3 ready-made review sets for this topic, 26 questions in all, marked SL or HL, to play as a class game on the projector. Free to host, and students join with a code.
Water entering the soil from the surface?
Topic 4 covers water systems (the stores and flows of the hydrological cycle), water access, use and security, aquatic food production (phytoplankton, fisheries, maximum sustainable yield and aquaculture), and water pollution: eutrophication, and measuring water quality with BOD and water quality indices. At higher level it adds the thermocline, upwelling and thermohaline circulation, water stress, hypoxia, and indicator species and biotic indices.
Play this set opens the set in splycr, where you can read every question and host it for your class straight away. Hosting needs no account, and students join with the code on the board. A free account lets you copy a set and edit it.
The questions come from the Biology by Bradford flashcard bank. Each one plays as multiple choice, and the wrong options are other answers from the same set.
ESS has had a higher level course since the guide first assessed in 2026. Sets marked SL suit every ESS student, because higher level students study the standard level content too. Sets marked HL cover the additional higher level material in topics 2 to 8; Topic 1 has none, so its sets are all SL. The three HL lenses (environmental law, economics and ethics) have no sets yet.
Water entering the soil from the surface?
Answer: Infiltration
Underground layer of permeable rock or sediment that stores groundwater, which can be extracted through wells?
Answer: Aquifer
Limited availability of water due to actual physical shortage or lack of infrastructure?
Answer: Water scarcity
The highest annual harvest that can be sustained indefinitely without depleting the stock?
Answer: Maximum sustainable yield (MSY)
Measure of dissolved oxygen consumed by microorganisms decomposing organic matter in water; indicates pollution?
Answer: Biochemical oxygen demand (BOD)
Excessive nutrient enrichment of water causing algal blooms, oxygen depletion and ecosystem damage?
Answer: Eutrophication
Ocean circulation driven by differences in water temperature and salinity (density); distributes heat globally?
Answer: Thermohaline circulation
Distinct boundary layer in a water body between warmer surface water and cooler deep water?
Answer: Thermocline
Score calculated from the presence and abundance of pollution-tolerant and pollution-intolerant species at a site?
Answer: Biotic index
Every set plays in all eight modes. These two fit this topic best.
The answers are short (upwelling, BOD, aquaculture), so the bomb moves fast and every student answers many times, and everyone plays to the last explosion.
Sabotage runs to a clock you set (3, 5 or 8 minutes), not through the deck, so the questions keep coming until time is up. Power cards (freeze, steal, swap, shield) keep a student who is behind in the game.