Effect of Sewage on Water Bodies

Q. What do the patches of green layer floating on the surface of stagnant water bodies like ponds and lakes consist of?

Q.

Explain the controlling measures for water pollution caused by sewage.

Q. The high value of BOD (Biochemical Oxygen Demand) indicates that:

1. Consumption of organic matter in the water is higher by the microbes
2. Water is pure
3. Water is highly polluted
4. Water is less polluted

Q.

A lake with an inflow of domestic sewage rich in organic waste may result in:

1. Drying of the lake very soon due to algal bloom

2. An increased production of fish due to a lot of nutrients

3. Death of fish due to lack of oxygen

4. Oxides of nitrogen

Q.

Name the disease caused by biomagnification of mercury in fishes.

Q.

What is biomagnification?

Q. State whether true or false:
Coliform bacteria are found in the small intestine of humans.

1. True
2. False

Q. When domestic sewage mixes with river water

1. Small animals like rats will die after drinking river water
2. The increased microbial activity releases micro nutrients such as iron
3. The increased microbial activity uses up dissolved oxygen
4. The river water is still suitable for drinking as impurities are only about 0.1%

Q.

Match the pollutants listed in column I with the respective diseases mentioned in column II:
$\begin{array}{cccc}& Column-IPollutants& & Column-IIDiseases\\ A& S{O}_x& e& Hypoxaemia\\ B& Domesticsewage& f& Bronchitis\\ C& Mercury& g& Minamatadisease\\ & & h& Amoebicdysenetry\end{array}$

1. A=f, B=h, C=g

2. A=e, B=f, C=g

3. A =h, B=g, C=f

4. A=g, B=e, C=h

Q. Which of the following phenomena helps in the degradation of complex substances of food into simpler ones?

1. Excretion
2. Assimilation
3. Digestion
4. Ingestion

Q. Foul smell in water bodies like tanks and ponds is due to

1. Aerobiosis
2. Anaerobiosis
3. Psammophytes
4. Biological magnification

Q. The image below is an example of ___

1. Eutrophication
2. Water pollution due to oil spill
3. Water pollution due to sewage water
4. Algal Bloom

Q. By using proper sewage treatment facility we can avoid ___ of water bodies.

Q. Biochemical Oxygen Demand (BOD) in a river water:

1. has no relationship with the concentration of oxygen in the water
2. gives a measure of Salmonella in the water
3. Remains unchanged when an algal bloom occurs.
4. Increases when sewage gets mixed with river water

Q. Excessive accumulation of organic matter in water leads to

1. Decrease in species diversity
2. Increase in species diversity
3. Greenhouse effect
4. No effect of species diversity

Q. Assertion [A]: Eutrophication shows an increase in productivity of water.
Reason [R]: With increasing eutrophication, the diversity of phytoplankton increases.

1. Both the reason and assertion are false.
2. Both assertion and reason are true and the reason is the correct explanation for assertion.
3. Both reason and assertion are true but the reason is not the correct explanation of the assertion.
4. Assertion is true but the reason is false.