Question 1

Q1: Choose the most appropriate option to describe the role of biogeochemical cycles in an ecosystem. (i) To provide food directly to all organisms. (ii)...

Accepted Answer

The most appropriate option is (ii) To recycle essential nutrients between biotic and abiotic components. Explanation: As stated in the chapter, biogeochemical cycles describe the continuous movement of matter and energy between the non-living (abiotic) and living (biotic) components of the Earth. T...

Question 2

Q2: Which of the following is primarily responsible for warming of the Earth? (i) Solar radiation is immediately absorbed by carbon dioxide, which then re...

Accepted Answer

The correct option is (iii) The Earth's surface absorbs solar radiation, which is then re-radiated and trapped by greenhouse gases. Explanation: The chapter explains that visible light from the Sun reaches and warms the Earth's surface. The surface then re-radiates this energy as infrared radiation...

Question 3

Q3: Explain how climate change affects the water cycle. Illustrate with examples.

Accepted Answer

Climate change, primarily driven by global warming, significantly affects the water cycle by altering the rates of evaporation, condensation, and precipitation. The chapter illustrates this with the following examples: 1.  Intensified Rainfall and Droughts: A warmer atmosphere can hold more moisture...

Question 4

Q4: Describe how albedo affects the Earth's surface temperature and its climate.

Accepted Answer

Albedo is the fraction of solar radiation that is reflected by a surface. It plays a crucial role in determining the Earth's surface temperature and climate by influencing how much solar energy is absorbed versus reflected.    High Albedo Surfaces: Surfaces with high albedo, such as snow and ice, ar...

Question 5

Q5: How are mountain and valley breezes formed? Suppose there are two mountains, one covered with grass and another covered with barren rocks; would the t...

Accepted Answer

Mountain and valley breezes are local winds caused by the uneven heating and cooling of mountain slopes and valley floors.    Valley Breeze (Daytime): During the day, mountain slopes that face the sun heat up more rapidly than the valley floor. The air above the slopes becomes warm, less dense, and...

Question 6

Q6: You have witnessed weather phenomena, such as winds, storms, rainfall, etc. Which atmospheric layer is mainly responsible for such phenomena and what...

Accepted Answer

The atmospheric layer mainly responsible for weather phenomena such as winds, storms, and rainfall is the troposphere. Primary Reason: The primary reason for the occurrence of these phenomena is the uneven heating of the Earth's surface by the Sun. The troposphere is heated from below by the Earth's...

Question 7

Q7: Explain the processes involved in the nitrogen cycle. How would life on Earth be affected if nitrogen were not cycled?

Accepted Answer

The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms, circulating between the atmosphere, terrestrial, and marine ecosystems. The main processes are: 1.  Nitrogen Fixation: The conversion of atmospheric nitrogen gas ($N_2$), which is unusable by most or...

Question 8

Q8: What are the impacts of deforestation on the Earth's oxygen and carbon cycles? What are the other consequences of deforestation?

Accepted Answer

Deforestation has significant impacts on the Earth's oxygen and carbon cycles.    Impact on Carbon Cycle: Forests are major carbon sinks, meaning they absorb large amounts of carbon dioxide ($CO_2$) from the atmosphere through photosynthesis. Deforestation, or the clearing of forests, reduces the Ea...

Question 9

Q9: Explain with suitable diagram the path that carbon takes to go back to the atmosphere. You may start from plants using $CO_2$ from the atmosphere.

Accepted Answer

The path of carbon from plants back to the atmosphere involves several key processes, as shown in the carbon cycle (refer to Fig. 13.13 in the textbook). 1.  Photosynthesis: Plants absorb carbon dioxide ($CO_2$) from the atmosphere and use it to create organic compounds (like glucose) for energy and...

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