Ecosystems and Biodiversity for CUET General Aptitude

AnswerA · producers

1. Green plants make their own food from sunlight, water and carbon dioxide by photosynthesis, so they produce the energy that enters the chain.

2. That makes them producers, and they occupy the first trophic level.

3. Primary consumers are the herbivores that eat them, secondary consumers eat the herbivores, and decomposers break down dead matter at every level.

AnswerB · Water flea

1. A primary consumer eats the producer directly.

2. The water flea eats algae, so it is a primary consumer (a herbivore). The small fish and water beetle eat animals, and the heron eats fish.

AnswerB · decomposers

1. Decomposers break complex dead matter into simple substances.

2. This returns nutrients such as nitrogen and phosphorus to the soil, where plants can use them again.

AnswerC · Temperature

1. Abiotic factors are the physical and chemical parts: sunlight, temperature, water, soil and air.

2. Grass, earthworms and fungi are living, so they are biotic.

AnswerA · The Sun

1. Green plants capture sunlight in photosynthesis and store it as chemical energy in food.

2. Every consumer gets its energy, directly or through other animals, from that food.

AnswerB · an omnivore

1. Herbivores eat only plants and carnivores eat only animals.

2. An animal with both in its diet is an omnivore; humans and crows are others.

AnswerB · 10%

1. Most of the energy at any level is spent on the organism's own respiration and movement, or lost as heat.

2. Only about a tenth is stored as body tissue and so becomes available to whatever eats it. This is usually called the ten per cent law.

3. Because the loss compounds at every step, food chains rarely run beyond four or five levels.

AnswerC · 5

1. Start at the producer, grass, and follow every path of arrows to a consumer that nothing eats (the hawk).

2. Grass → grasshopper → frog → snake → hawk; grass → grasshopper → sparrow → hawk; grass → rabbit → hawk; grass → mouse → snake → hawk; grass → mouse → hawk.

3. That makes 5 chains.

AnswerD · 5

1. List the chains: trees → deer → tiger; trees → caterpillar → bird → eagle; trees → caterpillar → bird → snake → eagle; trees → squirrel → snake → eagle.

2. The longest, through the caterpillar, bird and snake, has 5 organisms.

AnswerD · A secondary consumer, at the third trophic level

1. In this web the tiger eats only deer, and deer eat the trees.

2. Trees (level 1) → deer (level 2) → tiger (level 3): the tiger eats a herbivore, so it is a secondary consumer.

AnswerC · Fifth

1. Both chains to the shark have five links: phytoplankton → zooplankton → sardine → tuna → shark, and phytoplankton → zooplankton → jellyfish → turtle → shark.

2. So the shark is at the fifth trophic level.

AnswerA · The tuna and the seabird

1. In this web the tuna and the seabird each eat only sardines.

2. The shark would still have turtles, which eat jellyfish, so it keeps a food source.

AnswerB · 20 J

1. Only about 10% of the energy at one level passes to the next.

2. Grasshoppers get 2,000 J, frogs 200 J and snakes 20 J.

AnswerC · Energy passes from the Sun to producers to consumers, and the part lost as heat never returns to the plants

1. At each level most of the energy is used for life processes and lost as heat.

2. Plants cannot use heat to make food, so energy cannot flow back. Nutrients are recycled, but energy is not.

AnswerD · Fish-eating birds at the top of the food chain

1. DDT is not broken down or excreted, so it builds up in the bodies of organisms.

2. Each level eats many organisms from the level below, so the concentration rises at every step. This is biomagnification.

AnswerC · 3

1. A trophic level is the organism's position in a chain, counting the producer as level 1.

2. Grass → rabbit → hawk puts the hawk at level 3; grass → mouse → snake → hawk at level 4; grass → grasshopper → frog → snake → hawk at level 5.

3. So the hawk feeds at 3 different levels: 3, 4 and 5.

AnswerB · 3

1. The web has 5 chains: two pass through the water flea and three through the tadpole.

2. Algae → tadpole → small fish → large fish → heron; algae → tadpole → small fish → heron; algae → tadpole → water beetle → large fish → heron.

3. Removing the water flea breaks its two chains, leaving 3.

AnswerC · Peacock

1. Chains: wheat → rat → owl; wheat → rat → snake → peacock; wheat → locust → peacock; wheat → locust → lizard → snake → peacock.

2. The peacock is at levels 3, 4 and 5; the snake at 3 and 4; the owl only at 3; the rat only at 2.

AnswerA · spindle-shaped, narrow at the base and the top and wide in the middle

1. Count the organisms at each level: one tree (narrow base), thousands of insects (wide middle), a few birds (narrow top).

2. So the pyramid of numbers bulges in the middle. The pyramid of energy, by contrast, is always upright.

AnswerD · 78%

1. Dry air is about 78% nitrogen, 21% oxygen and about 1% argon, with a small amount of carbon dioxide.

AnswerD · leguminous plants such as peas, beans and gram

1. Rhizobium lives in nodules on the roots of legumes and turns nitrogen gas into compounds the plant can use.

2. In return the plant gives the bacteria food: this partnership is symbiosis.

AnswerA · By condensation as the air rises and cools

1. Warm, moist air rises and cools as it goes up.

2. Cooled vapour condenses on tiny dust particles into droplets, which gather as clouds and fall as rain: precipitation.

AnswerD · Photosynthesis

1. Plants and algae take in carbon dioxide and build it into sugars during photosynthesis.

2. Respiration, decomposition and burning all release carbon dioxide back into the air.

AnswerB · nitrates

1. Most plants cannot use nitrogen gas directly.

2. Their roots absorb dissolved nitrates (and some ammonium), which they use to make proteins and DNA.

AnswerA · carbon from ancient organisms, stored underground for millions of years

1. Fossil fuels formed from plants and animals buried long ago and changed by heat and pressure.

2. Burning them releases this long-stored carbon as carbon dioxide much faster than the cycle can absorb it.

AnswerD · transpiration

1. Plants draw water from the soil and lose most of it as vapour through their stomata.

2. Over a forest this transpiration puts large amounts of water back into the air, which later falls as rain.

AnswerB · 21%

1. Oxygen makes up about 21% of dry air; it is constantly renewed by photosynthesis.

AnswerB · denitrification

1. Denitrifying bacteria, common in waterlogged soils, turn nitrates into nitrogen gas.

2. This returns nitrogen to the air and completes the cycle.

AnswerC · Its heat joins nitrogen and oxygen into oxides, which rain carries down as nitrates

1. Nitrogen gas is very unreactive, but the great heat of a lightning flash makes it combine with oxygen.

2. The nitrogen oxides dissolve in rain and reach the soil as nitrates. This is atmospheric nitrogen fixation.

AnswerA · About 3%

1. About 97% of Earth's water is salt water in the oceans.

2. Only about 3% is fresh, and most of that is locked in ice caps and glaciers, so very little is easily available.

AnswerA · ammonia

1. Decomposers break down proteins and release the nitrogen as ammonia. This is ammonification.

2. Nitrifying bacteria then turn the ammonia into nitrates.

AnswerC · Bacteria in the pulse's root nodules add nitrogen to the soil

1. Legumes carry nitrogen-fixing Rhizobium in their root nodules.

2. After the pulse is harvested, the nitrogen left in the soil feeds the next cereal crop. This is crop rotation.

AnswerB · Respiration by animals

1. Respiration breaks down food and gives out carbon dioxide.

2. Photosynthesis, limestone formation and growing forests all lock carbon away instead.

AnswerC · nitrification

1. Ammonia → nitrite (by Nitrosomonas) → nitrate (by Nitrobacter).

2. Turning ammonia into nitrates is nitrification; plants then absorb the nitrates.

AnswerD · The phosphorus cycle

1. Phosphorus is released slowly as rocks weather, taken up by plants, passed along food chains and returned to soil and sediments.

2. Unlike carbon, nitrogen and oxygen, it has no major form as a gas in the air, so it is a sedimentary cycle.

AnswerB · the variety of living things in an area, from genes to species to ecosystems

1. Biodiversity is the variety of life at three levels: genetic diversity within a species, the variety of species, and the variety of ecosystems.

AnswerC · is found naturally only in that region

1. Endemic species occur naturally nowhere else, like the lion-tailed macaque of the Western Ghats.

AnswerA · Tropical rainforests

1. Rainforests are warm, wet and sunny all year, with many layers from the ground to the canopy.

2. These conditions support more species than any other land ecosystem.

AnswerC · the Western Ghats

1. The lion-tailed macaque lives in the rainforests of the Western Ghats in Kerala, Tamil Nadu and Karnataka.

2. It is endemic there and endangered.

AnswerC · 4

1. India shares four hotspots: the Himalaya, Indo-Burma, the Western Ghats and Sri Lanka, and Sundaland (which includes the Nicobar Islands).

AnswerD · The Thar Desert

1. India's hotspots are the Himalaya, Indo-Burma (the north-east), the Western Ghats and Sundaland (Nicobar Islands).

2. The Thar Desert has specially adapted life, but it is not a hotspot.

AnswerD · is one of a small group of countries that together hold most of the world's species

1. Seventeen countries, including India, Brazil, Indonesia and Australia, are listed as megadiverse.

2. Together they hold the majority of the Earth's known species.

AnswerB · the IUCN

1. The International Union for Conservation of Nature (IUCN) maintains the Red List of Threatened Species.

AnswerC · Cheetah

1. The cheetah was hunted out of India and declared extinct in 1952.

2. In September 2022, cheetahs from Namibia were released into Kuno National Park in Madhya Pradesh.

AnswerD · Loss and breaking up of habitats

1. Clearing forests and wetlands for farms, towns, roads and mines destroys the places where species live.

2. Other major threats are overexploitation, invasive species, pollution and climate change.

AnswerC · an invasive alien species

1. An alien species comes from outside the region; it is invasive when it spreads fast and harms native life.

2. Lantana and Parthenium (congress grass) are other invasive plants in India.

AnswerB · Mauritius

1. The dodo lived only on Mauritius in the Indian Ocean.

2. Hunting and the animals brought by sailors wiped it out within about a century of human arrival. It is a symbol of extinction caused by people.

AnswerA · has a very large number of endemic plants and has already lost most of its original habitat

1. A hotspot must have at least 1,500 species of endemic vascular plants (found nowhere else).

2. It must also have lost at least 70% of its original natural vegetation, so it is both rich and threatened.

AnswerB · The Biological Diversity Act, 2002

1. The Biological Diversity Act of 2002 set up the National Biodiversity Authority and local biodiversity management committees.

2. It controls access to biological resources and requires benefits to be shared with local communities.

AnswerA · genetic diversity

1. All rice varieties belong to one species; they differ in their genes.

2. Variation within a single species is genetic diversity.

AnswerA · keystone species

1. Like the keystone that holds an arch together, a keystone species holds its community in balance.

2. A tiger keeps deer numbers in check; without it, overgrazing would change the forest.

AnswerD · the one-horned rhinoceros

1. Kaziranga holds the largest population of the Indian one-horned rhinoceros in the world.

2. It is also a tiger reserve and a UNESCO World Heritage Site.

AnswerC · Gir National Park, Gujarat

1. Asiatic lions once ranged across Asia but now survive in the wild only in the Gir forests and nearby areas of Gujarat.

AnswerB · 1973

1. Project Tiger began in 1973, with nine tiger reserves at first, to save the tiger from extinction.

AnswerA · Jim Corbett National Park

1. The park in Uttarakhand was renamed after Jim Corbett, the hunter-turned-conservationist and author.

2. Project Tiger was launched there in 1973.

AnswerB · A seed bank

1. Ex situ means off-site: zoos, botanical gardens, seed banks and gene banks.

2. National parks, sanctuaries and biosphere reserves protect species where they live, which is in situ conservation.

AnswerD · wetland haven for resident and migratory birds

1. Keoladeo is a man-made wetland that draws hundreds of bird species, including winter migrants from Central Asia.

2. It is a UNESCO World Heritage Site and a Ramsar wetland.

AnswerA · the world's largest mangrove forest and its tigers

1. The Sundarbans, in the delta of the Ganga and Brahmaputra, form the largest mangrove forest in the world, shared with Bangladesh.

2. Its Royal Bengal tigers are adapted to swim between the islands.

AnswerD · Kerala

1. Silent Valley is a tropical rainforest in the Nilgiri hills of Kerala's Palakkad district.

2. Protests against a planned dam on the Kunthipuzha river led to it being declared a national park in 1984.

AnswerB · snow leopard

1. Hemis, a high-altitude park in Ladakh, has one of the densest snow leopard populations.

2. The clouded leopard and red panda live in the forests of the north-east and the eastern Himalaya instead.

AnswerB · hugging them to stop them from being cut

1. Chipko means 'to cling'. Villagers, many of them women, put their arms around trees to stop commercial felling.

2. The movement is linked with Sunderlal Bahuguna, Chandi Prasad Bhatt and Gaura Devi.

AnswerC · 1992

1. Project Elephant was launched in 1992 to protect elephants and to reduce conflict between elephants and people.

AnswerA · patches of forest protected by local communities for religious and cultural reasons

1. Local people have long left these forests untouched, believing them to belong to deities.

2. As a result they shelter rare and endemic plants and animals, a traditional form of in situ conservation.

AnswerD · Great Indian bustard

1. The great Indian bustard (godawan) lives in dry grasslands, mostly in the Thar region of Rajasthan.

2. Only a small number survive, and collisions with power lines are a major threat.

AnswerB · It permits limited human activity in a buffer zone around a strictly protected core

1. A biosphere reserve is built in zones. The core is strictly protected, a buffer zone around it allows research and controlled use, and an outer transition zone supports settlements and livelihoods.

2. That design treats the people living in and around the reserve as part of the system rather than as intruders to be excluded.

3. A national park protects a single area uniformly, and biosphere reserves are usually larger, not smaller — several contain national parks within their cores.

AnswerC · The Wildlife (Protection) Act

1. The Wildlife (Protection) Act, 1972 bans hunting of listed species and sets up protected areas.

2. The Biological Diversity Act came in 2002 and the Environment (Protection) Act in 1986.

AnswerC · Nilgiri Biosphere Reserve

1. The Nilgiri Biosphere Reserve, in the Western Ghats, was the first to be set up in India, in 1986.

2. It includes Mudumalai, Bandipur, Nagarhole and Silent Valley.

AnswerD · Only protection and limited research; no human settlement or ordinary use

1. A biosphere reserve has three zones: core, buffer and transition.

2. The core is strictly protected. The buffer around it allows research and education, and the outer transition zone allows settlements and farming.