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The following changes are expected due to development of a large town. 

1. Some plants and animal species will die out. 

2. Some will adapt to the new conditions sufficiently to survive in reduced numbers. 

3. Some will benefit by the new conditions and will increase in numbers.

1. Industrialization 

2. Damming rivers 

3. Draining marshes 

4. Re-claiming land from the sea 

5. Cutting down forests 

6. Using chemical fertilisers and pesticides

7. Building towns, cities, canals and motor ways. 

Aquarium is an example of human made ecosystem.

Ecosystem is a functional unit of environment.

(c) United Nations Environment programme

DDT is not a biodegradable pollutant.

D) Grass, Fish and Goat

1. We should think of alternatives. This is because these pesticides are toxic chemical whose usage leads to Bioaccumulation and Biomagnifications. 

2. When we use pesticides, they prevent our crop and food from pests effectively but indiscriminately destroys a vast number of other animals. 

3. This is causing unpredictable changes in food chains and upsetting the balance within the ecosystem. 

4. Most of the chemical pesticides that contain mercury, arsenic or lead are non - degradable. 

5. They enter into food chain, accumulate in the bodies of animals and pass right through food web. 

6. Being further concentrated at each step until animals at the top of the pyramid may receive enough to do considerable harm.

7. This is one of the reasons for ever decreasing number of butterflies, bees, small and large birds. 

8. Some of the pesticides are nerve poisons and might bring about changes in behaviour. 

9. As the human beings are at the end of the food chain, these pesticides may get accumulated in our bodies also. This shows some adverse effects on us, when their concentration becomes sufficiently high.

1. Use of toxic materials such as pesticides, herbicides and fungicides creates new problems in the ecosystem. 

2. As these toxic materials are often indiscriminate in their action and vast numbers of other animals may be destroyed. 

3. Some of them may be predators which naturally feed on these pests, others may be the food for other animals. 

4. Thus causing unpredictable changes in food chains and upsetting the balance within the ecosystem. 

5. Some toxic substances have a cumulative effect. 

6. Some of them are degradable, can be broken down into harmless substances in a comparatively short time usually a year. 

7. Others are non-degradable which are potentially dangerous as they accumulate in the bodies of animals and pass right through food web. 

8. This process of entering of pollutants in a food chain is known as “Bioaccumulation”. 

9. The tendency of pollutants to concentrate as they move from one tropic level to the next is known as “Biomagnifications”.

The indiscriminate use of DDT has resulted bio magnification in tropic level. A gradual increase in the concentration of DDT is has been detected in the tissues of small fishes; predatory birds and also in mother’s milk, therefore it is not advisable to use DDT. It is non biodegradable substance. DDT is chemically called Di chloro Diphenyl Tri chloro ethane.

Biological magnification is the Process of increasing the concentration of harmful chemicals like pesticides from first trophic level to the last trophic level in a food chain.

Increase in the concentration of a toxic substance or a pollutant, with every link in the food chain is called bio magnification.

In any ecosystem. For any food chain, the pyramid of energy. Will be always upright because the amount of usable energy available at each tropic level is about 10% of energy that was available at the previous tropic level.

1. In ecology not all the pyramids are always upright. 

2. Pyramid of number may be upright, inverted or partly upright. 

3. Pyramid of biomass may be upright or inverted. 

4. But the pyramid of energy is always upright. 

5. This is because energy will decrease when we move from producers to the high level consumers. 

6. Only 10% of the energy from one tropic level transfers to the other through food chain. 

7. So the energy at base is more, gradually decreases, and very less at the top. 

8. As a result the energy pyramid is always upright.

There are three types of ecological pyramids. 

They are: 

1. Pyramid of number 

2. Pyramid of biomass and 

3. Pyramid of energy.

Biodegradable wastes are those substances which are broken down into simpler, harmless substances in nature in due course of time by the biological processes such as action of micro organisms like certain bacteria.

Examples: Urine and faecal matter, sewage, agricultural residue, paper, wood, cloth and cattle dung

(a) Autotrophs prepare their food (carbohydrate) in presence of sunlight with the help of carbon dioxide and water. This process is called photosynthesis.

(b) According to 10% law, 10 % to 500J that is 50J is transferred to sheep (I consumer). Hence, 5J of energy is transferred to lion (II consumer) that is 10 % of 50 J.

The pesticides used in crop field are washed down into the water bodies. From water bodies, these are absorbed by aquatic plants and animals of a food chain and thereby degrades the environment.

The important function of presence of ozone in earth’s atmosphere is that it shields the surface of the earth from ultraviolet (UV) radiations of the sun.

(a) Solar energy to chemical energy

Decomposers act on all biodegradable substances and break them into simple inorganic materials and maintain the balance of materials in the ecosystem and cleanse the environment.

Due to ozone layer depletion, the ultraviolet rays reaches earth and causes certain ill-effects which are bad for us and for crops. Exposure to UV rays can lead to greater incidence of skin cancer, cataracts and damages to the eye and immune deficiency.

Two steps to limit this damage are : 

(i) Minimizing the use of CFCs.

(ii) CFC's released into air accumulates in the upper atmosphere and reacts with ozone resulting in reduction in the thickness of the ozone layer.

• Ozone layer is a high concentration of ozone molecules present in the stratosphere.

• The main function of the ozone layer is to absorb the Sun’s ultraviolet radiation, hence protecting the Earth from its harmful effects.

• Depletion of the ozone layer is a cause due to excessive use of CFCs or ammonia. 

• Damage of ozone layer is cause of concern because ultra violet radiation from the sun will reach the earth and will effect human beings, plants and animals. 

• After the Montreal Protocol, the Ozone layer is improving by the control use of CFCs and other harmful chemicals.

(i) Four appliances which releases Chlorofluorocarbon are :

(a) Aerosol spray

(b) Air conditioner

(c) Refrigerator

(d) Coolant

(ii) Exposure to U-V rays can lead to greater incidence of skin cancer, cataracts or other damages to the eye and immune deficiency.

Three steps to limit this damage are :

(a) Stop the release of Chlorofluorocarbon

(b) Removing the pollutant nitrogen monoxide

(c) Reduce the usage of air conditioners

The functions of an ecosystem are-

a) Regulating Function: 

Maintenance of essential ecological process and life support system. 

Explanation: Both biotic and abiotic components live in an ecosystem which interacts with each other forming a stable, self-supporting system. 

b) Energy Flow: 

The ecosystem act as a buffer through which the flow of energy takes place to all the organisms in the ecosystem. 

Explanation: Energy flow in a unidirectional manner starting from sunlight to producers, herbivores, carnivores and finally decomposers thus utilising solar energy to produce chemical energy in the form of glucose by plants which are the main source of energy for all living organisms. 

c) Recycling of nutrients 

The ecosystem is responsible for the recycling of the minerals in the biodiversity. 

Explanation: 

The plants take inorganic material from the soil and convert it into food with help of sunlight. The food is used to produce chemical energy by the secondary level organism which breaks them into simple organic compound when the secondary level organism dies it gets decomposed by the action of decomposers which convert the complex substance to simple inorganic substance which are then mixed with soil. Thus, the ecosystem is designed to recycle nutrients.

Methods to conserve insects and birds: 

1. Avoid indiscriminate usage of pesticides 

2. Protect the natural habitats of insects and birds. 

3. Development of bird sanctuaries 

4. Everyone should follow environmental ethics.

Steele (1974) proved that the gross ecological efficiency is about 20 to 30%.

1. The human activities badly affected the environment. 

2. Use of pesticides against the pest degraded the land.

Slobodkin (1959) suggested that the transfer of energy from one tropic level to the next is of the order of 10% and this is called “Gross ecological efficiency”.

(A) Bio-accumulation

A) do not break down

Decomposers like bacteria, fungi etc. act upon dead and decay organisms to convert organic compounds into simpler forms. These simple substances get mixed up in the soil and are used as nutrients by the producers. From producers it goes to consumers and so on. Thus there is recycle of matter which is done by decomposers that maintain balance in the ecosystem.

(D) Upputeru channel

The lake Kolleru discharges its excess water into Bay of Bengal through the twisty channel called Upputeru which is about 65 km long.

In November 1999, Government of Andhra Pradesh had declared the lake as Bird Sanctuary.

The species at the top of the pyramid get, more energy when the steps in a food chain are fewer.

The Kolleru lake is hosting 193 species of birds.

(B) 20,00,000 birds

• Frog and rabbit belong to second trophic level as they are carnivores feed on plants or producers.

• Eagle and tiger belong to third trophic level as they are carnivores feed on herbivores or primary consumers.

Flow of materials between organisms and their environment is called cycling of materials or biogeochemical cycles.

During the transfer of energy from one tropic level to the next, only about ten per cent of the energy from organic matter is stored as flesh. This is called “Ten per cent law”.

1. a. 1%

2. c. Photosynthesis

3. d. Sunlight → producers → herbivores → carnivores

4. c. Unidirectional

5. d. chemical energy

(i) Green plants have chlorophyll in their leaves due to which they can synthesize their own food in sunlight.

(ii) Consumers are the organisms which depend on others for their survival, or food. Consumers are herbivores, carnivores or omnivores. Man is omnivore which depends on others for its food either plants or flesh.

1. No, the sparrows were not really responsible for the loss of food grain. 

2. With no sparrows to eat the locust population crops were damaged and this led to fall in crop production.

1. Removal of organisms from any tropic level of a food chain or food web disturbs the ecosystem and leads to ecological imbalance. 

2. If we remove predators from food web, the prey population will increase enormously as there is no natural control over them. 

3. The producers population will decrease rapidly as the organisms feeding on them increase. 

4. After few generations the prey population also begins to decrease as some of the preys begin to die due to starvation. 

5. Some adaptations may also be developed by the organisms to bring the ecological balance. 

6. But it may take some generations, till that the ecosystem will be disturbed and imbalanced. 

7. For example, if we remove all the predators (carnivorous) from a forest ecosystem, the herbivorous animal population will increase as there are no carnivores to hunt them. 

8. As a result plant population will decrease as the ever increasing herbivores feed more and more on plants. 

9. After some generations the herbivore population begins to decrease as the decreasing number of plants are not sufficient to feed. 

10. Then some herbivorous animals may adapt to feed on other herbivores to increase their survival. 

11. Then scope for survival will increase for plants again which leads to ecological balance. 

12. But this may take lot of time to evolve new predators and to form ecological balance.

Any type of plant or animal material , that can be converted into energy is called Biomass

Energy flow in an ecosystem is unidirectional. Energy always flow from sun to the producers and then to the consumers. The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert it into food energy.

i. The group of organisms that occupy the same level in a food chain is called trophic level.

ii. For example, in a grassland ecosystem, the different species of grasses are primary producers make up one trophic level. 

iii. Similarly different species of grass eating animals (herbivores) are at one trophic level.

When green plants are consumed by the herbivores (primary consumers) most of the energy is liberated as heat to the environment, some amount goes into digestion and some energy used for growth and reproduction. Only 10% of the food eaten is turned into its own body and made available for the next level of consumers.