Biology Class 10 Notes Chapter 16 Man and His Environment Short Questions
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Man and His Environment Biology Class 10 Notes Chapter 16
Table of Contents
Q.1) Define the terms: Species, biosphere, and ecosystem.
Answer: Species: A species is a group of similar organisms that can breed with one another naturally to produce fertile offsprings. Biosphere: The part of the earth where life exists is called the biosphere. It is the broadest level of ecological organisation. Ecosystem: Ecosystem is the basic structural and functional unit of ecology. Ecosystem can be defined as a “natural area where the living organisms (plants and animals) and their environment interact and exchange materials between them.”
Q.2) Differentiate between population and community.
Answer: Populationis a group of individuals, belonging to the same species, living in the same place at the same time and sharing the same resources e.g. the population of students in a school. Whereas, a community consists of all the interacting organisms of different populations living in an area. e.g. all the fish, Turtles, plants, algae, and bacteria in the pond make up a community.
Q.3) Differentiate between food chain and food web.
Answer: Food chain comprises a sequence of consumption through which energy and nutrients are taken. Whereas the food web is the feeding relationship in a community, and many simple food chains are linked together. or A food web is a graphical description of feeding relationships among the organisms in an ecological community.
Q.4) How does deforestation affect the environment?
Answer: Deforestation Effects on the Environment: Deforestation has many negative effects on the environment;0
The most dramatic impact is the loss of habitat for millions of species.
70 % of the Earth’s land animals and plants live forests, and many cannot afford deforestation since it results in the destruction of their homes.
Deforestation also results in climate change. Forest soils are moist, but without protection from sun-clocking tree cover, they quickly dry out. Trees also help perpetuate the water cycle by returning water vapor back into the atmosphere. Without trees to fulfill these roles, many former forest lands can quickly become barren deserts.
Trees also play a critical role in absorbing the greenhouse gases that are responsible for global warming.
Q.5) Distinguish between herbivore, carnivore and omnivore.
Answer: In an ecosystem consumers cannot prepare their food and they depend upon other organisms for their food. A consumer that eats only producers (plants) is a Herbivore e.g. Horse. A consumer that eats only other consumers (animals) is a carnivore e.g. Lion, and a consumer that eats both Consumers (Animals) and Producers (plants) is an Omnivore e.g. Human and Bear.
Q.6) Outline the role of bacteria in the nitrogen cycle.
Answer: Role of Bacteria in Nitrogen Cycle: Nitrogen fixation is the process where N2 is converted to ammonium with the help of certain bacteria, e.g. Rhizobium. Nitrogen-fixing bacteria often form symbiotic relationships with legume (e.g. beans, peas).
Q.7) How can overpopulation affect the environment?
Answer: Overpopulation effects on the Environment: Overpopulation is arguably the most critical threat to the environment.
Increase the burden on available resources.
Threats to the already stressed ecosystem.
Moreland being brought under cultivation results in the destruction of habitats.
Over use of fertilizers polluted the soil and water.
Forests are destroyed to bring land under cultivation.
Clearing of land for agriculture, results in soil erosion.
Excessive irrigation can cause loss of top fertile soil.
Soil erosion results in silting, which decrease, the life span of dams.
Q.8) Name any five sources of water pollution.
1Incomplete Treatment of Sewage
5leakage from Underground Petroleum Storage
Q.9) Differentiate between parasitism and mutualism.
Answer: Parasitism: In parasitism, an organism called a parasite lives on or in the body of a larger living organism called the host. The parasite gets its nourishment from its host’s tissues and causes harm to it e.g. Mosquito and lice. Mutualism: In this type of relationship both partners are mutually benefited and none of them is harmed. For example, the roots of the leguminous plants (pea, bean, etc) have small nodules, which contains Nitrogen fixing bacteria. These bacteria get food from these plants. In return, bacteria convert the atmospheric nitrogen into nitrates and pass them on to the plant.
Q.10) Define nitrogen fixation and nitrification.
Answer: Nitrogen Fixation: Nitrogen fixation is the process where N2 is converted to ammonium with the help of certain bacteria, e.g. Rhizobium. Nitrogen-fixing bacteria often form symbiotic relationships with legume (e.g. beans, peas). Nitrification: Some of the ammonium produced by decomposition is converted to nitrate via a process called nitrification. It is accomplished by two groups of bacteria. One group of bacteria (Nitrosomonas) converts ammonia into nitrites and the second group of bacteria (Nitrobacter) converts nitrites into nitrates.
Long Question Biology Notes Chapter No 16
Q.1) Describe the nitrogen cycle in detail. What happen if the nitrogen cycle stopped working?
Answer: Nitrogen Cycle: Nitrogen (N) is an essential component of DNA, RNA, and proteins, the building blocks of life. All organisms require nitrogen to live and grow. The nitrogen cycle consists of four main stages, nitrogen fixation, nitrogen uptake, nitrification and denitrification. 1.Nitrogen fixation: Nitrogen fixation is the process where N2 is converted to ammonium with the help of certain bacteria, for example genus Rhizobium. Nitrogen fixing bacteria often form symbiotic relationships with legume (e.g. beans, peas), In addition to nitrogen fixing bacteria, high-energy natural events such as lightning, forest fires, and even hot lava flows can cause the fixation of smaller amounts of nitrogen. 2.Nitrogen Uptake and Decay: The ammonia produced by nitrogen fixing bacteria is incorporated into proteins and other organic compounds by bacteria themselves, or by another soil organism. When these organisms die, decomposers consume the organic matter. During this process, the organic compound are broken and nitrogen is converted to ammonium. This ammonium is available for use by plants or for further transformation into a nitrate ion (NO3–) through a process called nitrification. 3. Nitrification: Some of the ammonium produced by decomposition is converted to nitrate via a process called nitrification. Nitrification is accomplished by two groups of bacteria. One group of bacteria (Nitrosomonas) converts ammonia into nitrites and a second group of bacteria (Nitrobacter) converts nitrites into nitrates. 4. Denitrification: Through denitrification, oxidized forms of nitrogen such as nitrate and nitrite (NO2) are converted to molecular nitrogen (N2) and, to a lesser extent, nitrous oxide gas. Denitrification is carried out by bacteria (Pseudomonas), which converts nitrates to molecular nitrogen. Molecular nitrogen is rapidly lost to the atmosphere. Denitrification is the only nitrogen transformation that removes nitrogen from ecosystems, and it roughly balances the amount of nitrogen fixed by the nitrogen fixers described above. If Nitrogen Cycle Stopped Working: Probably there would be no living beings. Nitrogen is needed to create amino acids that in turn build proteins in all plants and animals. Without a nitrogen cycle that converts atmospheric nitrogen into other compounds, living creatures would not be able to grow. Perhaps only some primitive bacteria can still live without a nitrogen cycle, but no plant life would be possible
Q.2) Compare the flow of materials and the flow of energy in the ecosystem.
Answer: Comparison between Flow of Material and Energy: The sun is the ultimate source of energy in all ecosystems. It provides energy in the form of sunlight. A tiny fraction of sunlight reaches the Earth. The producers can use a small part of this sunlight. They transform sunlight into chemical energy. (food) through photosynthesis. The chemical energy “flows” through the ecosystem in the form of food. When respiration occurs, energy is released. The organism uses a portion of this energy for its metabolism and other activities, while the rest of it is lost in the surroundings as heat. All energy forms comes from the sun, and the ultimate fate of all energy in ecosystem is to be lost as heat. It means that energy does not recycle in the ecosystem. The producers obtain the inorganic materials (carbon dioxide, water, etc.) from the environment and use them to prepare organic material (food). The materials are passed from organism to organism, as one organism is consumed by another. Ultimately, all organism die and become detritus. Decomposers feed on detritus and break the organic materials into inorganic. The inorganic materials are returned to the environment to be taken up again. In this way, the materials are recycled in the ecosystem.
Q.3) Write a note on the energy flow through different components of an ecosystem.
Answer: The Sun is the primary source of energy for all ecosystems. Producers get solar energy and transform it into chemical energy by the process of photosynthesis. They store this energy in their tissues and also transform it into mechanical and heat energy during their metabolic activities. The energy in producers’ tissues flows to herbivores when producers are eaten. Herbivores transform it into mechanical and heat energy during their metabolic activities and store the rest in their tissues. Carnivores eat herbivores and get energy. They also use it for their body activities and store the rest in their tissues. After the death of producers and consumers, the energy stored in their tissues is used by decomposers. The storage and expenditure of energy in an ecosystem is in accordance with the basic law of thermodynamics i.e. ‘energy can neither be created nor destroyed but can be transformed from one form into another’. In an ecosystem there is,
Constant flow or transfer of energy from the Sun through producers to consumers and decomposers.
A significant decrease in useful energy during transfer of energy at each trophic level.
Q.4) What are the different ways through which organisms of the ecosystem interact with each other?
Answer: The existence of the living world depends on the flow of energy and circulation of materials through the ecosystem. In all ecosystems, the organisms living in the same area interact with same species or each other. These interactions may be intra specific i.e. between the organisms of the inter-specific i.e. between the organisms of different species. The following are some of the important interactions among organisms. 1. Competition: Competition is an interaction between organisms for limited supply of at least one resource (such as food, water and space). Competition is an important factor that affects the community structure. Competition may be intra specific (among members of the same species) or inter-specific (among individuals of different species). For example, lions and leopards compete with each other for prey (e.g. zebras). Similarly, many plant species compete for soil or sunlight. Competition maintains a balance between the resources and the size of populations. In competition, one species is able to use a resource more efficiently than the other. As a result, less of the resource is available to the weaker species. It results in a reduction in the size of the size of the weaker population or its complete elimination. 2. Predation: Predation is an inter-specific interaction i.e. between members of two different species. In predation the predator captures, readily kills and feeds on an individual of another species, called the prey. Predation has important effects on the distribution and abundance of organisms. A prey in an area without its natural predator becomes a menace for example the introduction of rabbits in Australia where without its predator, they multiplied enormously and became a menace for the local farmers. 3. Symbiosis: Symbiosis literally means, “living together”. It is defined as a close interaction between organisms of different species for an extended time. Although one species always benefits in a symbiotic relationship, the second species may be harmed, not affected or benefited. These are three types of symbiosis; (i). Parasitism (ii) Mutualism (iii) Commensalism
Q.5) Discuss the biotic components of the ecosystem.
Answer: Biotic Components of Ecosystem: These are the living components of an ecosystem. They are of three types, namely producers, consumers and decomposers. 1. Producers: Autotrophs are able to produce food by utilizing energy and inorganic nutrients. They are called producers. The producers themselves utilize a part of this food while consumers and decomposers utilize the remaining food. Green plants and algae are the major producers. They carry out photosynthesis in which they use sunlight for the preparation of food. Some types of bacteria are also producers. These bacteria carry out chemo synthesis, in which they use energy stored in inorganic molecules to produce food. 2. Consumer: Consumers cannot prepare food and depend upon the other organisms for their food. All animals, most protists, fungi, and many bacteria are included in this group. The consumers are also called heterotrophs. The consumers are of three types, namely primary, secondary and tertiary consumers. (i) Primary consumers: Also called herbivores, primary consumers feed directly on producers. Primary consumers in the terrestrial habitat are insects, rabbits, goats, sheep, cows, etc. In an aquatic habitat the primary consumers are crustaceans (arthropods), molluscs and some fishes. (ii) Secondary consumers: The secondary consumers feed on primary consumers (herbivores) or producers. Those which feed on herbivores, are called carnivores like lizards, frogs, etc. (iii) Tertiary consumers: They are the top consumers and get their food from primary consumers and secondary consumers e. g. lions, tiger, hawk etc. 3. Decomposers: Decomposers are also called saprophytes. They get their energy by decomposing the remains of dead animals and plants. Many bacteria and fungi are included in this group. The decomposers are also called cleaners of the ecosystem. They help to run various biogeochemical cycles like the nitrogen cycle, carbon cycle etc. In this way valuable nutrient are recycled for reuse.
Q.6) Write notes on the three types of symbiosis.
Answer: (i). Parasitism: In parasitism, an organism called a parasite lives on or in the body of a larger living organism called the host. The parasite gets its nourishment from its host’s tissues and causes harm to it. Parasites always get benefit from the host. The diseases in host organisms caused by parasites, are called infestations. Parasites such as aphids, lice, leeches, fleas, ticks, and mosquitoes remain on the outside of their hosts’ bodies. They are called ectoparasites. Many parasites live inside the host’s body and are called endoparasites e.g. plasmodium, tapeworm, polio virus etc. Some plants (e.g. cuscuta) also live as parasites. The cuscuta plant does not have green leaves. It cannot manufacture food. It grows on the surface of big plants (hosts). Here, it obtains food and causes harm to the host plant. The cuscuta plant attaches itself to a plant. The cuscuta plant attaches itself to a plant and wrap itself around it. After which it produces ‘haustoria’ (root) through which it inserts itself into the host. Subsequently, the original root of the cuscuta in the soil dies. The cuscuta can grow and attach itself to multiple plants. This is how the cuscuta plant draws nourishment from its host and weakens it. Parasites have a strong negative effect on the growth of the host’s population. The epidemics of parasitic diseases can even cause the extinction off the host population.
Biology Class 10 Notes Chapter 11 Homeostasis Short Questions (ii). Mutualism: In this type of relationship, both the partners are mutually benefited and none of them is harmed. For example, the roots of leguminous plants (pea, bean etc.) have small nodules, which contain Nitrogen fixing bacteria. These bacteria get food from these plants. In return, bacteria convert atmospheric nitrogen into nitrates and pass them on to the host plant. (iii). Commensalism: In commensalism only one partner is benefited and the other is neither benefited nor harmed. For example many epiphytes such as orchids are found growing on the branches of other trees. These epiphytes use the tree only for the attachment. They prepare their own food by photosynthesis. Here the orchids are benefited but the tree is neither benefited nor harmed. Similarly barnacles attach with the body of marine animals including whales. Barnacles get a ride to better places but the large animals are not affected.
Q.7) Enlist the causes of water pollution and also describe how water pollution can be controlled.
Control of Water Pollution: 1. Waste Water Treatment: This is the most direct method to control water pollution. It is the removal of impurities from waste water before it reaches water bodies (lakes, rivers, sea). 2. Removal of Pollutants from Underground Water: Water supply agencies should apply techniques, e.g. reverse osmosis and filtration, for the removal of pollutants from water. 3. Reutilisation and recycling of Wastes: Various wastes may be recycles to produce beneficial products, e.g. urban wastes may be recycled to generate chapter biogas and electricity. 4. Absorption by Plants: Certain Plants can absorb pollutants from the water present in soil.They accumulate such pollutants in their bodies without any harm.
Q.8) Write a comprehensive note on land pollution.
Answer: Land Pollution: Land pollution is the degradation of the Earth’s land surfaces often caused by human activities and misuse of land resources. It occurs when waste is not disposed off properly. The following are the major causes of land pollution. a. Municipal Solid Wastes: These are the solid materials added by homes, institutions and industry. Such wastes are of the following types:
Garbage: moist and decomposable (biodegradable) food wastes;
Rubbish: dry materials such as paper, glass, textiles, and plastic objects;
Medical wastes: surgical gloves, body fluids (e.g. blood), X-ray equipment
b. Agricultural Activities: Besides domestic waste, pesticides and herbicides used by farmers to increase crop yields also pollute the land when they are washed into the soil. c. Construction Debris: This includes wood and metal objects, concrete rubble, asphalt, and other materials produced when structures are built or demolished. d. Air and Water Pollutants: When polluted water enters the soil, it changes the quality of soil and causes land pollution. Similarly, air pollutants can also lead to land pollution. For example, acid rain dissolves away some of the important nutrients present in the soil and changes the composition of the soil.
Q.9) Explain, by making diagrams, the pyramids of number and biomass.
Answer: Pyramid of Numbers: It represents the number of organisms at each trophic level in an ecosystem. In pyramids of numbers, each successive trophic level has fewer organisms. The number of producers is largest in an ecosystem. At the next trophic level of primary consumers or herbivores, the number of organisms is less than the previous level. At the third trophic level of secondary consumers or carnivores, there are lesser number of organisms than primary consumers. Similarly, in all successive trophic levels, the numbers of organisms go on decreasing.
Pyramid of Biomass: The pyramid of biomass represents the amount of biomass (total amount of living or organic matter of all organisms) in each trophic level in an ecosystem. Because biomass is lost in the transfer from one level to the next, there is successively less total biomass as you move up trophic levels. In general, we would expect that higher trophic levels would have less total biomass than those below.
Q.10) Write a note on the causes and effects of air pollution.
Answer: Causes of Air Pollution: (a) Oxides of Carbon: Combustion of fuel processes produces oxides of carbon like carbon dioxide and carbon monoxides. (b) Oxides of Nitrogen: The sources of oxides of nitrogen are chemical fertilizers, lightning and decay of organic matter. (c) Oxides of Sulphur: Burning fuels in cars produce sulphur dioxide. It is also emitted from brick kilns and volcanic eruption. (d) Chlorofluorocarbons: CFCs emissions from refrigerators and air conditioners are major reasons for depletion of the ozone layer. (e) Lead Compounds: Compounds of lead cause air pollution, which can cause damage to the brain. (f) Particulates: These are the particles suspended in the air like dust particles, ethylene and acetylene. Effects of Air Pollution:
Reduced lung functioning
Irritation of eyes, nose, mouth and throat
Increased respiratory disease such as bronchitis, asthma
Reduced energy levels
Headaches and dizziness
Disruption of endocrine, reproductive and immune systems