Our Environment class 10th

 NOTES PREPARED BY

 ASHAQ HUSSAIN BHAT

TEACHER SCHOOL 

EDUCATION DEPARTMENT

JAMMU AND KASHMIR

INTRODUCTION

Literally speaking, organism's immediate surroundings constitute its environment which includes everything around the organism, i.e., both non-living (abiotic) and living (biotic) components. The abiotic components are the physical factors such as climatic factors (e.g., temperature, light, wind, humidity, precipitation, water etc.) and edaphic factors (e.g., soil texture, substratum, topography, background, minerals, pH etc.). The biotic components, on the other hand, include all kinds of living organisms with which the organism interacts. Both these abiotic and biotic components influence the organism and, in turn, get influenced. This interdependent interaction among organisms as well as with the abiotic components maintains a balance in nature. Human beings are the only organisms who try to change the environment to fulfil their needs (food, shelter, clothings, transport, industry etc.). Increase in human population and great advancement in technology in the recent past have damaged the balanced and healthy environment. This environmental imbalance, created by uncontrolled human activities, has given rise to various environmental problems.

The prominent environmental problems are :

1. Waste accumulation (biodegradable and non-biodegradable).

2. Depletion of ozone layer.

Define ecosystem?

The term ecosystem was used first by A. G. Tensely. An ecosystem may be defined as a self-sustained, stable system resulting from the interaction of living and nonliving factors of environment. It may also be defined as a structural and functional unit of the biosphere comprising living organisms and their nonliving environment that interact by means of food chains and chemical cycles resulting in energy flow, biotic diversity and material cycling to a from stable self-supporting system.

 Types of ecosystem:

a)Natural Ecosystem: These ecosystems operate under natural conditions without intervention of humans. They are further of two types:

i) Terrestrial: These operate on land. lake

ii) Aquatic: These operate in water. For Example: Pond, lack and river.

b) Artificial ecosystem: These ecosystems are created by man. For Example: Crop, land, Garden.

 What are the components of ecosystem?

(A) Biotic component: The living organisms  in an ecosystem forms the biotic component. Regarding the mode of obtaining food, the organisms occurring in an ecosystem are classified into three main categories:

i. Producers: This group includes plants which synthesize their own food from CO2, water and in presence of sunlight.

ii. Consumers or heterotrophs: These are the organisms which consume producers, i.e. they are unable to synthesize their food and depend upon the producers. For Example: Animals and human beings.

a. Herbivores: They feed on plants For Example: deer, cow, goat etc.

b. Carnivores: These are the organisms which feed on herbivorous For Example: loin, tiger etc.

c. Decomposers: These are the organisms which feed on dead and decaying matter of plants and animals. They decompose complex organic matter into simpler organic matter. For Example: Bacteria, fungi etc.

B) Abiotic components: The abiotic factors include the nonliving physic chemical factors of the environment. These components not only affect the distribution and structure of organism but also their behavior and inter relationships. Abiotic factors include:

1. Organic substances like carbohydrates, amino acids, lipids etc.

2. Inorganic substances carbon, nitrogen, oxygen calcium and their components.

3. Climatic factors like soil, temperature, light, wind, humidity.

What is food chain?

A food chain may be defined as a chain of organisms existing in any natural ecosystem, through which food, energy and matter are transferred.Or Series of organisms showing repeated eating and being eaten is referred to as food chain. 

All food chains begin with green plants which are original source of food. A food chain represents single directional flow of energy. For example: 

Green plants→ Insects→ Frog       →Birds

(Autotrophs)                 (Herbivorous)    (Carnivore)       (Top Carnivore)

Green plants →Goat or Deer  → Wolf→Lion/Tiger

Characteristics of food chain:-

(1) Food chain involves nutritive interaction between the living organisms of an ecosystem.

(2) A food chain is always straight and proceeds in a progressive straight line.

(3) In a food chain, there is unique directional flow of energy from sun to producers and subsequently series of different types of consumers.

(4) Usually there are three or four tropic levels in a food chain.

(5) At each transfer, generally 80 to 90% of energy is lost as heat in accordance with second law of thermodynamics.

What is food web?

 Food web is a network of food chains which become interconnected at various tropic levels. So as to form a number of feeding connections amongst different organisms of a biotic community. Thus a food web may be defined interlocked different chains forming interconnection at various tropic levels.

 Examples: In an open grass land, grass may be eaten by a rabbit it may be eaten by a mouse and the mouse is eaten directly by a hawk. In some other cases the mouse eaten by snake at the later then eaten by a  hawk. In this way a network of different food chains is formed. 

Characteristics of food web:

(1) Food webs are never straight instead; each food web is formed by interlinking of food chains.

(2) A food web provides alternative path ways of food availability.

(3) Greater alternative available in a food web make the ecosystem more stable.

(4) Food webs also help in checking the over populations.

(5) Food webs also help in ecosystem development.

Describe the energy flow in an ecosystem

Plants (Producers) prepare their food from CO2 and water in presence of sunlight. They utilize some part of this energy in their life activities and the remaining is stored in them. These producers are consumers. The herbivores utilize some part remains unutilized. These herbivores are then eaten by carnivores. They obtain their energy from the flash of herbivores. They utilize some part of this energy in their  metabolic activities but some part remains unutilized and then they are eaten by top carnivores and so on. This shows that energy flows only one direction i.e. unidirectional

What is Ten percent law?

During the transfer of energy from one trepic.level to another tropic level in an ecosystem there is loss of energy in the form of heat. It is estimated that approximately 90% of energy is not transferred from one tropic level to another tropic level and only 10% of energy is transferred from lower tropic level to higher tropic level. This law was given by Lindeman in 1942.

What is global warming?

The phenomenon of rise of average atmospheric temperature, Due to concentration of greenhouse gases in the atmosphere is called global warming. The gases in the atmosphere most  responsible for keeping the earth's surface warm are CO2, methane, chlorofluorocarbons (CFCs)  and nitrous oxide. These gases are called greenhouse gases.

 What is biological magnification?

 The phenomenon that involves progressive increase in concentration of harmfel non-biodegradable chemicals at different tropic levels in a food chain is called bio magnification.

What are solid wastes and management of solid wastes?

The wastes left over or discarded material are termed as wastes, the waste material in the form of solid such as vegetables, peeling of fruit,  paper, cow dung, human excreta, glass etc. are called solid wastes, in particular get accumulated in the environment for shorter or longer duration. These one the main sources of soil pollution.

Management of solid wastes Or Modes of waste disposal.

Wastes disposal literally means "getting rid of wastes”. Disposal of waste should be done scientifically depends on the nature of the waste. Some permanent methods of waste disposal are:

(1) Landfill: In urban areas majority of the solid wastes are buried in low lying areas to level the uneven surface of land.

(2) Recycling of wastes: Number of solid wastes (paper, plastics, metals) etc can be recycled by sending them to respective recycling units.

(3) Preparation of compost: House hold waste such as peeling of fruits and vegetable left over food, fallen dead leaves of kitchen garden plants and potted plants etc. can be converted into compost and used as manure.

(4) Incineration: It is the process of burning of substances at high temperature and ultimately converting them into ashes.

What are bio degradable and non-biodegradable wastes?

These waste substances which can easily be degraded by natural means that is by the action of microorganisms such as bacteria and fungi, into simpler - harmless substances in due course of time. Microorganisms are present in  abundance in our environment. These secrete specific enzymes and break down complex organic substances into simpler easily dissolvable substances. 

Harmful effects of bio degradable wastes:

(1) Decomposition of biodegradable wastes results in the product of foul smells which spreads to surrounding areas and makes the life miserable.

(2) Flies breed at huge heaps of solid wastes containing biodegradable substances easily the germs spread diseases such as diarrhea, typhoid,cholera etc.

3) These wastes also block the drains creating pulls of water which becomes the breading sites of mosquitoes.

4) Dumping of industrial wastes reduce the fertility of the soil leading to reduce reduced crop yield.

Non-biodegradable wastes:

These substances which cannot be degraded by natural means that is by the action of  microorganisms, into simpler harmless substances in due course of time. Only physical processes such as heat and pressure can affect such type of waste substance

What are the problems or effects caused by non-biodegradable wastes that we generate?

1) Some non-biodegradable substances such as pesticides, industrial chemicals heavy metals and radioactive substances are very harmful, because when these substances enter the food chains and their concentration goes on increasing from one tropic level to the next.

2) Excessive use of fertilizers and pesticides and dumping of industrial chemicals wastes affect the soil fertility and subsequently reduces the crop yield.

What is ozone?

Ozone is a form of oxygen. It is a tri atomic molecule made up of three atoms of O2. Ozone (O3) is highly poisonous gas and acts as a protective shield to earth. It absorbs most of the harmful radiations coming out from the sun.

            UV radiations

02→→ (0) + (0)

           UV radiations

02.+ (0)   → →  03

Ozone depletion: The thinning of ozone layer is commonly called ozone depletion. Its depletion is caused by chemicals like chlorofluro carbons coming from refrigerators and coolers, fire extinguishers, aerosol spray When these chemicals are released in the atmosphere causes destruction of ozone by breaking it into nascent oxygen.

            CFCS

03    →→ → →   02 + (0)

Effects of ozone layer: or Why is damage to the ozone layer a cause of concern? What steps are being taken to limit this damage?

i. UV radiations increase incidents of skin cancer and herpes.

ii. These radiations cause damage to eyes resulting in dimming of eye sight, photo burning as well as increased incidents of cataract in eyes.

iii. UV radiations cause damage to immune system and hence lowering the body's resistance to diseases.

iv. These radiations would increases mortality of developing embryo in the mother's uterus.

v. These radiations would result in 10 – 25 % decline of photosynthesis in plants.

vi. Decreased photosynthesis would result in increase in the concentration of CO2. This will results in global warming.

Control:

(a) Montreal protocolIn: 1987 the United Nations environment programmed succeeded in forging an agreement between nations to limit CFCS production to half the level of 1986. it was also decided that all the singing nations would take necessary steps to decrease the use of all ODS particularly CFCs. It was also recommended that alternate technology will be developed to replace the use of CFCs.

(b) Helsinki declaration; In 1989, majority of the nations pledged to phase out chlorofluoro-             -carbons by the Year 2000. Production of CFCs have been stopped since then and CFCs been replaced with hydro fluorocarbons (HFC) and hydro chlorofluorocarbons.

Why are some substances biodegradable and some non-biodegradable?

The wastes we generate in our daily life are biodegradable and non- biodegradable. It is so because in our environment are present micro- organisms (bacteria and fungi of decay) which secreté enzymes. These enzymes degrade organic compounds, present in the dead remains of plants and animals and their waste products, into simpler substances. Such wastes are termed biodegradable. On the other hand, these enzymes cannot degrade certain category of wastes such as plastics, glass objects etc. These wastes, therefore, persist as such in the environment and are termed as non- biodegradable wastes.

Give any two ways in which biodegradable substances would affect the environment?

(1) Decomposition of biodegradable wastes produces foul smell which spreads in the environment and makes the life of people miserable.

(ii) Flies breed at huge heaps of biodegradable wastes, carry the germs and spread diseases such as diarrhea, typhoid, cholera, tuberculosis etc.

Give any two ways in which non-biodegradable substances would affect the environment.

(i) Some of the non-biodegradable wastes (e.g., pesticides and heavy metals) enter the food chains, bio magnify and affect human beings and other biotic components of the environment.

(ii) Excessive use of non-biodegradable pesticides and fertilizers affects the fertility of soil and subsequently reduces the crop yield. The soil, thus, may become acidic or alkaline.

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

The distinct sequential steps in the food chain where transfer of energy occurs are called trophic levels. Let us consider the following food chain: Plants----->Goat-------> Tiger

In this food chain, plants are producers which convert solar energy into chemical energy of organic compounds by photosynthesis. Thus, producers belong to first trophic level (producer level). Goat is a herbivore and eats plant parts. Here, transfer of energy occurs from producers to herbivores. Thus, goat belongs to second trophic level (primary consumer level). Goat, in turn, is eaten by tiger (carnivore), involving transfer of energy from goat to tiger. Thus, tiger belongs to third trophic level (secondary consumer level).

What is the role of decomposers in the ecosystem?

Decomposers are essential components of ecosystem. They decompose dead remains of plants and animals and their waste organic products into simpler, inorganic substances. The latter are released into the environment for their reuse as raw materials by the producers. These, therefore, provide space for new life to settle in the biosphere.

What is ozone and how does it affect any ecosystem?

Ozone is a form of oxygen. A molecule of ozone contains three oxygen atoms (O3). In the stratosphere, ozone layer comprises high concentration of ozone some 18-50 km above. Here, it is being photo dissociated and generated by the absorption of harmful, short wavelength UV radiations. By absorbing harmful UV radiations, this layer protects all forms of life on earth. Certain harmful chemicals such as chlorofluorocarbons (CFCS), methane (CH4), oxides of nitrogen (NOx) etc., produced by human activities, are thinning the ozone blanket. As a result, more UV radiations penetrate ozone blanket to strike the earth and producing skin cancer, damage to eyes including increased incidence of cataract and damage to immune system of human beings and other animals. These also result in increased embryonic mortality decreased photosynthesis in plants and contribute towards global a warming.

How can you help in reducing the problem of waste disposal? Give any two methods.

Waste disposal literally means "getting rid of waste”. We can help in reducing the problem of waste disposal by changing our life style and attitude If we minimize the use of disposable articles and start using only those articles which can easily be recycled, we can reduce the generation of waste. We can also burry kitchen waste, fallen leaves etc. of kitchen garden into a pit and then using the manure formed due to their decomposition some prominent method of waste disposal are:

(i) Landfills (ii) recycling of wastes, (iii) preparation of compost, (iv) production of biogas and manure (v) incineration.

What will happen if we kill all the organisms in one trophic level?

If we kill as the organisms of one trophic level, the transfer of food energy to next level will stop. Also, there will occur overpopulations of individuals belonging to previous trophic level. It will bring imbalance in the ecosystem. Suppose, ail herbivores in an ecosystem are killed. There will be no food available for the carnivores of that area. Consequently, they will also die and will shift to other areas. Also, populations of producers will go on increasing in the absence of herbivores bringing imbalance in the ecosystem. 

Will the impact of removing all the organisms in a trophic level be different for different trophic level? Can the drganisms of any trophic level be removed without causing any damage to the ecosystem?

 Yes, the impact of removing all the organisms in a trophic level will be 
different for different trophic levels. Imbalance in ecosystem leading to its destruction will be time related. Suppose, all producers are killed. There will be no food available for herbivores present in the ecosystem. They also will 
die/ migrate. In the absence of herbivores, various categories of carnivores will be affected.
Since, all categories of organisms are linked in a food chain, removal of organisms of any trophic level will ultimately affect the ecosystem.

What is biological magnification? Will the levels of this magnification be
different at different
The phenomenon that involves progressive increase in concentration of harmful non-biodegradable chemicals at different trophic levels in a food chain is called biological magnification. Yes, the concentration of harmful
chemicals will be different at different trophic levels.

If all the Waste generates is biodegradable, will this have no impact on the environment?

If all the waste we generate biodegradable; it will have impact on the environment. It is so because it will not be broken down into simpler substances by the action of microorganisms at the right time. Hence, it will be accumulated and will act as pollutant. It, therefore, will result in harmful effect on the environment.