Explain BOD and its effects on aquatic ecosystem.

Question

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Answer

BOD is the amount of dissolved oxygen required by microorganisms for decomposing the organic matter present in water.
This can be measured by chemical testing and is expressed in milligram of oxygen per litre (nigT) of water.
If BOD of water is high, it denotes that the water is highly polluted with decomposing organic matter.
High BOD shows that water is not potable but is polluted with microorganisms and organic debris.
Waters with higher BOD will also cause death of resident aquatic organisms.
Lower BOD on the other hand can vouch for cleaner water.
BOD is an indicator of polluted ecosystem.

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Blood group	Antigen or agglutinogens On RBC	Antibody or agglutinins in the serum	Genotypes	Can donate blood to -	Can receive blood from -
A	___________	B	I^(A)I^(A) or I^(A)I^(O)	A and AB	A,O
B	B	A	or	_____	B,O
_____	___________	Nil	I^(A)I^(B)	AB	_____
O	Nil	_____	I^(O)I^(O)	________	0

Column A	Column B
(1) Organism	(a) Large unit with specific climatic zone
(2) Population	(b) Different species in particular area
(3) Community	(c) Same species in a geographical area
(4) Biome	(d) Basic unit of ecological hierarchy

By taking industrial melanism as one example. Explain the concept of natural selection.

Column A (Part of Anatropous ovule)	Column B (Terminology)
(1) Opening at the apex	(a) Hilum
(2) Stalk of the ovule	(b) Integument
(3) Protective covering	(c) Micropyle
(4) Place of attachment of body and stalk	(d) Funiculus