Environment & Ecology › Biogeochemical Cycles & Earth Systems – UPSC Prelims PYQs

With reference to the planet Earth, consider the following statements : I. Rain forests produce more oxygen than that produced by oceans. II. Marine phytoplankton and photosynthetic bacteria produce about 50% of world's oxygen. III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.

Which of the statements given above is/are correct?

In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?

Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter

Select the correct answer using the code given below.

Which of the following adds/add nitrogen to the soil?

1. Excretion of urea by animals
2. Burning of coal by man
3. Death of vegetation

Select the correct answer using the codes given below.

Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere, but a lot of it does not remain in the lower atmosphere because of

1. Its escape into the outer stratosphere,
2. The photosynthesis by phytoplankton in the oceans,
3. The trapping of air in the polar ice caps.

Which of the statements given above is/are correct?

Consider the following :

1. Photosynthesis
2. Respiration
3. Decay of organic matter
4. Volcanic action

Which of the above add carbon dioxide to the carbon cycle on Earth ?

Which one of the following reflects back more sunlight as compared to the other three?

Consider the following ecosystems:

1. Taiga
2. Tropical evergreen
3. Tropical deciduous
4. Tundra The correct sequence in decreasing order of the albedo values of these ecosystems is