Solution (d)

Statement Analysis:

Notes:

Adaptations are found in the natural world among animals, which help them in surviving in their habitat.

Other adaptations found in the animals- are-

Polar bears –

• They also have a layer of fat under their skin. They are so well-insulated that they have to move slowly and rest often to avoid getting overheated. Physical activities on warm days necessitate cooling. So, the polar bear goes for swimming.
• They have a strong sense of smell so that they can catch their prey for food.

Penguins –

• They also have a thick skin and a lot of fat to protect them from cold. Like polar bears, penguins are also good swimmers. Their bodies are streamlined and their feet have webs, making them good swimmers.

Solution (a)

Statement Analysis:

Solution (c)

Statement Analysis:

Solution (d)

Statement Analysis:

Notes:

Detritus food chain-

• This type of food chain starts from organic matter of dead and decaying animals and plant bodies from the grazing food chain.
• Dead organic matter or detritus feeding organisms are called detrivores or decomposers.
• The detrivores are eaten by predators.
• In an aquatic ecosystem, the grazing food chain is the major conduit for energy flow.
• As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain.
• Decomposers are also known as saprotrophs.

Solution (c)

Statement Analysis:

Notes:

Ecological niche-

• Ecological niche is a term for the position of a species within an ecosystem, describing both the range of conditions necessary for persistence of the species, and its ecological role in the ecosystem. 
• Ecological niche subsumes all of the interactions between a species and the biotic and abiotic environment, and thus represents a very basic and fundamental ecological concept.
• The reason is that ecology is about interactions between organisms, and if persistence of a species is determined by the presence of other species (food sources, competitors, predators, etc.); all species are naturally both affected by environment, and at the same time affect the environment for other species.
• Ecological niche may be defined as the functional role and position of species in its ecosystem.
• Dominant species occupy an extensive and broader ecological niche in comparison to less dominant species.

Solution (a)

Statement Analysis:

Notes:

Interdependence of Ecological Community-

Mutual interdependence includes all the direct and indirect effects that organisms have upon each other. The three such relationships are (a) competition, (b) stratification, and (c) dependence.

1. Competition: Demand for a common resource by different organisms results in competition. Competition between individuals of different species is called interspecific; when it occurs between individuals of the same species it is called intraspecific.
2. Stratification: Different organisms in a community develop a characteristic pattern of stratification to minimise competition and conflict among the members of the community. Plants and animals of each layer differ in size, behaviour and adaptation from those of other layers. Stratification is a practical strategy to minimise interspecific competition i.e competition between different species.
3. Dependence: In a community there are some species which are wholly dependent on the dominant member for survival. Bryophytes, thallophytes and a few vascular small plants are examples of such organisms. These dependent organisms require special conditions such as shade and moisture provided by the dominant species. The dependent species will die if the dominant species are eliminated.

Solution (c)

Statement Analysis:

Notes:

Ecological Succession-

• The gradual and fairly predictable change in the species composition of a given area is called ecological succession. 
• During succession some species colonise an area and their population become more numerous whereas populations of other species decline and even disappear. 
• The entire sequence of communities that successively change in a given area are called sere(s). The individual transitional communities are termed seral stages or seral communities. In the successive seral stages there is a change in the diversity of species of organisms, increase in the number of species and organisms as well as an increase in the total biomass.
• The present day communities in the world have come to be because of succession that has occurred over millions of years since life started on earth. Actually succession and evolution would have been parallel processes at that time. Succession is hence a process that starts in an area where no living organisms are there – these could be areas where no living organisms ever existed, saybare rock; or in areas that somehow, lost all the living organisms that existed there. The former is called primary succession, while the latter is termed secondary succession.
• Examples of areas where primary succession occurs are newly cooled lava, bare rock, newly created pond or reservoir. The establishment of a new biotic community is generally slow. Before a biotic community of diverse organisms can become established, there must be soil. Depending mostly on the climate, it takes natural processes several hundred to several thousand years to produce fertile soil on bare rock.
• Secondary succession begins in areas where natural biotic communities have been destroyed such as in abandoned farm lands, burned or cut forests, lands that have been flooded. Since some soil or sediment is present, succession is faster than primary succession.
• At any time during primary or secondary succession, natural or human induced disturbances (fi re, deforestation, etc.), can convert a particular seral stage of succession to an earlier stage. Also such disturbances create new conditions that encourage some species and discourage or eliminate other species.
• Based on the nature of the habitat – whether it is water (or very wet areas) or it is on very dry areas – succession of plants is called hydrarch or xerarch, respectively. Hydrarch succession takes place in wet areas and the successional series progress from hydric to the mesic conditions. As against this, xerarch succession takes place in dry areas and the series progress from xeric to mesic conditions. Hence, both hydrarch and xerarch successions lead to medium water conditions (mesic) – neither too dry (xeric) nor too wet (hydric).
• The species that invade a bare area are called pioneer species. In primary succession on rocks these are usually lichens which are able to secrete acids to dissolve rock, helping in weathering and soil formation. In primary succession in water, the pioneers are the small phytoplanktons, which are replaced with time by rooted-submerged plants, rooted-floating angiosperms followed by free-floating plants, then reedswamp, marsh-meadow, scrub and finally the trees. The climax again would be a forest.
• In secondary succession the species that invade depend on the condition of the soil, availability of water, the environment as also the seeds or other propagules present. Since soil is already there, the rate of succession is much faster and hence, climax is also reached more quickly.
• All succession whether taking place in water or on land, proceeds to a similar climax community – the mesic.

Solution (b)

Statement Analysis:

Notes:

Biomagnifications-

• It refers to the tendency of pollutants to concentrate as they move from one trophic level to the next. 
• In biomagnifications there is an increase in concentration of a pollutant from one link in a food chain to another. In order for biomagnifications to occur, the pollutant must be:

•  long-lived
• Mobile
• soluble in fats
• Biologically active

• It can be seen in the case of Mercury or DDT. The concentration of Mercury/DDT increases at the successive trophic levels. DDT concentration in zooplankton gets magnified when DDT contaminated water is consumed by the Zooplanktons. In the successive trophic levels like, small fish, big fish, and at top carnivore, the magnification is much higher, which proves the event of Biomagnifications.
• A pollutant having properties like long life, mobile, soluble in fat, biologically active will lead to the process of biomagnifications.

 Solution (c)

Statement Analysis:

Notes:

Organic Farming-

• India ranks first in number of organic farmers and ninth in terms of area under organic farming.
• Sikkim became the first State in the world to become fully organic and other States including Tripura and Uttarakhand have set similar targets.
• With the aim of assisting farmers to adopt organic farming and improve remunerations due to premium prices, two dedicated programs namely Mission Organic Value Chain Development for North East Region (MOVCD) and Paramparagat Krishi Vikas Yojana (PKVY) were launched in 2015 to encourage chemical free farming. 
• With the simultaneous thrust given by the Agri-export Policy 2018, India can emerge as a major player in global organic markets. 
• The major organic exports from India have been flax seeds, sesame, soybean, tea, medicinal plants, rice and pulses, which were instrumental in driving an increase of nearly 50% in organic exports in 2018-19.

Solution (c)

Statement Analysis:

Notes:

Carbon cycle-

• Carbon is a minor constituent of the atmosphere as compared to oxygen and nitrogen.
• However, without carbon dioxide life could not exist because it is vital for the production of carbohydrates through photosynthesis by plants.
• t is the element that anchors all organic substances from coal and oil to DNA (deoxyribonucleic acid: the compound that carries genetic information).
• Carbon is present in the atmosphere, mainly in the form of carbon dioxide (CO2).
• Carbon cycle involves a continuous exchange of carbon between the atmosphere and organisms.
• Carbon from the atmosphere moves to green plants by the process of photosynthesis, and then to animals.
• By process of respiration and decomposition of dead organic matter, it returns to the atmosphere. It is usually a short term cycle.
• Some carbon also enters a long term cycle. It accumulates as un-decomposed organic matter in the peaty layers of marshy soil or as insoluble carbonates in bottom sediments of aquatic systems which take a long time to be released.
• In deep oceans, such carbon can remain buried for millions of years till geological movement may lift these rocks above sea level.
• These rocks may be exposed to erosion, releasing their carbon dioxide, carbonates and bicarbonates into streams and rivers.
• Fossil fuels such as coals, oil and natural gas etc. are organic compounds that were buried before they could be decomposed and were subsequently transformed by time and geological processes into fossil fuels. When they are burned the carbon stored in them is released back into the atmosphere as carbon dioxide.

Solution (d)

Statement Analysis:

Notes:

Nitrogen fixation-

• Plants need nitrogen to make themselves. Without nitrogen, a plant cannot make the proteins, amino acids and even its very DNA. 
• This is why when there is a nitrogen deficiency in the soil, plants are stunted. They simply cannot make their own cells. If there is nitrogen all around us, as it makes up 78 percent of the air we breathe.
• In order for plants to use the nitrogen in the air, it must be converted in some way to nitrogen in the soil. This can happen through nitrogen fixation, or nitrogen can be ‘recycled’ by composting plants and manure.
• There are two routes to go when fixing a nitrogen deficiency in the soil, either organic or non-organic.

• Organic:

To correct a nitrogen deficiency using organic methods requires time, but will result in a more even distribution of the added nitrogen over time.

• • Adding composted manure to the soil 
  • Planting a green manure crop, such as borage Planting 
  • nitrogen fixing plants like peas or beans 
  • Adding coffee grounds to the soil

• Non-Organic:

Using a nitrogen fertilizer to fix a nitrogen deficiency in the soil will give a big, fast boost of nitrogen to the soil, but will fade quickly.

Solution (c)

Statement Analysis:

Notes:

Ecological Pyramids-

• Pyramid of numbers shows the number of the producers, herbivores and the carnivores at their successive Trophic levels. This pyramid can be either upright, or inverted or partially upright.
• In a forest ecosystem, the producers are large size trees which make the base of Pyramid. The herbivores such as fruit eating birds, deer, elephants etc. make the primary consumers and are less than primary producers. After that, the number goes down at each successive level. Thus the pyramid of number is upright in the forest ecosystem.
• In a grassland ecosystem, the number of producers (mainly grasses) is always maximum, followed by decreasing numbers at second Trophic level (herbivores), third Trophic level (carnivores) and least number of apex predators. Thus, a pyramid of numbers is upright in grassland ecosystem.
• Pyramid of Biomass shows the biomass of the producers, herbivores and the carnivores at their successive Trophic levels.
• Pyramid of biomass for terrestrial ecosystems (grasslands, forests) the biomass generally decreases at each higher Trophic level from plants via herbivores to carnivores. Thus the Pyramid of biomass is upright in grassland ecosystem.
• In the aquatic system, the biomass can increase at higher Trophic levels. For example, in Oceans, the food chain typically starts with phytoplankton and ends at predatory fish, which has largest biomass. Thus, the pyramid of biomass is inverted in the aquatic systems including marine, ponds etc.

Solution (c)

Statement Analysis:

Notes:

Food Chain and Food web-

• Organisms in the ecosystem are related to each other through feeding mechanism or trophic levels, i.e. one organism becomes food for the other. A sequence of organisms that feed on one another, form a food chain. 
• Food chain is a linear sequence of organisms which starts from producer organisms and ends with decomposer species. 
• Food web is a connection of multiple food chains. Food chain follows a single path whereas food web follows multiple paths. 
• From the food chain, we get to know how organisms are connected with each other.
• Food chain and food web form an integral 
• part of this ecosystem
• A food chain represents only one part of the food or energy flow through an ecosystem and implies a simple, isolated relationship.
• An ecosystem may consist of several interrelated food chains. More typically, the same food resource is part of more than one chain, especially when that resource is at the lower trophic levels.
• A food web illustrates, all possible transfers of energy and nutrients among the organisms in an ecosystem, whereas a food chain traces only one pathway of the food.

Solution (c)

Statement Analysis:

Notes:

Organic farming-

Organic farming is a holistic system designed to optimize the agricultural productivity and to reduce the impacts on diverse communities like soil organisms, plants, livestock and humans. Organic farming is a contemporary method of crop and livestock production that involves tools which do not use chemicals and artificial tools of cropping. It is an integrated farming system that strives for sustainability, enhancement of soil fertility and biological diversity.

Key characteristics of organic farming are:

• It relies primarily on local, renewable resources
• It makes efficient use of solar energy and the production potential of biological systems
• It maintains the fertility of the soil
• It maximizes recycling of plant nutrients and organic matter
• It does not use organisms or substances foreign to nature (e.g GMOs, chemical fertilizers or pesticides)

Substances which are prohibited in organic farming are:

• Chemical fertilizers and pesticides
• Genetically modified organisms
• Nanomaterials

Solution (c)

Statement Analysis:

Notes:

Invasive Species-

• Invasive species have devastating effects on wildlife.
• Human health and economies are also at risk from invasive species. Many of ourcommercial, agricultural, and recreational activities depend on healthy native ecosystems.
• Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label “invasive.”
• An invasive species does not have to come from another country.
• Invasive species are primarily spread by human activities, often unintentionally. People, and the goods we use, travel around the world very quickly, and they often carry uninvited species with them. 
• When a new and aggressive species is introduced into an ecosystem, it may not have any natural predators or controls. 
• It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader, or they may not be able to compete with a species that has no predators.
• One way to curb the spread of invasive species is to plant native plants and remove any invasive plants in your garden.

Solution (c)

Statement Analysis:

Notes:

Ecotone-

• An Ecotone is a transitional area of different Ecosystems, such as forest and grasslands. 
• An Ecotone may exist along a broad belt or in a small pocket, such as forest clearing, whereas two local communities blend together. Ecotone may be very narrow or quite wide. It has conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension.
• An Ecotonal area often has a higher density organism of one species and a greater number of species than are found in either flanking community. This tendency for increased diversity within the ecosystem is referred to as the ‘Edge effect’.
• Ecotone often has a large number of species and larger population densities than the communities on either side.
• Ecotone also appears where one body water meets another at boundary between the water and land ex: marshes.
• Grasslands is an ecotone between forest and desert ecosystem.

 Solution (b)

Statement Analysis:

Note:

The total amount or weight, or energy content, of (a portion of) organisms existing in a specific area at a particular time, is known as standing crop.

Solution (a)

Statement Analysis:

Notes:

Phosphorus Cycle-

• Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer systems. Many animals also need large quantities of this element to make shells, bones and teeth. The natural reservoir of phosphorus is rock, which contains phosphorus in the form of phosphates.
• When rocks are weathered, minute amounts of these phosphates dissolve in soil solution and are absorbed by the roots of the plants. Herbivores and other animals obtain this element from plants. The waste products and the dead organisms are decomposed by phosphate-solubilising bacteria releasing phosphorus.
• Unlike carbon cycle, there is no respiratory release of phosphorus into the atmosphere. The other two major and important differences between carbon and phosphorus cycle are firstly, atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs, and, secondly, gaseous exchanges of phosphorus between organism and environment are negligible.

Solution (b)

Statement Analysis:

Notes:

Solution (c)

Statement Analysis:

Notes:

The carrying capacity of an environment is the maximum population size of a biological species that can be sustained in that specific environment, given the food, habitat, water, and other resources available.

The carrying capacity is different for each species in a habitat because of that species’ particular food, shelter, and social requirements. Disease, competition, predator-prey interaction, resource use and the number of populations in an ecosystem all affect carrying capacity. It does not relate to the diversity of species. Important direct drivers affecting biodiversity are habitat change, climate change, invasive species, overexploitation, and pollution.

Populations grow through births and immigration and decline through deaths and emigration. When resources are unlimited, the growth is usually exponential but when resources become progressively limiting, the growth pattern turns logistic. The intrinsic rate of natural increase (r) is a measure of the inherent potential of a population to grow. The ‘intrinsic rate of natural increase’ is a very important parameter chosen for assessing impacts of any biotic or abiotic factor on population growth.

Solution (c)

Abanindranath Tagore believed in the traditional Indian techniques of painting. His philosophy rejected the “materialistic” art of the West and came back to Indian traditional art forms. He was influenced by the Mughal school of painting as well as Whistler’s Aestheticism. Most of his works revolved around Hindu philosophy. Bharat Mata, The Passing of Shah Jahan (1900), My Mother (1912–13), Fairyland illustration (1913), Journey’s End (circa 1913) were his famous paintings. Some of his books like ‘BudoAngla’, ‘KhirerPutul’ and ‘Rajkahini’ are best examples of Bengali children’s literature.

Context- Abanindranath Tagore’s 150th birth anniversary was recently celebrated.

Solution (d)

Statement Analysis:

Context – There was a Telangana High Court judgement on Preventive Detention

Solution (a)

Statement Analysis:

Context- Recently, the Chief Minister of Andhra Pradesh has launched Pneumococcal Conjugate Vaccine (PCV) immunisation drive for infants.

Solution (d)

Statement Analysis:

Context- PM DAKSH portal and app was launched recently

Solution (a)

Statement Analysis:

Context – The Ministry of Finance has launched ‘Ubharte Sitaare’ Alternative Investment Fund to facilitate debt and equity funding to export-oriented MSMEs (Micro Small and medium Enterprises

Solution (d)

The question demands the selection of 5 men from 7 men and 2 women from 3 women.
Number of ways to do this
= 7C5 × 3C2
= 7C2 × 3C1 [∵ nCr = nC(n-r)]
=(7×6)/(2×1)×3=21×3=63

Hence, Option(d) is the right answer.

Solution (b)

Since no box can be left empty, there can be only two cases.

Case 1: 1, 1, 3
(i.e., 3 balls are put in 1 box and 1 ball is put in each of the remaining 2 boxes).

Total number of ways in which this can be done = 1 (as both boxes and balls are identical)

Case 2: 1,2,2

(i.e., two balls are put in each of the two boxes and 1 ball is put in the remaining 1 box).

Total number of ways in which this can be done =1=1 (as both boxes and balls are identical).

From (1) and (2),
Required number of ways
=1+1=2 ways . Hence, Option(b) is the right answer.

Solution (a)                                                                               

Initially invite the 3 particular friends. This can only be done in 1 way …(1) 

Now he needs to invite 3 (=6-3) more friends from the remaining 6 (=9-3) friends. This can be done in 6C3 ways …(2) 

From (1) and (2), required number of ways = 1 × 6C3 = 6C3 = (6 × 5 × 4) /(3 × 2 × 1) = 5 × 4 = 20

Hence, Option(a) is the right answer.

Solution (c)

The word ‘BUTTER’ contains 6 letters. The letters U and E should always come together.

 So the letters are B, T, T, R, (UE). Number of ways in which the letters above can be arranged = 5!/2! = 60 (since the letter ‘T’ is repeated twice). 

Number of ways in which U and E can be arranged = 2! = 2 ways 

Therefore, total number of permutations possible = 60*2 = 120 ways.

Hence, Option(c) is the right answer.

Solution (d)

The main idea of the paragraph is conveyed in the last sentence: “Indeed, that movie scene exemplifies the so-called “CSI effect”—the phenomenon in which judges hold unrealistic expectations of the capabilities of forensic science.” Option d rephrases this. Also note that all other option are specific to voice recognition. The paragraph is more general and talks of forensic science.