Students can practice the best Class 9 Science MCQ and Class 9 Science Exploration Chapter 13 MCQ Online Test with Answers Earth as a System Energy Matter and Life for exam preparation.
Class 9 Science Chapter 13 Earth as a System Energy Matter and Life MCQ
Earth as a System Energy Matter and Life MCQ
Class 9 Science Chapter 13 MCQ online test
Question 1.
A massive volcanic eruption releases ash and sulfur dioxide into the atmosphere, which subsequently blocks sunlight and causes a temporary cooling of the Earth’s surface. Which spheres of the Earth are primarily interacting in this scenario?
(A) Geosphere, atmosphere and biosphere
(B) Hydrosphere, cryosphere and geosphere
(C) Biosphere, hydrosphere and atmosphere
(D) Cryosphere, biosphere and hydrosphere
Answer:
(A) Geosphere, atmosphere and biosphere
The volcano belongs to the geosphere; it releases gases into the atmosphere. This ash blocks or scatters the incoming solar radiations, which directly affects the growth of plants and animals (biosphere)
Question 2.
How much solar energy will be received by a 2m2 area in 30 minutes, if the insolation is 1 kW m-2?
(A) 3.6 × 106 J
(B) 1.8 × 106 J
(C) 3.6 × 105 J
(D) 7.2 × 106 J
Answer:
(D) 7.2 × 106 J
E = Intensity × Area × Time
E = 1 × 1000 Js-1m-2 × 2m2 × 1800 s
E = 3.6 × 106 × 2
= 7.2 × 106 J
Question 3.
The differential heating of the Earth’s surface is largely responsible for global wind patterns. Which of the following is not a primary factor causing this differential heating?
(A) The spherical shape of the Earth.
(B) The specific heat capacity of different surface materials.
(C) The distance of the Earth from the Moon.
(D) The axial tilt of the Earth.
Answer:
(C) The distance of the Earth from the Moon.
Earth’s shape, tilt and the specific heat of its surfaces cause differential heating. The Moon primarily affects tides, not the uneven heating of the Earth.
Question 4.
Consider two surfaces: a vast expanse of fresh snow in the cryosphere and a deep ocean in the hydrosphere. How does solar radiation interact differently with these two surfaces?
(A) The snow absorbs most radiation, while the ocean reflects it, causing oceans to stay cool.
(B) The snow has high reflectivity (albedo) bouncing back radiation, while the ocean absorbs most of it.
(C) Both surfaces absorb solar radiation equally due to the uniform nature of water molecules.
(D) The ocean reflects infrared waves, while the snow absorbs ultraviolet waves.
Answer:
(B) The snow has high reflectivity (albedo) bouncing back radiation, while the ocean absorbs most of it.
Light coloured and, bright surfaces like snow reflect almost all solar energy. Darker surfaces like deep oceans absorb most of the solar energy.
Question 5.
During a hot summer afternoon in a coastal city, a person standing on the beach notices a cool breeze blowing from the sea towards the land. What is the fundamental scientific reason for this phenomenon?
(A) The sea absorbs heat faster than the land, creating a high-pressure zone over the water.
(B) The land heats up faster than the sea, causing air above it to rise and creating a low pressure zone that draws in cooler air from the sea.
(C) The Earth’s rotation pushes the ocean currents towards the land during the daytime.
(D) Evaporation from the sea surface cools the air, which then naturally moves towards the warmer land.
Answer:
(B) The land heats up faster than the sea, causing air above it to rise and creating a low pressure zone that draws in cooler air from the sea.
Land has a lower specific heat capacity than water. It heats quickly, creating low pressure. The cooler, high-pressure air over the sea moves towards land to replace it.
Question 6.
Which of the following atmospheric phenomena is directly driven by the cooling of mountain slopes at night?
(A) Seabreeze
(B) Valley breeze
(C) Mountain breeze
(D) Land breeze
Answer:
(C) Mountain breeze
At night, mountain slopes cool faster than the valley floor. The cold, dense air flows down the slopes into the valley, creating a mountain breeze.
Question 7.
How does the tilt of the Earth’s axis primarily influence the Earth’s climate?
(A) It changes the distance between the Earth and the Sun throughout the year.
(B) It causes the Earth to wobble, changing the speed of its rotation.
(C) It alters the angle at which solar radiation strikes different latitudes at different times of the year, causing seasons.
(D) It directly controls the speed of ocean currents in the hydrosphere.
Answer:
(C) It alters the angle at which solar radiation strikes different latitudes at different times of the year, causing seasons.
The tilt tells how direct the sunlight has fallen on any surface. When a hemisphere is tilted towards the Sun, it gets direct rays (causing summer).
Question 8.
In the carbon cycle, which of the following biological processes acts as a crucial link between the abiotic environment (atmosphere) and the biotic environment (living organisms)?
(A) Cellular respiration and transpiration
(B) Photosynthesis and cellular respiration
(C) Nitrogen fixation and denitrification
(D) Evaporation and condensation
Answer:
(B) Photosynthesis and cellular respiration
Photosynthesis takes abiotic CO2 and turns it into biotic organic matter. Respiration breaks down organic matter, releasing abiotic CO2 back into the atmosphere.
Question 9.
Nitrogen is abundant in the atmosphere, but cannot be directly utilised by most plants and animals. How is this atmospheric nitrogen made available to the biotic environment?
(A) Through direct absorption by plant leaves during photosynthesis.
(B) Through the process of nitrogen fixation by specific bacteria in the soil or root nodules.
(C) Through the physical weathering of rocks in the geosphere.
(D) Through the continuous evaporation of water from the oceans.
Answer:
(B) Through the process of nitrogen fixation by specific bacteria in the soil or root nodules.
Atmospheric nitrogen (N2) cannot be directly used by most plants because of inert nature of N, bond. Nitrogen-fixing bacteria (e.g. Rhizobium) convert N2 into ammonia/nitrates which plants can absorb.
Question 10.
Biogeochemical cycles are vital for maintaining environmental balance. Which statement best describes the flow of matter and energy in these cycles?
(A) Both matter and energy are continuously recycled within the ecosystem.
(B) Matter flows in one direction and is lost, while energy is continuously recycled.
(C) Matter is continuously recycled between biotic and abiotic components, but energy flows in a one-way direction and is eventually lost as heat.
(D) Neither matter nor energy is conserved; both are constantly created and destroyed.
Answer:
(C) Matter is continuously recycled between biotic and abiotic components, but energy flows in a one-way direction and is eventually lost as heat.
Matter is continuously recycled between the biotic and abiotic components through biogeochemical cycles whereas, energy flows in a one-way direction from the Sun to producers then consumers trophic levels and is ultimately lost as heat. Hence, energy is not recycled.
Question 11.
The Earth’s atmosphere plays a crucial role in regulating weather and climate. If the Earth had no atmosphere, what would be the most immediate consequence regarding solar radiation?
(A) The Earth would experience extreme temperature variations between day and night.
(B) The entire Earth would become a hot, tropical zone.
(C) Solar radiation would not be able to reach the Earth’s surface at all.
(D) The oceans would absorb all the heat, leaving the landmasses frozen.
Answer:
(A) The Earth would experience extreme temperature variations between day and night.
The atmosphere acts as a blanket, trapping heat to keep nights warm and scattering sunlight to keep days from getting unimaginably hot. If there is no atmosphere on earth, then temperature varies uncontrollably making survival difficult.
Question 12.
Which of the following best defines the ‘Cryophere’ ?
(A) The layer of gases surrounding the Earth.
(B) All the liquid water present on the Earth’s surface.
(C) The frozen water part of the Earth system, including glaciers, ice caps and permafrost.
(D) The solid, outer part of the Earth, including the crust and upper mantle.
Answer:
(C) The frozen water part of the Earth system, including glaciers, ice caps and permafrost.
Question 13.
In a mountainous region, air is heated more on the slopes than in the valley bottom during the daytime. This causes the air to rise along the slopes. This phenomenon is known as
(A) mountain breeze
(B) valley breeze
(C) land breeze
(D) trade winds
Answer:
(B) valley breeze
During the day, mountain slopes heat up faster, causing air to rise along the slopes and draw air upward from the valley. This upward movement of air draws cooler air form the valley to replace it, called valley breeze.
Question 14.
Which of the following correctly explains the formation of planetary winds?
(A) Uneven heating creates pressure belts, causing air to move from high to low pressure and get deflected due to Earth’s rotation.
(B) Uniform heating of the Earth causes air to remain stationary across latitudes.
(C) Planetary winds are formed only due to ocean currents.
(D) Air moves directly from poles to equator without any deflection.
Answer:
(A) Uneven heating creates pressure belts, causing air to move from high to low pressure.
Due to Earth’s rotation, winds are deflected, forming planetary winds.
Question 15.
If a forest is cleared and replaced by a concrete parking lot, how will the interaction with solar radiation change in that specific area?
(A) Reflectivity will decrease and absorption will increase, causing localised warming.
(B) Reflectivity will increase and absorption will decrease, causing localised cooling.
(C) Both reflectivity and absorption will remain the same.
(D) The area will stop receiving solar radiation altogether.
Answer:
(A) Reflectivity will decrease and absorption will increase, causing localised warming.
Concrete and asphalt are darker and less reflective than forest canopies. They absorb more heat, leading to the ‘Urban Heat Island’ effect.
Question 16.
Which of the following factors is primarily responsible for driving ocean currents?
(A) Planetary winds causing friction on ocean surface
(B) Only the gravitational pull of the Moon
(C) Uniform temperature of ocean water
(D) Absence of land masses
Answer:
(A) Planetary winds causing friction on ocean surface
Ocean currents are primarily driven by planetary winds, which exert friction on the ocean surface, setting water in motion. Their movement is further influenced by temperature, salinity, Earth’s rotation, and the distribution of land masses.
Question 17.
Extensive deforestation in a mountainous region leads to severe soil erosion during heavy rainfall, which subsequently chokes a nearby river system with silt. Which spheres of the Earth are primarily interacting in this interconnected event?
(A) Atmosphere, cryosphere and geosphere
(B) Biosphere, geosphere and hydrosphere
(C) Hydrosphere, atmosphere and biosphere
(D) Geosphere, cryosphere and hydrosphere
Answer:
(B) Biosphere, geosphere and hydrosphere
The removal of trees affects to the biosphere. The resulting soil erosion involves the geosphere, and the subsequent siltation of the river directly affects the hydrosphere. This demonstrates a direct harmful effect across these three spheres.
Question 18.
Different surfaces on the Earth reflect and absorb solar radiation to varying degrees. Which of the following surfaces contributes the most to cooling the global climate due to its extremely high albedo?
(A) Dense tropical rainforests
(B) The open expanse of the ocean
(C) Fresh snow and glacial ice caps
(D) Urban landscapes dominated by asphalt
Answer:
(C) Fresh snow and glacial ice caps
Fresh snow and glacial ice caps possess the highest natural albedo, reflecting approximately 80-90% of incoming solar radiation back into space. By absorbing minimal thermal energy, they play a crucial role in maintaining cooler global temperatures.
Question 19.
Which of the following best explains the formation and direction of ocean gyres?
(A) Earth’s rotation deflects ocean currents, forming circular patterns that rotate clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere.
(B) Ocean currents move only due to differences in salinity without any deflection.
(C) Gyres are formed due to uniform heating of ocean water across all latitudes.
(D) Ocean currents flow in straight lines from poles to equator without forming circular patterns.
Answer:
(A) Earth’s rotation deflects ocean currents, forming circular patterns that rotate clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere.
Ocean gyres form mainly due to the coriolis effect caused by Earth’s rotation, which deflects currents and creates circular patterns clockwire in the Northern Hemisphere and anticlockwise in Southern hemisphere.
Question 20.
During the day time in coastal regions, a distinct pressure gradient is formed due to the differential heating of land and water. Which statement accurately describes the atmospheric conditions that generate a sea breeze?
(A) A high-pressure zone forms over the rapidly heating land, drawing cool air from the sea.
(B) The land heats up more slowly than the ocean, creating a low-pressure zone over the water.
(C) The land heats up rapidly, causing the air above it to rise and creating a low-pressure zone, which draws in cooler, denser air from the high-pressure zone over the sea.
(D) Both land and sea heat at the same rate, but oceanic evaporation pushes the air inland.
Answer:
(C) The land heats up rapidly, causing the air above it to rise and creating a low-pressure zone, which draws in cooler, denser air from the high-pressure zone over the sea.
Land possesses a lower specific heat capacity than water. Consequently, it heats up much faster during the day. The warmed air above the land expands and rises, creating a region of low pressure. To balance this gradient, cooler, denser air from the higher pressure region over the ocean flows inland, generating a sea breeze.
Question 21.
In the context of biogeochemical cycles, what is the primary biological mechanism by which carbon is removed from the abiotic atmosphere and incorporated into the living biosphere?
(A) Cellular respiration by terrestrial animals
(B) The process of decomposition by soil microbes
(C) Photosynthesis by green plants and phytoplankton
(D) The physical dissolving of carbon dioxide into ocean water
Answer:
(C) Photosynthesis by green plants and phytoplankton
Photosynthesis is the major biological process wherein plants, algae and certain bacteria utilise solar energy to convert abiotic atmospheric carbon dioxide and water into complex organic compounds (glucose), thereby introducing carbon into the biotic food web.
Earth as a System Energy Matter and Life Class 9 Assertion and Reason Questions
Direction (Question Nos. 1 – 6): In each of the following questions, a statement of Assertion (A) is given by the corresponding statement of Reason (R). Of the statements, mark the correct answer as
A Both A and R are true and R is the correct explanation of A.
B Both A and R are true, but R is not the correct explanation of A.
C A is true, but R is false.
D A is false, but R is true.
Question 1.
Assertion (A) The equatorial regions are signifi-cantly warmer than the polar regions.
Reason (R) Due to the spherical shape of the Earth, solar radiation strikes the equator almost vertically, delivering concentrated heat, whereas it strikes the poles at a slanted angle, spreading the same heat over a larger area.
Answer:
(A) Both A and R are true and R is the correct explanation of A.
Direct rays concentrate heat; slanted rays spread it out.
Question 2.
Assertion (A) Ocean currents play a significant role in regulating the Earth’s climate.
Reason (R) Ocean currents transport heat from equatorial regions towards the poles.
Answer:
(A) Both A and R are true and R is the correct explanation of A.
Ocean currents redistribute heat by carrying warm water from equatorial regions to higher latitudes and cold water towards the equator. This heat transfer moderates global climate, thereby validating the assertion.
Question 3.
Assertion (A) A high concentration of green-house gases in the atmosphere leads to an increase in the Earth’s average temperature.
Reason (R) Greenhouse gases trap the long wave infrared radiation emitted by the Earth’s surface, preventing it from escaping into space.
Answer:
(A) Both A and R are true and R is the correct explanation of A.
Green house gases traps IR radiations emitted by Earth’s surface. Thereby, increasing earth’s temperature.
Question 4.
Assertion (A) The accelerated melting of Arctic sea ice contributes to a further increase in global atmospheric temperatures.
Reason (R) The open ocean water revealed by melting ice has a significantly lower albedo than the ice, leading to an increased absorption of solar radiation.
Answer:
(A) Both A and R are true and R is the correct explanation of A.
Ice reflects most sunlight, whereas dark ocean water absorbs it. As ice melts, more dark water is exposed, which absorbs more heat and consequently increases the warming effect.
Question 5.
Assertion (A) Almost all major weather pheno-mena, including the formation of clouds and precipitation, occur in the stratosphere.
Reason (R) The stratosphere contains the protective ozone layer, which actively absorbs highly energetic ultraviolet (UV) radiation from the Sun.
Answer:
(D) A is false, but R is true.
Weather phenomena predominantly occur in the troposphere, which is the lowest layer of the atmosphere. However, the reason correctly states that the stratosphere has the ozone layer and absorbs UV radiation.
Question 6.
Assertion (A) Photosynthesis and cellular respi-ration act as mutually interdependent processes within the global carbon cycle.
Reason (R) Photosynthesis extracts carbon dioxide from the atmosphere to synthesise organic matter, whereas cellular respiration breaks down organic matter, releasing carbon dioxide back into the atmosphere.
Answer:
(A) Both A and R are true and R is the correct explanation of A.
These two fundamental biological processes form a continuous loop, ensuring that the concentration of atmospheric carbon dioxide remains relatively stable and is systematically cycled through the biosphere.