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MATSEC IM Environmental Science study materials
MATSEC IM Environmental Science study resources

MATSEC IM Environmental Science practice questions

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Question 1The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which gas makes up the largest proportion of Earth's dry atmosphere by volume?

  1. Oxygen
  2. Nitrogen Correct answer.
  3. Argon
  4. Carbon dioxide

Explanation

Dry air is roughly 78% nitrogen and 21% oxygen, with argon at about 0.9% and carbon dioxide near 0.04%. Nitrogen therefore dominates the atmosphere, while oxygen is the second most abundant gas.

Question 2The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which layer of Earth's interior is liquid and generates the main geomagnetic field through its motion?

  1. The continental crust
  2. The outer core Correct answer.
  3. The lower mantle
  4. The asthenosphere

Explanation

The outer core is molten iron-nickel, and its convective motion combined with planetary rotation drives the geodynamo. The inner core is solid, the mantle deforms slowly but is not liquid, and the crust is rigid rock.

Question 3The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process in the hydrological cycle returns water vapour from plants directly to the atmosphere?

  1. Infiltration
  2. Condensation
  3. Transpiration Correct answer.
  4. Precipitation

Explanation

Transpiration is the loss of water vapour through stomata in plant leaves, and together with evaporation from soil it forms evapotranspiration. Infiltration moves water into soil, condensation changes vapour to liquid, and precipitation delivers water downwards.

Question 4The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

At a convergent boundary where an oceanic plate meets a continental plate, which feature is typically produced?

  1. A rift valley bounded by normal faults
  2. A mid-ocean ridge with new basaltic crust
  3. A subduction trench and volcanic arc Correct answer.
  4. A transform fault with lateral sliding

Explanation

Oceanic lithosphere is denser than continental lithosphere, so it subducts and forms a deep trench with a volcanic arc above the descending slab. Mid-ocean ridges form at divergent boundaries, transform faults involve lateral motion, and rift valleys form where continental crust is pulled apart.

Question 5The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process removes carbon dioxide from the atmosphere over geological timescales by locking carbon into carbonate rocks?

  1. Respiration by soil microorganisms
  2. Combustion of fossil fuels
  3. Silicate weathering and carbonate deposition Correct answer.
  4. Volcanic degassing of magma

Explanation

Atmospheric carbon dioxide reacts with silicate minerals during chemical weathering, and the resulting bicarbonate is later precipitated as carbonate sediment on the sea floor. Respiration, fossil-fuel combustion, and volcanic degassing all add carbon to the atmosphere rather than removing it over long periods.

Question 6The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which group of organisms converts atmospheric nitrogen gas into ammonia compounds usable by plants?

  1. Denitrifying bacteria
  2. Decomposer fungi
  3. Nitrifying bacteria
  4. Nitrogen-fixing bacteria Correct answer.

Explanation

Nitrogen fixation, carried out by bacteria such as Rhizobium in root nodules and by free-living soil bacteria, reduces inert nitrogen gas to ammonia. Nitrifying bacteria oxidise ammonia to nitrate, denitrifiers return nitrogen to the atmosphere, and fungi mainly break down organic matter.

Question 7The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which type of rock forms when existing rock is altered by high heat and pressure without melting?

  1. Metamorphic rock Correct answer.
  2. Volcanic glass
  3. Sedimentary rock
  4. Igneous rock

Explanation

Metamorphism recrystallises minerals in the solid state under elevated temperature and pressure, producing rocks such as slate or schist. Igneous rocks crystallise from melt, sedimentary rocks form from deposited particles, and volcanic glass forms when lava cools too rapidly to crystallise.

Question 8The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which combination of changes would most likely strengthen the Atlantic Meridional Overturning Circulation?

  1. Melting Greenland ice and greater precipitation at high latitudes
  2. Higher surface salinity and stronger cooling at high latitudes Correct answer.
  3. Less evaporation in the subtropics and weaker trade winds
  4. More freshwater entering the North Atlantic and surface warming

Explanation

The overturning circulation is driven by density differences: cold, salty water at high latitudes sinks and forms deep water. Freshening from ice melt or precipitation and warming both reduce density and weaken sinking, whereas higher salinity and stronger cooling increase density and strengthen overturning.

Question 9The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Loss of Arctic sea ice tends to amplify regional warming mainly because open water absorbs more solar radiation than reflective ice. Which statement describes this feedback?

  1. Open water has a higher albedo than snow-covered ice
  2. Open water absorbs more solar radiation than reflective ice Correct answer.
  3. Sea ice releases large amounts of latent heat when it melts
  4. Ice formation removes heat from the ocean through conduction

Explanation

Ice has a high albedo and reflects most incoming shortwave radiation, whereas dark open ocean absorbs it and warms. This positive ice-albedo feedback increases heat uptake, melts more ice, and amplifies warming in the Arctic.

Question 10The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which statement best explains why phosphorus is often the limiting nutrient in freshwater ecosystems?

  1. It is produced mainly by denitrification in sediments
  2. It cycles rapidly through the atmosphere via volatilisation
  3. It has no gaseous phase and is released mainly by rock weathering Correct answer.
  4. It is abundant in the atmosphere and fixed by bacteria

Explanation

Phosphorus lacks a significant atmospheric reservoir; its main natural source is the slow weathering of phosphate-bearing rocks, so supply to fresh water is limited. Nitrogen, by contrast, has an atmospheric reservoir and is fixed biologically.

Question 11The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

In which atmospheric layer is most of the ozone that absorbs harmful ultraviolet radiation concentrated?

  1. Troposphere
  2. Mesosphere
  3. Thermosphere
  4. Stratosphere Correct answer.

Explanation

The stratosphere contains the ozone layer, where ozone molecules absorb most incoming ultraviolet radiation. This absorption warms the stratosphere and protects life at the surface.

Question 12The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process in the hydrological cycle changes water vapour into liquid droplets, forming clouds?

  1. Infiltration
  2. Condensation Correct answer.
  3. Evaporation
  4. Surface runoff

Explanation

Condensation occurs when moist air cools to its dew point, causing water vapour to form tiny liquid droplets. These droplets grow and combine to make cloud droplets.

Question 13The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which term describes igneous rock formed when lava cools quickly at Earth's surface?

  1. Extrusive Correct answer.
  2. Intrusive
  3. Foliated
  4. Clastic

Explanation

Extrusive igneous rock forms from lava that cools rapidly at the surface, so crystals are usually small. Intrusive rock cools slowly underground and tends to have larger crystals.

Question 14The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which microbial process converts nitrate to nitrogen gas and returns nitrogen to the atmosphere?

  1. Nitrification
  2. Ammonification
  3. Denitrification Correct answer.
  4. Assimilation by plants

Explanation

Denitrification is carried out by certain bacteria in anaerobic or low-oxygen soils and sediments. It reduces nitrate to nitrogen gas, which escapes to the atmosphere and closes the nitrogen cycle.

Question 15The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which surface condition would most increase overland flow after a heavy rainstorm?

  1. Dense vegetation cover
  2. A high infiltration capacity
  3. A gentle slope with deep soil
  4. An impermeable paved surface Correct answer.

Explanation

Overland flow increases when water cannot enter the soil quickly. Paved surfaces are impermeable, so a larger share of rainfall runs off rather than infiltrating.

Question 16The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Why does air temperature generally decrease with height in the troposphere?

  1. It contains the ozone layer, which cools with increasing altitude.
  2. Air pressure rises with height and removes thermal energy.
  3. It is heated from below, and rising air expands and cools. Correct answer.
  4. It absorbs most solar ultraviolet radiation directly from the Sun.

Explanation

The troposphere is warmed mainly by heat transferred from Earth's surface, not directly by the Sun. As air rises, lower pressure lets it expand, which uses energy and lowers its temperature.

Question 17The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

At a divergent boundary between two oceanic plates, which feature is typically produced?

  1. A volcanic island arc
  2. A deep ocean trench
  3. A fold mountain belt
  4. A mid-ocean ridge Correct answer.

Explanation

Divergent oceanic boundaries are where plates move apart and magma rises to fill the gap. This creates new oceanic crust and a mid-ocean ridge, often with a central rift valley.

Question 18The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

At a high-latitude Northern Hemisphere monitoring station, atmospheric CO2 concentration typically falls during summer. Which explanation best accounts for this seasonal drawdown?

  1. Lower rates of plant respiration in winter
  2. Increased ocean release of carbon dioxide
  3. Reduced fossil-fuel burning in summer
  4. Enhanced photosynthesis by Northern Hemisphere vegetation Correct answer.

Explanation

In summer, active Northern Hemisphere vegetation takes up CO2 through photosynthesis faster than respiration and decomposition release it. This seasonal biological uptake produces the observed summer decline in atmospheric CO2.

Question 19The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which condition most favors an artesian well?

  1. A thick clay layer immediately beneath the well screen
  2. A perched water table separated from the main aquifer by clay
  3. A confined aquifer with a potentiometric surface above the wellhead Correct answer.
  4. An unconfined aquifer whose water table lies below the well screen

Explanation

An artesian well taps a confined aquifer in which pressure raises the potentiometric surface above the wellhead. Water can then rise without pumping, sometimes flowing at the surface.

Question 20The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which combination best explains why coastal areas often have smaller annual temperature ranges than inland areas?

  1. Oceans receive more solar radiation per unit area than land at the same latitude.
  2. Land surfaces have lower albedo than water, so they absorb less sunlight.
  3. Water has a high heat capacity and mixes, storing and releasing heat slowly. Correct answer.
  4. Water evaporates only when warmer than the overlying air, which prevents cooling.

Explanation

Water absorbs and stores large amounts of heat for a relatively small temperature rise because of its high specific heat capacity. Ocean mixing and evaporation also spread and release heat slowly, moderating nearby coastal temperatures.

Question 21The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which term describes Earth's rigid outer shell, comprising the crust and the uppermost part of the mantle?

  1. Outer core
  2. Mesosphere
  3. Asthenosphere
  4. Lithosphere Correct answer.

Explanation

The lithosphere is the rigid outer shell that includes the crust and the uppermost mantle. It is broken into tectonic plates that move over the weaker, partially molten asthenosphere beneath.

Question 22The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which energy source drives most atmospheric circulation and the hydrological cycle on Earth's surface?

  1. Tidal forces from the Moon and Sun
  2. Chemical energy stored in rocks
  3. Geothermal heat from Earth's interior
  4. Solar radiation Correct answer.

Explanation

Solar radiation heats Earth's surface unevenly and provides the energy that drives evaporation, atmospheric convection and winds. Geothermal and tidal energy affect Earth systems but are far smaller drivers of weather and the hydrological cycle.

Question 23The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which property of water molecules explains their ability to dissolve many ionic compounds and transport nutrients in Earth systems?

  1. Polarity and hydrogen bonding Correct answer.
  2. High density in the solid state
  3. Low latent heat of vaporisation
  4. Low viscosity at room temperature

Explanation

Water molecules are polar and form hydrogen bonds, allowing them to surround and separate many ions and polar molecules. This solvent action is central to nutrient transport in soils, rivers and living organisms.

Question 24The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

An unsaturated parcel of air is cooled at constant water vapour content. Why does its relative humidity rise?

  1. The density of liquid water decreases substantially at lower temperatures.
  2. The saturation vapour pressure of water decreases as temperature falls. Correct answer.
  3. The actual water vapour pressure in the parcel increases sharply as the temperature falls.
  4. The parcel gains additional water vapour from the surrounding air as it cools.

Explanation

Relative humidity is the ratio of actual vapour pressure to saturation vapour pressure. Cooling at constant water vapour content lowers the saturation vapour pressure, so the ratio and relative humidity rise.

Question 25The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process transports carbon from the ocean surface to the deep ocean and sediments as sinking organic particles?

  1. Biological carbon pump Correct answer.
  2. Upwelling of deep water
  3. Sea-air gas exchange
  4. Carbonate dissolution

Explanation

The biological carbon pump moves carbon from the surface ocean to depth as organisms form organic matter and particles sink. Some of this carbon reaches sediments, where it can be stored for long periods.

Question 26The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

At a mid-ocean ridge, basaltic lava erupted underwater commonly forms which structure because the lava surface cools rapidly?

  1. Pillow lavas Correct answer.
  2. Continental rhyolite domes
  3. Contact metamorphic aureoles
  4. Layered intrusions

Explanation

Submarine basaltic lava is chilled rapidly by seawater, forming a solid skin that inflates into rounded pillow shapes. Repeated pillow eruptions build pile-like structures along mid-ocean ridges.

Question 27The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Thawing permafrost can create a positive climate feedback mainly because

  1. It decreases atmospheric water vapour and weakens the greenhouse effect.
  2. It increases albedo and reflects more solar radiation.
  3. It causes sea ice to form more rapidly in winter.
  4. It releases stored carbon as carbon dioxide and methane. Correct answer.

Explanation

Thawed permafrost exposes organic matter that microbes decompose, releasing carbon dioxide and methane. Because both are greenhouse gases, the extra warming can thaw more permafrost, creating a positive feedback.

Question 28The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which sequence explains a rain shadow on the leeward side of a mountain range?

  1. Air rises and cools on the windward side, then descends and warms on the leeward side. Correct answer.
  2. Air remains stationary on both sides, producing equal precipitation.
  3. Air descends continuously on the leeward side, cools as it sinks, and becomes more humid, causing heavy rain.
  4. Air rises and warms on the windward side, losing moisture before it crosses the ridge.

Explanation

Air is forced to rise over the windward slope, cooling and condensing water vapour to produce precipitation. On the leeward side the air descends, warms and becomes drier, creating a rain shadow.

Question 29The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

In a catchment over one year, precipitation is 900 mm, evapotranspiration is 450 mm, streamflow is 300 mm, and deep groundwater outflow is 100 mm. Assuming no other gains or losses, what is the change in catchment water storage?

  1. 0 mm
  2. +50 mm Correct answer.
  3. -50 mm
  4. +150 mm

Explanation

The catchment water balance is precipitation minus evapotranspiration, streamflow and deep groundwater outflow. Here 900 - 450 - 300 - 100 = 50 mm, so storage increases by 50 mm over the year.

Question 30The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Why is stratospheric ozone depletion most severe over Antarctica in spring?

  1. Antarctic ozone is depleted because the Antarctic continent emits large amounts of chlorofluorocarbons directly during the spring season.
  2. Sunlight is strongest over Antarctica in spring and directly destroys ozone without any catalytic chemical cycle.
  3. Polar stratospheric clouds and the vortex activate chlorine, and spring sunlight drives rapid ozone loss. Correct answer.
  4. Ozone depletion is strongest in spring because stratospheric temperatures are highest then.

Explanation

In the Antarctic spring, polar stratospheric clouds enable heterogeneous reactions that convert reservoir chlorine into active forms. The polar vortex isolates the air, and returning sunlight then drives rapid catalytic ozone destruction.

Question 31The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which gas makes up the largest proportion of the dry troposphere by volume?

  1. Argon
  2. Carbon dioxide
  3. Nitrogen Correct answer.
  4. Oxygen

Explanation

Dry tropospheric air is about 78% nitrogen and 21% oxygen by volume. Argon is close to 1%, and carbon dioxide is a trace gas near 0.04%. Nitrogen therefore dominates, even though oxygen is the second most abundant component.

Question 32The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process moves water from soil into the atmosphere through plant leaves?

  1. Groundwater recharge
  2. Transpiration Correct answer.
  3. Infiltration
  4. Surface runoff

Explanation

Plants take up soil water through their roots and release water vapour through stomata in a process called transpiration. This flux is often grouped with evaporation as evapotranspiration. It differs from runoff, infiltration, and recharge, which move liquid water through or across the landscape.

Question 33The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which rock type forms when existing rock is altered by heat and pressure without melting?

  1. Igneous
  2. Metamorphic Correct answer.
  3. Volcaniclastic
  4. Sedimentary

Explanation

Metamorphic rock forms when pre-existing rock recrystallises in the solid state under elevated temperature and pressure. Melting would produce magma and later igneous rock, not metamorphic rock. Sedimentary rock forms by deposition and lithification, while volcaniclastic material is produced by volcanic processes.

Question 34The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which feature of the phosphorus cycle most strongly limits phosphorus availability in undisturbed freshwater ecosystems?

  1. Rapid atmospheric fixation by bacteria
  2. A large gaseous reservoir in the troposphere
  3. High solubility of phosphate minerals in water
  4. Slow release from rocks and sediments Correct answer.

Explanation

Phosphorus has no significant gaseous phase in its biogeochemical cycle, so the atmosphere is not a major reservoir. Its main stores are phosphate minerals in rocks and sediments, which weather and release phosphate slowly. This low external input, together with strong recycling in the water column, makes phosphorus often limiting.

Question 35The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

In the Northern Hemisphere, horizontal air flow is deflected to the right of its path. Which factor directly causes this deflection?

  1. Pressure-gradient force
  2. Coriolis effect Correct answer.
  3. Frictional drag
  4. Buoyancy

Explanation

The Coriolis effect arises from Earth's rotation and deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. It acts only on air that is already moving, so it does not initiate motion. Pressure gradients start movement, friction slows it near the surface, and buoyancy mainly affects vertical motion.

Question 36The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which aquifer property most directly controls the rate at which groundwater can flow through a rock unit?

  1. Permeability Correct answer.
  2. Mineral hardness
  3. Bedding thickness
  4. Porosity

Explanation

Permeability describes how readily a material transmits fluid and depends on the size, shape, and connectedness of pore spaces. A highly porous rock can still be impermeable if its pores are isolated. Hardness and bedding thickness affect rock strength or structure but do not directly measure groundwater flow.

Question 37The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

At a convergent boundary where oceanic lithosphere meets continental lithosphere, why does the oceanic plate usually subduct?

  1. It is moving more slowly than continental lithosphere.
  2. It is thicker than continental lithosphere.
  3. It is denser than continental lithosphere. Correct answer.
  4. It is less dense than continental lithosphere.

Explanation

Oceanic lithosphere is composed mainly of denser mafic rock, while continental lithosphere is dominated by less dense felsic rock. At a convergent boundary, the denser oceanic plate bends and sinks into the asthenosphere beneath the continental plate. Plate speed alone does not determine which plate subducts; density contrast is the key control.

Question 38The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Over geological timescales, which process removes carbon dioxide from the atmosphere by converting it into dissolved bicarbonate and carbonate minerals?

  1. Silicate rock weathering Correct answer.
  2. Photosynthesis in surface ocean waters
  3. Combustion of fossil fuels
  4. Respiration by soil organisms

Explanation

Chemical weathering of silicate minerals consumes atmospheric carbon dioxide and produces dissolved bicarbonate, which can later form carbonate minerals. This process transfers carbon from the atmosphere to the lithosphere over long timescales. Photosynthesis and respiration cycle carbon rapidly, while fossil-fuel combustion adds carbon dioxide to the atmosphere.

Question 39The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

As Arctic sea ice melts, the exposed ocean has a lower albedo than the ice. What effect does this change have within the climate system?

  1. It reduces evaporation and weakens the water cycle.
  2. It prevents further sea ice loss by increasing ocean salinity.
  3. It increases reflection of solar radiation and cools the region.
  4. It increases solar absorption and amplifies warming. Correct answer.

Explanation

Ice has a high albedo and reflects much of the incoming solar radiation, whereas dark ocean water absorbs more solar energy. Replacing ice with open water therefore adds heat to the ocean and promotes further ice loss, a positive ice-albedo feedback. The feedback amplifies the initial warming rather than reversing it.

Question 40The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

In high-latitude oceans, which combination of surface conditions most strongly promotes the formation of deep water masses?

  1. Warm, low-salinity water
  2. Cold, high-salinity water Correct answer.
  3. Cold, low-salinity water
  4. Warm, very high-salinity water

Explanation

Seawater density increases as temperature falls and salinity rises. At high latitudes, surface cooling and salt enrichment through sea-ice formation can make surface water dense enough to sink and form deep water masses. Warm or fresher water is less dense, so those combinations do not favour deep convection.

Question 41The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which layer of Earth's interior is liquid and responsible for generating the planet's magnetic field?

  1. The inner core
  2. The lithosphere
  3. The outer core Correct answer.
  4. The lower mantle

Explanation

The outer core is molten iron and nickel. Its convection, together with Earth's rotation, generates the geodynamo that produces the magnetic field. The inner core is solid because of immense pressure, while the mantle and lithosphere are not liquid.

Question 42The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which rock type forms when magma cools slowly beneath Earth's surface, producing large interlocking crystals?

  1. Extrusive igneous rock
  2. Sedimentary rock
  3. Intrusive igneous rock Correct answer.
  4. Metamorphic rock

Explanation

Slow cooling of magma at depth allows atoms time to arrange into large interlocking crystals, which is characteristic of intrusive igneous rock. Extrusive igneous rock cools quickly at the surface and is typically fine-grained. Metamorphic and sedimentary rocks form by other processes.

Question 43The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which property of water allows large water bodies to absorb and release heat with only small temperature changes, moderating coastal climates?

  1. Its high latent heat of vaporisation
  2. Its high specific heat capacity Correct answer.
  3. Its low viscosity
  4. Its high surface tension

Explanation

Specific heat capacity is the energy needed to raise the temperature of a unit mass by one degree. Water's high value means it absorbs or releases large amounts of heat with little temperature change, so coastal areas have milder climates. Latent heat concerns phase changes, while surface tension and viscosity do not control heat storage.

Question 44The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Air rises near the equator in the Hadley cell and sinks near 30° latitude. Which surface winds blow from the subtropical highs toward the equator?

  1. Monsoon winds
  2. Westerlies
  3. Trade winds Correct answer.
  4. Polar easterlies

Explanation

Trade winds blow from the subtropical high-pressure belt toward the equatorial low-pressure belt. Coriolis deflection makes them north-easterly in the Northern Hemisphere and south-easterly in the Southern Hemisphere. Westerlies lie farther poleward, polar easterlies are near the poles, and monsoons are seasonal reversals.

Question 45The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Why does a rising parcel of unsaturated air cool even if it does not exchange heat with its surroundings?

  1. It expands and does work as pressure falls Correct answer.
  2. It radiates heat rapidly to outer space
  3. It mixes with cold stratospheric air
  4. It condenses vapour and releases latent heat

Explanation

As the parcel rises, surrounding pressure falls, so the parcel expands and does work on the surrounding air. This uses internal energy and lowers the parcel's temperature, which is adiabatic cooling. Radiation, mixing with stratospheric air, and condensation are not the cause; condensation would release latent heat and warm the parcel.

Question 46The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which process converts atmospheric nitrogen gas into ammonia or related compounds that plants can use?

  1. Biological nitrogen fixation Correct answer.
  2. Denitrification
  3. Ammonification
  4. Nitrification

Explanation

Biological nitrogen fixation uses bacteria such as Rhizobium to convert inert atmospheric N2 into ammonia or ammonium that plants can assimilate. Nitrification later converts ammonium to nitrate, denitrification returns nitrogen to the atmosphere, and ammonification releases ammonium from dead organic matter.

Question 47The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

Which chemical weathering process is mainly responsible for dissolving limestone and forming caves?

  1. Carbonation Correct answer.
  2. Oxidation
  3. Hydration
  4. Hydrolysis

Explanation

Rainwater absorbs carbon dioxide and forms weak carbonic acid, which reacts with calcium carbonate in limestone and dissolves it. This carbonation process enlarges fractures and can produce caves and karst features. Oxidation, hydrolysis, and hydration act mainly on other minerals and do not dissolve limestone in the same way.

Question 48The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

In a wet climate, which soil process removes soluble nutrients such as nitrate from the upper soil layers?

  1. Erosion
  2. Capillary rise
  3. Leaching Correct answer.
  4. Salinisation

Explanation

Leaching is the downward movement of dissolved ions through soil as percolating water carries them below the root zone. In wet climates this removes mobile nutrients such as nitrate and can make soils acidic and nutrient-poor. Salinisation, erosion, and capillary rise move or accumulate material differently.

Question 49The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

During a strong El Niño event, what happens to the Walker circulation and coastal upwelling off Peru?

  1. Upwelling reverses as the Humboldt Current turns and flows northward
  2. Upwelling strengthens as trade winds intensify and cold water rises faster
  3. Upwelling stops as the thermocline deepens strongly in the western Pacific
  4. Upwelling weakens as trade winds slacken and warm water shifts east Correct answer.

Explanation

El Niño involves weaker easterly trade winds, which reduce equatorial upwelling and allow warm surface water to spread eastward across the Pacific. The thermocline deepens in the eastern Pacific, so nutrient-rich water no longer reaches the surface and fisheries decline. The other options describe La Niña or unrelated circulation changes.

Question 50The physical environment: Earth systems, atmosphere, hydrosphere, lithosphere and biogeochemical cycles

What produces the symmetrical pattern of magnetic stripes on either side of a mid-ocean ridge?

  1. Movement of magnetic minerals by deep-sea currents after formation
  2. Magnetic field reversals recorded in newly formed oceanic crust Correct answer.
  3. Seasonal changes in solar radiation affecting ocean crust
  4. Alternating layers of sediment deposited by ocean currents

Explanation

As basaltic magma cools at a mid-ocean ridge, magnetic minerals align with Earth's field at that time. When the field reverses, alternating normal and reversed polarity stripes are locked into the new crust, and sea-floor spreading carries them symmetrically away from the ridge. Sediment layers, solar cycles, and post-formation currents do not create this pattern.