Biology For Class X - Chapter No. 7 - Man And His Environment - Review Exercise From Text Book

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CHAPTER 7: MAN AND HIS ENVIRONMENT
Review Exercise From Text Book

By Mrs. Ayesha Arif
Vice Principal
(Jauhar Progressive School)

A. MULTIPLE CHOICE QUESTIONS

Choose the correct answer:
1. The life sustaining envelop of earth is:
(a) Biomass
(b) Biomes
(c) Biosphere ✓
(d) Atmosphere

2. The group of organisms belong to the same species live in a particular area called:
(a) Community
(b) Species
(c) Genes
(d) Population ✓

3. An area where community interacts with non-living environment is called:
(a) Community
(b) Ecology
(c) Ecosystem ✓
(d) Biome

4. Any biological region recognized by its climate or vegetation is called:
(a) Ecosystem
(b) Biomes ✓
(c) Biosphere
(d) Biomass

5. The transfer of food material from producers through some organisms with repeated eating and being eaten is called:
(a) Food pyramid
(b) Food chain ✓
(c) Food web
(d) Ecological pyramid

6. The elements in ecosystem recycle through organisms with environment is called:
(a) Food chain
(b) Food web
(c) Chemical cycle
(d) Biogeochemical ✓

7. Process where nitrogenous compound of living organism convert into nitrates is called:
(a) Ammonification
(b) Nitrification ✓
(c) Denitrification
(d) Deamination

8. The cold war between the organisms of a community occupying the same habitat is called:
(a) Predation
(b) Competition ✓
(c) Mutualism
(d) Commensalism

9. The association between two different types of organism which get benefit to each other, cannot live without each other is called:
(a) Parasitism
(b) Commensalism
(c) Mutualism ✓
(d) Predation

10. The amount of solid waste or concentration of gases other than oxygen increase in atmosphere is called:
(a) Air pollution ✓
(b) Ozone depletion
(c) Acid rain
(d) Greenhouse effect

B. SHORT QUESTIONS

i) What is the effect of light on ecosystem?
Ans: LIGHT:
Light is the most vital factor, without it life can not exist. It is a source of energy for every ecosystem.
Plants convert light energy into chemical energy by the process of photosynthesis. This chemical energy is stored in the form of food which is needed by every living things.

Effect Of Light On Organism:
Light influence the ecosystem in many ways, directly or indirectly. Distribution of plants and animals is affected by:

1. The type Or the quality (wavelength)
2. Intensity of light,
3. Exposure time or duration of light (photoperiod)

1. Quality Or Type of Light:

• A small amount of light is utilized for photosynthesis i.e. out of seven colours of visible light, chlorophyll absorbs only red and blue light.
• Ultraviolet rays of light is harmful for life.
• Most of the light reaching the earth is converted to heat and thus it maintains the temperature of the earth and atmosphere in the ecosystem.

2. Intensity of Light:

• Intensity of light controls plants growth. 
• It may destroy the chlorophyll.
• It also affects opening and closing of the stomata, permeability of the cell membrane, height and surface area of plant etc.
• In animals light affects development of pigments.

2. Exposure time of light (Photoperiod):

• Light is also necessary for vision.
• Duration of light (photoperiod) affects starts of certain biological processes e.g. flowering of certain plants, leaf fall and other aspects of plant growth.
• In animals biological rhythms such as reproductive cycles, sleep cycles, hibernation, migration, are affected by light duration.
• Making Vitamin D in human being.

ii) Which one is the first trophic level of ecosystem and how?
Ans: FIRST TROPHIC LEVEL OF ECOSYSTEM OR PRODUCER:
Producers always occupy the first trophic level in any food chain because only producers have the ability to trap and convert solar energy (sunlight) with the help of chlorophyll into food molecules by the process of photosynthesis.

• The producers produce food for themselves and other organisms of ecosystem.
• They are primary source of energy for other organisms.
• All members of community depend, directly or indirectly on the producers for their food and energy.
• Producers utilize a part of their food while consumers and decomposers utilize the remaining food.
• Example:
  Green plants and algae are the major producers. Some types of photosynthetic bacteria are also producers.

iii) Define nitrogen cycle? What do we mean by nitrogen fixation and how it occurs in an ecosystem?
Ans: NITROGEN CYCLE:
Definition:
"The exchange of nitrogen between soil and atmosphere and its circulation through bodies of living organisms takes place through interrelated processes known as nitrogen cycle."
This cycle consist of three steps:

1. Nitrogen fixation
2. Nitrification
3. Denitrification

NITROGEN FIXATION:

"Conversion of atmospheric free nitrogen gas into soluble nitrogen compounds (nitrates) is called nitrogen fixation."

Nitrogen Fixation Occurs In Ecosystem:
Following are the sources of nitrogen fixation:

1. Nitrogen Fixation by Thunderstorm:
   The atmospheric Nitrogen combines with oxygen during lightning to make certain compound which ultimately form nitrates and reach to soil by rain water.
   
   
2. Nitrogen Fixation by Living Organism (Nitrogen Fixing Bacteria):
   The second source to fix atmospheric Nitrogen are three types of bacteria.
   * The first group lives in water are called cyanobacteria. They are photosynthetic.
   * Second group lives in soil.
   * Third group of bacteria lives in the roots of certain leguminous plants.
   These bacteria which help in nitrogen fixation are called nitrogen fixing bacteria.

iv) What is interaction?
Ans: INTERACTION OR RELATIONSHIP IN THE ECOSYSTEM:
In an ecosystem the living organisms develop number of relationship according to their needs. They not only interact with their physical environment but also with each other i.e. the herbivores develop their relation with producers, in the same manner carnivores depend on herbivores for their food. These association maintain balance in growth and population. Such interactions take place between the two organisms by permanent or temporary association. It may be beneficial or harmful.
Positive Interactions:
Such interaction may be beneficial for only one without harming the other or for both the associates.
Negative Interactions:
Such interaction may be beneficial to one and harmful to the other.

TYPES OR RELATIONSHIP:
Some types of relationships are:

• Competition
• Predation
• Symbiosis

v) What is pyramid of number?
Ans: PYRAMID OF NUMBERS:
The pyramid of numbers was advanced by Charles Elton in 1927. It is define as:

"Graphical representation of members of population in an area at different in trophic level is called pyramid of number."

It is an upright pyramid in an ecosystem. When number of organisms is counted at each level, it is observed that the producers are always more in number than other trophic levels and vice versa.

For example:

• The grasses sit at the lowest trophic level or the base of the number pyramid because of their abundance.
• The primary consumer, such as a grasshopper, occupies the next higher trophic level. Grasshoppers are fewer in number than grass.
• The next trophic level is a primary carnivore, such as mice. There are fewer mice than grasshoppers because they consume grasshoppers.
• Secondary carnivores, such as snakes, occupy the next higher trophic level and feed on mice.
• Subsequently snakes are eaten by hawks, which occupy the highest trophic level and are least in number.
• This relationship is also expressed in the form of pyramid known as pyramid of number.

OR

vi) What is greenhouse effect?
Ans: GREEN HOUSE EFFECT OR GLOBAL WARMING:
Due to excessive burning of fossil fuels, CO₂ and methane are produced which are generally called greenhouse gases.
These gases, if produced in high quantity in atmosphere, they will accumulate below the ozone layer, which do not allow heat energy of sun to reflect back in space. As a result, heat remains with in the earth’s atmosphere and increases the temperature. This phenomenon is called global warming or greenhouse effect.
Effects: The possible effects of global warming are:

• Due to global warming more evaporation of H₂O which ultimately reach to high rainfall.
• Melting of the polar ice and glaciers at high rate, rises the sea level and ultimately reach to flood.
• Warming of atmosphere can cause heavy rains and strong hurricanes and storms.

vii) What is algal bloom and how it destroy the life of an aquatic ecosystem?
Ans: EUTROPHICATION OR ALGAL BLOOM:

"Growth of algae with very high rate due to increase in phosphorous and nitrogen compounds is called algal bloom or eutrophication."

Sewage water and agricultural field run off poses rich quantity of phosphorus and nitrogen containing compounds such as detergents. They accumulate in water reservoirs and promote algal growth upto dangerous level i.e. algal bloom.
Effects Of Algal Bloom On Aquatic life:
Algal bloom when floats on water surface:

• They spoil fishing, swimming and recreational qualities of water.
• These algal species when die not only add more organic matter to water but sometimes release toxins which have lethal effect to various organisms.
• The excessive growth of other decomposers also use the excessive oxygen present in water which leads to the death of fishes and other organisms due to deficiency of oxygen.
• It also reduces the light reaching to lower layer of water.

viii) What measure can be taken to control water pollution?
Ans: CONTROL OF WATER POLLUTION:

• Public awareness at all levels is important. It should be through social media, political leaders, institution from pre-primary level.
• Strict legislation and implementation is required on sewage treatment and industrial recycling processes.
• No industrial and agricultural waste should be added to water bodies before complete treatment.

ix) Write down the name of some endangered mammals of Pakistan.
Ans: ENDANGERED MAMMALS OF PAKISTAN:

• Punjab Urial
• Markhor
• Snow Leopard
• Asia snadspit green turtle
• Indus river dolphin
• Bear of Deosai

x) Draw the diagram of nitrogen cycle.

xi) Write down the name of some endangered birds of Pakistan.
Ans: ENDANGERED BIRDS OF PAKISTAN:

• Siberian Crane
• Falcon
• Cheer Pheasant
• Chacor
• Long Billed Vulture
• Red Avadavar

xii) Illustrate acid rain and its effect?
Ans: ACID RAIN:
Due to urbanization and industrialization more fuel burn, more acids are used in industries, as a result of these consumptions more CO₂, SO₂, NO₂ are liberated in air from their chimneys. When rain falls through these polluted air H₂O react with these gases in air and produce carbonic acid, sulphuric acid and nitric acid respectively. These acids remain as vapours and condense into liquid when temperature falls. Such rain is called acid rain.
Effect:
The acid destroy soil, microorganisms of soil, skin of animals, building material.

xiv) What is meant by ozone layer and depletion of ozone layer?
Ans: OZONE LAYER:
In upper atmosphere a protective layer of ozone (O₃) gas is present which is very important for us because it checks the ultraviolet radiations from sun which are lethal for living organisms. This layer is called ozone layer.

DEPLETION OF OZONE LAYER:
Scientist have found ozone layer is gradually depleting (getting thin) due to chlorofluorocarbon (CFC), as they react with ozone and convert it into O₂. This process is called depletion of ozone layer.
Cause: The CFC used as propellant in pressurized aerosol, foaming agent, refrigerators etc. Each one atom of chlorine converts more than 100000 molecules of ozone O₃ to Oxygen O₂.

xv) Draw diagram for sewage treatment?
Ans: SEWAGE TREATMENT:

C. EXTENSIVE RESPONSE QUESTIONS:

i. Describe biotic factors of an ecosystem.
Ans: BIOTIC COMPONENTS OF AN ECOSYSTEM:
The living organisms which interact in an ecosystem are called biotic component.
These living components include:

• Producers
• Consumers of all types and
• Decomposers.

1. Producers:
Producers always occupy the first trophic level in any food chain because only producers have the ability to trap and convert solar energy (sunlight) with the help of chlorophyll into food molecules by the process of photosynthesis.

• The producers produce food for themselves and other organisms of ecosystem.
• They are primary source of energy for other organisms.
• All members of community depend, directly or indirectly on the producers for their food and energy.
• Producers utilize a part of their food while consumers and decomposers utilize the remaining food.
• Example:
  Green plants and algae are the major producers. Some types of photosynthetic bacteria are also producers.

2. Consumers:
Animals and all other organisms which cannot make their own food are called consumers. They get energy and food from producers directly or indirectly.
Types Of Consumers:
On the basis of feeding level (trophic) mainly consumers are of three types:

1. Primary consumers:
   The consumers which directly feed on producers i.e. get energy and food directly from producers are called Primary consumers. They are basically herbivores.
   Example: A grasshopper or caterpillar feeding on leaves of plants are primary consumers.
   
   
2. Secondary consumers:
   The type of consumers which feed on primary consumers i.e. get energy and food from primary consumers are called secondary consumers. They are basically carnivores.
   Example: A bird is a secondary consumer gets its energy and food when it eats grasshopper or caterpillar.
   
   
3. Tertiary consumers:
   The organisms which eats the secondary consumers to get energy and food are called tertiary consumers and they are carnivores.
   Example: An eagle which eat the small bird, which has already eaten grasshopper.

3. Decomposers:
Microorganisms which break down complex food molecules of dead organisms are called decomposers.

• They recycle the nutrients because they return it by decomposing and converting the complex organic molecules into simple inorganic molecules.
• Example: They are generally bacteria and fungi.

ii. Describe nitrogen cycle as biochemical cycle in detail?
Ans: NITROGEN CYCLE:
Nitrogen is one of the important constituent of protein and DNA. It is therefore, an essential element in the structure of all living things. Plant use atmospheric nitrogen in the form of nitrates. Thus,
"The exchange of nitrogen between soil and atmosphere and its circulation through bodies of living organisms takes place through interrelated processes known as nitrogen cycle."
This cycle consist of three steps:

1. Nitrogen fixation
2. Nitrification
3. Denitrification

NITROGEN FIXATION:

"Conversion of atmospheric free nitrogen gas into soluble nitrogen compounds (nitrates) is called nitrogen fixation."

Nitrogen Fixation Occurs In Ecosystem:
The atmosphere contains about 78 percent nitrogen gas. It is an inert gas and the organisms cannot use it directly. Therefore, nitrogen is first changed to soluble nitrogen compounds such as nitrates (NO₃) which the plants can absorb from the soil.
Source of Nitrates: The following are the sources of nitrates for living organisms:

1. Nitrogen Fixation by Thunderstorm:
   The atmospheric Nitrogen combines with oxygen during lightning to make certain compound which ultimately form nitrates and reach to soil by rain water.
   
   
2. Nitrogen Fixation by Living Organism (Nitrogen Fixing Bacteria):
   The second source to fix atmospheric Nitrogen are three types of bacteria.
   * The first group lives in water are called cyanobacteria. They are photosynthetic.
   * Second group lives in soil.
   * Third group of bacteria lives in the roots of certain leguminous plants.
   These bacteria which help in nitrogen fixation are called nitrogen fixing bacteria.

NITRIFICATION:
Process where nitrogenous compounds of living organisms converts into nitrates is called Nitrification.
It is also performed by microorganisms who live in soil. These nitrates are reabsorbed by plants and the nitrogen cycle starts again. Protein of dead animals and plants, the excretory waste like ammonia, urea, uric acid are all nitrogenous wastes which are decomposed and the nitrates are recycled.

DENITRIFICATION:
The process of converting nitrogenous compounds into free nitrogen is called denitrification.

• It takes place by special bacteria which lives in anaerobic condition of soil. These bacteria called denitrifying bacteria.
• These bacteria breaks ammonia and nitrates back into free nitrogen, which is released in air so as to complete the cycle and to keep the nitrogen balance in nature.

iii What is pollution? Describe different types of hazardous effects caused by air pollution.
Ans: POLLUTION:
Literally pollution means "destruction of purity."
Scientifically pollution may be define as:

"Any undesirable change in the physical, chemical or biological characteristics of environment (air, land, water and soil), which may or will harmfully affect human life, plants, animals or industrial processes, living conditions and cultural assets."

CLASSIFICATION OF POLLUTION:
Pollution is classified into two categories:
i) Material Pollution:
where some material or substance become excessive in environment; like air, water or soil pollution.

ii) Non-Material Pollution:
where material does not increase but environment disturb or become unbearable to live, i.e. noise, heat or radiation pollution.

AIR POLLUTION:
When amount of solid waste or concentration of gases other than oxygen increases in atmosphere it is called air or atmospheric pollution.

Hazardous Effects Caused By Air Pollution:
Industrial machines produce smoke, carbon monoxide (CO), carbon dioxide (CO₂), sulphur oxide (SO₂), nitrogen oxide (NO₂), chlorofluorocarbon (CFC) etc. Due to industrial toxic waste photochemical haze produces, as a result:

• Acid rain occur.
• Greenhouse effects or global warming take place.
• Ozone depletion occurs.

1. Acid Rain:
Due to urbanization and industrialization more fuel burn, more acids are used in industries, as a result of these consumptions more CO₂, SO₂, NO₂ are liberated in air from their chimneys. When rain falls through these polluted air H₂O react with these gases in air and produce carbonic acid, sulphuric acid and nitric acid respectively. These acids remain as vapours and condense into liquid when temperature falls. Such rain is called acid rain.
Effect:
The acid destroy soil, microorganisms of soil, skin of animals, building material.

2. Global Warming Or Greenhouse Effect:
Due to excessive burning of fossil fuels, CO₂ and methane are produced which are generally called greenhouse gases.
These gases, if produced in high quantity in atmosphere, they will accumulate below the ozone layer, which do not allow heat energy of sun to reflect back in space. As a result, heat remains with in the earth’s atmosphere and increases the temperature. This phenomenon is called global warming or greenhouse effect.
Effects: The possible effects of global warming are:

• Due to global warming more evaporation of H₂O which ultimately reach to high rainfall.
• Melting of the polar ice and glaciers at high rate, rises the sea level and ultimately reach to flood.
• Warming of atmosphere can cause heavy rains and strong hurricanes and storms.

DEPLETION OF OZONE LAYER:
Scientist have found ozone layer is gradually depleting (getting thin) due to chlorofluorocarbon (CFC), as they react with ozone and convert it into O₂. This process is called depletion of ozone layer.
Cause: The CFC used as propellant in pressurized aerosol, foaming agent, refrigerators etc. Each one atom of chlorine converts more than 100000 molecules of ozone O₃ to Oxygen O₂.

Source: Special Thanks To Sir Syed Arif Ali