12th Class Biology Chapter 11 Ecosystem Short Questions Answer

It is defined as the study of the relationship of animals to their environment.

The ecosystem consists of two basic interacting components: 1) The living or biotic. 2) The physical or a-biotic factors.

Niche is defined as the ultimate distributional unit within which a species is restrained by the limitations of its physical structure and its physiology.

When one is studying a single population’s relationship to its environment it will be called as autecology.For example we are studying 50 to 100 plants of soybean for effect of water pollution on their growth and yield we are studying the single or one population of soybean plant this is autecology.

The living components of the exosystem is called biotic while non-living components are called Abiotic.

At different places in an environment the study of only one population is autecology while study of different populations or a community is called synecology.

Food chain is a linear relation relationship of eating ad being eaten while food web is the interaction of many food chains.

Succession begins by a few hardy invaders called pioneers and with a diverse and relatively stable plants called climax community.

Primary succession that starts in a pond is called Hydrosere while primary succession that starts on a dry soil or rock is called derosere.

The parasites which live within the body of the host are called endoparasites while those which live out side the body are called ectoparasites.

The organism which kills and eats the other organism is called predator while an organism which being killed and eaten is called prey.

Mycorrhiza is an association between certain fungi and the roots of plants growing in acid soil.The host is pine beech or heather and it provides the fungus with an enzyme to digest carbohydrates in leaf litter.In return the fungus passes mineral ions from the soil to the host.

The process by which the limited amount of nitrogen is circulated and re-circulated through out the world of living organisms is known as the nitrogen cycle.

The process by which the limited amount of nitrogen is circulated and re-circulated through out the world of living organisms is known as the nitrogen cycle.

a) In both root nodules and mycorrhiza atmospheric nitrogen is fixed Both show mutualistic relationship. b) In mutualism and lichens both the organisms are benefited. c) In parasitism and commensalism only one of the partners is benefited.

The back and forth movements of chemical elements between organism and environment along particular circular paths are known as biogeochemical cycles.

Many animals like rabbits goat sheep,cow,bufflo and horses feed on grasses.This mode of feeding is called grazing and these animals are called grazers.

1%.

Environment is all of the external factors affecting an organism.These factors may be other living organisms of nonliving variables,such as water soil climate light and oxygen.

A natural area where living organisms and physical environment interact and exchange materials between them so as to achieve functional stability is known as ecosystem.

Major regional ecological community of plants and animals forms biomes.There are six major terrestrial biomes forest grass land wood land shrub land semi desert shrub and desert.Combined biomes of earth form the planetary ecosystem.

Biosphere is a thin layer of earth in which all living organisms exist in other words the earth’s relatively thin zone of air,soil and water that is capable of supporting life ranging from about 10 km into the atmosphere to the deepest ocean floor in called biosphere.

The actual location or place where an organism lives is called its habitat while occupation or profession or job of an organism is called its niche.

i) Individual ii) Population iii) Community

In ecological term they are called as: i) Atmosphere ii) Hydrosphere iii) Lithosphere

An ecosystem is made up of three main components the producers the consumers and the decomposers.All are concerned with the feeding processes the circulation of chemical elements and the flow of energy.

Producers are the green photosythetic plants,which capture and bring light energy into the ecosystem.They are able to manufacture organic food from simpler inorganic substances.They are autotrophic organisms.

Consumers are all the organisms primarily animals which obtain energy directly or indirectly from the producers as ready-made organic food.They are mainly heterotrophic organisms.

Decomposers are mainly the fungi and bacteria which obtain their energy from the dead and decaying plants and animals.They release chemical elements as ions such as nitrates ammonia phosphates potassium and calcium.

Succession is change in the community structure of an eoosystem over a period of time.Succession begins by a few hardy invaders called pioneers and end with a diverse and relatively stable climx community.

During primary succession an ecosystem is forged from bare reck sand or clear glacial pool where there is no trace of previous life.

Primary succession that starts on a dry habitat is called xerosere.

During secondary succession a new exosystem develops after an existing ecosystem is disturbed as in case of forced fire or an abandoned farm field.It happens much more rapidly than primary succession because the previous community has left improved soil and seeds.

Xerosere has following different stages. i) Crustose Lichen Stage. ii) Foliose Lichen Stage. iii) Moss stage. iv) Herbaceous stage. v) Shrub Stage. vi) Climax Forests.

An animal that preys other animals is called predator so it is a consumer.The animals that is caught and eaten is called prey.The over all process is called predation.

Cat/mouse,fox/rabbit,Seal/fish,frog/mosquito,Hawk/small birds.

This is an association between a host and a parasite which involves providing the parasite with protection and conditions for its survival.The parasite may or may not harm the host.

Diseases in living organisms caused by parasites are called infestations.

An association between organisms belonging to different species,which live together for mutual benefit or one partner gets benefit and the other is neither benefited nor nharmed is called symbiosis.

Mutualism is the symbiotic relationship in which both the partners get benefit while in commensalism only one organism benefit from the relationship.The other is not affected at all.

The legume plants Pea and been are the hosts to symbiont bacteria which ingabit the outgrowths on roots called root nodules.The root nodule bacteria fix nitrogen converting it into amino acid which the host uses.IN return host provides bacteria with food and protection

Lichens are dual organism composed of symbiotic association of algae living within a fungus mycelium.The fungus gets food from alga while alga might get protection by the fungus from intense sunlight and desiccation or the minerals absorbed by the fungus might be transferred to the alga.

The chemical elements essential for life in living organisms are called biogenic elements or nutrient elements.

These are required by organism in large amount like water carbon hydrogen oxygen nitrogen phosphorus sulphur and calcium.

The amount of energy left after plants have met their respiratory needs is net primary production which shows up as plant biomass.

The nutrient cycles are also called biogeochemical cycles as the nutrients move from living to non-living and back to living portions of ecosystem in a cyclic manner.

The micro-organisms use the proteins and amino acids and release excess of ammonia or ammonium ions.This process is known as ammonification.

Several bacteria in soil are able to oxidize ammonia or ammonium ions this oxidation is known as Nitrification.

The conversion of nitrate within the plant cell back to ammonium.Is called assimilation.This process requires energy.

Nitrates are also lost as a result of the activities of certain soil bacterial in the absence of oxygen these bacteria break down nitrates releasing nitrogen back into the atmosphere and using the oxygen for their own respiration.This process is known as de-nitrification.

The term ecology is derived from two Greek words viz. oikos, meaning “family household” and logos, meaning “Study”.

Ecology is defined as the study of the relationships between the organisms and their environment.

A German zoologist, Ernst Haeckel used the term ecology for the first time in 1866.

It is the complete range of eternal conditions under which an organism lives, including non-living and living factors.

Population is a group of organisms of the same species living in the same area at the same time.

A community is a group of populations of different organisms living in the same area at the same time.

A community of organisms interacting with one another as well as with the environment in which they live and with which they also interact, is known as the ecosystem.

A regional ecosystem extending over a large natural area is known as a biome. The examples are grasslands, deserts, tropical rain forests and tundra etc.

All the biomes of the earth together constitute the planetary ecosystem.

These are the atmosphere (air), lithosphere (earth) and hydrosphere (water).

The earth, its atmosphere and the depths of the oceans which are inhabited by the living organisms are collectively known as the biosphere. It extends about eight to ten kilometers up into the atmosphere and similar distance down in the depth of the oceans.

Habitat is a specific locality with particular set of environmental conditions where organisms live.

The ecological niche is defined as the functional role a species plays in the community, including behavior and influence.

An American ornithologist proposed the term niche in ecology in 1917.

Ornithology is the branch of zoology which deals with the study of birds.

Autecology is the study if relationship of a single population (species) to its environment.

Synecology (community ecology) is the study of relationship of different populations of a community to their environment.

The biotic components of the ecosystem are the producers (photosynthetic plants), consumers (animals) and the decomposers (bacteria and fungi etc.) whereas the abiotic ones are the water, soil, light, air, minerals and temperature etc.

Producers are the autotrophic organisms that can build up food from inorganic materials by photosynthesis, such as green plants.

Consumers are the heterotrophic organisms (mostly animals) that feed upon the plants (producers) and the animals (other animals).

Decomposers are the organisms that feed upon dead and decaying organisms and derive energy by breaking them down into simpler substances releasing chemical elements, as ions. The examples are the bacteria and the fungi.

The transfer of food energy from the source in plants through a series of organisms with repeated stages of eating and being eaten is known as food chain.

Food web is the combination of all the food chains interconnected with one another in an ecosystem.

A group of minute, green, floating plants (algae) of sea or lake is called as the phytoplankton.

These are: (1) producers (2) primary consumers (3) secondary consumers (4) tertiary consumers and so on.

Primary consumer animals may be called herbivores whereas the secondary and tertiary ones as the carnivores.

The variety of alterative pathways in the food web help maintain the stability of the ecosystem. The greater the number of alternative pathways in a food web, the more stable is the community of the organisms which constitute the web.

Succession is a progressive series of changes in plant and animal life of an area from initial colonization to the final stabilized stage or climax.

Pioneer community means the plants such as algae and lichens, with which begins the colonization of bare rock or soil during the primary plant succession.

An animal which captures and readily kills living animals for its food is known as a predator.