Topic 2 - Environmental Cycles

Question 1

The Water Cycle

Answer 1

The cycling of water through the lithosphere, biosphere, hydrosphere, and atmosphere. It’s driven by solar energy.

Question 2

Transpiration

Answer 2

• Water is absorbed by plants from the soil though their roots.
• The water travels up the stem of the plant to the leaves.
• The water is releases into the atmosphere through stomata.

Question 3

Condensation

Answer 3

• Cooling of water vapour (gas) in atmosphere.
• Water vapour condenses into water droplets (liquid) – forming clouds

Question 4

Precipitation

Answer 4

• Water drops formed by condensation fall to earth.
• Can fall as rain, snow, or hail (depends on how cold it is).

Question 5

Surface Run Off

Answer 5

• Refers to the movement of water over the land surface.
• Runoff ends in streams, rivers, lakes, and oceans.
• Can transport sediment, nutrients, and pollutants to other areas.

Question 6

Infiltration

Answer 6

• Precipitation that falls onto land can soak into the soil, refilling groundwater sources.

Question 7

Ground Water Flow

Answer 7

• Water that infiltrates into the soil becomes groundwater, which slowly moves through underground aquifers.

Question 8

Aquifer

Answer 8

A layer of rock or soil that can hold and transmit groundwater, serving as an important source of fresh water for drinking, irrigation, and other uses.

Question 9

Evaporation

Answer 9

• The sun heats bodies of water such as oceans, lakes and rivers.
• Causes water to change from liquid water to water vapour (gas) and rise into the atmosphere.

Question 10

Freezing

Answer 10

• Freezing converts water from the liquid state to the solid state.
• Acts as water storage.
• Removed from the water cycle until it is melted again.

Question 11

Melting

Answer 11

• Converts ice and snow back into liquid water.
• After melting, snow and ice refills rivers, lakes, and oceans.

Question 12

Sublimation

Answer 12

• Transforms a solid straight into a gas (skips liquid phase).
• Ice ➡️ water vapour

Question 13

Deposition

Answer 13

• Transforms a gas straight into a solid (skips liquid phase).
• Forms ice, snow, and glaciers.

Question 14

Percolation

Answer 14

• The movement of water through soil and rock.

Question 15

The Carbon-Oxygen Cycle

Answer 15

The cycle that transfers carbon through the atmosphere, lithosphere, biosphere, and hydrosphere.

Question 16

Volcanic Eruptions

(in the carbon-oygen cycle)

Answer 16

Release large amounts of carbon dioxide into the atmosphere.

Question 17

Carbon Sequestration

Answer 17

• On land, plants take in carbon dioxide to use in photosynthesis and store within their tissues (cells)
• In the ocean, phytoplankton and other marine organisms take in carbon through photosynthesis.
• Oceans also dissolve carbon dioxide.
• CO2 combines with the water and forms calcium formation of calcium carbonate shells.

Question 18

Cellular Respiration

Answer 18

• Animals eat the plants and take in O2 to power cellular respiration, and then release CO2 into the atmosphere.
• Works with photosynthesis to act as carbon transfer between organisms.

Question 19

Photosynthesis

Answer 19

• Plant cells absorb solar energy, carbon dioxide and water and convert them into oxygen, water and glucose (energy).
• Works with cellular respiration to act as carbon transfer between organisms.

Question 20

Decomposition

Answer 20

• When organisms die, their organic matter becomes available for decomposition by decomposers.
• Decomposers break down complex organic molecules (like glucose) into simpler compounds (such as CO2)

Question 21

Fossilisation and Unavailable Carbon

Answer 21

• Involves the burial and transformation of organic matter into fossil fuels such as coal, oil, and natural gas.
• Removes carbon from the cycle as it is transformed into fossil fuels.
• Once fossil fuels are formed, they remain underground until extracted.

Question 22

Combustion of Fossil Fuels

Answer 22

• When burned, fossil fuels release large amounts of carbon dioxide into the atmosphere.
• Fossil fuels are burned for energy production, transportation, industrial processes, and heating.
• Not part of natural carbon cycle (human impact).

Question 23

Limestone and Weathering

Answer 23

• Limestone is primarily composed of calcium carbonate (CaCO3)
• Calcium carbonate reacts with acids found in rainwater and soil.
• Produces CO2 which is released into the atmosphere.

Question 24

Deforestation and Fires

Answer 24

• When trees and vegetation are cut down, burned, or left to decay, the carbon stored in their tissues and cells is released into the atmosphere as CO2.
• Also results in the loss of carbon sinks.

Question 25

The Nitrogen Cycle

Answer 25

The nitrogen cycle transforms and circulates nitrogen in various forms through Earth’s spheres.

Question 26

Atmospheric Nitrogen Fixation

Answer 26

• Lightning strikes generate enough energy to separate nitrogen gas (N2) into nitric oxide (NO) and nitrogen dioxide (NO2)
• These smaller molecules dissolve in water droplets in clouds - forming nitric acid.
• Nitric acid is transported to the Earth’s surface through precipitation.

Question 27

Assimilation of Nitrites, Nitrates and Ammonia by Plants

Answer 27

Plants and some microorganisms take up ammonium (NH4+) and nitrate ions from the soil to use in cell processes.

Question 28

Consumption

Answer 28

Animals acquire organic nitrogen by consuming plants or other animals.

Question 29

Ammonification

Answer 29

• Decomposers (bacteria and fungi) break down nitrogen compounds found in dead organisms and other organic matter.
• Converts them to ammonia or ammonium ions.
• These simpler forms of nitrogen are released back into the soil.

Question 30

Volcanic Eruptions

Answer 30

• Volcanic eruptions release nitrogen gas straight into the atmosphere.
• Heat and pressure created by eruptions leads to transformation of atmospheric nitrogen into nitrogen oxides.
• Reacts with water vapour to form precipitation.

Question 31

Denitrification by Bacteria

Answer 31

• Denitrifying bacteria convert nitrate (NO3-) and nitrite (NO2-) ions into nitrogen gas.
• Nitrogen gas is returned to the atmosphere, where it can be accessed again by nitrogen-fixing bacteria.

Question 32

Nitrogen Fixation by Bacteria

Answer 32

• Atmospheric N2 is converted into ammonia or ammonium ions by nitrogen-fixing bacteria found in the soil.

Question 33

Nitrification

Answer 33

• Ammonia (from nitrogen fixation) is converted to nitrite ions by nitrifying bacteria.
• Nitrite ions are then oxidized into nitrate ions by other nitrifying bacteria (Nitrobacter).