Solutions – MCQs Based on Environment & Ecology (Concepts)

Solutions – MCQs Based on Environment & Ecology (Concepts)

1aThe term niche means the sum of all the activities and relationships of a species by which it uses the resources in its habitat for its survival and reproduction. A niche is unique for a species while many species share the habitat. No two species in a habitat can have the same niche. This is because if two species occupy the same niche they will compete with one another until one is displaced.
2aPrimary succession takes place an over a bare or unoccupied areas where no community has existed previously. Secondary succession is the development of a community which forms after the existing natural vegetation that constitutes a community is removed, disturbed or destroyed by a natural event or by human related events.
3aA pioneer species generally show high growth rate but short life span.
5bAmensalism – one species is inhibited while the other species is unaffected. Commensalism – One species  benefits, while the other species  is neither harmed nor inhibited
6aMicroorganisms (biotic)
7dWe talk about organic compounds when we talk about living organisms.ex – Proteins & Carbohydrates. Organic compounds are said to be the ones that contain a carbon-hydrogen bond. Most of the inorganic compounds do not contain carbon. However, there are exceptions. Organic substances include water, metals, non metals, acids, bases, salts and gases like carbon dioxide, oxygen.
8bThese are mostly bacteria and fungi that feed on dead decomposed and the dead organic matter. They play a very important role in recycling of nutrients.
10bPhytoplanktons are producers. (a) Zooplanktons are floating animals. Cyclops, Cypris
(b) Nektons are the animals that can swim and navigate at will. Eg. fishes
(c) Benthic animals are the bottom dwellers: beetle, mites, mollusks and some crustaceans.
11cHomeostasis (or cybernetic) or feedback control mechanisms
12cThe total rate at which the radiant energy is stored by the process of photosynthesis in the green plants is called Gross Primary Production (GPP). This is also known as total photosynthesis or total assimilation. From the gross primary productivity a part is utilized by the plants for its own metabolism. The remaining amount is stored by the plant as Net Primary Production (NPP) which is available to consumers.
13aThe quantity of energy flowing through the successive trophic levels decreases.
14cIn some instances the pyramid of number may be inverted, i.e herbivores are more than primary producers as you may observe that many caterpillars and insects feed on a single tree.
15aPyramiad of biomass in a pond ecosystem is inverted.
16aEnergy pyramids are never inverted
18c(i) Atmospheric fixation: Lightening, combustion and volcanic activity help in the fixation of nitrogen. (ii) Industrial fixation: At high temperature (400oC) and high pressure (200 atm.), molecular nitrogen is broken into atomic nitrogen which then combines with hydrogen to form ammonia. (iii) Bacterial fixation: There are two types of bacteria- (i) Symbiotic bacteria e.g. Rhizobium in the root nodules of leguminous plants. (ii) Freeliving or symbiotic e.g. 1. Nostoc 2. Azobacter 3. Cyanobacteria can combine atmospheric or dissolved nitrogen with hydrogen to form ammonia.
21cEcotone is a zone of junction between two or more diverse ecosystems e.g. the mangrove forests. They represent an ecotone between marine and terrestrial ecosystem.Some more examples of ecotone are – grassland, estuary and river bank Wetlands are ecotones between terrestrial and aquatic ecosystems
22cSometimes the number of species and the population density of some of the species is much greater in ecotone zone 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 song birds is greater in the mixed habitat of the ecotone between the forest and the desert.
25dFish farming is cultivation of fish in a controlled environment often a coastal or inland pond and harvesting when they reach the desired size. Fish ranching is a practice of keeping which fishes in captivity for the first few years in floating cages in coastal lagoons and releasing them from captivity into water bodies.
26cFly ash is ejected mostly by thermal power plants as by products of coal burning operations. Fly ash pollutes air and water and may cause heavy metal pollution in water bodies. Fly ash affects vegetation as a result of its direct deposition on leaf surfaces or indirectly through its deposition on soil. Fly ash is now being used for making bricks and as a land fill material.
27aDisplexia is caused by lead and itai itai by cadmium
28aIncrease in water temperature due to thermal pollution decreases dissolved oxygen in water which adversely affects aquatic life..
29aSomatic damage refers to damage to cells that are not associated with reproduction.Genetic damage refers to damage to cells associated with reproduction.
30bBacterial – Typhoid, Cholera & leptospirosis

Viral – Hepatitis

Protozoan – Dysentry & Diarrhoea

32aModern agriculture uses a lot of nitrogenous fertilizers and manures. This leads to increased levels of nitrates in the ground water. Babies drink large quantities of water. When water containing nitrates is consumed and it reaches intestines, the intestinal bacteria convert nitrates into nitrites. The nitrite ions combine with haemoglobin to form methaemoglobin which inhibits the oxygen carrying capacity of the blood and the babies gradually acquire a blue tinge and hence the name – “Blue Baby disease”.
34bIn coal mining areas coal dust is the main air pollutant to which miners are exposed everyday. The deposits of coal dust makes miners lungs look black instead of a healthy pink and hence the name black lung disease.
35aDense > Open > Mangrove > Scrub
37 cA small amount of uv-radiation is necessary for well-being of human beings and other organisms, such as uv-B promote synthesis of vitamin-D. UV-radiation also act as a germicide to control microorganisms. UV radiations can be divided into three forms: UV-A (wavelength between 320-400nm), UV-B (wave length lesser than 280 nm), and UV-C (wavelength lesser than 280 nm).
39aHalon is used in fire fighters and carbon tetrachloride is used as solvent. HFCs are not ozone depleting but green house.
42dNational Bureau of Fish Genetic Resources – lucknow
44cIndian government has also started some conservation projects for individual endangered species like Hungal (1970), Lion (1972), Tiger (1973), Crocodiles (1974), Brown-antlered Deer (1981) and Elephant (1991-92). Hangul’ (Kashmiri stag) is the only surviving species of the red deer family in Kashmir.  Brow-antlered deer, is an endangered species of deer indigenous to Southeast Asia. The sangai is an endemic, rare and endangered subspecies of brow-antlered deer found only in Manipur, India.
45aIt is an international convention came in force in 1975. The United Nations Educational, Scientific and Cultural Organisation (UNESCO) serves as the Depositary for the Convention, and its secretariat, the Ramsar Bureau, is in Gland, Switzerland. India became signatory to this convention on in 1981. In international law, a depositary is a government or organization to which a multilateral treaty is entrusted.
46bCPCB (Central Pollution Control Board) is statutory organisation, constituted under the Water (Prevention and Control of Pollution) Act, 1974.
47aNational Board for Wildlife (NBWL) is a statutory Board constituted on 22nd September 2003 under Section 5 of the Wild Life (Protection) Act, 1972. The NBWL is chaired by the Hon’ble Prime Minister. As per the amendment of the Act in 2002, a provision was incorporated for the constitution of the  National Board for Wildlife, replacing the Indian Board for Wildlife.

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