Matric Notes Biology Class 10th Ch 16 Man and His Environment Extra Short and Long Questions
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Q1: Write a note on abiotic component of an ecosystem.
Ans: Abiotic Components:
Definition: The non-living factors present in ecosystem are called abiotic components.
Example: The important non-living factors are:
• Water
• Temperature
• Atmosphere and wind
• Soil
• Gravity
They are define as:
• Sunlight light: Sunlight influences the growth and distribution of living organisms. Plants utilizes sunlight during the photosynthesis and prepare food. Light intensity, light quality and light duration affects lives of animals and plants in one way or in the other. For example: The plant growth during the insufficient light do not develop chlorophyll and a very high intensity of light destroy chlorophyll.
• Water: Water is a vital component of life. Water covers more than 70% of the surface of the Earth and act as a universal solvent. It dissolve minerals in the soil which is then taken by plants. Water is one of the raw material of photosynthesis. In the desert environment, water is scarce and therefore there are few species, while rainforest have plenty of rainfall throughout the year, so it has numerous species and are full of life.
• Temperature: Temperature plays an important role in the distribution of plants and animals. Temperature has great effects on the growth, function and distribution of organisms. The range of temperature for the activity of life lies between 10◦C to 45◦C. Cells may rupture if water in them freezes at the temperature below 0◦C . Enzymes and protein may denature at temperature above 45◦C.
• Atmosphere and wind Atmosphere is the gaseous reservoir, which surrounds the Earth. It contains nitrogen (78%), oxygen (21%) and carbon dioxide (0.04).
Nitrogen: Nitrogen forms a significant part of proteins, chlorophyll, nucleic acids and vitamins in living things. Some bacteria and algae present in the soil fix nitrogen from the atmosphere and convert it into compounds of nitrogen. Plants utilize these for the synthesis of proteins and other compounds. Animal feeding on plants get these proteins and other nitrogenous compounds. When plants and animals die bacteria and fungi present in the soil converts the nitrogenous waste into nitrogenous compounds, which are in turn used by the plants again.
Nitrogen gas: Certain other bacteria covert some parts of nitrogenous wastes into nitrogen gas, which goes back to the atmosphere. Therefore, green plants fix nitrogen in the atmosphere and its level remains constant.
Oxygen: Oxygen is required for respiration of organisms.
Carbon dioxide: Carbon dioxide is essential for photosynthesis.
Humidity: Humidity is also an important factor in controlling the rate of evaporation and transpiration. It also effects the behaviours of animals e.g. desert animals come out of their hideouts only at the time when moisture in the air at is maximum.
Wind: The atmosphere in motion is called wind which is an important abiotic factor. Strong wind can damage buds on the windward side and produce flag form trees. Strong wind cause soil erosion, uproot trees and breaks branches. Wind is also responsible for pollination and dispersal of seeds and fruits.
• Soil Soil the upper layer of the Earth’s crust. Plants are anchored in the soil and it is a source of water and nutrients for them. The structure and chemical makeup of soil in an area affect the types of plants that grow there. For example: little grasses have extensive roots that obtain scarce moisture in the soil. In aquatic environments, the characteristics of the underlying sand affects the types of plants and algae that can grow. This in turn influences the other organisms found there.
• Gravity Gravity is a constant abiotic factor, which acts as an external stimulus on the growth of the roots of plants. As a result of gravity roots grow downwards into the soil and can access nutrients. Conversely some organisms have adapted to deal with gravity. For instance, birds overcome the problem of the gravitational pull due to wings and light bones.
Q2: Write a note on carbon cycle?
Carbon cycle:
Introduction: Carbon atom is the principal building block of many kinds of biomolecules. Carbon is found as graphite and diamond in nature. It also occur as carbon dioxide in atmosphere.
Sources: Major source of carbon for the living world is carbon dioxide present in atmosphere and water. Carbonates of earth crust also give rise to carbon dioxide. Fossil fuel also contain carbon like:
• Coal
• Natural gas
• Petroleum
Photosynthesis: The major process that bring carbon from atmosphere or water into living world is called photosynthesis. Producer take in carbon dioxide from atmosphere and convert it into organic compound. In this way, the carbon become the part of the body of producers.
Carbon in Animals: This carbon enter food chain and is passed to:
• Carnivores
• Omnivorous
• Decomposers
Respiration: Carbon dioxide is released back to environment by respiration of producer and consumer.
Decomposers: It is also released by the decomposition of organic waste and dead bodies by decomposers.
Combustion: Burning of wood and fossil fuels also adds large amount of carbon dioxide in atmosphere.
Perfect cycle: Carbon cycle is perfect in the sense that carbon is returned to atmosphere as soon as it is removed.
Upset of Carbon cycle: The balance of carbon cycle has been upset by human activities such as:
• Excessive burning of fossil fuels
Consequences: As a result, the amount of carbon dioxide in atmosphere is increasing, causing:
• Global warming
Q3:What is the balance of the ecosystem? Also describe Human impact on ecosystem.
Ans: Balance in the Ecosystem and Human effect: A balanced ecosystem is important not only for a single specie but also for the whole biodiversity of the ecosystem. All the organisms living in the earth are dependent on the environment for their needs. The environment provides all the resources, which are necessary for the survival of organisms. The species living in an ecosystem get the resources through the interaction with the environment and among themselves. Biogeochemical cycle also play an important role in the availability of natural resources to the species. In a balanced ecosystem, the interaction and biochemical cycles run smoothly and the species get natural resources.
Human impact: Human being try to modify their environment to meet their needs. This has disturbed the delicate balance in the environment.
For example: Until the beginning of the 19 century, the size of the human population was small in relation to environmental resources. So, there was no immediate shortage of environmental resources. However, with resources at an increasing rate. This has not only created, like population, deforestation etc.
Due to tremendous increase in population, urbanization and industrialization more sewerage enters the rivers and more gases are released into atmosphere. Thus, the environmental condition become gradually worse. The local problem of the environmental pollution has now become global ones. Now industrial products, toxic chemicals and solid wastes have made the land, air and water polluted. Thus, the degradation and depletion of resources and the modification of the environment are the direct results of human intervention.
Q4: What do you know about global and regional environmental problems?
Ans: There are the following global and regional problems:
• Urbanization
• Deforestation
• Acid rain
• Global warming
Q5: What do you about overpopulation?
Ans: Overpopulation:
Population definition: A group of the organisms of the same species inhabiting a specific geographical area (habitat) at a particular time is called a population.
World population:
Past: When the industrial revolution started some 250 years ago, the world population was 600 million.
Present: Now the world population is almost ten times 6 billion.
Future: The population will grow to 8 billion by 2015.
Reason: The following things have contributed in population growth:
• Lowered mortality rates
Q6: What is urbanization?
• Urbanization: The growing of cities is called urbanization.
Reason: People move from rural areas to cities in search of:
• Education opportunities
• Higher standard of living.
Problems for government: If there is rapid urban growth, the government find its difficult to provide even the basic facilities:
• Education
• Shelter
• Water
• Electricity
Urban poverty: Most of the migrants in cities do not find good jobs and become the part of the urban poor.
Overcrowding: There is overcrowding in schools, hospitals etc. The slum areas increases in number and people living there are at greater risk of diseases.
Global problem: Urbanization is a global problem and cannot be stopped but it can be managed.
Urbanization in Pakistan: The current level of urbanization in Pakistan is about 37% which is not high by global standard but it is increased uniformly over the decades.
Planned urbanization: A planned urbanization can solve many problems.
• The open spaces in cities should be reserved through zoning and land plans.
• The urban spread-out should be controlled.
• Utilization of public transport instead of individual transports also proves effective way to manage urbanization.
Q7: What do you know about deforestation?
Deforestation: The clearing of forest by natural causes or humans is called deforestation.
Reason of deforestation:
• More land is required for cultivation.
• Trees are removed to develop pastures for grazing.
• Wood is used both as timber or fuel wood.
• Some plants are collected for their medicinal importance.
• Some plants are removed to give us fibre.
• Timber mafia cuts trees for cash.
Effects on the environment:
Effects: The effects of deforestation includes:
2. Drought
3. Landslides
4. Soil erosion
5. Global warming
6. Loss of habitat of many species
Other effects: Deforestation has many negative effect on the environment.
✓ Loss of habitat: The most dramatic impact is a loss of habitat for millions of species. 70% of the Earth’s land animals and plants live in forest, and many cannot afford deforestation since it results in the destruction of their home.
✓ Climate change: Deforestation also result in climate change. Forest soil are moist, but without protection from sun-blocking tree cover, they quickly dry out.
✓ Water cycle: The trees also help perpetuate the water cycle by returning water vapours back into the atmosphere. Without trees to fulfil these roles, many former forest lands can quickly become barren deserts.
✓ Absorbing greenhouse gases: Trees also play a critical role in absorbing the greenhouse gases that are responsible for global warming.
Q8: What do you about acid rain?
Ans: Acid rain: The rain consisting of sulphuric acid and nitric acid is called acid rain.
Formation of acid rain: When rain falls through polluted air, it comes across chemicals such as oxides of sulphur and nitrogen. These chemicals interact with water vapours in the presence of sunlight to form sulphuric acid. These acids remain as vapours at high temperature.
pH level: As temperature falls, the acids began to condense into liquid form and mix with rain or snow, on the way down to the Earth. This makes rain acidic with pH range of 3 to 6.
Significant ill effect of acid rain:
• Destruction of nutrients: Acid rain destroys the necessary nutrients present in the waters of rivers and lakes. Acid rain washes nutrients out of soil.
• Lowering pH level: It also lower the pH of water. Most of the aquatic animals cannot survive at this pH.
• Damage to trees: It damages the bark and leaves of trees and harms root hairs. Leaf pigments like chlorophyll are also destroyed.
• Corrosion: Metallic surfaces exposed to acid rain are easily corroded.
• Loss of strength: The following products lose their material strength or disintegrate easily due to acid rains:
✓ Paper
✓ Leather
• Damage to building material: Building material are weakened with acid rain because of the following soluble compounds such as:
✓ Marble
✓ Dolomite
✓ Mortar
✓ Slate
• Damage to historical monuments: Acid rain is dangerous for historical monuments. The building of famous Taj Mahal has been corroded at many places, due to acid rain.
Q9: What do you about global warming?
Ans: Global warming: The increase in the temperature of the earth due to the accumulation of the greenhouse gases is called global warming.
Explanation: The addition of greenhouse gases in atmosphere increases the temperature of the Earth.
These greenhouse gases are:
✓ Methane
✓ Ozone
Reflecting back of solar radiation: These gases remain in the lowest part of Earth’s atmosphere and do not allow solar radiation to reflect back into space. As a result, heat remains within the Earth’s atmosphere and increases its temperature.
Effects: Due to global warming:
✓ Sea water is also expanding causing sea level to rise.
✓ Due to melting glacier, rivers overflow and causes floods.
Q10: Write a note on greenhouse effect.
ANS: Greenhouse Effect: The term “Greenhouse Effect” refer to the phenomenon in which certain gases called greenhouse gases trap heat in the atmosphere.
Escape of heat: These gases act like the glass in a greenhouse, which does not allow the inner heat to escape. When sunlight reaches the surface of the Earth, much of its energy transformed into heat energy. The Earth surface reflects this heat energy towards space as infrared radiation. The greenhouse gases trap infrared radiation and send it back to Earth.
Greenhouse gases: Some important greenhouse gases are:
• Methane
• Nitrous oxide
Increases in concentration: Since 1800, there is remarkable increase in the amount of the following gases in atmosphere.
• Methane Doubled
• Nitrous oxide 8 %
Q11: What do you know about control of air pollution?
Ans: Control of air pollution:- For effective control of air pollution, it is important to create public awareness about the ill-effects of air pollution. Air pollution can be controlled by the following ways:
1. Afforestation: The establishment of new forests by planting on non-forest area is called afforestation. Forest are effective mean to control air pollution because plants can filter and absorb air pollution.
2. Modification of industrial effluents: The air pollutants coming from industries should be passed through filters and other devices, so that the particulate matter is removed before the waste gases are released out. The smoke producing unit should have long chimneys to take the pollutant gases far above and then disperse over a large area. Industries should also invest for solar cookers or for producing bio gas.
3. Environment friendly fuels: Lead-free fuels should be used in automobiles. Similarly, sulphur-free fuel should be used in coal based industry to reduce pollution by sulphur dioxide.
4. Use of public transportation: Government should encourage people to use public transportation or adopt car-pooling to save energy and money.
5. Conservation of energy: Large amounts of fossil fuels are burnt to produce electricity. On a personal level saving electricity should be made a habit.
For example: Switching off fans and lights when not in the room. Energy saver light/LED consume less electricity as compare to traditional bulbs and tube-lights.
6. Use of clean energy resources: Clean energy technologies like solar, wind and geothermal are in high demand these days. These will reduce the amount of electricity being produced through the burning of fossils fuels.
Q12: Write a note on conservation of nature and explain 3R Principle.
ANS: Conservation of nature:
Meaning: Conservation of nature means the Conservation of nature resources.
Need of conservation: Everything that we use or consume e.g. food, petrol etc. is obtained from natural resources. The renewable nature resources e.g. air are reproduced easily but the non- renewable resources (e.g. mineral and fossil fuels) are not replenished once they get depleted. We have to conserve the non- renewable resources because there reserves are limited and humans are heavily dependent on them for daily needs. The renewable resources have to be judiciously.
Methods for the Conservation of nature:-
1. Reduce:
• We should use this principle at different places in our daily life.
• We should not waste water, electricity, fuel etc.
• We should turn of the tap when not in use.
• We should bathe with bucket instead of shower.
• The lights and fans should be off, when where not in room.
• We should take public transport (like buses) or walk short distances instead of using motor fuel.
• We should not waste food and should give unused food to poor people.
2. Reuse:
We should use things again and again. We should not throw away material such as glass, containers, plastic bags, paper, cloth etc. These should be reused at domestic level rather than being thrown. It also reduces solid waste pollution.
3. Recycle:
Materials such as paper, plastic, glass etc. can be recycle. This decrease the volume of refused and helps in the conservation of natural resources and recycling of one ton of paper can save 17 trees.
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