Daily Quiz: UPSC Prelims Marathon- September 22

Statement 1 is Incorrect:

The pyramid of numbers can either be upright for ex:  Pyramid seen in grassland ecosystem and pond ecosystem.

Or Inverted for ex: Tree ecosystem.

Statement 2 and 3 is correct:

• To compare the functional roles of the trophic levels in an ecosystem, an energy pyramid is most suitable.
• An energy pyramid represents the amount of energy at each trophic level and loss of energy at each transfer to another trophic level. Hence the pyramid is always upward, with a large energy base at the bottom.

• In many aquatic ecosystems, the pyramid of biomass may assume an inverted form. [Pyramid of numbers for aquatic ecosystem is upright]
• This is because the producers are tiny phytoplankton that grow and reproduce rapidly.
• Here, the pyramid of biomass has a small base, with the consumer biomass at any instant actually exceeding the producer biomass and the pyramid assumes inverted shape.

All are Incorrect

Bio-accumulation, Bio-concentration and Bio-magnification are three different concepts.

Bio-accumulation refers to increase in concentration of a substance in certain tissues of organism’s body. While Bioaccumulation occurs when an organism absorbs a toxic substance from all sources at a rate greater than that at which the substance is lost.

Bioconcentration occurs when an organism absorbs a toxic substance from ONLY Water at a rate greater than that at which the substance is lost.

Biomagnification refers to the is the INCREASE in concentration of the POPs such as DDT, that occurs in a food chain as a consequence of persistence, high lipid solubility and low water solubility. The substances become more and more concentrated in tissues or internal organs as they move up the chain.

• An ecotone is a zone of junction or a transition area between two biomes [diverse ecosystems]. It is where two communities meet and integrate.
• For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are grassland (between forest and desert), estuary (between fresh water and salt water) and river bank or marsh land (between dry and wet).

Edge Effect- Edge Species:

• In ecology, edge effects refer to the changes in population or community structures that occur at the boundary of two habitats (ecotone).
• Sometimes the number of species and the population density of some of the species in the ecotone is much greater than either community. This is called edge effect.
• The organisms which occur primarily or most abundantly in this zone are known as edge species.
• In the terrestrial ecosystems edge effect is especially applicable to birds. For example the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert.

All are correctly matched:

Metamorphic Rocks

• Formed when original structure of igneous & sedimentary rocks partially or wholly change under the action of heat & pressure
• Contains no fossils
• No stratification
• For ex. Clay →Slate

All statements are correct.

Statement 1 is Incorrect:

Bioindicator: A bioindicator is a living organism that gives us an idea of the health of an ecosystem. Some organisms are very sensitive to pollution in their environment, so if pollutants are present, the organism may change its morphology, physiology or behaviour, or it could even die.

Keystone Species: Keystone species, in ecology, a species that has a disproportionately large effect on the communitiesin which it occurs. Such species help to maintain local biodiversity within a community either by controlling populations of other species that would otherwise dominate the community or by providing critical resources for a wide range of species.

Statement 2 and 3 is Correct:

• Bioindicators can be plants, animals or microorganisms.
• A lichen is a composite organism that arises from algae or cyanobacteria (or both) living among filaments of a fungus in a mutually beneficial relationship (symbiotoc relationship).
• The hardy lichens are useful bioindicators for air pollution, especially sulfur dioxide pollution.

• The Three Gorges Dam is located in the Yiling district in the Hubei province of China. It is a hydroelectric dam spanning the Yangtze River being the longest river in China. Comprising 32 turbines with an installed capacity of 22,500 MW, it is the world’s largest power station.
• The Aswan Dam, also known as High Dam, is located across the Nile River in Aswan, Egypt. The first dam was designed by Sir William Willcocks, and its construction started in 1898 ending in 1902. It has greatly impacted the agriculture and economy of Egypt.
• Hoover Dam, named after President Herbert Hoover, was originally called Boulder Dam after the name of the labor colony built in the vicinity of the dam for the workers. It is located in the Black Canyon of the Colorado River near Boulder City at the borders of the U.S. states of Nevada and Arizona.
• The Itaipu Dam is named after the island Itaipu that existed at the site of the dam. In the Guaranj language, ‘Itaipu’ means ‘the sounding stone.’ The dam is owned commonly by Brazil and Paraguay. It is located about 15 kilometers to the north of the Friendship Bridge on the Panama River at the border of Brazil and Paraguay. In terms of its operating output, it is the largest hydroelectric dam, while in terms of installed capacity, it is next only to the largest dam in the world, the Three Gorges Dam with a 22,500 MW installed capacity.