Science Write notes.

(i) Biodiversity is the richness of living organisms in nature due to presence of varieties of organisms, ecosystems and genetic variations within a species. Biodiversity occurs at three different levels.
(a) Genetic Diversity: Occurrence of diversity among the organisms of same species is genetic diversity. For example, each human being is different from the other.
(b) Species Diversity Innumerable species of organisms occur in nature. This is called as species diversity. Species diversity includes various types of plants, animals and microbes.
(c) Ecosystem Diversity Many ecosystems are present in each region. Ecosystem is formed through the interaction between plants, animals, their habitat and changes in the environment. Each ecosystem has its own characteristic animals, plants, microbes and abiotic factors. Ecosystems are also of two types, natural and artificial.

(i) In the 1970s, an opposition to the destruction of forests spread throughout India and came to be known as the Chipko movement.
(ii) The name of the movement comes from the word 'embrace' as the villagers hugged the trees and prevented the contractors from felling them.
(iii) Many communities in India have helped save nature. One such is the Bishnoi community of Rajasthan.
(iv) The original chipko movement was started around 260 years back in Rajasthan by this community. A large group of villagers led by a lady called Amrita Devi laid down their lives in an effort to protect the trees from being felled on the orders of the Maharaja of Jodhpur.
(v) After this incident the Maharaja gave a strong royal decree preventing the cutting of trees is all Bishnoi villages.
(vi) The success achieved by this protest led to similar protests in other parts of the country.

(i) Various dangerous events occur many times in the environment These are called as disasters.
(ii) (i) Various dangerous events occur many times in the environment These are called as disasters.
(ii) These are' all of a sudden troubles to the mankind. Such events cause sudden changes in the environment and thereby, cause damage to it.
(iii) Disaster is a sudden event that leads to huge loss of life and property.
(iv) Some disasters are short time, while some others are long time.
(v) Disaster management is either prevention of disasters or making arrangements to face them or at least achieve the abilities to face them.
(vi) In case of disaster management, there should be an attempt to minimize the losses.
(vii) Disasters are never planned but losses due to them can be prevented in a planned manner.
(viii) Disaster management is achieving or time to time improving the ability to face the disaster through scientific and careful observations and analysis of data.
(ix) For example, preparing the action plan through study of various aspects like preventive measures, rehabilitation and reconstruction and executing that plan is management of disaster.
(x) Increasing awareness about disaster management among the general public through training programs, mass media etc. will enable them to be always prepared for disaster rescue.

(i) All the developed, developing and underdeveloped countries have accepted the responsibility of environment protection.
(ii) It will be possible to answer the environmental problems only if environmental protection- conservation becomes an effective public movement.
(iii) For this purpose, values like positive attitude and affection towards environment, knowledge about it etc. should be inculcated among the children since their childhood.
(iv) Human established dominance over the nature. In an attempt to live satisfactory life, human kept on snatching from the nature as much as possible and this leads to increase in problems.
(v) Environmental conservation is Our social responsibility.
(vi) Various laws are enacted about environmental conservation. Human has a crucial role in environmental conservation.
(vii) These laws are to be implemented strictly and whoever is a culprit, should be severely punished.
(viii) There should be positive attitude of human being towards the environment for welfare of the entire living world.
(ix) A person can be a conservator, organizer, guide, or plant-friend etc.

(i) An ecosystem consists of many food chains that are interconnected at various levels. This is called food web.
(ii) An organism may be the prey for many other organisms.
(iii) For example, an insect feeds upon leaves of various plants but the same insect is the prey for different animals like wall lizards, birds etc.
(iv) This forms an intricate web instead of a linear food chain. Such an intricate network is called as food web.
(v) Generally food webs are formed everywhere in nature.

(i) Food chain is a linkage of organisms within an ecosystem, in which each link feeds on the one before it and is fed on by the one after it.
(ii) Only the first link in the chain is a producer and all the rest are consumers.
(iii) In the ecosystem, the energy is transferred from one organism to another with food, in a definite sequence.
(iv) Initially, solar energy is absorbed by producers and with the help of photosynthesis the food is synthesized.
(v) Energy gets transferred from producers to consumers of different levels.
(vi) Decomposers derive energy from dead organisms by decomposition.
(viii) The flow of energy is unidirectional
e.g. Grass → Grasshopper → Frog → Snake → Hawk.