ENVIRONMENTAL SCIENCE
CLASS: 11th Year 2020
Time: 3 Hours Maximum Marks: 70
Section- A
Note: Question number 1-8 to be answered in one word or one sentence: (1 marks each).
1. Plants which grow on saline Environment are called halophytes.
2. Lichen is association between algae and fungi.
3. The chemical and organic process dead organisms undergo to become coal is carbonization.
4. Ozone which act as shield for uv-radiations occurs in which atmospheric layer stratosphere.
5. Widal test is done for identifying which disease typhoid fever.
6. Expand WHO. World Health Organization.
7. The maximum population size a particular environment can support is carrying capacity.
8. Natality is scientific term for births rate.
Section- B
Note: - Q. Nos. 9-18 to be answered in 30 words. (2 marks each0.
9. What
is Bt cotton?
Ans. Bt cotton is a Genetically Modified Organism or we can say
genetically modified pest resistant cotton plant which produce an insecticide
to combat bollworm disease of cotton plants.
10. What are the major environmental issues?
Ans. The major environmental issues are as follows:
Global warming, climate change, population explosion, desertification
various types of pollutions and much more.
11. Enlist
few products obtained from animals.
Ans. Meat, fur, leather, milk, eggs, etc.
12.Why is World Environment Day Celebrated on 5th June?
Ans. It is celebrated on June 5 every year since 1974 with an aim of
encouraging worldwide awareness about the threat to the environment due to
various environmental issues and to take actions for the protection of
environment.
13. Write
a short note on Botulism.
Ans. According to WHO Botulism is a serious and potentially fatal disease
caused by ingestion of contaminated foods.
14. What
is Gene Bank?
Ans. A Gene Bank is a place where the genetic material of rare plants and
animal species is preserved for future use.
15. Define
Health as per WHO guidelines.
Ans. According to WHO ‘Health’ is a state of
complete physical, mental and social well-being and not merely the absence of
disease or infirmity.
16. Define
malnutrition.
Ans. Malnutrition is a disease caused by lack of proper nutrition.
17. Briefly
describe Global warming.
Ans. The average increase
in the temperature of the earth is known as global warming.
18. What
do you mean by sustainable development?
Ans. The development that meets the needs of the present without
compromising the ability of future generation to meet their own needs is termed
as sustainable development.
Note: - Q. Nos. 19 to 27 to be answered in 40 words. (3 marks each).
19.Elaborate
uses and abuses of nuclear energy.
Ans. The uses of nuclear energy are:
Nuclear energy produce large amount of energy as compared to other
sources
It is a green energy
It is reliable and safe
It is considered as most concentrated form of energy
It requires low operating cost
Abuses:
Produce radioactive waste
Non-renewable because it depends on uranium which is an exhaustible fuel
It can be used for making weapons
Difficult to transport.
20. Write
a note on biogas and its uses.
Ans. Biogas is an eco-friendly fuel which is produced as a result of
decomposition of organic matter under anaerobic conditions. The chief
constituents of biogas are carbon dioxide and methane.
Uses:
It can be used as a fuel for cooking and other heating processes,
It can also be used as fuel in vehicles,
Electricity is also generated from biofuel.
21. What
are biogeochemical cycles? Name their types.
Ans. The cyclic movement of nutrients and other elements between biotic
and abiotic factors of the environment is termed as biogeochemical cycle.
Following are the different types:
Water cycle, Carbon cycle, Nitrogen cycle, oxygen cycle, phosphorous
cycle and Sulphur cycle.
22. What
are the objectives of EVS?
Ans. To impart an awareness of the environment,
To impart basic knowledge about the environment and its related problems,
To motivate general public to participate in environmental protection and improvement.
23. Briefly
describe three water borne diseases.
Ans. Water borne disease are those that are caused by microorganisms such as viruses and bacteria that are ingested through contaminated water. These include
Diarrhea: It is one of the most common water borne disease. The symptoms of this disease are dehydration, pale skin, dizziness.
Typhoid fever: In this water borne disease the patient suffers from prolonged fever, nausea, loss of appetite, headache.
Cholera: It is another common water borne disease which spread through contaminated water and cause severe dehydration, diarrhea, nausea, muscle cramps, vomiting.
24. “Alternative
to deforestation”. Explain.
Ans. The alternative to deforestation include agroforestry system,
natural forest management and forest reestablishment.
25. Write
a note on bio pesticides.
Ans. According to USEPA bio pesticides are certain types of pesticides
derived from natural materials like such as animals, plants, microorganisms and
minerals which are used to control pests by non-toxic mechanism. Example:
canola oil, baking soda etc.
26. What is importance of environmental studies?
Ans. It makes us aware about environmental problems
It helps in maintaining ecological balance
It helps us to achieve sustainable development
It helps us to protect environment and the biodiversity.
29. Give graphic representation of oxygen cycle?
 |
| Figure: Graphic representation of oxygen cycle |
Section- D
Note: - Q. Nos. 28 to 30 to be answered in 75-100 words. (5 marks each).
28. What
are the impacts of human population explosion on the environment?
Ans. The global population is growing very rapidly; the population
exceeds the planets carrying capacity. As we know that the relationship between
the overpopulation and environment impacts are interrelated and very much
complex.
With the increase in population the demand of food supply also increased
to a great extent which forced food growers to go for extensive farming and for
farming deforestation is done on large scales to create new farm lands hence
this create an environmental imbalance.
Another environmental impact of over population is that the farmers are
using excessive pesticides in farm lands to meet the growing demand of food.
The use of these chemical fertilizers show negative impacts on almost every components
of the environments like water, air, soil etc.
Population explosion also resulted in the extensive growth and surge in
the number of industries, since these industries use fossil fuels which
resulted in the increase of greenhouse gases especially carbon dioxide into the
atmosphere and thus resulted major environmental implications such as global
warming and climate change.
Or
Elaborate various factors effecting human population size.
Ans. A population is defined as a group of individuals of same species that inhibit the sane area. The various factors which affect human population size are categorized under two headings
[A]. Factors that increase the population size
[B]. Factors that decrease the population size
[A]. Factors that increase the population size:
There are two important factors that results in the increase of human
population size these include natality and immigration
Natality:
Natality is defined as the number of new individuals that are added to a
population over a period of time as a result of reproduction. It is also
described as natality rate or birth rate, that is, number of individuals born per
1000 individuals per year.
Immigration:
Immigration is termed as the movement of individuals to a new area which
results in the increase in the population of that area in which it entered
[B]. Factors that decrease the population size:
Again there are two important factors that results in the decrease in the
population size these include: mortality and emigration
Mortality:
Mortality is defined as the number of individuals that die in a
population over a period of time. In terms of human population mortality is
defined as the mortality rate or death rate that is the number of individuals
die per 1000 individuals per year.
Emigration:
The living of a place or habitat by individual with an aim of permeant
moving to a different place or habitat is termed as emigration. Thus this act
results in the decrease of the population size from where it moved.
29. What is ecological succession? write a note on types of succession?
Ans. The successful colonization of one community by different group of
communities naturally in a definite sequence over a period of time is termed as
succession.
Types of succession:
[A]. Depending upon the nature of bare area being colonized, the
different types of succession are:
1. Primary succession:
The succession which starts on any bare substratum for the first time on
which there was no previous vegetation exists is termed as primary succession.
The very first group of organisms which starts colonization are known as
pioneers.
2. Secondary succession:
The succession which starts from previously built up substrata which was
once occupied by original vegetation but later on disappeared due to external
forces like fire, rain, strong winds, drought etc. is termed as secondary succession.
Primary and secondary successions are further of various types depending upon the substratum where succession takes place.
(a). Hydrosere: the type of succession which take place in aquatic environment is known as hydrosere
(b). Halosere: the type of succession which take place in saline water
(c). Xerosere: the type of succession which take place in dry habitat is termed as xerosere.it is further of two types:
· Pasmosere: the succession that starts on sand.
· Lithosere: the succession that stars on rocks.
[B]. Depending upon the replacement of one community by another succession is of two types:
1. Autogenic succession:
When an already existing community modifies its own environment causing its own replacement by new communities it is known s autogenic succession.
2. Allogenic succession:
When an existing community is replaced by force it is termed as allogenic
succession.
Or
What are ecological pyramids? Draw sketch of pyramid of number and pyramid of biomass.
Ans. The diagrammatic representation of the relationship among successive
trophic levels of a food chain in terms of their number, biomass and energy
content is known as ecological pyramids. The bar diagrams indicate the
quantities of parameters at each trophic level by the length of the bar, in
this way the base of the pyramid is occupied by producers, consumers constitute
intermediate bars and top of the pyramid is constituted by top carnivores. That
is why ecological pyramids are also known as bar pyramids.
The ecological pyramids are given by Charles Eltonian and hence also
known as Eltonian pyramids. Ecological pyramids are of three types:
Pyramid of number, pyramid of biomass and pyramid of energy.
 |
| Figure 1. Pyramid of number in grassland ecosystem |
|
 |
Figure 2. Pyramid of biomass in terrestrial ecosystem
Ans.
The inherited physiological, behavioral or
morphological characters that develop over successive generations in an
organism for self-regulation, self-preservation and protection in response to
changing environment so as to avoid extinction is termed as adaptation.
On the basis of nature and role in environment the adaptations are of two
types. Short-term adaptation and long-term adaptation.
Long-term adaptation:
Long-term adaptations are permanent changes inherited by an organism in
response to external change in the environment. These type of adaptations play
an important role in evolution of species because the DNA of the organism is
also changed in this type of adaptation.
The various examples of long term adaptations are:
Modification of Cactus leaves into spines,
Use of thick tail by Kangaroo as fifth limb for balancing during running.
Or
What
are interspecific interactions? Elaborate positive interactions with examples.
Ans. The type of interactions which occur between the individuals of the different species are known as interspecific interactions. Interspecific interaction is further of two types
(I). Positive interspecific interaction and
(II). Negative interspecific interactions.
Positive interspecific
interactions:
Those types of interspecific
interactions in which either both the partners are benefited or one is
benefited but no one is harmed.
Types of positive interactions
1. Mutualism:
A symbiotic relationship
between the individuals of different species in which both individuals are
benefited from their association. It is an obligatory relationship that is,
necessary one.
Example. Bees and Flowers. Bees get nectar from flowers and in return flowers get pollinated.
2. Proto-cooperation:
Proto-cooperation is a
positive interaction in which both the partners are mutually benefited however
the interaction is not obligatory for the survival, both can live without the
interaction.
Example. Crocodile bird enter the mouth of the crocodile and feed on parasite leeches, bird gets food crocodile gets rid of blood sucking parasites.
3. Commensalism:
The type of positive
interaction between two organisms of different species in which one of the
partner is benefited whereas the other is unaffected.
Example Arboreal.
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