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level: 2.4 Water and its function

Questions and Answers List

level questions: 2.4 Water and its function

QuestionAnswer
The dipolar water molecule- Has positive and negative poles - So its dipolar
Water and hydrogen bonding- Opposite charged molecules attract, hydrogen bonding - Each bond is fairly weak - Together they form important forces that cause cohesion
Specific heat capacity of water- Takes lots of energy to separate molecules - So the boiling point of water is higher than expected - Water acts as a buffer against sudden temperature variations
Latent heat of vaporisation of water- A lot of energy needed to evaporate 1 gram of water as molecules held together by hydrogen bonds
Cohesion and water- Molecules sticking together - Allows it to be pulled through tubes e.g xylem
Surface tension and water- When water molecules meet air they tend to be pulled back into the body of water rather than escaping it - Its strong enough to support small organisms
Water in metabolism- Water used in hydrolysis + condensation reactions - Needed in photosynthesis - Chemical reactions take place in aqueous mediums
Water as a solventDissolves: - Gases such as O and CO2 - Ammonia and urea - Inorganic ions and small hydrophilic molecules
Other important features of water- Evaporation cools organisms, controls temperature - Not easily compressed, provides support - Transparent, aquatic plants can photosynthesise
Inorganic ions- Found in cytoplasm and bodily fluids
Functions of inorganic ions- Iron ions are found in haemoglobin, transport oxygen - Phosphate ions have a structural role in DNA and ATP - Hydrogen ions are important in determining pH - Sodium ions in the co-transport of glucose and amino acids