Water

Question 1

role of water

Answer 1

-major component in cells

Question 2

explain how hydrogen bonds occur between water molecules

Answer 2

-water is polar molecule
-slightly negatively charged oxygen atoms attract slightly positively charged hydrogen atoms of other water molecules

Question 3

list 5 properties of water that are important in biology

Answer 3

-metabolite
-solvent (can dissolve solutes)
-(relatively) high specific heat capacity
-(relatively) large latent heat of vaporisation
-strong cohesion between water molecules

Question 4

explain the importance of water being a metabolite

Answer 4

-used in condensation / hydrolysis / photosynthesis / respiration

Question 5

explain the importance of water being a solvent

Answer 5

1. allows metabolic reactions to occur (faster in solution)
2. allows transport of substances eg. nitrates in xylem, urea in blood

Question 6

explain the importance of water having a relatively high specific heat capacity

Answer 6

-buffers changes in temperature
-as can gain / lose a lot of heat / energy without changing temperature
1. good habitat for aquatic organisms as temperature more stable than land
2. helps organisms maintain a constant internal body temperature

Question 7

explain the importance of water having a relatively large latent heat of vaporisation

Answer 7

-allows effective cooling via evaporation of a small volume (eg. sweat)
-so helps organisms maintain a constant internal body temperature

Question 8

explain the importance of water having strong cohesion between water molecules

Answer 8

1. supports columns of water in tube-like transport cells of plants
   eg. transpiration stream through xylem in plants
2. produces surface tension where water meets air, supporting small
   organisms (to walk on water)