Earth as a System: Energy, Matter, and Life

20 Questions | 60 Marks

The Indian Meteorological Department (IMD) monitors various atmospheric parameters to predict weather patterns. A recent report highlighted a consistent rise in sea surface temperatures in the Arabian Sea over the past two decades. This phenomenon is linked to increased evaporation from the sea.(a) How would increased evaporation from the Arabian Sea potentially affect the southwest monsoon over India? [2 marks](b) Explain the concept of albedo and how changes in ice cover (cryosphere) due to rising global temperatures might impact Earth’s overall albedo and subsequent warming. 3marks

Assertion (A): The Earth's atmosphere plays a crucial role in regulating surface temperature.Reason (R): Greenhouse gases in the atmosphere trap outgoing infrared radiation from the Earth’s surface.(a) If both A and R are true and R is the correct explanation of A.(b) If both A and R are true but R is not the correct explanation of A.(c) If A is true but R is false.(d) If A is false but R is true. 1mark

A student observes that a dark-coloured shirt feels hotter in the sun than a white-coloured shirt. Based on the concept of solar radiation interaction with surfaces:(a) Which shirt has a lower albedo? [1 mark](b) Explain why this difference in albedo leads to a difference in temperature. 2marks

Consider the process of photosynthesis in plants. This process takes in carbon dioxide (

C O_{2}

) from the atmosphere and releases oxygen (

O_{2}

). Respiration by plants and animals, and the burning of fossil fuels, release

C O_{2}

back into the atmosphere.(a) Describe the role of photosynthesis in the carbon cycle. [2 marks](b) Explain how the burning of fossil fuels disrupts the balance of the carbon cycle and contributes to global warming. 3marks

A group of scientists is studying the impact of a new industrial plant near a river. The plant releases treated wastewater that is slightly warmer than the river water and contains some dissolved minerals.(a) How might the warmer wastewater affect the dissolved oxygen levels in the river (hydrosphere)? [2 marks](b) If the wastewater also increases the salinity of the river water, how could this impact marine life (biosphere) downstream? 2marks

Assertion (A): Equatorial regions receive more direct solar radiation than polar regions.Reason (R): The Earth is spherical, causing sunlight to spread over a larger area at the poles compared to the equator.(a) If both A and R are true and R is the correct explanation of A.(b) If both A and R are true but R is not the correct explanation of A.(c) If A is true but R is false.(d) If A is false but R is true. 1mark

In many mountainous regions, residents observe a 'valley breeze' during the day and a 'mountain breeze' at night.(a) Explain the formation of a valley breeze, specifying the pressure conditions and direction of air movement. [2 marks](b) How do these local winds influence the local climate and agricultural practices in the valleys? 2marks

A farmer in India is concerned about the decreasing level of groundwater in their region over the past decade. This has led to difficulties in sustaining agriculture, especially during dry months.(a) How might changes in the water cycle, such as increased rainfall intensity in some areas and drought in others, contribute to reduced groundwater recharge? [3 marks](b) Identify two Earth spheres that are directly affected by this farmer's problem. 1mark

Scenario: A large forest is cleared for an agricultural project.(a) How might the removal of trees (biosphere) affect the water cycle, specifically regarding transpiration and infiltration? [2 marks](b) Discuss the potential impact of this deforestation on the local atmospheric conditions and soil erosion (geosphere). 2marks

The Earth's atmosphere is divided into several layers. Weather phenomena like clouds, storms, and rainfall primarily occur in the troposphere.(a) Why do most weather events happen in the troposphere? [1 mark](b) Explain why temperature decreases with height in the troposphere. 2marks

Assertion (A): Ocean currents play a significant role in regulating global climate.Reason (R): Warm equatorial currents carry heat towards the poles, moderating temperatures.(a) If both A and R are true and R is the correct explanation of A.(b) If both A and R are true but R is not the correct explanation of A.(c) If A is true but R is false.(d) If A is false but R is true. 1mark

Imagine a scenario where the Earth's rotation suddenly stopped. How would this affect the planetary wind patterns and ocean currents? Explain your reasoning based on the Coriolis effect. 3marks

Source-based Question: Anna Mani, an Indian atmospheric scientist, made significant contributions to understanding solar insolation across India. Her work highlighted the vast potential for solar energy in the country.(a) What is 'insolation'? [1 mark](b) How does India's geographical location contribute to high insolation levels, and what is the significance of this for the country? 2marks

Nitrogen is essential for life, but atmospheric nitrogen (

N_{2}

) is not directly usable by most organisms.(a) Describe the process of nitrogen fixation and name one type of bacteria involved. [2 marks](b) Explain how the overuse of fertilisers, which are often nitrogen-based, can negatively impact water bodies through a process called eutrophication. 3marks

Assertion (A): Cities are generally warmer than surrounding rural areas, especially at night.Reason (R): Urban areas have more buildings and roads made of concrete and asphalt, which absorb and retain heat.(a) If both A and R are true and R is the correct explanation of A.(b) If both A and R are true but R is not the correct explanation of A.(c) If A is true but R is false.(d) If A is false but R is true. 1mark

Some scientists are studying the impact of increased CO2 levels on marine plankton. They observe that as atmospheric CO2 increases, more CO2 dissolves in ocean water, making it more acidic.(a) How does increased acidity in ocean water potentially harm marine plankton and coral reefs (biosphere)? [2 marks](b) Explain why warmer ocean water might reduce its capacity to act as a carbon sink. 2marks

The oxygen cycle involves the exchange of oxygen between the atmosphere, land, oceans, and living organisms.(a) Name the two primary processes that maintain the balance of oxygen in the atmosphere. [1 mark](b) Explain why this balance is crucial for life on Earth. 2marks

Application-based Question: A city is experiencing unusually high temperatures for several consecutive days. The local authorities are investigating potential causes. They note a recent increase in the number of vehicles on the roads and the operation of several new factories.(a) How do vehicular emissions and factory emissions contribute to the increase in atmospheric temperature? [2 marks](b) Suggest two measures, based on the chapter's concepts, that the city administration could implement to mitigate the rising temperatures and reduce pollution. 2marks

Scenario: Snowfall in the Himalayas has been significantly less for the past few winters. This has led to a reduced flow of water in rivers like the Ganga and Brahmaputra during the summer months.(a) Identify the Earth spheres involved in this scenario and describe their interrelationship. [3 marks](b) What are the potential consequences for agriculture and freshwater availability in the regions dependent on these rivers? 2marks

Assertion (A): The Earth is unique because it has an atmosphere that supports life.Reason (R): The atmosphere protects life by filtering harmful UV radiation and trapping heat, preventing the Earth from becoming too cold.(a) If both A and R are true and R is the correct explanation of A.(b) If both A and R are true but R is not the correct explanation of A.(c) If A is true but R is false.(d) If A is false but R is true. 1mark

Answers

1.(a) Increased evaporation from the Arabian Sea leads to more moisture in the atmosphere. This can result in heavier rainfall during the southwest monsoon season in India, potentially causing floods in some regions while also affecting rainfall patterns elsewhere.(b) Albedo is the fraction of solar radiation reflected by a surface. Surfaces like snow and ice have high albedo, reflecting most sunlight. As global temperatures rise, ice cover melts, exposing darker surfaces (land or ocean) with lower albedo. These darker surfaces absorb more solar radiation, leading to further warming, creating a positive feedback loop.

(a) If both A and R are true and R is the correct explanation of A.

3.
(a) The dark-coloured shirt has a lower albedo.
(b) Surfaces with lower albedo absorb more solar radiation and heat up more quickly. Dark colours absorb most of the light falling on them and reflect very little, causing them to become hotter. Light colours reflect more sunlight, hence remaining cooler.

4.
(a) Photosynthesis is the process by which plants use atmospheric $C O_{2}$ and sunlight to produce glucose (food) and oxygen. It acts as a natural mechanism to remove $C O_{2}$ from the atmosphere, thus playing a crucial role in regulating atmospheric carbon levels.
(b) Burning fossil fuels releases large amounts of stored carbon into the atmosphere as $C O_{2}$ at a rate much faster than natural processes can remove it. This excess $C O_{2}$ is a greenhouse gas that traps heat, leading to an enhanced greenhouse effect and global warming.

5.
(a) Warmer wastewater can reduce the amount of dissolved oxygen in the river water because warmer water holds less dissolved gas than cooler water. This can stress or harm aquatic life that relies on dissolved oxygen for respiration.
(b) An increase in salinity makes the water denser. This can disrupt the natural movement and distribution of aquatic organisms. Organisms adapted to specific salinity levels may struggle to survive, potentially leading to a decline in biodiversity.

(a) If both A and R are true and R is the correct explanation of A.

7.
(a) During the day, mountain slopes heat up faster than the valley floor. This warm air rises, creating a low-pressure region on the slopes. Cooler, denser air from the valley moves up the slopes to replace the rising air, forming a valley breeze.
(b) Valley breezes can help regulate temperature in the valleys, preventing extreme heat. They can also influence moisture levels. For crops, consistent air movement can aid in pollination and reduce the risk of frost damage during cooler periods.

8.
(a) Climate change can lead to more intense, shorter-duration rainfall events in some areas, causing increased surface runoff and less infiltration into the soil. Simultaneously, other regions might experience prolonged droughts. This variability means less water seeps into the ground to recharge groundwater aquifers, especially during dry periods when reliance on groundwater increases.
(b) The spheres directly affected are the hydrosphere (groundwater, rivers) and the geosphere (soil, land). The biosphere (crops, plant life) is also directly impacted due to lack of water.

9.
(a) Deforestation reduces the amount of water released into the atmosphere through transpiration by trees. It also reduces the interception of rainfall by tree canopies, leading to more direct impact on the soil. This can alter local rainfall patterns and reduce soil moisture. Less vegetation means less absorption of rainwater into the ground, decreasing groundwater recharge.
(b) The removal of trees reduces photosynthesis, decreasing the absorption of $C O_{2}$ from the atmosphere and potentially increasing its concentration. The lack of tree roots to bind the soil increases the risk of soil erosion by wind and rain. This can lead to land degradation and habitat loss for many species.

10.
(a) The troposphere is the lowest layer of the atmosphere, and it is heated from the Earth's surface. As warm air rises from the surface, it cools and condenses, leading to the formation of clouds and precipitation, which are the primary components of weather phenomena.
(b) In the troposphere, temperature decreases with height because the Earth's surface absorbs solar radiation and heats the air above it. As altitude increases, the distance from this heat source increases, and the air becomes thinner and less able to retain heat.

(a) If both A and R are true and R is the correct explanation of A.

If the Earth's rotation stopped, the Coriolis effect would cease to exist. Planetary winds, which are currently deflected due to Earth's rotation, would likely flow directly from high-pressure belts to low-pressure belts. Similarly, ocean currents, which are also influenced by the Coriolis effect causing gyres, would flow more directly, potentially leading to different heat distribution patterns globally.

13.
(a) Insolation is the amount of solar radiation received by a particular region on the Earth's surface.
(b) India's geographical location in tropical and sub-tropical regions means it receives abundant sunlight throughout the year. This high insolation is significant because it drives the southwest monsoon, crucial for India's climate and agriculture, and offers immense potential for harnessing solar energy.

14.
(a) Nitrogen fixation is the process by which atmospheric nitrogen gas ( $N_{2}$ ) is converted into ammonia ( $N H_{3}$ ) or other nitrogen compounds that can be used by plants. This is primarily carried out by nitrogen-fixing bacteria, such as Rhizobium found in the root nodules of legumes.
(b) Overuse of nitrogen-based fertilisers leads to excess nitrates entering rivers and lakes through runoff. These excess nutrients cause rapid growth of algae (algal blooms). When these algae die and decompose, they consume large amounts of dissolved oxygen in the water, leading to oxygen depletion and the death of fish and other aquatic organisms. This process is known as eutrophication.

(a) If both A and R are true and R is the correct explanation of A.

16.
(a) Increased acidity in ocean water can dissolve the shells and skeletons of marine organisms like plankton and corals, which are made of calcium carbonate. This can weaken their structures, hinder their growth, and ultimately threaten their survival and the entire marine ecosystem.
(b) Warmer ocean water holds less dissolved gas, including $C O_{2}$ . Therefore, as ocean temperatures rise, their capacity to absorb atmospheric $C O_{2}$ decreases, making them less effective as a carbon sink and potentially leading to more $C O_{2}$ remaining in the atmosphere.

17.(a) The two primary processes are:

Photosynthesis (by plants, algae, and cyanobacteria), which produces oxygen.

Respiration and combustion (by organisms and processes that consume oxygen), which consume oxygen.(b) This balance is crucial because oxygen is essential for aerobic respiration, the process by which most living organisms obtain energy. A significant disruption in this balance, leading to a depletion of oxygen, would be catastrophic for aerobic life on Earth.

18.(a) Vehicular emissions (like

C O_{2}

, nitrogen oxides) and factory emissions contribute to air pollution. These pollutants, especially greenhouse gases like

C O_{2}

, trap heat in the atmosphere, leading to an enhanced greenhouse effect and rising temperatures. Some pollutants can also react with sunlight to form smog and ground-level ozone, which further contributes to atmospheric warming.(b) Two measures:

Promote the use of public transport, electric vehicles, and cycling to reduce vehicular emissions.

Encourage industries to adopt cleaner production technologies and install pollution control devices. Investing in and expanding renewable energy sources (like solar and wind) can also reduce reliance on fossil fuels, which are major sources of pollution and greenhouse gases.

19.
(a) The spheres involved are:

Cryosphere: Reduced snowfall in the Himalayas (glaciers and snow).
Hydrosphere: Reduced flow of water in rivers (Ganga, Brahmaputra).
Geosphere: Impact on soil moisture and groundwater recharge.
Biosphere: Impact on plant life, agriculture, and ecosystems dependent on river water.
Interrelationship: Melting snow and glaciers (cryosphere) are a major source of water for rivers (hydrosphere). Reduced snowfall means less meltwater, leading to lower river flows. This directly impacts agriculture and ecosystems (biosphere) that rely on this water, and can affect soil moisture and groundwater levels (geosphere).
(b) Reduced river flow during summer months can lead to water scarcity for irrigation, severely impacting crop yields and potentially causing crop failure. This can lead to reduced food production, economic hardship for farmers, and a lack of freshwater for drinking and domestic use in downstream regions.

(a) If both A and R are true and R is the correct explanation of A.

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Earth as a System: Energy, Matter, and Life — Competency Based Questions

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