AMEND EDUCATION
ACADEMY CLASS 10 SCIENCE OUR ENVIRONMENT
An ecosystem
consists of biotic components including living organisms and abiotic components, the physical
factors like temperature, rainfall, wind, soil and minerals.
• An ecosystem can be natural or artificial. Organisms in the ecosystem can be categorised into producers, consumers and decomposers.
Producers are the organisms that produce their own food without the help of any other organism.FOR EXAMPLE PLANTS
• They are also known as autotrophs.
• They make their food from inorganic substances through a process called photosynthesis.
• Autotrophs are green plants, phytoplankton and blue green algae.
Consumers are the organisms which cannot produce food but depend on producers for the same.
• These are also called as called heterotrophs.
• Heterotrophs are the animals can be classified into herbivores, omnivores, carnivores and parasites based on their food pattern.
Decomposers are the organisms which feed on dead and decaying matter.
• Decomposers break down the complex organic compounds present in dead animals and plants, which are then used by other members of the ecosystem.
• Decomposers like bacteria and fungi are known as saprobes.
Food chains describe the feeding relationship between the organisms of an ecosystem.
• The flow of energy from one species to another at various biotic levels forms a food chain.
• The successive levels in the food chains of a community are called as trophic levels.
• Various trophic levels in a food chain include producers, primary consumers, secondary consumers and tertiary consumers.
• A web of cross-linked food chains is called a food web.
• An ecosystem can be natural or artificial. Organisms in the ecosystem can be categorised into producers, consumers and decomposers.
Producers are the organisms that produce their own food without the help of any other organism.FOR EXAMPLE PLANTS
• They are also known as autotrophs.
• They make their food from inorganic substances through a process called photosynthesis.
• Autotrophs are green plants, phytoplankton and blue green algae.
Consumers are the organisms which cannot produce food but depend on producers for the same.
• These are also called as called heterotrophs.
• Heterotrophs are the animals can be classified into herbivores, omnivores, carnivores and parasites based on their food pattern.
Decomposers are the organisms which feed on dead and decaying matter.
• Decomposers break down the complex organic compounds present in dead animals and plants, which are then used by other members of the ecosystem.
• Decomposers like bacteria and fungi are known as saprobes.
Food chains describe the feeding relationship between the organisms of an ecosystem.
• The flow of energy from one species to another at various biotic levels forms a food chain.
• The successive levels in the food chains of a community are called as trophic levels.
• Various trophic levels in a food chain include producers, primary consumers, secondary consumers and tertiary consumers.
• A web of cross-linked food chains is called a food web.
Ozone is
molecule formed by the combination of three oxygen atoms. There is a layer of
ozone in the stratosphere. It acts as a natural sun-block and shields us from
the UV radiations of the sun which are dangerous to living organisms.Ozone
depletion is the sharp reduction of ozone in the stratosphere due to
chlorofluorocarbons (CFC’s) used as refrigerants and in fire extinguishers.
Increased use of non-biodegradable items have left the environment polluted with them.
Increased use of non-biodegradable items have left the environment polluted with them.
Important Definitions
1) ECOLOGY – The study of the
interaction of living organisms with each other and their surroundings is called
ecology.
2) ENVIRONMENT – Everything that
surrounds organisms and influences its life.
a) Biotic components of environment --- The living organisms
.e.g. Plants and animals.
b) Abiotic components of environment
---
The nonliving components like water, air, light, etc.
It
is the sum total of all external conditions and influences that affect the life
and the development of organisms i.e.,it includes all the biotic and abiotic
factors.
3) ECOSYSTEM – All interacting
organisms in an area together with the nonliving constituents of environment.
(Functional unit of an environment)
Functions
of ecosystem:-
a)
Flow of energy b) Cycling of
nutrients(bio-geo chemical cycles).
4) PRODUCERS --- They make the
energy from sunlight available to the rest of the ecosystem.
5) CONSUMERS --- Animals can not
manufacture their own food. They are called consumers.
6) BIODEGRABLE ---- Substances that
are broken down by the action of bacteria or other saprophytes. e.g. – Paper.
7) NONBIODEGRABLE --- Substances that
are not broken down by the action of bacteria or saprophytes. e. g. Plastic.
8) FOOD CHAIN -The process of one
organism eating the other.
GRASS--
> GRASSHOPPER-- >; FROG -> SNAKE
Importance
of food chain
1.It
helps in transfer of food energy from one organism to another.
2.It
is a pathway for the flow of energy.
3.
It helps in understanding the interdependence amongst different organisms.
Trophic
levels are the various steps in the food chain .
Producers
--- first trophic
level
Herbivores --- second trophic levels
Carnivores
--- third trophic
level
Top carnivores --- fourth trophic level
9) FOODWEB ----- It is a
network of food links between populations in a community.
10)
FLOW OF ENERGY -Ten percent law Energy available at each successive trophic
level is 10 % of the previous level. (Lindeman 1942)
The
law states that, “ only a 10 % amount of the total available energy is
transferred from one trophic level to the next. The rest 90% of energy is used
up or lost to the surrounding.”
11) BIOLOGICAL MAGNIFICATION --- Progressive
accumulation of non- biodegradable waste at various trophic levels of food
chain.
12. Differences between food chain
& food web
Food
chain
1.
The process of eating & being eaten to transfer food energy. 2. It
forms a part of food web.
3.
It has limited populations.
Food
web
1.
It is a system of interconnected food chains. 2. It contains many food chains.
3.
It has several populations of different species.
13.
HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT?
Two
major problems:-
a)
Depletion of ozone layer
b)
Disposal of waste
Good
ozone and bad ozone
The
thick blanket of ozone layer in the atmosphere which forms a protective cover
& prevents UV radiation from reaching the earth‘s surface. This is called
good ozone and is found in the stratosphere.
Ozone
when present in the troposphere act as a pollutant . This harmful ozone is
called bad ozone.
14.
Depletion of ozone layer : The ozone layer protects all the organisms from the
harmful ultra violet rays.
Ozone
depleting substances: CFCs, N2O, CH4 , CCl4
These
chlorine containing compounds are used in: Aerosols, solvents,
refrigerants and fire extinguishers. Ozone hole developed over
Antarctica.
Important
Question/Answers
1. Why are some substances
biodegradable and some non-biodegradable?
Answer Substances are classified as biodegradable and non-biodegradable because some substances can be decomposed by microorganisms and some cannot.
Substances that are broken down into simple soluble forms are called biodegradable substances and the substances that are not decomposed by microorganisms into harmless substances are called non biodegradable substances.
Answer Substances are classified as biodegradable and non-biodegradable because some substances can be decomposed by microorganisms and some cannot.
Substances that are broken down into simple soluble forms are called biodegradable substances and the substances that are not decomposed by microorganisms into harmless substances are called non biodegradable substances.
2.
Give any two ways in which biodegradable substances would
affect the environment.
Answer: Biodegradable substances can affect the environment in
following ways:
By
recycling the raw materials in nature.
By
improving the humus content in soil.
3. . Give any two ways in
which non-biodegradable substances would affect the environment.
(i) They contaminate soil and water resources as they cannot be
decomposed by micro-organisms.
(ii) These substances, when accidentally eaten by stray animals,
can harm them and can even cause their death.
1. What are trophic levels? Give an example
of a food chain and state the different trophic levels in it.
A
trophic level is the level of species in an ecosystem on the basis of the
source of nutrition such as producers, primary consumers, secondary consumers,
etc.The producers form the first trophic level as they manufacture food. The primary consumers form the second trophic level, the secondary consumers form the third, and the tertiary consumers form the fourth trophic level.
2.
What is the role of decomposers in the ecosystem?
Decomposers include micro-organisms such as bacteria and fungi
that obtain nutrients by breaking down the remains of dead plants and animals.
They help in the breakdown of organic matter or biomass from the body of dead
plants and animals into simple inorganic raw materials, such as CO2,
H2O, and some nutrients.
3.
What is ozone and how does it affect any ecosystem?
Ozone is a colourless gas that acts as a screen for ultraviolet
radiation. It is continuously formed at the higher levels of the atmosphere due
to the action of UV rays on molecular oxygen. The high energy UV radiations
break down O2 molecules into nascent oxygen.
How can you help in reducing the problem of waste disposal? Give
any two methods.
The problem of waste disposal can be solved by proper waste
management including the collection, transport, processing, and disposal of the
waste materials.
The problem of waste management can be solved by the following
given measures:
·
Use separate bins (blue and green) for disposing
non-biodegradable and biodegradable wastes.
o
Reduce the usage of non-biodegradable products such as plastics.
4.
What will happen if we kill all the organisms in one trophic
level?
If all the organisms of any one trophic level are killed, then
it will disrupt the entire food chain.
For example, in a food chain, if all the plants are killed, then
all the deer will die due to lack of food. If all the deer are dead, then soon
the tigers will also die. Due to the death of these animals, the decomposer’s
population will rise in that area.
This is just an example of one food chain. However, in nature,
food chains are not isolated. They are interconnected in the form of food web.
Therefore, killing all the plants of an area will not only affect the deer, it
will also affect other herbivores such as goat, cattle, sheep, etc.
5.
What is ozone and
how does it affect any ecosystem?
Answer: Ozone is a form of oxygen. Ozone is a triatomic
molecule while oxygen is a diatomic molecule. Ozone forms the ozone layer in
our atmosphere. Ozone plays an important role in the ecosystem. The ozone layer
wards off harmful ultraviolet radiations from the sun and thus protects the
living beings.
6.
Why is damage to
the ozone layer a cause for concern? What steps are being taken to limit this
damage?
Answer: Ozone layer works like a protective shield for living
beings. The ozone layers wards off harmful ultraviolet radiations from the sun.
Damage to the ozone layer can result in increased level of ultraviolet
radiations in our atmosphere. This would be very dangerous for all life forms.
In 1987, the UNEP
(United Nations Environment Programme) succeeded in forging an agreement among
different nations to freeze the CFC production at 1986 level. Later, an
agreement was signed among different nations to phase out CFCs. It is important
to note that CFC is used in refrigerators and aerosol spray. India is also a
signatory of that agreement and thanks to the efforts by the United Nations and
different environmentalists, the CFC emission has been put under some control.
