Free Biology NEET Video Lectures for Ecosystem

00:00:44 Hello dear students, welcome to the IIT PAL series of biology. I am Rkisha Bhik PGT Biology at Kindra Vidales Sector 2 AK Puram, New Delhi. In today's session, I have brought for you a set of multiplechoice questions from the topic ecology and environment. Ecology and environment is an important component of various competitive examinations be it uh EIPMT or uh the civil services examination. Almost all the entrance examination of the state level and national level comprises of the questions from ecology and environment.

00:01:23 Basically this trend has emerged lately because of the rising importance of these topics on our lives. Ecology is that branch of biology which helps us in giving a holistic perspectives about the things being happening in the nature or the environment. Just like the diversity in living organism, biology is also a diverse subject in itself having so many branches like botney, zoologology, microbiology, molecular biology and biochemistry etc. But there are certain threads which link these different

00:02:02 branches into a unifying principle. And ecology is one such unifying principle which gives us a holistic perspective and it helps us in understanding the various concept with an insight. So let us begin with our question answer session. Question number one. The term biod diversity is commonly used to describe the number, variety and variability of living organisms. What is the heritable variation within and between population of organisms called? Here I would like you to recall the concepts which we learned in the chapter

00:02:44 biod diversity. We have learned about the various levels of biodiversity. If you remember and there are three major levels of biodiversity. One at the genetic level, the other at the species level and thirdly at the ecological level. So the options are as given species diversity, genetic diversity, ecosystem diversity, all of the above. So what will be the correct answer? Yes, since the question is asking about the variety and variability of living organism. The diversity which is particularly related is the genetic

00:03:21 diversity. So let us recapulate what points uh we should remember and recall while answering such question. Genetic diversity which accounts for the difference in genes among individuals and species. Species diversity refers to the diversity among the species level within a particular region. Ecological diversity is the variation in ecosystem found in a region or over the whole planet. So we are moving from the genetic to the species and to the ecological level. Moving on to the next question which is again from

00:03:59 biodiversity. The question is biod diversity forms the basis for human existence in the following ways. Number one soil formation number two prevention of soil erosion. Number three recycling of waste and number four pollination of crops. So what is the question? Which one do you agree with? Biod diversity is essential for soil formation because soil formation occurs by the process of weathering. And we know that there is an interaction of the biotic and abiotic factors which helps in breaking down the

00:04:40 rocks and boulders and form the soil. Moreover, the litter and the dead matter also gradually form the humus and adds to the fertility of the soil. Secondly, prevention of soil erosion. We cannot agree more. The presence of plants, trees, grasses, the roots, they hold the soil together and helps in preventing soil erosion. The third one is recycling of waste. Recycling of waste. We know that there are certain microorganism which not only helps in nutrient cycling but it also helps in decomposition

00:05:18 process. So the third one is also correct with reference to the biod diversity. And the fourth one is pollination of crops. Pollination of crops is undertaken by the pollinators. Basically there are two type of pollination. Autogami and xenogami. Autoami is self-pollination and xenogami is the crosspollination. In plants where there is self-pollination although there is no need of pollinators but for the for the crosspollination purposes we need different groups of insects or birds bats or animals which help in

00:05:57 pollination. So this is also basically a function or a feature of biod diversity. So the answer will be that we agree with all of them. Biod diversity is essential for soil formation, prevention of soil erosion, recycling of waste and pollination of crops. Moving on to the next question. Which one of the following is not a site for insetu method of conservation of flora? Again this this question is also from biodiversity. We have learned about the method of biodiversity conservation where we classified the methods in into

00:06:37 two. One was institute and the other was exitu. So here the question pertains to the insitu method of conservation. Institute means on the site method of preservation and protection of the organisms. So what are the options? Number one biosphere reserve. B is botanical garden. C is national park and D is wildlife century. So if you remember can you answer this question? Institute method of conservation. I told you what are the different methods which comprises in situ. Biosphere reserve yes. Botanical

00:07:13 garden no. It is a method of exitu conservation. National park is yes. And wildlife century is also in situ method of conservation. So the correct answer here will be botanical garden which is not a site for institute method of conservation of flora. So what points should we remember? Institute conservation is the on the site conservation or the conservation of genetic resources in natural populations of plants or animal species. And the example the basic examples which comprise them are biosphere reserves,

00:07:49 national parks, wildlife centuries and sacred groups. Next, the red data books published by the international union for conservation of nature and natural resources IUCN contains list of number one endemic plants and animal species present in the biodiversity hotspots, number two threatened plant and animal species, number three protected sites for conservation of nature and natural resources in various countries. So we have described about the IUCN, International Union for Conservation of Nature and we have seen

00:08:29 that IUCN is the organization which is responsible for enlisting or maintaining a catalog of the threatened species and this the catalog is published by IUCN on a regular basis. So what will be the correct answer? Yes, you are right. The correct answer is second threatened plant and animal species. Uh but here in the question select the correct answer using the codes given below. One and three, two only, two and three, three only. So in such question you need to understand the question properly. You

00:09:06 need to read the question properly. What actually the question is asking. At times it happens that we know the answer but because we are not uh understanding the question properly we end up giving wrong answers. So it is better to read the question properly. But in these option we know that IUCN only enlist the threatened plants and animal species. So the correct option is B two only. Moving on to the next question. Three of the following criteria have contributed to the recognition of western Gart's Sri Lanka and Indo-urma

00:09:44 regions as hot spots of biod diversity. So here the question is asking about hot spots of biodiversity. We have also discussed this the hot spots they are characterized by three important features if you remember. So let us see the question. These are in listing various characteristic. Number one species richness. Number two vegetation density. Number three is endemism. Number four is ethnobotanical importance. Number five is threat perception. Number six is adaptation of flora and fauna to warm and humid

00:10:22 conditions. So if you remember the three important characteristics of hotspot biod diversity hotspots these those were number one it should be rich in species. So first one is correct. Secondly it should have a lot many endemic species within it. So the third one appears to be correct and the third feature was that it should be under enormous threat of extinction. So the fifth one appears to be correct. So here we can say safely that the options which we will take are number one species richness, number

00:11:03 three endemism and number five threat perception. These are the basic characteristics of biodiversity hotspots. Moving on next. Resource conservation is an ancient practice that refers to the management of resources by humans. Many Indian indigenous communities have adopted traditional methods to conserve their natural resources such as the formation of sacred groups. In which Indian state is the sacred group irring cavu located? Again the sacred group we have mentioned in the earlier question that it is a method of on the site

00:11:45 conservation in situ conservation and sacred grooves are the stretches or the patches of forest trackcts which are conserved and preserved by the local people because it is intricately linked with the culture and religion. So India boasts of many such sacred groups and irr. Let us see the options. Jaran, Kerala, Rajasthan, Maharashtra. So you have to remember here thatul Kavu is located in Kerala. It is a famous Hindu temple which is dedicated to goddess Da situated in Kunatunad Talok of Anakulum district. It

00:12:32 is 5 kilometer from Paramuir which is in Kerala and it is a sacred group. So let us move to the next question. A biosphere reserve conserves and preserves. Is this statement true for any or all of the categories mentioned? Wild animals, land, vegetation, all of the above. So again if you recall biosphere reserve it was constructed under the man and biosphere program and the concept behind biosphere reserve is to link man with nature and I also uh made you understand this the structure of biosphere reserve uh with

00:13:15 the help of three concentric circle as you can see in this figure that the core zone buffer zone and manipulation zone three zones are present in a biosphere reserve. The core zone is basically for the protection of plants and animals. The buffer zone is for educational and research activities in order to find out solution for their preservation. And the manipulation zone has the local peoples residing within it. But these local people they use the resources here but they do not destroy them and they live

00:13:49 in harmony with nature. So we can safely say that all these three are protected under a biosphere reserve. Wild animals, land as well as vegetation. So the correct option will be D. All of the above. So what should you remember here? Under the program MAB, man and biosphere of UNESCO, the creation of biosphere reserve was initiated which happened in the year 1975. A biosphere reserve is divided into three zone core buffer and manipulation. Next, the effects of climate change are alleviated by forest

00:14:30 that reduce the level of carbon dioxide in the atmosphere. the forest. We know that as the forest the forest comprises basically of the trees which undergo the process of photosynthesis and in this process of photosynthesis they consume carbon dioxide to reduce uh it into carbohydrates as food. So basically they are using the carbon dioxide and oxygen is released as a byproduct in this process of photosynthesis. When forest thrive, atmospheric carbon dioxide is absorbed by forest in their woods, leaves and

00:15:10 soil. For this particular natural activity, forest are also known by which of the following terms? Number one, carbon shakers, carbon sinks, carbon absorbers or carbon fighters. Here the correct option will be B, carbon sinks. What is a carbon sync? A carbon sink is anything that absorbs more carbon than it releases as carbon dioxide. For example, European forest are currently a net carbon sync as they take in more carbon than they emit. In the climate negotiations, this temporary reduction of carbon dioxide in

00:15:51 the atmosphere is also known as negative emissions. We are much worried about the carbon emissions in the air in the form of pollutant. But these forest can actually help us in uh building negative emissions of carbon because they act as carbon sinks. Next question is what are endemic species? In in a previous question uh we discussed about the biodiversity hotspot where we mentioned that a biodiversity hotspot has three important feature. Number one it has species richness. Number two, it has many endemic species.

00:16:31 And number three, it is under constant threat of extinction. So what are endemic species? The options are A critically critically endangered species, B species having cosmopolitan distribution, species found only in a particular region or the extinct species. The correct answer is C. Species found only in a particular region. The endomic species are those which are confined to a particular region and they are found nowhere else and so they are also under threat or they are vulnerable to extinction because if that particular

00:17:10 region is destructed or destroyed those endemic species will not uh survive. So what uh you need to remember here is that endemism is the ecological state of a species being unique to a defined geographical location such as an island, nation or a country. Endomic species for example in western G of India are lion tailed macau, nilgiri langur, brown palm cywood and nil nilgiri thar. So these are the examples of the endemic species found in western g of India. Next moving on to our 10th question.

00:17:51 Employed in the manufacturer of solar cells, which is this element that is the second most abundant in the earth's crust after oxygen. So the question is telling you one more fact that oxygen is the most abundant element on the earth's crust. Which one is the second one? If you don't remember, there is a additional hint that it is used in the manufacturing of solar cells. Let us see the options. Titanium, magnesium, silicon, aluminium. Probably you might have guessed the correct answer by now. Yes,

00:18:26 it is silicon. Silicon is the second most abundant element on the earth's crust. It is used in the manufacturer of solar cells or photovoltaic cells because it is a semiconductor. Next question. Marine biodiversity is facing a serious threat today due to falling pH levels of the oceans. This is one of the greatest challenges affecting marine life as it increases the level of carbon dioxide in the atmosphere. What is the phenomenon called? A utriofication, the B option is ocean acidification. C plastic waste

00:19:08 contamination and D none of the above. So here the correct option will be because there is falling pH level that is means acidification. So the correct answer will be ocean acidification. But we need to remember something about it. Uh what is ocean acidification? It is the ongoing decrease in the pH of the earth's oceans caused by the uptake of carbon dioxide from the atmosphere. Seawater is basic in nature. slightly basic in nature means the pH is more than seven and the process in question is a shift towards

00:19:46 pH neutral condition. When the pH is lowering down it means that it is becoming neutral rather than acidic. So uh the ocean acidification can be a misnomer in sense but since there is a reduction in the level of pH we will say that the process involved here is ocean acidification and naturally this process is detrimental to all the aquatic organisms because it will impact their osmotic balance. Next question. Chlorofluocarbons or CFC's known popularly they are the ozone depleting substances. They were used in the

00:20:27 production of plastic foams in the production of tubeless tires in cleaning certain electronic components and as pressurizing agents in aerosol cans. Which of these statement given above are correct? These CFCs were widely used earlier before we came to know before we understood that these are the substances which are responsible for ozone depletion and these were rampantly used in plastic foams in tubeless tires. It was used as refrigerants. It was used in cleaning electronic components and also

00:21:04 as pressurizing agent in aerosol cans. So all these options are correct and we will select the D option as the correct one. 1 2 3 and four. Next. Which among the following are the examples of secondary pollutants? Pollutants. What are pollutants? They are the contaminants. For example, if we talk about air pollutants, the air has a composition which comprises of nitrogen, oxygen, carbon dioxide, water vapor and other gases. If their concentration increases or if there is a substance which is other than what is what should be

00:21:46 present in its composition that is termed as a contaminant or pollutant. These pollutants can be divided into two types. Number one is primary pollutant and the other is the secondary pollutant. In this question you have to identify the secondary pollutants. The options are A smog, B pan peroxy acetile nitrate, C is ozone and D all of the above. So you should remember what we mean by primary pollutant and what we mean by secondary pollutant in this question. Primary air pollutants are those materials that when released pose

00:22:26 health risk in the unmodified forms or those emitted directly from identifiable sources. So uh there are these are those pollutants which are directly emitted from the identifiable sources. The secondary air pollutants are those primary pollutants which interact with one another sunlight or natural gases to produce new harmful compounds. So the sources are identifiable and the emissions which we can identify from those sources are the primary pollutants. For example, carbon dioxide, carbon monoxide, sulfur oxide, nitrogen

00:23:08 oxide, particulate matter. All these are the primary air pollutants. And the secondary air pollutants, the pollutants which are which are the primary pollutants which are already present in the air. when they combine with something like sunlight or water or natural gases and they form a new pollutant which is very harmful for the organism that is known as secondary pollutant and the examples include photochemical smoke peroxy acidile nitrate ozone all of the above will be the correct answer. Coming to

00:23:43 the next one. Acid rain is caused by the pollution of environment by A option carbon dioxide and nitrogen. B carbon monoxide and carbon dioxide. C ozone and carbon dioxide and D is nitrous oxide and sulfur dioxide. So basically what is acid rain? When we are talking about acid rain actually the the pollutants which are already present in the air for example the sulfur oxides or the carbon dioxide let us take carbon dioxide and when it rains we have water H2O. So when carbon dioxide and water reacts it

00:24:36 forms H2 CO3 which is carbonic acid. A reaction takes place resulting in the formation of acid and similar occurs with the sulfur oxides which results in the formation of sulfuric acid. nitrous oxide which reacts with water to form nitric acid. So again uh this acid rain can also be uh categorized under the secondary pollutant because the ma the pollutants are already present in the air and when they react with the precipitate or the water it forms a new compound carbonic acid or the respective acids and these

00:25:37 acids are very harmful for living organisms especially the aquatic living organism the lower organisms. And also we have also seen the impact of acid rain on the famous monument Taj Mahel. The marble is starting yellowing because of the impact of acid rain because it degrades the calcium carbonate present in the marble. What will be the correct answer here? The correct answer will be nitrous oxide and sulfur dioxide. Acid rain is caused by emission of basically sulfur dioxides and nitrogen oxides which react with the water

00:26:17 molecules in the atmosphere to produce acids. Next question is biomagnification and it it is asking the cause of biomagnification. Biomagnification is mainly caused by hydrocarbons, organo chlorines, organo phosphates or none of the above. So we first need to know what we mean by biomagnification. There are actually two terms associated with this kind of principle. One is bioaccumulation and the other is biomagnification. And these are associated with the trophic levels in the food chain. Bioaccumulation is the

00:26:59 accumulation of certain toxic substance at a particular trophic level of the food chain. Whereas biomagnification is the successive increase in that particular toxic chemical or compound with the increasing trophic levels. As there is a food chain and there are trophic levels which are linked together. the compound which is showing this kind of tendency to accumulate as well as increase with the respective trophic level and this and this phenomenon is known as biomagnification and it is basically

00:27:34 seen with the organo chlorines. So what will you remember in this question? Biommagnification also known as bioamplification or biological magnification is the increasing concentration of a substance such as a toxic chemical in the tissues of organisms at successively higher levels in a food chain. Organo chlorines like DDT, PCBs, polycllorin chlorinated bifpheniles, cyanide, selenium and other heavy metals they have been found to cause biomagnification. So the correct answer here will be B. Organo

00:28:16 chlorines. Next question. A pond with high value of BOD is highly polluted, highly productive, highly clean. None of these. Again, BOD is biochemical oxygen demand. Biochemical oxygen demand. oxygen demand and it is written as BOD commonly the short form is used BOD. Uh so what is BOD? BOD is actually an indicator for water pollution. It is an indicator for water pollution. uh but we need to know what is the meaning of BOD. What is BOD? POD biochemical oxygen demand is actually the amount of oxygen which would be

00:29:22 consumed by the aerobic microorganisms or decomposer to consume all the organic matter which is present in one liter of the water to oxidize it. So biochemical oxygen demand is the amount of oxygen required by these decomposers to oxidize the organic matter present in one liter of water. The organic matter is an indicator of the pollutant. The seawage is organic in nature. If there is more organic matter, the oxygen demand will be more. So if there is more oxygen demand, there will be more BOD. So we can say

00:30:04 that more is BOD more polluted is the water body. And one more thing which we need to remember here is that BOD shows an inverse relationship with dissolved oxygen content because the water has dissolved oxygen which is utilized by these organism for oxidizing the organic matter. But if the dissolved oxygen content is less because of the accumulation of or more organic matter then more oxygen will be required and this is known as BOD. More is the BOD less is the dissolved oxygen content. So what option will you select here? A pond

00:30:55 with high value of BOD is a highly polluted. Next question is al bloom results in you must have seen the ponds covered with a scum of algae throughout. This is known as alal bloom and it results in acidification, saltation, utrification or biomagnification. What will be the correct answer? Al bloom is associated with utrofication. Utrification is basically the cultural aging of is the natural aging of the lakes. Utrification refers to the aging of lakes. With time we know that there is a succession and the lakes or water

00:31:41 bodies gradually over a period of time will turn into land. But it has been seen that due to some human activities there has been tremendous growth in the algae in the water bodies which is leading to acceleration of this natural process of utrofication and this is also known as cultural utrofication. It occurs when excessive fertilizers run into lakes and rivers. We have been using fertilizers, pesticides and chemicals. These fertilizers they flow with the water and they enter into the water bodies and

00:32:21 when they do so the algae they get immense nutrition to grow at a very high rate. So this encourages the growth of algae and the other aquitic plants as well. Following this the lake or the water body uh faces overcrowding and there is a competition for the sunlight space and oxygen. Eventually when these organism will die they will need to be oxidized by the bacteria. They will need to be decomposed and that will require oxygen which will be consumed. So a condition like hypoxia will be created

00:32:58 in the lake. There will be a loss of oxygen from the water body resulting into the killing of aquatic life totally. I hope this question was quite clear. Next, moving on to the 18th question. Under the provisions of the forest conservation act, prior approval of the central government is essential for diversion of forest land for any nonforestry purposes. The basic objective of the act is to regulate the indiscriminate diversion of forest land. In which year did this act come into force? 1980, 1988, 1970 or

00:33:43 1960. So there has been a conservation act for forest by the Indian government and this mandates a particular proportion or percentage of land to be covered by forest and the diversion of that forest land for any other purpose is to be regulated with the help of this act. This act was given in 1980. It was enacted in 1980 and further amendments were made in 1988. It was enacted to help conserve the country's forest. It strictly restricts and regulates the dreservation of forest or use of forest land for

00:34:24 non-forest purposes without the prior approval of central government. U this also gives us the guideline that there should be 33% land area covered by forest but unfortunately we have only 21% of our land presently as forest. Next question. The most frequently quoted definition of sustainable development is sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Which of the following reports highlights and promotes this definition?

00:35:11 I have also told you earlier that there has been many conventions and the terminologies which we see today is a result of those convention. One such important convention or report was the Bruntland report which gave us this term sustainable development. So obviously I have told you the answer in this question. The correct answer is Bruntland report. There has been other options also basal document kartagina protocol RS convention but the one associated with sustainable development or the concept of sustainable

00:35:50 development is the Bruntland report. It was an enlightening report given by the Bruntland Commission and the title of this report was our common future. It was released in October 1987 and this document actually coined this term sustainable development. Next question. There are a large number of global agreements and conventions within agenda to protect wildlife. Which of the following agreement specifically targets the conservation of migratory species of wild animals? A born convention. B Ramsar

00:36:34 convention. C Kartagena protocol and D is Vana convention. Again this is a factual question pertaining to the knowledge or awareness of the environmental issues and the steps being taken. So you need to remember them. Let us let us understand them what they were. The born convention convention on migratory species Ramsar convention this has been discussed in my previous session. It was an international treaty for the conservation of wetlands. Carterina protocol was a global protocol to ensure safe transfer,

00:37:14 handling and use of living modified organisms arising out of biotechnology and the via convention is for the protection of ozone layer. So the correct answer here is a born convention which targets the conservation of migratory species of wild animals. Moving on to the next question. Question number 21. Here you have to pick up the correct food chain. You must remember here that a food chain comprises of producer followed by a primary consumer, secondary consumer and then the tertiary consumer. So the first option is grass,

00:37:57 chameleon, insect followed by bird. But we know that there is some error here. Insect should be eating grass followed by chameleon. B option grass eats uh is eaten by fox. Fox is eaten by a rabbit and then bird. Again there is some error here because there should be rabbit and then fox. The C1 is phytolanton followed by zoo plankton and then the fish. This appears to be correct. This is actually correct. Phytolantons present in the ocean. They are eaten by the zoo plankton followed by the fish. And the

00:38:38 last one is fallen leaf followed by bacteria followed by insect larae. uh this is actually showing the uh detritis food chain fallen leaf but it should be followed by insect larae and then the bacteria should come into play. So the correct answer is C. Phytolanton followed by zup plankton followed by fish. Point to remember here is that you should know what is a food chain. The transfer of food energy from the producer through a series of organism herbivores to carnivores then top carnivores or decomposers with

00:39:16 repeated eating and being eaten is known as food chain. In nature basically two types of food chain are recognized. One is the grazing food chain which always starts with the producer and it has the herbivore carnivore and top carnivore. And the other one is the detritus food chain which again will start with the dead matter be it the leaves or the animals followed by the detrity wars which will feed on them followed by the decomposers and it will help in nutrient cycling and all. Moving on to the next

00:39:54 question. Energy flows in ecology refer to the flow of energy in a food chain. In which direction do energy flow operate in an ecosystem? First is unidirectional, B bidirectional and C is multidirectional, D is none of the above. Again if you remember that energy flow in ecology how what is the source of energy? The source of energy is the sun. All the energy we are getting is the sun. Sun is the ultimate source of energy for all the living organism present on earth. And this sunlight or the sun's energy is being transferred

00:40:36 into chemical energy of food by the process of photosynthesis which occurs in green plants. So the energy flow will always be unidirectional. The correct option here will be yes it is a unidirectional. So you have to remember this that energy flows through ecosystem in one direction typically from the sun through photosynthetic organisms including green plants and algae to herbivores to carnivores and decomposers. Next question. What is the process by which one natural community changes into another over a time scale

00:41:15 of several years to centuries called? The options are A progression, B succession, C reproduction and D none of the above. We see that in an ecosystem there is a succession of community. There is a subsequent succession of the communities. The first one which invades a land first are the pioneer species. But there are certain serial stages in between until there is a stable stage which is known as the climax community. And this series or this this subsequent series is known as succession. So the

00:41:57 correct option is B succession. You have to remember ecological succession is the gradual process by which ecosystem change and develop over time. nothing remains the same and habitats are constantly changing. There are two main types of succession the primary and the secondary. Primary and secondary again the primary succession is the one which take place where there was no living organism present already. And the secondary one is that uh where there were some life present but it was harmed it was destroyed and again a new

00:42:40 succession arose from it. So the these are the basic two types of succession primary and secondary. Next question number 24. An ecosystem consists of both biotic and abiotic components. Biotic the living organisms and abiotic the physical components. Which of the following comprises the biotic components? A is producers, B consumers, C decomposers and D all of the above. I think this is a very easy question. Producers, consumers, decomposers, all are the living components and all will comprise the biotic component. So the correct

00:43:22 option will be D. All of the above. An ecosystem consists of biotic component the living organism abiotic component which are the non-living or the physical factors like light, temperature, water, nutrients, topography etc. Evolution by natural selection is driven by these ecological interaction between the biotic and the abiotic as well as among themsel. Question number 25. Which of the following term is used for the total sum of ecosystem found on the planet? So we have learned about diversity. We have

00:44:01 learned the three levels species, genetic and ecological. And we also know about ecosystem. Ecosystem is a functional place where there is an interaction between the biotic and the abiotic components. And there are so many ecosystem. Ecosystem can be very small and ecosystem can be very large. A pond is an ecosystem. There are man-made ecosystem like aquarium. And the sum total of all the ecosystem. What uh will it be called? The option here is lithosphere, atmosphere, hydrosphere and biosphere. The correct option will be

00:44:38 yes, you are right. It is biosphere. Biosphere is the global sum of all the ecosystem. It is actually a narrow zone of life which is uh connected by the lithosphere, atmosphere, hydrosphere all are present in that particular zone. This is known as biosphere. It can be referred to as a closed self-regulating zone of life. Moving on to the next question. Pyramid of number in a grassland ecosystem is so there are various ecological pyramids which we make. Eltonian pyramids which are the graphical representation showing the trophic

00:45:19 levels in a food chain. These are of three types. Pyramid of number, pyramid of biomass and pyramid of energy. So this question is asking about the pyramid of number in a grassland ecosystem always inverted always upright both A and B or spindle-shaped. uh you can have some idea with the help of this pyramid. You can see that in a grassland there are grasses which are the producers which are large in number followed by the herbivores which are the primary consumers followed by the primary carnivores which are the

00:45:56 secondary consumer and very few secondary carnivores or the tertiary consumer and this kind of pyramid is known as upright pyramid. So the pyramid of number in a grassland ecosystem is always upright. Pyramid of energy will always be upright because we know that sun is the ultimate source of energy. The maximum energy will be taken by producer. Then there is the 10% law law which states that only 10% of the energy will be passed on to the next trophic level. So there will be reduction in the energy as we move on to the next trophic

00:46:35 levels. So the pyramid of energy is always upright. Pyramid of biomass and pyramid of number however can be upright or inverted in certain cases and the spindle shape is when that the the middle portion is wider than the uh initial one and the final one. It is known as spindle shape. So depending upon the situation they can be of different types. Next question. Ecosystems have the ability to maintain normal patterns of nutrient cycling and biomass even after being subjected to ecological disturbance. What is this phenomenon

00:47:16 known as? A ecological resilience, B ecological footprint, C ecological diversity or D none of the above. The ability to maintain normal pattern of nutrient cycling and biomass that means to withstand adverse condition and the commonly used term for it is resilience and when it is being noted in reference to ecosystem it will be ecological resilience. So the correct answer is A. Ecological resilience is defined as the amount of disturbance that an ecosystem could withstand without changing self-organized

00:47:59 processes and structures. And whereas on the other hand what is an ecological footprint? It is a measure of the human impact on the earth's ecosystem. How the human is impacting the earth ecosystem. his footprints by the this is basically measured by the carbon emission which takes place in the air. Next, a food chain comprises a number of trophic levels. Which is the trophic level most vulnerable to extinction? We know the trophic levels in a food chain. These are the producer level, primary consumer level, secondary

00:48:39 consumer level and the tertiary consumer level. So which one do you think will be the most vulnerable? Yes, obviously the one which are showing the least number and in most of the cases we see that there are more producers as compared to the primary consumers followed by the secondary consumer and tertiary consumer which are lesser and lesser in number. So what will be the correct answer? The tertiary consumer level. For instance, if we see a forest in a forest there will be only one tiger. one or two tigers and uh so

00:49:14 because their number is less in the forest uh it will be the tertiary consumer level and it will be under the most threat of extinction. So we need to remember here that although every species has their own importance to the functionality of an ecosystem some species are more vulnerable to extinction than others. And what are those species? Number one, those which are at the top of food chains such as large carnivores. Number two, endemic local species. I told you earlier that endemic species are also vulnerable because they

00:49:52 have a very limited distribution. Third, species with chronically small population. The species which are having very small population again they are vulnerable. And the next one is the migratory species which migrate from one place to another. And if that particular migr migratory habit gets destroyed the species will not get the required resources and it might pose a threat to them. Next question. What is the full range of habitat type known as wherein a species can exist and reproduce without

00:50:31 any competition from others species? The options here are A fundamental niche, B fundamental existence, C fundamental growth and D none of the above. The term niche I explained you in the earlier session that actually niche is characterized by a place where the organism not only lives but also establishes itself. It has a role and function in that particular habit. So the full range of habitat type where the species can exist, reproduce and does not face competition from other species is a fundamental

00:51:17 niche. The full range of habitat type in which a species can exist and reproduce without any competition from other species is called a fundamental niche. Moving on to the next question. Every year 5th June is observed as A World Wildlife Day, B World Forest Day, C World Environment Day and D Biodiversity Conservation Day. Again these are factual question but since they are pertaining to ecology and ecology is an important component of the various competitive exams. So you need to remember these facts. So let us try

00:51:58 to remember them. World Wildlife Day is on 3rd March. World Forest Day 21st March. World Environment Day is celebrated on 5th June. And Biodiversity Conservation Day is celebrated on 22nd May. And all these day has been formed by the UN regulation, United Nations regulation. Next question. What are organisms that live at the bottom of oceans known as? Again, ocean is also an important o ecosystem and in ocean there are various layers depending on the sunlight which falls on it. The options here are benthic

00:52:43 organism, pelagic organism, periphyon organism or none of the above. So here if you know what are the various layer of the oceans known as you can simply answer it. The ocean has the uppermost layer which is in direct exposure to the sun that is known as epipilagic region followed by the misopilagic and the lowest one which is deep is the benthos region. So the organisms which live at the bottom of ocean is the benthic organism coming from the name benthos the layer benthos. The benthic organism

00:53:25 the answer will be a organisms that live in and on the bottom of the ocean floors are known as benthos or benthic organism and such organisms are worms, clams, crabs, lobsters, sponges etc. uh below the benthic uh region below the benthos there will be the abisil region which is the lowermost region and uh supposedly deprived of any life. Next question. In 1750 uh more than 350 people from the Bishnoi community in Rajasthan, India sacrificed their lives trying to protect a particular tree species which is this

00:54:07 tree kri ruanja rohida kanjjo. The Bishnois of Ashnavite sect living in western Rajasthan on the fringe of the Thar desert have for centuries been conserving the flora and fauna to the extent of sacrificing their lives to protect the environment. You must be knowing about the Amita Dvi Bishnoi award for conservation of wildlife. It has been constituted in recognition of their immense faith, immense sacrifice towards conservation and preservation of nature. So the the tree name is kri. Answer is a. It is a acacia

00:54:47 plant. Next question. To increase the spread of forest trees are planted in areas where there were none. What is this process called? Your options are aforestation, agroforestation, deforestation and reforestation. Reforestation, building forest again, deforestation, removal of forest or cutting of forest, agroforestation which is linked with the agriculture and aforestation is actually your correct answer. Uh these are the the this is the process where the trees are planted uh where the trees uh where no trees were

00:55:24 present earlier. Moving on to the next question. Exponential growth occurs when there is a no environmental resistance, limited resources present, a fixed carrying capacity, great environmental resistance. So here we are talking about exponential growth. The exponential growth curve actually comes out to be a Jshaped curve. There is exponential growth if we plot the graph between population density with respect to time. And this exponential growth will occur when there are when there is which will

00:56:07 be the correct option when there is no environmental resistance and there is abundance of natural resources present in the nature. So when the resources are unlimited population exhibit uh exponential growth resulting in a J-shaped curve. When the resources are limited population exhibit logistic growth. So this is the exponential growth curve and the logistic growth curve which is somewhat realistic comes out to be a sshaped curve. This is the S-shaped curve which comes out to be in the case of logistic

00:56:52 growth curve. Here you can see that there is a lag phase. There is a gradual increase followed by acceleration or deceleration phase and this is the asympto phase when it has reached its carrying capacity which is denoted by K. K is the carrying capacity. The amount of resources which is present in that particular habitat which can sustain the organisms living in it is the carrying capacity. So the last question is the carrying capacity of a population is determined by a natality b mortality c growth rate

00:57:32 and d limiting resources. What will be the correct answer? I hope you will be able to answer it. The carrying capacity of a population is determined by the limiting resources present in that particular habitat. So you have to remember the carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely given the food, habitat, water and other necessities available in the environment. With this I hope this session was good

00:58:07 enough for you because we discussed so many topics with the help of the MCQs multiplechoice questions and these are a general feature of many of the competitive exams. Moreover, ecology helps you in understanding many things. It gives you a holistic perspective of everything of how the organisms interact, how they uh live in the nature and how a imbalance in ecology or ecological imbalance will lead to detrimental will lead to adverse effect on us. With this I hope you enjoyed this lecture. Thank you and have a nice day.

00:58:47 [Music] Oh, [Music]