Question 2

Freshwater versus marine ecosystems; noise pollution versus thermal pollution

10 marks

Question

Question 2 · 10 marks

Differentiate between the following, attempting any two (2×5=10)

Reworded from the university paper; the task is the same. The original paper belongs to the University of Delhi. See DU's question bank.

Read off the question and its marks

20 minfor 10 marks

any twoAnswer any 2 of the 3, 5 marks each. Only 2 are marked: a third earns nothing.
Differentiate betweenSet the differences out in a table, basis by basis, not as two separate essays.

The parts stand alone: start with the one you are surest of.

Short on time? A few lines on every part beat a full answer to one: each part is capped at its own marks.

Try it first. About 20 minutes for 10 marks. Write it out, then open the solution.

Hover or tap a marked figure, like 72,000, to see how it is made and where else it appears.

The question asks for any two of the three pairs. Pairs (a) and (b) are answered.

(a) Freshwater ecosystems and marine ecosystems

Aquatic ecosystems are divided by the salt content of their water into freshwater, brackish and marine ecosystems.

Basis	Freshwater ecosystems	Marine ecosystems
Salinity	Very low salt content	Highly saline sea water
Kinds	Running water (streams, rivers) and still water (ponds, tanks, lakes); wetlands, whose water level swings with the seasons	Open ocean, deep sea, shallow seas, coral reefs and seashores
Share of Earth's water	A very small share, yet the main source of drinking water	By far the largest share
Organisms	Algae, water plants, insects, frogs, freshwater fish such as rohu and catla	Phytoplankton to large seaweeds; marine fish, sharks, whales; coral reefs, which are very rich in species
Adaptations	Organisms keep salts in and let water out of their bodies	Organisms withstand high salt, waves, tides and great pressure in the deep
Uses	Drinking, irrigation, inland fishing, hydropower	Marine fishing, sea trade and transport, salt
Indian example	Dal Lake, Wular Lake, the Ganga	Arabian Sea, Bay of Bengal, coral reefs of the Gulf of Mannar

(b) Noise pollution and thermal pollution

Basis	Noise pollution	Thermal pollution
Meaning	Unwanted or undesirable sound loud enough to harm health and the quality of the environment	The discharge of heated water into a river or other water body
Medium	Air (and buildings)	Water bodies
Sources	Factories, vehicles, loudspeakers at festivals and functions; indoors, loud music systems and gadgets	Industries and power plants that draw water to cool their condensers and return it hot, at least 15 °C above normal
Measured as	Sound level in decibels	Rise in water temperature
Persistence	Does not build up in the environment; it stops when the source stops	Lasts as long as the hot discharge continues and changes the whole water body
Effects	Temporary or permanent hearing loss, high blood pressure, stress, poor concentration and more accidents	Less dissolved oxygen, faster fish metabolism, a changed balance of species; fish used to warm water die when the plant shuts down suddenly
Control	Silencers and maintenance of machines, sound barriers and tree belts, ear protection	Cooling ponds or cooling towers before the water is returned

Both are forms of energy, not substances, entering the environment: noise as sound, thermal pollution as heat.

#	Component	Marks
1	(a) Freshwater versus marine ecosystems	5
2	(b) Noise versus thermal pollution	5
	Total	10

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