ecology & bio environment geography section 1 MCQ Questions & Answers Detailed Explanation

Answer: (c)

The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases such as Carbon dioxide, and is re-radiated in all directions.

Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. Human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming.

Answer: (a)

Productivity is the rate of organic matter or biomass production. The average ocean productivity is about 50 grams of carbon per square meter per year; while, the average land productivity is 160 grams of carbon per square meter per year.

Salt marshes and mangroves have one of the highest productivity of 3300-6000 grams of carbon per square meter per year.

So the correct sequence of the ecosystem in the order of decreasing productivity is:

Mangroves > Grasslands > Lakes > Oceans.

Answer: (d)

Forests are considered as sinks of carbon dioxide. A carbon sink is anything that absorbs more carbon that it releases, whilst a carbon source is anything that releases more carbon than is absorb. It is for this reason that they are indispensable in the present global scenario marked by increasing global warming and climate change.

Answer: (a)

Deciduous means “falling off at maturity” or “tending to fall off”, and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe.

In a more general sense, deciduous means the dropping of a part that is no longer needed or falling away after its purpose is finished.

Answer: (d)

Our ever-increasing addiction to electricity from coal-burning power plants releases enormous amounts of carbon dioxide into the atmosphere. 40% of U.S. CO2 emissions come from electricity production, and burning coal accounts for 93% of emissions from the electric utility industry.

Every day, more electric gadgets flood the market, and without widespread alternative energy sources, we are highly dependent on burning coal for our personal and commercial electrical supply.

Answer: (b)

The biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, geosphere, hydrosphere, and atmosphere. It is termed the zone of life on Earth.