ESS IB EXAM 2024 QUESTIONS &
ANSWERS 100% CORRECT
Biochemical oxygen demand (BOD) - ANSWERSAmount of oxygen required by aquatic bacteria to
decompose given load of organic waste; a measure of water pollution.
Biotic index - ANSWERSA measure of water quality that uses the diversity and abundance of organisms
living within it.
Deep water currents - ANSWERSDeep ocean currents are driven by density and temperature gradients.
Thermohaline circulation is also known as the ocean's conveyor belt (which refers to deep ocean density-
driven ocean basin currents).
Eutrophication - ANSWERSexcessive richness of nutrients, particularly phosphorus and nitrogen, in a lake
or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life
and death of animal life from lack of oxygen.
Fishery - ANSWERSAn area with a large population of valuable ocean organisms;
a commercially harvestable population of fish within a particular ecological region
Indicator species - ANSWERSSpecies that serve as early warnings that a community or ecosystem is being
degraded.
Water budget - ANSWERSDescribes the income and the spending of water in a region;
A summation of inputs, outputs, and net changes to a water system, such as a groundwater basin, or an
entire state, over a fixed period
Water pollution - ANSWERSAny physical or chemical change in surface water or groundwater that can
harm living organisms or make water unfit for certain uses.
,surface water - ANSWERSWater above the surface of the land, including lakes, rivers, streams, ponds,
floodwater, and runoff.
ground water - ANSWERSunderground water that is held in the soil and in pervious rocks
hydrology - ANSWERSthe study of water and its effects on and in the earth and in the atmosphere
salination - ANSWERScontamination of soil by salt water;
process in which plants are rendered incapable of growth by salts deposited into topsoil through
continual irrigation
phosphates - ANSWERSPhosphorous-based nutrients commonly found in fertilizers and pesticides;
can cause serious water quality issues when running into a body of water.
hydroelectric - ANSWERSElectricity generated by flowing water
desalination - ANSWERSThe process of obtaining fresh water from salt water by removing the salt.
upwelling - ANSWERSThe movement of cold water upward from the deep ocean that is caused by wind.
cloud seeding - ANSWERSthe scattering of chemicals into clouds to bring about rain
watershed - ANSWERSan area or ridge of land that separates waters flowing to different rivers, basins, or
seas;
An area of land that drains into a river or lake.
el nino - ANSWERSan irregularly occurring and complex series of climatic changes affecting the
equatorial Pacific region and beyond every few years, characterized by the appearance of unusually
warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.
,la nina - ANSWERS"Normal" year, easterly trade winds and ocean currents pool warm water in the
western Pacific, allowing upwelling of nutrient rich water off the West coast of South America.
zone of saturation - ANSWERSRegion below Earth's surface where all the pores of a material are
completely filled with groundwater.
turnover time - ANSWERSThe time required to replace all water in a system (e.g. groundwater) through
the water cycle in years.
water table - ANSWERSThe upper level of the saturated zone of groundwater;
the top of the saturated zone
recharge zone - ANSWERSan area in which water travels downward to become part of an aquifer;
area above an aquifer
xeriscaping - ANSWERSa method of landscaping that uses plants that are well adapted to the local area
and are drought resistant;
landscaping using native plants, which minimize the need for additional water
potable water - ANSWERSWater that is safe for humans to drink
grey water - ANSWERSwater that can be used for a second time (e.g. bath water used to water the
garden).
black water - ANSWERSWater that contains animal, human or food waste and would not be reused for
other purposes
effluent - ANSWERSthe waste from a range of human activities that is discharged into water bodies
hatchery - ANSWERSplace for hatching eggs of fish, hens, etc
, phytoplankton - ANSWERSMicroscopic, free-floating, autotrophic organisms that function as producers
in aquatic ecosystems
turbidity - ANSWERSA measure of how clear water is.
algae bloom - ANSWERSRapid increase in the population of algae in an aquatic system usually due to an
abundance of nutrients: sometimes lowers water's DO.
spawning - ANSWERSmethod of reproduction in fishes and some other animals where a large number of
eggs are fertilized outside of the body
carrying capacity - ANSWERSLargest number of individuals of a population that a environment can
support
raceway - ANSWERSalso known as a flow-through system, is an artificial channel used in aquaculture to
culture aquatic organisms
dissolved oxygen - ANSWERSoxygen dissolved in water, dissolved oxygen is important for fish and other
aquatic animals
non-point source pollution - ANSWERSPollution that enters a body of water from a large area, such as
lawns, farms, construction sites, and roads;
water pollution that does not have a specific point of origin
point source pollution - ANSWERSPollutants discharged from a single identifiable location (e.g., pipes,
ditches, channels, sewers, tunnels, containers of various types).
leaching - ANSWERSremoval of dissolved materials from soil by water moving downwards through soil.
dead zone - ANSWERSa location within a body of water that does not have enough dissolved oxygen to
sustain life.
ANSWERS 100% CORRECT
Biochemical oxygen demand (BOD) - ANSWERSAmount of oxygen required by aquatic bacteria to
decompose given load of organic waste; a measure of water pollution.
Biotic index - ANSWERSA measure of water quality that uses the diversity and abundance of organisms
living within it.
Deep water currents - ANSWERSDeep ocean currents are driven by density and temperature gradients.
Thermohaline circulation is also known as the ocean's conveyor belt (which refers to deep ocean density-
driven ocean basin currents).
Eutrophication - ANSWERSexcessive richness of nutrients, particularly phosphorus and nitrogen, in a lake
or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life
and death of animal life from lack of oxygen.
Fishery - ANSWERSAn area with a large population of valuable ocean organisms;
a commercially harvestable population of fish within a particular ecological region
Indicator species - ANSWERSSpecies that serve as early warnings that a community or ecosystem is being
degraded.
Water budget - ANSWERSDescribes the income and the spending of water in a region;
A summation of inputs, outputs, and net changes to a water system, such as a groundwater basin, or an
entire state, over a fixed period
Water pollution - ANSWERSAny physical or chemical change in surface water or groundwater that can
harm living organisms or make water unfit for certain uses.
,surface water - ANSWERSWater above the surface of the land, including lakes, rivers, streams, ponds,
floodwater, and runoff.
ground water - ANSWERSunderground water that is held in the soil and in pervious rocks
hydrology - ANSWERSthe study of water and its effects on and in the earth and in the atmosphere
salination - ANSWERScontamination of soil by salt water;
process in which plants are rendered incapable of growth by salts deposited into topsoil through
continual irrigation
phosphates - ANSWERSPhosphorous-based nutrients commonly found in fertilizers and pesticides;
can cause serious water quality issues when running into a body of water.
hydroelectric - ANSWERSElectricity generated by flowing water
desalination - ANSWERSThe process of obtaining fresh water from salt water by removing the salt.
upwelling - ANSWERSThe movement of cold water upward from the deep ocean that is caused by wind.
cloud seeding - ANSWERSthe scattering of chemicals into clouds to bring about rain
watershed - ANSWERSan area or ridge of land that separates waters flowing to different rivers, basins, or
seas;
An area of land that drains into a river or lake.
el nino - ANSWERSan irregularly occurring and complex series of climatic changes affecting the
equatorial Pacific region and beyond every few years, characterized by the appearance of unusually
warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.
,la nina - ANSWERS"Normal" year, easterly trade winds and ocean currents pool warm water in the
western Pacific, allowing upwelling of nutrient rich water off the West coast of South America.
zone of saturation - ANSWERSRegion below Earth's surface where all the pores of a material are
completely filled with groundwater.
turnover time - ANSWERSThe time required to replace all water in a system (e.g. groundwater) through
the water cycle in years.
water table - ANSWERSThe upper level of the saturated zone of groundwater;
the top of the saturated zone
recharge zone - ANSWERSan area in which water travels downward to become part of an aquifer;
area above an aquifer
xeriscaping - ANSWERSa method of landscaping that uses plants that are well adapted to the local area
and are drought resistant;
landscaping using native plants, which minimize the need for additional water
potable water - ANSWERSWater that is safe for humans to drink
grey water - ANSWERSwater that can be used for a second time (e.g. bath water used to water the
garden).
black water - ANSWERSWater that contains animal, human or food waste and would not be reused for
other purposes
effluent - ANSWERSthe waste from a range of human activities that is discharged into water bodies
hatchery - ANSWERSplace for hatching eggs of fish, hens, etc
, phytoplankton - ANSWERSMicroscopic, free-floating, autotrophic organisms that function as producers
in aquatic ecosystems
turbidity - ANSWERSA measure of how clear water is.
algae bloom - ANSWERSRapid increase in the population of algae in an aquatic system usually due to an
abundance of nutrients: sometimes lowers water's DO.
spawning - ANSWERSmethod of reproduction in fishes and some other animals where a large number of
eggs are fertilized outside of the body
carrying capacity - ANSWERSLargest number of individuals of a population that a environment can
support
raceway - ANSWERSalso known as a flow-through system, is an artificial channel used in aquaculture to
culture aquatic organisms
dissolved oxygen - ANSWERSoxygen dissolved in water, dissolved oxygen is important for fish and other
aquatic animals
non-point source pollution - ANSWERSPollution that enters a body of water from a large area, such as
lawns, farms, construction sites, and roads;
water pollution that does not have a specific point of origin
point source pollution - ANSWERSPollutants discharged from a single identifiable location (e.g., pipes,
ditches, channels, sewers, tunnels, containers of various types).
leaching - ANSWERSremoval of dissolved materials from soil by water moving downwards through soil.
dead zone - ANSWERSa location within a body of water that does not have enough dissolved oxygen to
sustain life.
