Test: Environment- 8 - UPSC MCQ

Since each higher trophic level receives only a fraction of energy of the lower trophic levels, the energy pyramid is narrow at the top.
But, generally (barring some aquatic ecosystems) lower trophic levels have higher biomass as compared to the higher trophic levels.

• The mechanisms used by most mammals to regulate their body temperature are similar to the ones that we humans use. We maintain a constant body temperature of 37 degree C. In summer, when outside temperature is more than our body temperature, we sweat profusely.
• The resulting evaporative cooling, similar to what happens with a desert cooler in operation, brings down the body temperature. In winter when the temperature is much lower than 37 degree C, we start to shiver, a kind of exercise which produces heat and raises the body temperature.
• Plants, on the other hand, do not have such mechanisms to maintain internal temperatures.
• Thermoregulation is energetically expensive for many organisms. This is particularly true for small animals like shrews and humming birds. Heat loss or heat gain is a function of surface area. Since small animals have a larger surface area relative to their volume, they tend to lose body heat very fast when it is cold outside; then they have to expend much energy to generate body heat through metabolism. This is the main reason why very small animals are rarely found in polar regions
   

• Phosphorous cycle is mainly terrestrial. The main storage for phosphorus is in the earth’s crust. On land phosphorus is usually found in the form of phosphates.
• It occurs in large amounts as a mineral in phosphate rocks and enters the cycle from erosion and mining activities.
• By the process of weathering and erosion phosphates enter rivers and streams that transport them to the ocean.
• Being an important nutrient, phosphorous promotes eutrophication in lakes. Along with nitrogen related compounds it leads to undesirable situations like algal bloom.

• Exotic species introduced to new environments often reset the ecological conditions in that new habitat, threatening the species that exist there; this is the reason that they are also termed invasive species.
• Invasive species that are closely related to rare native species have the potential to hybridize with the native species; harmful effects of hybridization have led to a decline and even extinction of native species.
• Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide little to no food value for wildlife.
• Lakes and islands are particularly vulnerable to extinction threats from introduced species.

• “Bioluminescent organisms are usually found in the ocean environments, but they are also found on terrestrial environments. The colour of the light emitted by the organism depends on their chemical properties.”
• In the case of fungi, the luminescence comes from the enzyme, luciferase. “The [green] light emits when luciferans is catalysed by the enzyme luciferase, in the presence of oxygen. During the chemical reaction, several unstable intermediate products are released as excess energy that makes them visible as light.
• Bioluminescent mushrooms may glow for a number of reasons. The simplest explanation could be that bioluminescence attracts insects, which helps in dispersing spores. It may also be a mechanism for the organism to protect itself from frugivorous (or fruit-eating) animals.

• A parasite is an organism that lives in or on another living organism, deriving nutrients from it. In this relationship the parasite benefits, but the organism being fed upon, the host, is harmed. The host is usually weakened by the parasite as it siphons resources the host would normally use to maintain itself. The parasite, however, is unlikely to kill the host. This is because the parasite needs the host to complete its reproductive cycle by spreading to another host.
• The reproductive cycles of parasites are often very complex, sometimes requiring more than one host species. A tapeworm is a parasite that causes disease in humans when contaminated, undercooked meat such as pork, fish, or beef is consumed. The tapeworm can live inside the intestine of the host for several years, benefiting from the food the host is bringing into its gut by eating. The parasite moves from species to species as it requires two hosts to complete its life cycle.

Production/unit area depends on the number and diversity of producers. Mangroves are one of the high productive regions in the world whereas ocean has least productivity.

• Phytoplankton float on top surface of water bodies and require sunlight to thrive. Ice cover will reduce their breeding grounds and population.
• The snow cover blocks exchange of nutrients and oxygen from the atmosphere, however the same may continue within the water stream. But it is worse than before.
• Snow cover of ice on water body can effectively cut off light, plunging the waters into darkness.
• Hence photosynthesis stops but respiration continues. Thus, in shallow lakes, oxygen gets depleted, and due to lack of oxygen there is large scale death of fishes and other organisms. This condition is known as winterkill.

The coastal ecosystems of mangroves, tidal marshes, and seagrass meadows provide numerous benefits and services that are essential for climate change adaptation along coasts globally, including protection from storms and sea level rise, prevention of shoreline erosion, regulation of coastal water quality, provision of habitat for commercially important fisheries and endangered marine species, and food security for many coastal communities. Additionally, these ecosystems sequester and store significant amounts of coastal blue carbon from the atmosphere and ocean and hence are now recognized for their role in mitigating climate change.

• Corals that inhabit the colder deep waters of continental shelves and offshore canyons, ranging from 50 to over 1000m depths lack zooxanthellae and may build reef-like structures or occur solitarily.
• Cold-water corals are different from their warm-water counterparts because they do not contain symbiotic algae for photosynthesis and grow more slowly.
• Cold-water corals obtain all their energy from organic matter and zooplankton, which they catch from the currents drifting past.
• Cold-water corals can be found over a wide range of latitudes, from tropical to Polar Regions, and from the shallow to the deep seas.

Some of the Ramsar sites in India include

• Chilika Lake in Odisha
• Keoladeo National Park in Rajasthan
• Harike Lake in Punjab
• Loktak Lake in Manipur
• Wular Lake in Jammu and Kashmir

• Peatlands are formed due to the accumulation of partially decomposed plant remains over thousands of years under conditions of water-logging.
• Peatlands, which play a crucial role in regulating global climate by acting as carbon sinks, are facing degradation.
• Peatlands (lands with peat at the surface) are highly space-effective carbon stocks: they cover only 3% of the land, but contain more carbon than the entire forest biomass of the world.
• Peatlands contain 30 per cent of the world’s soil carbon. When drained, these emit greenhouse gases, contributing up to one gigaton of emissions per year through oxidation.
• Peatlands occur in different climate zones. While in tropical climate, they can occur in mangroves, in Arctic regions, peatlands are dominated by mosses. Some mangrove species are known to develop peatland soils under them.
• Besides climate mitigation, peatlands are important for archaeology, as they maintain pollen, seeds and human remains for a long time in their acidic and water-logged conditions.
• In many countries, pristine peatlands are important for recreation activities. These areas also support livelihood in the form of pastoralism.
• The vegetation growing on pristine peatlands provide different kinds of fibres for construction activities and handicrafts.

What is coral bleaching?
According to the National Oceanic and Atmospheric Administration (NOAA), when corals are stressed by changes in conditions such as temperature, light or nutrients, they expel the algae living in their tissue, causing them to turn white, hence bleached.
Coral bleaching does not mean the corals are dead, but make them vulnerable, hence increasing their mortality. Warm ocean temperatures are one condition that could lead to coral bleaching. For instance, in 2005, the US lost half of its coral reefs in the Caribbean in one year due to a massive bleaching event.
Even so, NOAA says that not all bleaching events are due to warmer temperatures. In January 2010, cold water temperatures in the Florida caused a coral bleaching event that resulted in some coral deaths.
List of triggers

• increased water temperature (marine heatwaves, most commonly due to global warming), or reduced water temperatures
• oxygen starvation caused by an increase in zooplankton levels as a result of overfishing
• increased solar irradiance (photosynthetically active radiation and ultraviolet light)
• increased sedimentation (due to silt runoff)
• bacterial infections
• changes in salinity
• herbicides
• extreme low tide and exposure
• cyanide fishing
• elevated sea levels due to global warming (Watson)
• mineral dust from African dust storms caused by drought
• pollutants such as oxybenzone, butylparaben, octyl methoxycinnamate, or enzacamene: four common sunscreen ingredients that are nonbiodegradable and can wash off of skin
• ocean acidification due to elevated levels of CO₂ caused by air pollution
• being exposed to Oil or other chemical spills

Wetlands are regulated under the Wetlands (Conservation and Management) Rules, 2017. The 2010 version of the Rules provided for a Central Wetland Regulatory Authority; the 2017 Rules replace it with state-level bodies and created a National Wetland Committee, which functions in an advisory role. The newer regulations removed some items from the definition of “wetlands” including backwaters, lagoon, creeks, and estuaries.
Wetlands International is a global organisation that works to sustain and restore wetlands and their resources for people and biodiversity. It is an independent, not-for-profit, global organisation, supported by government and NGO membership from around the world.

Most of the organic toxins are water insoluble and non-biodegradable.
These high persistent toxins are, therefore, transferred from lower trophic level to higher trophic level through food chain.

Indicator species, organism—often a microorganism or a plant—that serves as a measure of the environmental conditions that exist in a given locale.
Example – Lichens: Quality of air can be determined based on its presence.

There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. This property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes for agricultural purposes. Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. Such methods  also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds. Another advantage of vegetative propagation is that all plants produced are genetically similar enough to the parent plant to have all its characteristics.

Ecological pyramid doesn’t give evidence on introduction of new species.

Commensalism is a type of symbiotic relationship between organisms in which one organism benefits without harming the other.
Many birds form a commensal relationship with some species of ants like the army ants. A great number of army ants trail on the forest floor, and while moving, stir up many insects lying in their path. The birds follow these army ants and eat up the insects that try to escape from them. The birds benefit by catching their prey easily, while the army ants are totally unaffected.

• Burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides.
• SO₂ and NO₂ after oxidation and reaction with water are major contributors to acid rain, because polluted air usually contains particulate matter that catalyze the oxidation.
• These lead to formation of acid rain that has deleterious effect on the overall ecology of the region.

Ocean acidification refers to a reduction in the pH of the ocean over an extended period of time, caused primarily by uptake of carbon dioxide (CO₂) from the atmosphere. Nitrogenous compounds contribute fraction to ocean acidification.
Sea grass has ability to control ocean acidification.

• Electronic scrap components, such as CPUs, contain potentially harmful materials such as lead, cadmium, beryllium, or brominated flame retardants.
• CRTs have a relatively high concentration of lead and phosphors (not to be confused with phosphorus), both of which are necessary for the display.
• Country’s first e-waste clinic is being opened in Bhopal, Madhya Pradesh. It would enable segregation, processing and disposal of waste from both household and commercial units.

• Nitrous oxide emissions occur naturally through many sources associated with the nitrogen cycle, which is the natural circulation of nitrogen among the atmosphere, plants, animals, and microorganisms that live in soil and water.
• Nitrous oxide is actually removed from the atmosphere when it is absorbed by certain types of bacteria or destroyed by ultraviolet radiation or chemical reactions.
• A natural source of nitrogen oxides occurs from a lightning stroke. The very high temperature in the vicinity of a lightning bolt causes the gases oxygen and nitrogen in the air to react to form nitric oxide. The nitric oxide very quickly reacts with more oxygen to form nitrogen dioxide.

Exposure to POPs can lead to cancer, damage to central & peripheral nervous systems, diseases of immune system, reproductive disorders and interference with normal infant and child development.

Uniqueness of POPs:

• POPs are lipophilic, which means that they accumulate in the fatty tissue of living animals and human beings.
• In fatty tissue, the concentrations can become magnified by up to 70 000 times higher than the background levels.
• As you move up the food chain, concentrations of POPs tend to increase so that animals at the top of the food chain such as fish, predatory birds, mammals, and humans tend to have the greatest concentrations of these chemicals.