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Class 10 Class 12

Which domestic sewage mixes with river water

• small animals like rats will die after drinking river water

• the increased microbial activity releases micronutrients such as iron

• the increased microbial activity uses up dissolved oxygen

• the river water is still suitable for drinking as impurities are only about 0.1%

C.

the increased microbial activity uses up dissolved oxygen

Domestic sewage consists a lot of degradable organic matter. When this sewage is released into river water, it will result in an increase of Biochemical oxygen demand (BOD) and decrease the amount of dissolved oxygen due to the decomposing activity of microbes.

Domestic sewage consists a lot of degradable organic matter. When this sewage is released into river water, it will result in an increase of Biochemical oxygen demand (BOD) and decrease the amount of dissolved oxygen due to the decomposing activity of microbes.

What trophic level is occupied by the birds in an ecosystem ?
• First
• Second
• Third
• Fourth

C.

Third

The green plants in the ecosystem-terminology are called :
• Producers
• Consumers
• Herbivores
• Carnivores

A.

Producers

The animals that feed on plants are called :
• Producers
• Carnivores
• Insectivores
• Herbivores

D.

Herbivores

Cockroaches can feed both on plant and animal food, they are called :
• Herbivores
• Carnivores
• Omnivores
• None of the above

C.

Omnivores

What trophic level is occupied by the Phytoplankton in an ecosystem ?
• First
• Second
• Third
• Fourth

A.

First

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