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All 20 Flashcards — Properties of water that support life
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Question
What does it mean that water is polar?
Answer
Water has an uneven charge distribution: oxygen is slightly negative and the hydrogen atoms are slightly positive, creating a dipole.
💡 Hint
Uneven charges (dipole).
Question
What is a hydrogen bond in water?
Answer
A weak attraction between the slightly positive hydrogen of one water molecule and the slightly negative oxygen of another water molecule.
💡 Hint
Weak between molecules.
Question
What is the difference between cohesion and adhesion in water?
Answer
Cohesion is attraction between water molecules; adhesion is attraction between water molecules and other surfaces (like soil or plant tissue).
💡 Hint
Water-water vs water-surface.
Question
Why is water called an excellent solvent?
Answer
Because its polarity allows it to surround and separate ions and other polar molecules, so they dissolve and can be transported.
💡 Hint
Polarity helps dissolve ions.
Question
Give one environmental importance of surface tension in water.
Answer
Surface tension (from cohesion) supports small organisms at the surface and helps water move through plants via capillary action.
💡 Hint
Think: small insects, plants.
Question
Define specific heat capacity.
Answer
The energy required to raise the temperature of 1 kg of a substance by 1°C.
💡 Hint
Energy to warm 1 kg by 1°C.
Question
Why do oceans moderate coastal climates?
Answer
Water has a high specific heat capacity, so oceans heat up and cool down slowly, reducing temperature extremes near coasts.
💡 Hint
Slow temperature change.
Question
What is latent heat in the context of water?
Answer
Energy absorbed or released during a phase change (melting/evaporation/condensation) without a temperature change.
💡 Hint
Phase change energy.
Question
How does evaporation cool the environment?
Answer
Evaporation requires energy (latent heat) which is taken from the surroundings, reducing local temperature.
💡 Hint
Energy is taken from the surface.
Question
Why is water vapour considered a positive feedback in climate?
Answer
Warming increases evaporation, adding more water vapour (a greenhouse gas) which increases warming further.
💡 Hint
Warming → more vapour → more warming.
Question
What is water’s density anomaly?
Answer
Water is less dense as a solid than as a liquid, so ice floats on liquid water.
💡 Hint
Ice floats.
Question
Why does ice floating matter for aquatic ecosystems in winter?
Answer
Floating ice forms an insulating layer so water below stays liquid, allowing aquatic organisms to survive.
💡 Hint
Insulation effect.
Question
What is the photic zone?
Answer
The upper layer of water where light penetrates enough for photosynthesis to occur.
💡 Hint
Where photosynthesis happens.
Question
How does turbidity affect aquatic productivity?
Answer
Turbidity reduces light penetration, shrinking the photic zone and lowering photosynthesis and primary productivity.
💡 Hint
Cloudier water = less light.
Question
Give one link between water clarity and biodiversity.
Answer
Clear water allows deeper light penetration, supporting more photosynthetic organisms and often higher biodiversity in the photic zone.
💡 Hint
More light supports more life.
Question
What is the main reason water has unique properties?
Answer
Hydrogen bonding between polar water molecules causes unusual thermal, density, and solvent properties.
💡 Hint
H-bonds drive the properties.
Question
Name two water properties that help regulate climate.
Answer
High specific heat capacity and high latent heat (especially during evaporation and condensation).
💡 Hint
Heat storage + phase change.
Question
How does water’s polarity support life in ecosystems?
Answer
It makes water a solvent for ions and polar molecules, enabling nutrient transport and chemical reactions in organisms.
💡 Hint
Solvent for nutrients.
Question
Why is ice floating described as life-saving for lakes?
Answer
Because it prevents lakes from freezing solid, keeping liquid water and habitat available below the ice.
💡 Hint
Liquid water remains below.
Question
Exam skill: Link water’s properties to an ESS outcome in one sentence.
Answer
Hydrogen bonding makes water a stable climate buffer and a life-supporting solvent, shaping ecosystem productivity and survival.
💡 Hint
Mechanism → outcome.
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Full study notes for Properties of water that support life
Topic 4.1 hub
Water systems
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