Notesale: Turn your study into money

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Our environment
Environment- the surroundings or conditions of an organism which includes biotic and abiotic components
constitute its environment
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e
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Non biodegradable - materials which cannot be broken down into simpler form by biological process and
thus persist in the environment under ambient conditions
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Natural ecosystem - ecosystem in which biotic and abiotic components are controlled by nature
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example
aquarium ,botanical garden,crop field ,zoo
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Example plants and cyanobacteria
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Food Chain- a series of organisms each dependent on the next as a source of food is called as food chain
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One organism may occupy more
than one trophic level in a food web
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Producers always occupy first trophic level
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e
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Omnivores- organisms which eat both plant and animals
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Parasites- organisms which live in or on the body of other organisms and derive food from the host causing
harm to the host organism
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g leech, ticks and lice are animal parasites while cuscuta is a plant parasite
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Biomagnification - accumulation of toxic non biodegradable chemical which increases progressively at each
trophic level is called as biomagnification
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Higher the trophic level higher is the biomagnification therefore the top carnivore in the food chain will show
highest bio magnification , while the producers will exhibit the least biomagnification
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Why forest is a natural ecosystem while crop field is an artificial ecosystem?
A1
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Q2
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Enzymes are highly specific in their action they catalyse the breakdown of specific substrates only hence
same enzyme does not break down everything we eat for example amylase acts only on starch
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Give two ways in which biodegradable substances affect the environment
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i) Decomposition of biodegradable substances produces foul smell does polluting the air
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Q4
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A4
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2) Non biodegradable substances like pesticides find their way into food chain causing biomagnification of
toxic chemicals
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Why aquarium needs regular cleaning while a lake or a pond does not?
A5
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In lakes The decomposers
breakdown the dead organic matter into simpler in organic nutrients which are utilised by autotrophs
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Q6
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A6
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e herbivores
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g lion feeds on goat
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g a snake (tertiary consumer) eating a frog
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What will be the effect of absence of decomposers in the environment?
A7
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2
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3
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Q8
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First second Third
Grass
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Lion
Producer Primary consumer secondary consumer
Aquatic food chain
Trophic level
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Small fish Shark Producer Primary consumer secondary
consumer tertiary Consumer consumers consumers
Q9
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1% of solar energy is captured by green plants is converted into food
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Depict trophic levels diagrammatically
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Why food chains generally consist of three or four trophic levels?
A11
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Q12
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The energy that is captured by autotrophs does not revert back to the solar input
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Once the energy is passed to the next trophic
level it's no longer available to the previous level
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Which phenomenon is responsible for presence of toxic chemicals like pesticides in grains fruits meat
etc
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Toxic chemicals are washed down into soil or water bodies which are absorbed by plants with water and
minerals from the soil
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Organisms occupying last trophic level in
any food chain will show maximum biomagnification while the plants i
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Q14
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Organic farming in which plant based bio pesticides are used without any use of harmful synthetic
chemicals, can help reduce our intake of pesticides
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What is the role of decomposers?
A15
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Thus decomposers help in nutrient cycling and provide space for new life to settle
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What is ozone, how is it formed?
A16
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These oxygen atoms when combined with molecular oxygen it forms ozone
UV rays

O2 O + O
O2 +O
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What was the cause of sharp decline in the amount of ozone in the atmosphere?
A17
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Q18
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UNEP -United Nations environment programme
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Q19
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Ozone layer in the higher atmosphere acts as a protective layer preventing harmful UV rays from
entering earth’s surface which is highly damaging and can cause skin cancer
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How can you help in reducing the problem of waste disposal?
A20
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Segregation of waste into biodegradable and non-biodegradable waste
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2
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3
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Q21
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Kullahds use was suggested as an alternative to plastic cups however making of kulhads at large scale
lead to depletion of top fertile soil therefore its use was discontinued
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Give examples of heterotrophs in an ecosystem
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Animals and decomposers
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Which among Producers, Primary consumer and secondary consumer are highest in number in an
ecosystem
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Producers are highest in number
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What type of a consumer is
i) a beetle feeding on plants
ii) Human drinking milk
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Study the food chain and calculate how much an energy will be fixed in the plants and at the level of
secondary consumer
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Plants
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Sparrow Hawk
Plants fix 1% of solar energy during photosynthesis

100,000 x 1/100=1000KJ

Insects receive 10%o energy available in plants

1000 x 10/100= 100KJenergy available to primary consumers or insects
Secondary consumer is sparrow
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100 X10/100= 10KJ is the energy available to the secondary consumer- sparrow

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