Water

Question 1

bonding in water?

Answer 1

Weak hydrogen bonds form between water molecules due to the slightly positive hydrogen ions and slightly negative oxygen ions

Question 2

Water in Metabolic Reactions

Answer 2

• Required for photosynthesis
• Metabolic product of respiration which is important for organisms in dry habitats
• Hydrolysis and Condensation Reactions

Question 3

Water as a solvent

Answer 3

• to transport nutrients e.g glucose in the blood, sucrose in phloem
• to remove excretory products e.g urea in ammonia
• as a medium in which metabolic reactions occur

Question 4

Water for Temperature Regulation

Answer 4

• High heat capacity = absorbs large amount of heat energy (hydrogen bonds) before changing temperature preventing dangerous fluctuations on temperature in aquatic habitats
• Large latent heat of vaporisation = a cooling effect is provided with little loss of water which helps some animals maintain a constant body temperature

Question 5

Water for internal support

Answer 5

• Cohesive forces between water molecules support water columns in tube like transport cells (e.g. xylem) which allows transport
• Water is not easily compressed and therefore provides support in non woody plants via turgor pressure and sometimes in animals ( hydrostatic skeleton in earthworms)

Question 6

Water for external support

Answer 6

• Strong cohesive forces between the water molecules provide surface tension where the water meets the air and allows organisms such as pond skaters and mosquito larvae to be suspended at the surface
• Provides buoyancy for aquatic creatures (e.g. whales)