water

Question 1

Describe the formation of a hydrogen bond between two molecules of water and explain why water can form these bonds.

Answer 1

1 between O and H (of adjacent molecules) ;
2 between , electropositive / δ+
/ delta+
(H), and ,
electronegative / δ-
/ delta-
(O) ;
3 water molecule , is polar / has charge separation ;

Question 2

Hydrogen bonds allow water to act as a solvent.Why is the ability of water to act as a solvent important for the survival of organisms?

Answer 2

medium for (metabolic) reactions ;
(because) allows (named) ionic compound(s) to
separate ;
transport ;
two named transport , systems / media
OR
one example of a transport , medium / system , with a
named example of what is transported ;
(organisms can) absorb / take in , (named) minerals /
ions / (named) gas / food ;
able to dilute toxic substances ;

Question 3

Example of water as transport medium

Answer 3

• minerals in lakes and seas
• removal of metabolic waste eg urea and ammonia in urine
• blood and lymph transport

Question 4

Thermoregulation

Answer 4

• high heat capacity means organisms are thermostat or and less prone to heat damage
• cooling of organisms due to high latent heat of vaporisation; releases energy eg sweating

Question 5

Lubricant properties and examples

Answer 5

• cohesive and adhesive; making it viscous
• synovial fluid in joints
• pleural fluid ; lungs and thoracic cage during breathing
• mucus; easy passage of faeces, lubricates vagina and penis during sex

Question 6

Solvent properties

Answer 6

• polarity; solvent for other polar molecules

Question 7

Metabolic functions

Answer 7

• reagent in photosynthesis
• hydrolysed macromolecules in digestions
• medium for biochemical reactions to take place

Question 8

• density and freezing properties

Answer 8

• when cools as molecules slow down and form max hydrogen bonds
• expands when it freezes, less dense than liquid water; ice floats

Question 9

High latent heat of vaporisation

Answer 9

• high energy needed to vaporise water
• hydrogen bonds continuous attract to other water molecules
• high boiling point