Environment & Ecology Mixed Quiz: Set 4

The correct answer is B, inverted. In a pond the producers are phytoplankton, tiny floating plants whose total weight at any one moment is small. They multiply very rapidly, however, so over time they can feed a far greater mass of zooplankton and fish. Measuring the biomass present at a single moment therefore gives a pyramid that stands on its head.

Option A is true of a forest, where the great mass of trees at the base supports a much smaller mass of animals. Option C describes no real pyramid. Option D is wrong because the pyramid of energy remains upright in the pond as well; energy lost as heat at each transfer ensures that it can never be inverted. Keep the exceptions ready: numbers inverted in a tree ecosystem, biomass inverted in a pond, energy never inverted.

The correct answer is B, Endangered species. The Red Data Book is the source book that keeps a record of endangered animals, plants and fungi, so that governments and conservationists know which living species face the greatest risk of dying out. It is linked to the Red List prepared by the International Union for Conservation of Nature (IUCN), which was founded in 1948 and has its headquarters at Gland in Switzerland. Species at risk are placed in categories such as Critically Endangered, Endangered and Vulnerable, which together are called threatened species. Many countries, including India, also prepare their own Red Data Books for local species, and the Botanical Survey of India compiles one for Indian plants. Option A is wrong because the book is meant to help save living species; extinct species cannot be saved and are not its main record. Option C is wrong because common species are not at risk. Option D is wrong because invasive species, such as water hyacinth, are harmful newcomers and are tracked in separate lists. Exam tip: Red Data Book means endangered species; IUCN is at Gland, Switzerland, founded 1948.

The correct answer is B. Gross primary productivity is the total amount of energy that producers fix by photosynthesis. Plants use a part of it for their own respiration, and what remains stored in plant bodies is the net primary productivity. That remainder is the food actually available to herbivores, so it decides how much life the ecosystem can support.

Option A adds respiration instead of subtracting it and would give a figure larger than the energy actually captured. Option C is wrong because green plants capture only a small fraction of the sunlight that reaches them, the rest being reflected or passing through. Option D describes the standing biomass of consumers, which is a stock at a moment in time, not a rate of production. Productivity is always expressed per unit area per unit time.

The correct answer is A, The International Union for Conservation of Nature. The Invasive Species Specialist Group (ISSG) is one of the expert groups of the IUCN's Species Survival Commission, and it manages the Global Invasive Species Database. The ISSG is a network of scientists and policy experts that gathers information on alien species that spread and harm native wildlife, and it also compiled the well-known list of '100 of the World's Worst Invasive Alien Species'. The IUCN, founded in 1948 and based at Gland in Switzerland, also publishes the Red List of Threatened Species. Invasive plants such as Lantana, water hyacinth and Prosopis juliflora are a major threat to Indian forests and wetlands. Option B is wrong because UNEP runs environmental programmes and conventions but not this specialist group. Option C is wrong because the World Commission on Environment and Development, the Brundtland Commission, is known for its 1987 report 'Our Common Future'. Option D is wrong because WWF is a separate conservation NGO. Exam tip: IUCN means the Red List, the Species Survival Commission and the invasive species database.

The correct answer is B, biomagnification. DDT and mercury compounds are not broken down in the body and are not excreted, so they build up in the tissues of every organism that takes them in and are passed on to whatever eats it. The concentration therefore rises at each step, and top carnivores such as fish-eating birds and human beings receive the largest dose; in birds it caused eggshells to become thin and break.

Option A, eutrophication, is the excessive growth of algae in a water body enriched by fertilisers and sewage, which strips the water of oxygen. Option C, ecological succession, is the gradual change of a community over time until it reaches a stable climax stage. Option D, biodegradation, is the breaking down of substances by microorganisms, which is exactly what DDT resists.

The correct answer is B, 1973. Project Tiger was launched on 1 April 1973 by the Government of India under Prime Minister Indira Gandhi, from Jim Corbett National Park in Uttarakhand, to save the Bengal tiger and its habitat. It began with nine tiger reserves, including Corbett, Kanha, Bandipur, Ranthambore, Sundarbans and Manas, and the network has since grown to more than fifty. Each reserve has a core area free of human activity and a buffer zone around it. Since 2005 the project is run by the National Tiger Conservation Authority, a statutory body under the Wildlife (Protection) Act, and the tiger census is done every four years. A, 1985, is not linked to the tiger programme. C, 1972, is the year of the Wildlife (Protection) Act, the law that came a year before the project and is often confused with it. D, 1970, is when India banned tiger hunting. Exam tip: 1970 hunting ban, 1972 Wildlife Act, 1973 Project Tiger, 1992 Project Elephant.

The correct answer is C, Secondary consumers. In a food chain each step at which energy is transferred is a trophic level, and secondary consumers stand at the third step. The first trophic level is the producers, green plants that make food by photosynthesis; the second is the primary consumers, herbivores that eat plants; the third is the secondary consumers, carnivores that eat the herbivores; and the fourth is the tertiary or top consumers. In the chain grass, grasshopper, frog, snake, eagle, the frog is at the third level. Only about 10 percent of energy passes from one level to the next (Lindeman's ten percent law), so chains rarely go beyond four or five levels. A is wrong because primary consumers are the herbivores of the second level. B is wrong because top consumers sit at the fourth or final level. D is wrong because producers form the first level, the base of every chain. Exam tip: producers 1, herbivores 2, carnivores 3, top carnivores 4.

The correct answer is B, Oxygen. A greenhouse gas is one whose molecules absorb the long-wave infrared radiation given off by the warm surface of the Earth and send part of it back, keeping the planet about 33 degrees Celsius warmer than it would otherwise be. Such absorption needs molecules made of three or more atoms, or of two different atoms, that can vibrate in the right way. Oxygen (O2) and nitrogen (N2), which together make up 99 percent of the air, are made of two identical atoms, do not absorb infrared radiation and therefore are not greenhouse gases, even though they are the most abundant gases. A, Water vapour, is the largest natural contributor to the greenhouse effect. C, Carbon dioxide, is the main greenhouse gas added by humans through burning coal, oil and gas, and it is the reference gas for global warming potential. D, Methane, traps about 28 times more heat than carbon dioxide over a century and comes from paddy fields, cattle and landfills. Exam tip: the main greenhouse gases are water vapour, CO2, methane, nitrous oxide, ozone and CFCs; N2 and O2 are not.

The correct answer is A, 1%. Green plants are the producers of a terrestrial ecosystem, and NCERT's Class 10 chapter Our Environment states that they capture about 1 percent of the energy of the sunlight that falls on their leaves and convert it into food energy through photosynthesis. The rest of the sunlight is reflected, passes through the leaf or is lost as heat. This tiny fraction is the base of every food chain, and only about 10 percent of it passes from one trophic level to the next, which is Lindeman's ten percent law; that is why food chains rarely have more than three or four steps and why energy flow in an ecosystem is unidirectional. B, 5%, C, 8%, and D, 10%, are all too high: 10 percent is the share of energy transferred between trophic levels, not the share of sunlight captured by plants, and students often mix up these two numbers. Exam tip: plants capture about 1 percent of sunlight; about 10 percent of energy moves up at each trophic level.

The correct answer is B, greenhouse gases emission. The Kyoto Protocol, adopted at Kyoto, Japan on 11 December 1997 under the UN Framework Convention on Climate Change, was the first treaty to set binding targets for cutting emissions. It came into force on 16 February 2005 and asked industrialised countries to cut their greenhouse gas emissions by an average of about 5 per cent below 1990 levels during 2008 to 2012. It covered six gases, including carbon dioxide, methane and nitrous oxide, and created market tools such as the Clean Development Mechanism, which let projects in countries like India earn carbon credits. India ratified it in 2002 but, as a developing country, had no binding target. A is wrong, because cutting poverty is the aim of goals such as the UN Sustainable Development Goals, not Kyoto. C is wrong, because nuclear arms are dealt with by treaties like the Non-Proliferation Treaty of 1968. D is wrong, because farm subsidies fall under the WTO's Agreement on Agriculture. Exam tip: Kyoto 1997, in force 2005, binding cuts for rich nations; Paris 2015, pledges from all nations.

The correct answer is D, stratification. It means the layering of an ecosystem from top to bottom, with each layer holding its own set of species. The NCERT example is a forest: tall trees form the top layer, shrubs the second, and herbs and grasses the bottom layer, and each layer gets a different amount of light, heat and moisture. A tropical rainforest shows the most layers, with emergent trees, the canopy, the understorey and the forest floor, and animals such as birds, monkeys and insects also live at particular heights. Lakes are stratified too, into a warm upper layer and a cold bottom layer. Stratification lets many species share the same patch of land without competing directly. A is wrong because levelling is not a term used in ecology for vertical layers. B is wrong because grouping simply means putting things together and says nothing about height. C is wrong because ramification means branching and describes how a plant spreads, not layers of species. Exam tip: vertical layering in an ecosystem is stratification; trees, shrubs, herbs from top to bottom.

The correct answer is D, Forest Act 1878. The Indian Forest Act of 1878 created the three classes of reserved, protected and village forests. British interest in Indian forests grew as the railways and shipbuilding needed huge amounts of timber. The Imperial Forest Department was set up in 1864 with Dietrich Brandis as the first Inspector General of Forests, and the first Indian Forest Act followed in 1865. That Act was soon found too weak, so the 1878 Act replaced it, giving the state firm control over forest land and sharply cutting down villagers' customary rights, above all in reserved forests. Its successor, the Indian Forest Act, 1927, kept the same three classes and is still the main forest law. Option A is wrong because 1864 is the year the Forest Department was created, not a classification law. Option B is wrong because the 1865 Act only began state control and did not create the three classes. Option C is wrong because 1866 is not linked with this classification at all. Exam tip: 1864 department, 1865 first Act, 1878 three classes, 1927 Act still in use.

The correct answer is D, 1866. The German zoologist Ernst Haeckel coined the word 'Oekologie' in 1866 in his book Generelle Morphologie der Organismen. He built it from the Greek oikos, meaning house or household, and logos, meaning study, so ecology is the study of living things in their home, their relations with each other and with their surroundings. That is why the question speaks of the 'economies' of living forms, since economy comes from the same oikos. Haeckel was a strong supporter of Darwin and also gave biology words such as phylum. A related date that papers test is 1935, when the British ecologist A. G. Tansley coined the term 'ecosystem'. A is wrong because 1888 has no link with the word; by then it had been in use for over twenty years. B is wrong because 1884 is also too late and is not a date tied to ecology's naming. C is wrong because 1887 is likewise unconnected with Haeckel's coinage. Exam tip: ecology by Haeckel in 1866, ecosystem by Tansley in 1935.

The correct answer is D, Turbidity of water. NTU stands for Nephelometric Turbidity Unit. A nephelometer shines a beam of light through a water sample and measures how much of it is scattered sideways by suspended particles such as clay, silt, algae and microbes; the more the scattering, the more turbid, or cloudy, the water is. Turbidity is a key test for drinking water because the particles can shield germs from chlorine and other disinfectants, so water supply agencies try to keep it very low before the water reaches homes. High turbidity in a river or lake also cuts off sunlight for aquatic plants. Option A is wrong because water pressure is measured in units such as the pascal or the bar. Option B is wrong because temperature is measured in degrees Celsius or in kelvin. Option C is wrong because acidity is shown on the pH scale, where 7 is neutral and values below 7 are acidic. Exam tip: NTU = turbidity (cloudiness); pH = acidity; BOD = organic pollution, in milligrams per litre.

The correct answer is D, Impala will die of starvation due to higher population. In this food chain grass is the producer, the impala is the herbivore and the hyena is the predator that keeps the impala population in check. If all hyenas are removed, impalas multiply quickly because nothing hunts them. The larger herd overgrazes the grassland until there is not enough food, and then many impalas starve and their numbers crash. This chain reaction, where removing a top predator upsets every level below it, is called a trophic cascade. It is also why predators such as tigers are protected: they keep an ecosystem in balance. A is wrong because without predators the impala population cannot stay stable; it first rises sharply. B is wrong because the impalas' good time lasts only until the grass runs out. C is wrong because the grassland is the first to suffer, from overgrazing. Exam tip: remove the predator, the prey multiplies, food runs out and the prey starves; only about 10 per cent of energy passes to the next level.

The correct answer is A, Carbon captured by oceans and coastal ecosystems. Blue carbon is the carbon stored by marine and coastal ecosystems, especially mangroves, salt marshes and seagrass meadows. These plants take in carbon dioxide, and because their waterlogged soils have little oxygen, dead matter decays slowly and the carbon stays locked in the sediment for hundreds or even thousands of years. Area for area, they can store several times more carbon than tropical forests, which is why protecting the Sundarbans and India's seagrass beds counts as climate action. When these habitats are cleared, the stored carbon goes back into the air. Option B is wrong because carbon held in forest biomass and farm soils is called green carbon. Option C is wrong because carbon in petroleum and natural gas is fossil carbon, which is released as carbon dioxide when burnt. Option D is wrong because carbon dioxide in the air is simply atmospheric carbon, not stored carbon. Exam tip: blue carbon means coasts and oceans, green carbon means forests and soils.

The correct answer is C, 1, 3 and 5 only. Earthworms, millipedes and woodlice feed on dead plant and animal matter, called detritus, so they are detritivores. Detritivores break dead leaves and bodies into small pieces, which speeds up the work of decomposers such as bacteria and fungi that finish the breakdown and return nutrients to the soil. Earthworms eat decaying leaves and soil, millipedes chew leaf litter on the forest floor, and woodlice are small land crustaceans that live under logs and eat rotting wood. The key difference is that detritivores swallow detritus, while decomposers digest it outside their bodies. Jellyfish (2) are wrong because they are carnivores that sting and eat plankton and small fish. Seahorses (4) are wrong because they suck in tiny live crustaceans. So options A, B and D, which include jellyfish or seahorses, are wrong. Exam tip: earthworms, millipedes, woodlice and dung beetles are detritivores; bacteria and fungi are decomposers.

The correct answer is A, Fig. Each fig species is pollinated only by its own tiny fig wasp, and the two have evolved together over millions of years. A fig 'fruit' is really a closed bulb, the syconium, with hundreds of small flowers inside. A female wasp squeezes in through a tiny opening, pollinates the flowers and lays her eggs in some of them. The young wasps grow inside, mate, and the new females fly out carrying pollen to another fig. Without the wasp the fig cannot set seed, and without the fig the wasp cannot breed; this is obligate mutualism. Figs such as the banyan and peepal are keystone species, because their fruit feeds many birds and mammals through the year. Option B is wrong because mahua flowers are pollinated mainly by bats and some birds. Option C is wrong because sandalwood, a root hemiparasite, is visited by many kinds of insects, not one. Option D is wrong because silk cotton (semal) is pollinated mainly by birds. Exam tip: fig and fig wasp are the classic example of co-evolution and obligate mutualism.

The correct answer is D, Statement-I is incorrect but Statement-II is correct. Rainforest soil is actually poor in nutrients, even though the forest above it is the richest on land. Heat and heavy rain make dead leaves decompose within weeks, and the released nutrients are taken up almost at once by the dense roots and fungi of the trees. So most nutrients are stored in the living biomass, not in the soil, and only a thin layer of humus lies on the surface. Constant rain also washes minerals down through leaching, leaving red, acidic, laterite-type soils rich mainly in iron and aluminium oxides. This is why cleared rainforest land loses its fertility after a few harvests. Statement-II is right because fast decomposition is exactly what this hot, wet climate causes. Options A and B are wrong because Statement-I is false. Option C is wrong because it reverses which statement is true. Exam tip: in a rainforest the nutrients sit in the trees, not the soil; cool forests keep more in the soil because decay is slow.

The correct answer is D, Forest. A forest forms and runs on its own, without any human effort, so it is a natural ecosystem. Its plants make food by photosynthesis, animals feed on the plants or on one another, and fungi and bacteria break down dead matter and return nutrients to the soil, so the cycle keeps going by itself. Ponds, lakes, grasslands, deserts, rivers and oceans are other natural ecosystems. Ecosystems that people create and have to maintain are called artificial or man-made ecosystems. A is wrong because a crop field is sown, watered, weeded and harvested by farmers. B is wrong because an aquarium is a man-made tank that needs regular cleaning, feeding and aeration. C is wrong because a garden is planted and looked after by people, and left alone it would slowly change into something else. Exam tip: made by nature = natural (forest, pond, desert); made and kept by humans = artificial (crop field, aquarium, garden, park).