List the events that reduce the Biological Oxygen Demand (BOD) o

Subject

Biology

Class

CBSE Class 12

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 Multiple Choice QuestionsShort Answer Type

1.

According to de-Vries what is saltation?

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2.

Excessive nutrients in a fresh water body cause fish mortality. Give two reasons

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3.

Suggest the breeding method most suitable for animals that are below average in milk productivity.

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4.

State a difference between gene and an allele.

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5.

Sugggest a technique to a researcher who needs to separate fragments of DNA.

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6.

Explain the significance of meiocytes in a diploid organism.

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7.

Mention the kind of biodiversity of more than a thousand varieties of mangoes in India represent. How is it possible?

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8.

List the events that reduce the Biological Oxygen Demand (BOD) of a primary effluent during sewage treatment. 


After the primary treatment, the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it.This leads to the vigorous growth of useful aerobic microbes (Flocs of bacteria and fungi). The microbes consume a major portion of the organic matter of the effluent and thus reduce the BOD significantly.

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9.

Discuss the role the enzyme DNA ligase plays during DNA replication.

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10.

Name the causative organism of the disease amoebiasis. List three symptoms of the disease.

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