WBBSE 9th Class Science Solutions Life Science & Environment Chapter – 5 Environment and its Resources

WBBSE 9th Class Science Solutions Life Science & Environment Chapter – 5 Environment and its Resources

West Bengal Board 9th Class Science Solutions Life Science & Environment Chapter – 5 Environment and its Resources

WBBSE 9th Class Life Science & Environment Solutions

TOPIC – 1

ECOLOGY AND ECOLOGICAL ORGANISATION

SUMMARY

• Ecology is the study of interactions between organisms and their environment including other organisms.
• Levels of organisation in ecology include organism the population, community, ecosystem and biosphere.
• An ecosystem is all the living things in an area interacting with all of the abiotic parts of the environment.
• Adaptations allow organisms to live in different types of habitats. Sun loving plant is called heliophytes and shade tolerant plant is called sciophytes. Plants of dry areas are called xerophytes. Some animals resist the effect of cold called freeze tolerant animals, some are drought resistants or drought evaders. Places with high humidity have greater biodiversity.
• Megatherms are the plants adapted to high temperature and microtherms are the plants adapted to cold climate. Animales undego hibernaion to avoid cold climate and to avoid high temperature they undergo aestivation.
• Members of a species, inhibiting same place, collectively called population. Natality, mortality, migration are some factors that affect population growth.
• Interactions amongst different species in a biotic community are-cooperation, competition, predation and parasitism. Cooperation may be of different types-(i) symbiosis, (ii) mutualism and (iii) commensalism.
• Functional interrelation between biotic community and their habitat constitutes an ecosystem.
• An ecosystem constitutes two types of components or factors-(i) abiotic and (ii) biotic.
• The functioning of ecosystem depends on the food chain, food web, energy flow and nutrient cycle.

Long Answer Type Questions

1. Symbiosis: Symbiosis is an interspecific cooperation, in which two species live in a close physical association and both are benefited some way or the other. Symbiosis may be obligate (both the species entirely depend upon one another for survival) or facultative (both the species do not depend on their partner for survival).
   Example-In lichens, algae and fungi develop symbiotic association. Here, the fungus acts as a settling platform and provides water and mineral to the alga. In return, the alga synthesises food for both.
2. Mutualism: Mutualism is the cooperation between two species, in which both are benefited but close physical association and nutritional interdependence between them is not evident.
   Example-Insects collect nectar and pollen from flowers. In exchange, they help in spreading pollen grains from one place to another that help in plant reproduction.
   
3. Protocooperation: Protocooperation is a positive interspecific interaction, where both members are benefited but, they do not depend on one another for survival. Growth and survival of both the species is possible even in the absence of this interaction.
   Example-Sea-anemone often rides on the shell of hermit crab. Here sea-anemone intakes discarded food of the hermit crab and in return protects it from the predators by its stinging cells. This relation is not obligatory because both can live independently.
4. Commensalism: Commensalism is the cooperation between two species, where one of the members is benefited, but the other member is neither benefited nor harmed. In this relation, close association occurs between the two species, but nutritional interdependence is not developed.
   Example-Epiphytic orchids grow on the branches of big trees, but carry out photosynthesis independently. By this process, orchids escape predation, but the host tree is neither harmed nor benefited.

1. Parasitism: Parasitism is the most advanced type of interspecific interaction, in which one species depends upon other species for food or shelter or both. Here, the dependent member (parasite) is benefited, but the other member (host) is deprived.
   Example-Tapeworms (Taenia sp.), roundworms (Ascaris sp.), etc. are the parasitic worms that draw nutrients from human (host). Dodder plants (Cuscuta sp.) suck nutrients from phloem of the host plants.
   
2. Competition: Competition can be defined as a negative interaction, where members of the same or other species fight with each other to acquire limited supply of environmental resources food, water, shelter and mates. Competition is mainly of two types-[A] intraspecific competition and [B] interspecific competition.
   [A] intraspecific competition: In this competition, members of the same species fight among themselves for food and mate.

   Example-Fighting among dogs or fighting among cats.

   [B] interspecific competition: This competition takes place between members of two or more different species, for food and shelter.

   Example-Sparrows quarrelling with common maina or dogs fighting with cats.
3. Predation: Predation is another type of interspecific interaction, in which one species attacks another species to kill and consume it. Here, the attacker is known as predator and the one, which is attacked, is called the prey. The predator obtains nutrition and energy from the prey.
   Example-Tigers kill deer, praying mantis kills other insects, pitcher plants trap insects, etc. In all the above examples, the former ones are the predators and the latter ones are the prey.

1. 1 Ectoparasites: These parasites draw nutrients from outside the body of the host.
   Example-Louse, ticks, bedbugs live on body surface of mammals. In case of parasitism in plants, Dodder plant needs a special mention. Dodder plant (Cuscuta sp.) produces root like structures, called haustoria, which penetrate the vascular bundle of the host and derive nutrition directly.
2. Endoparasites: These parasites live inside the body of the host and collect nutrients from them.
   Example-Tapeworm, roundworm, Plasmodium (malarial parasite), liver fluke, etc. live inside human body.
   On the basis of the dependence of parasitism, they may be of two types

   

3. Obligatory parasites: These species completely depends upon a host to complete their life cycle.
   Example-Tapeworm, roundworm, Plasmodium, etc. spend their life permanently as parasites.
4. Facultative parasites: These species can survive without the parasitic mode of life but can also adapt a parasitic life.
   Example-The parasitic nematode Strongyloides stercoralis can also be free living.

1. Abiotic factors: Abiotic factors include the non-living components of ecosystem. They have direct impact on life process of living organisms. Various abiotic component of the ecosystem are-organic component, inorganic component and physical component.
   1. Organic component: Different organic matters, such as carbohydrate, protein, fat, etc. are obtained from the dead and decaying organic remains of plants and animals. These organic matter mix with the soil and produce humus, which play a significant role in regulating soil fertility.
   2. Inorganic component: It includes various mineral elements (such as calcium, magnesium, salts of sodium, potassium, sulphur, etc.) and gases (such as oxygen, nitrogen, carbon dioxide, etc.). Green plants use these elements for synthesizing their own food.
   3. Physical component: The physical component of ecosystem includes various factors, such as light, temperature, humidity, altitude, steepness of slope, firmness of soil. Of these, the most important physical factor is light, more specifically sunlight. Green plants trap the solar energy and convert it to chemical energy to prepare their own food by the process of photosynthesis.
2. Biotic factors: The living organisms constitute the biotic factors of an ecosystem. Various components of biotic factors are-autotrophs and heterotrophs.
   1. Autotrophs: All those organisms, capable of synthesizing their own food by photosynthesis or chemosynthesis, are known as autotrophs. All green plants, photosynthetic and chemosynthetic microorganisms are the examples of autotrophs.
   2. Heterotrophs: The living organisms, which depend directly or indirectly on autotrophs for their nutrition are known as heterotrophs. Heterotrophs may be classified into three typesconsumers, decomposers and transformers.
      1. Consumers: These organisms directly or indirectly consume autotrophs, especially green plants and plant products, to gain nutrition and energy. So, they are called consumers. Depending upon the nature of food they eat, consumers are classified into three types-
         (a) Primary consumers: These animals directly consume green plants or plant products for nutrient and energy. Example-Deer, cow, grasshopper, etc. (all herbivores).
         (b) Secondary consumers: These animals directly consume herbivores for nutrition. Example-Frogs, small birds, rat, lizards, etc.
         (c) Tertiary consumers: These are larger consumers, which feed on both primary and secondary consumers. Example-Owl, tiger, lion, falcon, king cobra, etc.
      2. Decomposers and transformers: The organisms, which get their nutrients from dead organisms and decaying organic matter and in this process break the larger organic compounds into smaller molecules, are called decomposers. Different microorganisms (such as bacteria) and some fungi (such as Agaricus) belong to this group. Some bacteria act upon those small organic ules, that are the end products of decomposition. These bacteria completely break those organic molecules and return the elementary components in nature. They are called transformers.

1. Acquiring energy: All green plants and other photosynthetic microorganisms can trap radiant energy from the sun. Only 0.02% of the total energy of sun comes to the earth as light. Of this, only 0.1% is trapped by means of photosynthesis. This process is called acquiring energy.
2. Utilizing energy: The light energy from the sun, trapped by the green plants, is oxidized during respiration to produce chemical energy. This energy is necessary to carry out different metabolic activities. This process is called utilization of energy.
3. Transfer of energy: From the green plants, net primary production passes to different level of consumers through food chain. The herbivores or primary consumers directly get their share of energy from producers. By respiration, primary consumers utilize a greater portion of the transferred energy. the remaining portion of energy is then transferred to the higher level of consumers in the same way.
   When energy flow occurs from one trophic level to another, subsequently an amount of energy is lost in the process which cannot be regained further. Moreover, the energy that follows from producer to consumer, can never be returned to the producer. Hence, the flow of energy is always unidirectional.
   According to famous scientist, Lindeman, out of the total energy produced or received in a particular trophic level, only 10% of it is transferred to the next trophic level. This is known as Lindeman 10% law. As a result, very less amount of energy is received by the members of highest trophic level.

1. Solar energy is the main source of energy in all ecosystem.
2. Energy flow is unidirectional.
3. Amount of energy gradually decreases along the trophic level.
4. Energy flow in an ecosystem occurs through three steps-acquiring of energy, utilisation of energy and transfer of energy.
5. Energy flow in an ecosystem obeys the first and second laws of thermodynamics.
6. In the year 1942, Lindemann formulated 10% law of energy flow. According to this law, only 10% of total energy of any trophic level is transmitted to next trophic level during energy flow through several trophic levels.

1. Organism: It is the lowest level of organisation, which includes both unicellular and multicellular organisms. All the living species in this level exhibits all the characteristics required for the existence of life.
2. Population: A population is a group of individuals of a single species living together within a particular geographic area. They inter breed and complete with each other for resources.
3. Community: It refers to the several populations that interact and inhabit a common environment and are inter dependent.
4. Ecosystem: It is a set of all living species and abiotic components existing and interacting in a given area. There is an interaction with both living and non-living components of the environment.
5. Biosphere: It is highest level of organisation. It is the global ecological system which consists of all the living organism and other factors which supports life. Biosphere mainly refers to the part of the earth’s crust.

1. Abiotic components: They are formed as a result of the mixture of some organic and inorganic materials. They have directly or indirectly effect in aquatic organisms of the pond. These includes-light, temperature, dissolved oxygen, carbon dioxide, other gases, pH of water, turbidity, dissolved minerals.
2. Biotic components: They are the living components which consist of-
   1. Producers: They are the aquatic green plants, which may be divided into two groups-
      1. Microphytes (Phytoplanktons): They are microscopic autotrophs, which fix solar energy. Example-Spirogyra, Zygonema, Volvox, Oedogonium, etc.
      2. Macrophytes: They are large plants, which manufacture complex food. Example-Pistea, Hydrilla, etc.
   2. Consumers: They are those heterotrophic organisms, which consume producers as food. Their types are-
      1. Primary consumers: These herbivorous animals depend on autotrophic organisms such as microscopic plant eaters or zooplanktons, molluscs, beetles, Cyclops, Daphnia, etc.
      2. Secondary consumers: These are primary carnivores, which depend on herbivorous animals for food. Example-Insects, fishes, frogs, crab, etc.
      3. Tertiary consumers: These are the second grade of carnivores. They feed upon plants and animals (secondary consumer), therefore are called carnivores. Example-Large fishes, frogs.
   3. Decomposers: Most of the decomposers of pond ecosystem are sparophytes but some parasites are also found. Bacteria, fungi, like Aspergillus, Cladosporium, Rhizopus, Alternaria, Fusarium, Saprolegnia, etc. are decomposers. Generally, the decomposers either live in the soil layer beneath water or in the mud. They act on dead and decayed organic matter of plants and animals and supply raw materials to the producers.

1. Biotic components:
   1. Producer organisms: In a forest, the producers are mainly trees. Apart from trees, climbers, epiphytes, shrubs and ground vegetation. Dominant species of trees are in major types of forest ecosystems are-Tectona grand acer, betula, picea, pine, cedrus.
   2. Consumers: In a forest, consumers are of three main types-
      1. Primary consumers: These are herbivores which feed directly on producers. Example-Ants, beetles, bugs, spiders, etc. feeding on tree leaves. Larger animals like elephants, deer, giraffe, etc. grazing on shoots and/or fruits of trees.
      2. Secondary consumers: These are carnivores and feed on primary consumers. ExampleBirds, lizards, frogs, snakes and foxes.
      3. Tertiary consumers: These are secondary carnivores and feed on secondary consumers. These include top carnivores like lion, tiger, etc.
   3. Decomposers: These include wide variety of saprotrophic microorganisms, like bacteria (Bacillus sp., Clostridium sp.), fungi (Aspergillus sp., Ganoderma sp., Fusarium sp.), actinomycetes (Streptomyces sp.). They attract dead or decayed bodies of organisms and thus decomposition takes place. Therefore, nutrients are released for reuse.
2. Abiotic components: These include basic inorganic and organic compounds present in the soil and atmosphere. In addition, dead organic debris is also found littered in forests.

Short Answer Type Questions

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

Answer in a single word or sentence

Fill in the blanks

State True or False

TOPIC – 2

NATURAL RESOURCES AND ITS SUSTAINABLE USE

SUMMARY

• Natural resources are those which are used for the wellbeing of mankind. They are the stock of nature such as air, water, soil, coal, minerals, animals and plants that are useful to mankind in many ways.
• On the basis of the chances of recovery, natural resources can be categorized as(1) Renewable resources (sunlight, air, wind, water etc.) and (ii) Non-renewable resources (coal, petroleum etc).
• Some common problems of degradation of resources by improper utilisation are-soil erosion and desertification, water logging and soil salinity, Deforestation etc.
• Water is renewable natural resource. Rain water harvesting is essential because surface water is inadequate to meet our demand and we have to depend on ground water. But excess use of ground water may decrease the level of it. Sometimes the lower level of ground water polluted by arsenic contamination. The one and only way to avoid these hazards is to harvest rain water.
• Food is one of the most important natural resource for all living organism. The different sources of food for human consumptions are plants and domestic animals.
• The alternative food resources offer a diverse profile in terms of availability, nutrition and other important uses. Example-Insects, single cell protein, etc.
• The underlying reasons behind the food scarcity around the world are proverty, inequal distribution of crops, corruption, national policies, etc.
• Energy resources are two types-Conventional (coal, petroleum) and Non-conventional (solar energy, wind power, etc). Excess use of energy from conventional sources may lead towards the scarcity of these resources. So we have to plan for different resources like non conventional sources to meet the excess demand of energy.

Long Answer Type Questions

1. Discuss the environmental and economic importance of a forest.

Ans. Importance of a forest

1. Watershed protection: Afforestation along the slope of watershed prevents runoff and reduces the deposition of slit in riverbed. Some plants with mycorrhizal root absorb heavy and toxic metals from soil and reduce the chance of water toxicity.
2. Atmospheric regulation: Scarcity of plants and excessive industrialization in urban areas reduces O₂ and increases CO₂ content in the atmosphere. Forest regulate 0₂-CO₂ balance. By respiration organisms release CO₂ and absorb O₂ from the atmosphere. By the process of photosynthesis, green plants of a forest release O₂ and absorb CO₂. In this way, balance of O₂ and CO₂ in the atmosphere is maintained.
3. Erosion control: Erosion means washing or blowing away of top layer of soil. Forests prevent soil erosion by several methods. They are- -[A] The branches of roots firmly bind the soil particles with the ground. [B] The dense leaves of forest prevent raindrops from hitting the soil particles directly and loosening it from the upper layer of soil. [C] The litter formed by the leaves on the forest floor, partly decompose to form sticky humus. This sticky humus increases the adhering capacity of the soil particles and prevents soil erosion.
4. Local use: Humans exploit forest in different ways. People living in nearby villages collect firewood from forest. Forest provide honey, timber, resin, honey, cotton, fur, wool, meat (from herbivores), etc. that are collected and marketed.
5. Productive use: From productive point of view, forest has immense importance. Timber is the main economically important product of forest, used to prepare sleepers, posts, log houses, plywood, laminates, galleries, etc. Ecotourism is another productive aspect of the forest, from which the government earns huge amount of revenue. Honey, rubber and several medicinally important materials are collected from the forest.

2. Briefly discuss the causes of deforestation.

Ans. Causes of deforestation

1. Subsistence agriculture: It is an unscientific method of farming, where farmers concentrate on growing enough food for themselves and their family. They cut trees and burn smaller vegetation to prepare land for cultivation and cattle grazing.
2. Indiscriminate felling of trees: Growing population has increased demand of wood products, starting from match-sticks to furniture. Accordingly, price of wood has also been increased. Due to this high price of wood, traders encourage indiscriminate felling of trees.
3. Urbanisation: For development of the state infrastructure, roads and railway tracks are laid through forestland. Moreover, miners acquired the forestland for oil, coal and ore mining. This level of human intervention has affected the lifestyle of both animals and plants and leads to habitat fragmentation.
4. Forest fire: In drier seasons, the local farmers and forest communities burn dry grasses to expand grazing area. High concentration of oxygen in forest atmosphere drives this small fire into a firestorm. It goes out of control and destroys hundreds of trees and many smaller and bigger wild animals.
5. Desertification: Rivers and streams flowing through forestlands often carry industrial pollutants. These toxic materials cause soil pollution, which leads to polluting forest ecosystem.

3. Describe the consequences of deforestation.

Ans. Consequences of deforestation

1. Global warming: Due to deforestation and rapid pace of industrialisation, concentration of greenhouse gases like CO₂ increases in the atmosphere. This results in global warming.
2. Climatic change: Transpiration by trees increases humidity in atmosphere, which in turn enhances the chance of rainfall. In many parts of the world, rate of rainfall has dropped significantly due to deforestation.
3. Change of soil character and erosion: The litter, deposited in forest floor, decomposes to form humus, that keeps the soil healthy and moist in normal situation. Due to deforestation, soil gets exposed to sun and dries out. Moreover, soil particles become loose without binding of roots. Due to this, rain and wind washes off and blow away soil particles, reduce chance of humification resulting in soil erosion.
4. Flood and drought: Incidence of flood and drought has increased in every part of the world due to deforestation.
5. Wildlife extinction: Forests provide habitat for millions of species of flora and fauna. Deforestation makes them homeless. As a result, certain number of species as well as part of wildlife gets extinct.
6. Environmental pollution: Deforestation results in decrease in atmospheric oxygen level. At the same time carbon dioxide increases, which is a cause of air pollution. Mycorrhiza developing in the root system of some trees can remove heavy and toxic metals from the soil. In case of deforestation soil becomes polluted.

4. Why should we conserve forests? Mention few methods of forest conservation.

Ans. Reasons of forest conservation

Conservation is protection, augmentation and scientific management of resources so as to maintain them in their optimum level providing benefit to the present as well as future generations. Forests must be conserved because of their immense economic, protective and regulative properties. Forest conservation is important-[1] to maintain ecosystem of forest, [2] to maintain O₂ -CO₂ balance in the environment, [3] to maintain the supply of forest products like timber, food etc., [4] to maintain natural beauty and livelihood of the local people.

Methods of forest conservation

1. Afforestation: It is growing of forests on unprotected barren lands.
2. Reforestation: It is developing forest cover in the area which has been damaged or cleared during exploitation.
3. Separation of commercial forestry: Useful plants required by industry should be planted separately preferably on waste land.
4. Grazing: Grazing should be regulated according to the availability of pasturage.
5. Social Forestry: It is growing of useful multipurpose trees and shrubs on common village lands, roadsides, railsides, etc. by cooperative efforts of people of the area. The plants provide fodder, small timber and fire wood to villagers.
6. Agroforestry: Multipurpose trees and shrubs are planted on the sides of crop fields to provide fodder, fuel and timber.

Both social forestry and agroforestry reduce pressure on the forests. Trees are also planted at all vacant place and along roads in urban areas (urban forestry) for reducing air and noise pollution.

5. Mention the uses of water. Briefly describe the causes of water scarcity. 

Ans. Uses of water

Water is an essential component of life. Water is one of the most vital natural resources on Earth for life to sustain. The availability and the quantity of water have always played a significant part in determining not only where population can grow but also their quality of life. It is used in several ways.

1. Drinking: Water is the most essential and a universal drink necessary for life.
2. Agriculture and industrial purpose: A large quantity of water is used for irrigation of crop fields. Different industries, such as metal, paper, chemical, wood, petrochemical etc. and boilers of power plants require large quantity of water. Water is used as raw material, solvent, coolant and washing medium.

Causes of water scarcity

1. Drop in rainfall: Rainfall has dropped radically in different parts of the world, resulting in moderate to severe water scarcity.
2. Global warming: Excessive heat dries out surface water. But this loss is not totally replenished by rain.
3. Over-utilisation of water: Over-utilization of ground water is a result of poor water management, that leads to water scarcity and increased chance of arsenic contamination.
4. Pollution: Disposal of sewage water in streams and lakes is a wasteful technique. By this process, sources of freshwater are polluted and wasted.

6. How is rain water utilised to counter scarcity of fresh water. Mention the advantages and disadvantages of rain water harvesting?

Ans. Utilisation of rain water

Rain water is the largest source of fresh water. By scientific harvesting of rain water, the fresh water scarcity can be controlled to a great extent. Rain water harvesting is a simple and effective method of water management by which rain water is collected, stored and used to meet the demand for fresh water.

The easiest and popular method is rooftop rain water harvesting. In this process, rain water pipes of roof are connected to a ground level or underground reservoir. The rain water is stored in the reservoir and is used according to necessity. This water can be used directly for any nonpotable purposes like watering plants, washing and cleaning, bathing and toilets. For cooking and drinking, this water must be disinfected and filtered. For using rain water at community level, reservoirs of all premises are connected to one or more large community reservoirs. Finally, this water is treated and disinfected centrally and then pumped to the overhead water supply tank or the main well of the village.

Advantages and disadvantages of rain water harvesting

1. Advantages: [A] Rain water is generally free from germs and contaminants. [B] It is soft water with slightly acidic pH and does not contain any salt. [C] Rain water contains no corrosive substances, so it does not harm water pipes and reservoirs.
2. Disadvantages: [A] Rain water harvesting is not practiced in areas with excessive suspended particulate matters in air. [B] Toxic gaseous materials pollute the atmosphere at regions near chemical industries and fertilizer factories. [C] These gaseous pollutants mix with rain water and make it harmful.

7. Briefly describe different sources of food for human consumption.

Ans. Different sources of food for human consumption

1. Crop production: The maximum quantity of food we consume are plant products. These include cereals (paddy, wheat, maize, millets, etc.), pulses (moong, masur, gram, pea, etc.) and oil seeds (mustard seed, sunflower seed, groundnut seed, rape seed, etc.)
2. Horticulture: Horticulture includes the cultivation of fruits, vegetables, nuts, seeds, herbs, etc. We get fruits and vegetables from horticultural farms. The fruits and vegetables which we use in cooking, are also horticultural products.
3. Cattle farming: This industry is involved in breeding and rearing of animals like cows, goats, pigs, etc. It provides us with animal products like meat and milk.
4. Poultry: This industry is involved in breeding and rearing domestic birds like chickens, ducks, etc. This industry provides us with poultry producers like meat and eggs.
5. Fishery: Fisheries are meant for scientific breeding and rearing of fishes. Fisheries supplies fishes to our platter.

8. Briefly describe the situation of food scarcity on global basis. Mention the impacts of food scarcity on earth.

Ans. Global food scarcity

During the last century, industrialization and urbanization have reached the peak. This situation has pushed agriculture already at the back row. Now the rate of agricultural production cannot meet the global demand of food crops. The environmental changes and increasing population have aggravated this problem. All these factors have developed scarcity of food all over the world. The situation has become more adverse in poorer and developing countries. Out of 70 billion of total world population, about 10 billion have been suffering from malnutrition and partial starvation. A few millions are dying out of starvation or diseases caused by malnutrition. People of Africa, Latin America and Asia are the main victims of food scarcity.

Impact of food scarcity

Food scarcity is not only taking lives due to starvation and malnutrition, besides these, it also has some other impacts on human life and environment. To increase crop production, a land is cultivated two or three times in a year. In developing countries, chemical fertilizers are applied indiscriminately to increase yield. By this practice, the natural fertility of soil is lost, also the soil pH changes. Forest lands are encroached upon by farming. This practice results in deforestation which is followed by soil erosion and flood. Random use of pesticides in the crop fields cause soil and water pollution that may result into many incurable diseases. Irrigation of crop fields by suction of underground water is reducing the underground water reserve and causing arsenic pollution.

9. Refer to a specific incident related to world food problem. Give examples of different alternative food sources.

Ans. Special incident related to world food problem

Between July 2011 and mid 2012, a severe drought affected the entire East Africa region. The drought caused a severe food crisis across Somalia, Ethiopia and Kenya that threatened the livelihood of 9.5 million people. The United Nations officially declared famine in two regions in the southern part of Somalia.

Alternative food sources

To meet the additional demand for food, scientists and nutrition experts have found dietary potentials in some plant products, other than the common food materials. [1] Moringa oleifera has incredible nutritional value. Many edible parts, like fruits, seeds, leaves, flowers are rich in protein, iron, Vitamin A and Vitamin C. It also has great medicinal importance. [2] Yam bean contains enough carbohydrates, dietary fibres and Vitamin C. it can be consumed raw as salad or cooked, baked and even fried. Yam bean seeds contains oil. [3] Sago is a carbohydrate rich matter, extracted from the stem of some palm trees. The granular shape is obtained by mechanical processing. It is tasty and has good nutritive value. [4] Gum arabic is used to prepare chewing gum. Gaur gum is applied as thickener in confectionary formulations. [5] Green gaur beans are eaten as vegetable and are used as fodder.

10. Discuss the causes of world food problem.

Ans. Causes of world food problem

1. Increase in price of food: For the last three decades, the price of food has been increasing globally. Due to high price rise, people of developing countries are facing serious problem.
2. Old method of farming: The practice of conventional farming like monoculture (without crop rotation), using of low yielding seed varieties, using of chemical fertilizers, farming without soil testing and lack of co-ordination between farmers and marketing sectors are the main reasons of food problems in developing countries.
3. Climatic change and natural calamities: Scarcity of rainfall or excessive rain may affect the production rate. Natural calamities, like flood or drought, also reduces the productivity of food throughout the world.
4. Erosion of soil and soil pollution: Soil erosion reduces the land, available for cultivation. Extensive use of chemical fertilizer reduces soil fertility and productivity. This is another cause of food problem.
5. Population explosion: On an average, 80 million people are born every year. But yearly production of food does not always reach that level to feed those new mouths. Therefore, increase in total number of population also increase food scarcity.

11. Classify the resources of energy on the basis of use. Mention the importance of conservation of energy resources.

Ans. Classification of energy resources

1. Conventional energy resources: Conventional energy resources are those which have been traditionally used for many years. These resources are also widely used at present and likely to be depleted. Example-Coal, petroleum, natural gas, hydel power.
2. Non-conventional energy resources: Non-conventional energy resources are alternate energy resources to the conventional energy resources which are being considered to be used on large scale. The conventional energy resources are likely to be depleted in about 50-60 years and non-conventional energy resources should be fully developed by then to meet the energy requirement. Example-Solar energy, wind energy, geothermal energy, tidal power, biogas, etc.

Importance of conservation of energy resources

[1] Energy is of the basic needs of life, therefore resources of energy must be conserved.

[2] The conventional resources of energy, especially coal and petroleum are non-renewable, therefore they must be conserved for future generation.

12. Mention three basic steps towards conservation of energy resources. Mention the different uses of energy. 

Ans. Basic steps towards conservation of energy resources

Steps towards conservation of energy resources are as follows-[1] Thermal power generation is to be regulated to conserve coal. [2] Conventional sources of energy are to be replaced by nonconventional energy sources as far as practiceable. [3] Misuse and wastage of energy resources must be cut down substancially.

Different uses of energy

1. Domestic use: In rural areas, wood, coal and kerosene oil are utilized for heating and lighting purpose. In urban areas, energy is used for cooking, lighting rooms, heating, cooling, running electronic gadgets, washing machines, dishwasher, vacuum cleaners, water suction pumps etc.
2. Commercial use: In commercial buildings, such as shops, malls, hotels and restaurants, energy is used for lighting, cooling, heating and running utility gadgets.
3. Industrial use: In industries, coal, oil and natural gas are used for heating, burning and melting purposes. Lighting and running machines depend upon electrical energy.
4. Use in transport: Most of the vehicles, ranging from motor-bikes to aeroplanes, motor-boats to huge ships, run by petroleum based fuels.

Nowadays, atomic energy is used to run huge submarines and aircraft carriers.

13. Mention the methods of energy conservation in daily life.

Ans. Method of energy conservation in daily life

1. Lighting: Walls to be painted in lighter shade. Lamps should be kept dust free. Incandescent bulbs needs to be replaced with CFL to LED lamps. Electronic chokes be used instead of copper chokes.
2. Fans: Fans to be switched off before leaving room. Electronic regulators be fitted.
3. Electric iron: Ironing is to be done at right temperature. Sprayer is to be used for moistening.
4. Kitchen appliances: Grinders should be used for wet grinding. Machines are not to be run in over or under-load condition. Door of microwave-oven is not to be opened frequently to check food. Flat bottom pans are to be used for induction oven.
5. Gas oven: Cooking should be done in regulated flame. Pressure cookers are to be used as much as possible. Pans to be kept covered while cooking. Before cooking items to be allowed to reach room temperature after taking out of refrigerator.
6. Water heater: Solar water heaters to be used replacing electric water heater.
7. Electronic devices: Before leaving room even for short intervals, TV and audio systems should be turned off.
8. Computers: Computer monitor to be turned off during long time downloading.
9. Refrigerator: Star-rated energy saver models are to be used. Frequent opening of the door should be avoided. Door padding should be air-tight.
10. Washing machines: Washing machines should be run in full load condition at optimum water level. Perfect water and detergent quantity should be maintained.
11. Air conditioners: Energy saving star-rated equipments are to be installed and to be selected according to cooling capacity and room size. Outdoor unit is to be fitted in shady place. Filters should be cleaned regularly. Doors and windows of the room are to be sealed perfectly.

14. Mention the need for conservation of natural resources classify natural resources.

Ans. Need for conservation of natural resources

1. To support life by supporting ecological balance.
2. To ensure that the future generation will be able to access the resources.
3. To preserve the biodiversity.
4. To ensure the survival of human races.

Classification of natural resources

Short Answer Type Questions

1. What do you mean by resources?

Ans. Resources are anything that available to fulfill human needs. It should be easily accessible, economically feasible, socially and culturally acceptable.

2. What is meant by natural resources?

Ans. Natural resources are those components, which occur in nature, are invaluable for humans and on which our survival depends.

3. What is meant by sustainable development?

Ans. Sustainable development is the developmental process that meets the demand of the present, without destroying the scope of the future generation to meet their needs. In this other process, industrial, agricultural and developmental processes are carried out without causing any harm to the environment.

4. Why the sustainable development is necessary?

Ans. The natural resources that are present in our environment are continuously being utilized to maintain human lifestyle. With the advancement of human civilization and increase in population, these resources are being misused and wasted, rather than utilized. As a result, scientists and environmentalists have been trying to adopt measures to conserve these resources and save the environment, and subsequently carrying out all activities necessary for human development. For this reason, sustainable development is necessary.

5. What do you mean by forest?

Ans. A forest is defined as a large area of land, that is covered with trees as well as other woody and non-woody vegetation. Forests are the predominant terrestrial ecosystem of earth and are distributed across the globe.

6. What do you mean by sustainable forestry? Give example. 

Ans. Sustainable forestry: The practice of regulating forest resources to meet the needs of society and industry while preserving the forest.

Example: Sustainable forestry involve the planting of trees to extend forest lands, as well as the creation of protected forests that provide safe habitats for various plant and animal species.

7. Why is forest considered as a resource?

Ans. Forest plays important roles in improving the socio-economic condition of a country. They are-[1] Forest serves as a source of raw materials for various industries. [2] Forest serves as an important source of timber, which is used for making houses, furniture, boats etc. [3] Forest serves as an important source for honey, latex, resin and other medicinal plants. [4] Forest plays an important role in the conservation of biodiversity, regulation of climate and prevention of soil erosion. For these reasons forest is considered as an important natural resource.

8. What is meant by forest conservation?

Ans. Forest conservation is the practice of maintaining forested areas for the benefit and sustainability of future generations. By this process, over-utilization and improper use of forest resource is prevented and the biodiversity is conserved as well.

9. What is water cycle?

Ans. Surface water from seas, lakes etc. evaporates to form water vapour and rises upwards. Transpiration by plants also contributes to this. This water vapour mixes with dust particles and combine with each other to form clouds. The clouds precipitate on the earth as rain, which mixes with rivers and streams and ultimately reverts back to sea. This continuous cyclic flow of water is known as water cycle.

10. Write down two important effects of water cycle?

Ans. [1] It maintains water balance between landmass and water bodies. [2] It maintains the supply of drinking water and surface water.

11. What is ground water? 

Ans. The water present beneath the surface of the earth in the tiny spaces between soil particles to large fractures of rocks, is known as groundwater.

12. What is drinking water?

Ans. The water that is safe enough for drinking and food preparation and does not cause any harm to human being, is known as drinking water. Drinking water is also known as potable water.

13. What do you mean by over-utilization of water?

Ans. The water, collected from the surface and underground sources, are often misused or used indiscriminately. This is known as over-utilization of water.

14. Give examples of over-utilization of water.

Ans. Over utilization of water occurs in many ways, such as-[1] While brushing teeth, bathing and washing, leaving the tap running. [2] In urban areas, fresh water is suctioned from underground much more than its normal demands, thereby lowering the underground reserve of fresh water. [3] Agricultural fields are irrigated with underground water. [4] Large amount of water is exploited in various industries.

15. Mention two causes of lowering of ground water level.

Ans. Two causes of lowering of groundwater level are -[1] The groundwater is suctioned in large quantity by means of motor pumps in order to meet human demands. [2] In rural areas, huge quantity of groundwater is being used for irrigation.

16. Why is rain water considered pure as compared to the water of other water bodies?

Ans. Only the water particles present on the surface of water bodies evaporate and accumulate to form clouds, which comes down as rain. The mineral salts or the harmful pollutants present in the water bodies do not evaporate to form clouds. As a result, these harmful particles do not come down with rain. So, rain water is considered pure as compared to the water of other water bodies.

17. What is meant by agriculture? 

Ans. Scientific practice of farming, including cultivation of soil for growing economically important crops and rearing of animals for food, wool, silk and other products, is called agriculture.

18. What is meant by horticulture?

Ans. Horticulture is a branch of agriculture that includes the cultivation of fruits, vegetables, seeds medical plants, mushrooms, ornamental plants.

19. What is aquaculture. Mention the relationship between aquaculture and pisciculture.

Ans. The farming of freshwater and salt water organisms such as finfish, molluscs, crustaceans and aquatic plants is called aquaculture.

Aquaculture is the farming of economically important aquatic organisms while pisciculture is mainly farming of eadible fishes. So pisciculture is considered as a part of aquaculture.

20. What is meant by pisciculture?

Ans. Pisciculture is a branch of agriculture that deals with the scientific practice of breeding, rearing and marketing of fish, prawn and other economically important aquatic animals.

21. What is poultry farming?

Ans. Poultry farming is a branch of agriculture that deals with the scientific practice of breeding and rearing of birds like chicken, duck, quail, turkey efe: for meat and egg.

22. What is meant by animal husbandry?

Ans. Animal husbandry is the branch of agriculture that deals with the scientific practice of breeding and rearing of farm animals (cattle, sheep, poultry birds).

23. What are the main causes of food insecurity in India?

Ans. In developing countries like India, the root causes of food insecurity include poverty, corruption, national policies that do not promote equal access to food for all, environmental degradation, barriers to trade, insufficient agricultural development, population growth, low levels of education, social and gender inequality, poor health status, cultural insensitivity, natural disasters etc.

24. What do you understand by energy resources?

Ans. Energy resources are the main sources of energy from which energy can be extracted and utilized for mankind.

25. What is nuclear energy? What are the advantages of it?

Ans. Nuclear energy: Nuclear energy, also called atomic energy, that is released in significant amount by the process that affect atomic nuclei, the dense core of atom. Nuclear energy has been released explosively by both nuclear fusion and nuclear fission.

Advantages: [1] It produces as large amount of useful energy from a very small amount of a nuclear fuel. [2] Once the nuclear fuel is loaded into the reactor, the nuclear power plant can go on producing electricity for 2-3 years at a stretch. There is no need of feeding the fuel again and again. [3] It does not produce gases like CO₂ or SO₂.

26. What is meant by energy crisis?

Ans. With the development of industry and upliftment of lifestyle, the utilization of energy has increased to a great extent. But the generation of energy has not been increased to meet up that demand. This situation has developed a worldwide problem, that is popularly known as energy crisis.

27. Mention two common examples of wastage of electrical energy.

Ans. [1] Leaving the room, office, classrooms etc. with fans and lights switched on. [2] Keeping the street lights switched on during the daytime. These are two common examples of energy wastage.

28. What is CNG and its uses?

Ans. CNG: Methane stored at high pressure is commonly known as Compressed Natural Gas (CNG), a fuel that can be used in place of gasoline, diesel and liquefied petroleum gas (LPG).

Uses: [1] It produces less pollutants than LPG. [2] It is cheaper and cleaner than LPG. [3] It mixes very easily with air than the other gaseous fuels. [4] Noise level is much less than diesel.

29. What is LPG and its uses?

Ans. LPG: Liquefied Petroleum Gas is a natural hydrocarbon fuel made up of propane and butane. When stored under pressure it becomes a dense liquid allowing large quantities of gas to be stored in a relatively small space. LPGs have a variety of uses including cooking/heating fuel, refinery feedstock, automotive power, etc.

Uses: Mainly used for cooking heating, commercial appliances. It is affordable, safe and cleaner energy sources for cooking and space heating. It is effective source for household energy.

30. What is a renewable natural resource?

Ans. The renewable natural resources are those which may drop quantitatively after being harvested but are replenished naturally after a certain period of time. Examples-Trees of forest, population of fish, etc.

31. What is a non-renewable natural resource?

Ans. The non-renewable natural resources are those, which drop quantitatively after utilization and are never replenished by means. Examples-Coal, petroleum, etc.

32. How different natural resources are intimately connected with our existence on earth? 

Ans. Forests, water, food and energy are the basic resources offered by nature. Forest acts as the habitat of life. It provides shelter to thousands of living organisms. Water is the main substance of life. Without water, no organism can survive. Food is the fuel of life, which provides energy, that perpetuates life. Thus, natural resources are intimately connected with our survival on earth.

33. What is White revolution?

Ans. To achieve sustainability in milk production, advanced cattle breeding programme has been undertaken. This programme is called ‘Operation flood. Now this drive has shown it’s success. This is known as white revolution.

34. What is Blue revolution?

Ans. To achieve the target of feeding the growing population of India, modern techniques of fish culture have been developed. This programme is popularly known as blue revolution, which has successfully reached its goal.

35. What is Green revolution?

Ans. In the middle of sixties, in order to achieve sustainability in crop production, intensive agricultural management has been practiced by applying hybrid crops, proper application of fertilisers, agricultural equipments, proper irrigations etc. This is known as green revolution.

Very Short Answer Type Questions

Multiple Choice Questions & Answers [MCQ]

1. The concept, which supports that conservation of environment and development of economy must go on parallelly, is called-

A. Human development

B. Sustainable development

C. Industrial development

D. Unidirectional development

Ans. B

2. A natural resource, which may be replenished is-

A. Coal

B. Forest

C. Petroleum

D. Natural gas

Ans. B

3. A non-renewable natural resource is-

A. Coal

B. Solar energy

C. Water

D. Wood

Ans. A

4. Trees of a forest continuously provide us-

A. Furniture

B. Oxygen

C. Coal

D. Wood

Ans. B

5. Most of the members of a forest are-

A. Producers

B. Decomposers

C. Primary Consumers

D. Secondary consumers

Ans. A

6. A forest cannot be used for-

A. Pisciculture

B. Apiculture

C. Harvesting medicinal plants

D. Ecotourism

Ans. A

7. Which is not a cause of deforestation?

A. Expansion of cultivation

B. Forest fire

C. Flood

D. Industrial development

Ans. C

8. Sudden deforestation in an area may be due to-

A. Expansion of cultivation

B. Industrial expansion

C. Laying railway track

D. Forest fire

Ans. D

9. Production of prawn is a practice of

A. Epiculture

B. Horticulture

C. Pisciculture

D. Lac culture

Ans. C

10. A conventional source of energy is—

A. Sunlight

B. Petroleum

C. Wind

D. All of these

Ans. B

11. A non-conventional source of energy is

A. Coal

B. Natural gas

C. Petroleum

D. Wind

Ans. D

12. Which of the following has a role in food production?

A. Lac culture

B. Agriculture

C. Pearl culture

D. None of these

Ans. B

13. Which part of forest trees prevents soil erosion?

A. Shoot

B. Root

C. Root and shoot

D. Stem

Ans. B

14. Coal is used mostly in-

A. Cooking

B. Running rail engine

C. Steel industry

D. Thermal power plants

Ans. D

15. A renewable natural resource is-

A. Livestock

B. Natural gas

C. Petroleum

D. None of these

Ans. A

16. Deforestation causes-

A. Soil erosion

B. Global warming

C. Drought

D. All of these

Ans. D

17. The method of water conservation is

A. Plantation

B. Rain water harvesting

C. Digging water pits

D. All of these

Ans. D

18. Source of Vitamin C and amino acid is

A. Sago

B. Yam bean

C. Moringa oleifera

D. Gum arabic

Ans. C

19. Which appliance does help in conservation of energy?

A. Refrigerator

B. Solar water heater

C. Computer

D. Air purifier

Ans. B

20. One of the non-human causes of deforestation is

A. Expansion of grazing land

B. Expansion of cultivating land

C. Industrial expansion

D. Forest fire

Ans. D

21. Main problem for Indian rivers is

A. Water scarcity

B. Silting

C. Low water current

D. Pollution

Ans. D

22. The World summit on ‘Fight against hunger’, organised by United Nation’s Food and Agriculture Organisation was held in Rome in-

A. 1996

B. 1999

C. 2003

D. 2006

Ans. A

23. Pisciculture deals with-

A. Culture of mushroom

B. Culture of poultry birds

C. Culture of prawn

D. Culture of fish

Ans. D

24. Source of fruits and vegetables is-

A. Horticulture

B. Floriculture

C. Apiculture

D. Pisciculture

Ans. A

25. Most modern concept of environmental development is-

A. Urbanization

B. Sustainable development

C. Control of industrialisation

D. Deforestation

Ans. B

26. Social development, economical development and ecological development are the three basic steps of-

A. Human development

B. Industrial development

C. Sustainable development

D. Unidirectional development

Ans. C

Answer in a single word or sentence

1. Name two natural resources.

Ans. Forest and water

2. What are the types of natural resources?

Ans. Natural resources are of two types-[1] Renewable natural resources and [2] Nonrenewable resources.

3. Name two renewable natural resources.

Ans. Water and wind

4. Name two non-renewable natural resources.

Ans. Coal and petroleum

5. In West Bengal, what percentage of land is under forest cover?

Ans. 16.5% of West Bengal is covered by forest.

6. What percent of the total area of a country should be under forest cover?

Ans. 33% of the total area of a country should be under forest cover.

7. Name one economically important forest product.

Ans. Wood

8. Name some products, which we get from the forest.

Ans. Honey, timber, latex, resin, etc.

9. What is the best way to conserve biodiversity?

Ans. Afforestation is the best way to conserve biodiversity.

10. What is the medicinal utility of forest?

Ans. Forest comprises several varieties of medicinal herbs like gingko, ginger, garlic ginseng from which medicines are obtained.

11. What is the main cause of deforestation?

Ans. Explosion of human population

12. Write down one natural cause of deforestation.

Ans. Forest fire

13. Write down one man-made cause of deforestation.

Ans. Urbanisation

14. Which is the ‘natural buffer’ of an environment?

Ans. Forest is the natural buffer’ of an environment.

15. How much water on the earth do we get as freshwater?

Ans. Only 2% of the total water on the earth is utilised as freshwater.

16. In which two states of India, rain water harvesting is necessary.

Ans. In Rajasthan and Gujrat, rain water harvesting is necessary.

17. By which natural process, earth gets freshwater?

Ans. Earth gets freshwater in the form of rain.

18. Which branch of economic botany includes the cultivation of medicinally important herbs?

Ans. Cultivation of medicinally important herbs is included under horticulture.

19. In Gangetic plains, which is the main source of dietary protein?

Ans. Fish is the main source of dietary protein in the Gangetic plains.

20. Which decade was famous for green revolution?

Ans. The decade of nineteen sixties was famous for green revolution.

21. Name of the food products of animal husbandry.

Ans. The food products of animal husbandry are meat, milk and egg.

22. Name two edible mushrooms.

Ans. Agaricus bisporus and Boletus edulis.

23. Mention one cause of global food crisis.

Ans. Population explosion is an important cause of global food crisis.

24. Give some examples of fossil fuel.

Ans. Coal, petroleum, natural gas, mineral oil, etc

25. Mention one process of energy conservation in daily life.

Ans. Using LED bulbs instead of ordinary bulbs reduces energy consumption at least by times.

Fill in the blanks

1. The litter on the forest floor, is partly decomposed to form sticky ………..

Ans. Humus

2. ……….. is used to prepare chewing gum.

Ans. Gum arabic

3. ……….. is the main economically important product of forest.

Ans. Timber

4. Rain water has a slightly ………. pH.

Ans. Acidic

5. Sago is extracted from ……… trees.

Ans. Palm

6. Coal, petroleum, natural gas are conventional sources for ………. power.

Ans. Thermal

7. ………. by trees increases humidity of air.

Ans. Transpiration

8. ………. is the conventional source for hydel power.

Ans. Water

State True or False

1. Forestation along the slope of watershed reduces the deposition silt in riverbed.

Ans. True

2. Ecotourism is a productive aspect of forest, from which government earns huge amount of money.

Ans. True

3. Sago is a protein-rich matter.

Ans. False

4. Due to deforestation, concentration of greenhouse gases increases in the atmosphere.

Ans. True

5. Afforestation helps to reduce soil erosion.

Ans. True

6. Rain water is generally free from germs and contaminants.

Ans. True

7. Rain water harvesting is practiced in areas with excessive suspended particulate matters in air.

Ans. False

8. Fossil fuels are renewable sources of energy.

Ans. False

9. Fossil fuels include coal and natural gas only.

Ans. False

10. Coal, natural gas, firewood are examples of non-conventional energy sources.

Ans. False