suitable culture media.Here callus divide & form root & shoot after organogenesis.
