water

Question 1

what is water

Answer 1

Water is a major component of cells. It has several properties that are important in biology

Question 2

water’s uses

Answer 2

is a metabolite in many metabolic reactions, including condensation and hydrolysis reactions

is an important solvent in which metabolic reactions occur

has a relatively high heat capacity, buffering changes in temperature

has a relatively large latent heat of vaporisation, providing a cooling effect with little loss of water through evaporation

has strong cohesion between water molecules; this supports columns of water in the tube-like transport cells of plants and produces surface tension where water meets air.

Question 3

shanti - chemical functions of water

Answer 3

water is a metabolite - molecule that participates in biochemical reactions as a reactant or product

water is a reactant - hydrolysis, photosynthesis

water as a product - condensation, respiration

Question 4

shanti - other properties and functions of water

Answer 4

universal solvent
- dissolves all polar molecules eg ions, amino acids
- molecules can be transported around the organism by dissolving in xylem, phloem, blood
- molecules can be dissolved eg in the cytoplasm - move easily, bind to active site of enzyme to form enzyme-substrate complex

high surface tension - the surface of the water gets stretched like a skin - insects, eg pond skaters can use water as a habitat

ice - less dense than water - floats on top and insulates the water underneath - aquatic habitat

cohesion - water molecules stick to each other by H-bonds - can be transported in continuous stream in xylem

transparent - light can pass through for aquatic plants to photosynthesise

high specific heat capacity of water - a lot of energy is required to raise the temp
- maintain a stable temp in aquatic habitats
- maintain a stable temp of cytoplasm for reactions to occur

high latent heat of fusion - a lot of energy is needed to convert liquid water to ice - aquatic habitats do not easily freeze

high latent heat of vaporisation - a lot of energy is required to convert liquid water to water vapour - evaporation of sweat cools down the body

Question 5

water - universal solvent

Answer 5

• dissolves all polar molecules eg ions, amino acids
• molecules can be transported around the organism by dissolving in xylem, phloem, blood
• molecules can be dissolved eg in the cytoplasm - move easily, bind to active site of enzyme to form enzyme-substrate complex

Question 6

water - high surface tension

Answer 6

the surface of the water gets stretched like a skin - insects, eg pond skaters can use water as a habitat

Question 7

water - ice

Answer 7

less dense than water - floats on top and insulates the water underneath - aquatic habitat

Question 8

water - cohesion

Answer 8

water molecules stick to each other by H-bonds - can be transported in continuous stream in xylem

Question 9

water - transparent

Answer 9

light can pass through for aquatic plants to photosynthesise

Question 10

water - high specific heat capacity

Answer 10

a lot of energy is required to raise the temp
- maintain a stable temp in aquatic habitats
- maintain a stable temp of cytoplasm for reactions to occur

Question 11

water - high latent heat of fusion

Answer 11

a lot of energy is needed to convert liquid water to ice - aquatic habitats do not easily freeze

Question 12

water - high latent heat of vapourisaton

Answer 12

a lot of energy is required to convert liquid water to water vapour - evaporation of sweat cools down the body

Question 13

why is water a polar molecule

Answer 13

Oxygen is more electronegative than Hydrogen - attracts the electron density in the covalent bond more strongly