Water

Question 1

Cohesion and adhesion

Answer 1

Cohesion and adhesion describe different properties of water molecules. Cohesion is interaction among water molecules, while adhesion is interaction between water molecules and a surrounding material or surface.

Question 2

Specific heat

Answer 2

The specific heat capacity is the amount of energy needed to heat up one gram of water by one degree Celsius. The latent heat of vaporisation is the amount of energy needed to change water liquid into water vapour (gas).

Question 3

Cohesive properties benefit

Answer 3

• Allows water to be pulled up from the roots to the leaves of plants.
• Permits insects, such as pond skaters, to walk/float on the surface of water to catch their prey.

Question 4

Adhesive properties

Answer 4

• Capillary action generated by adhesive forces assists the pumping action of the heart to help blood move through blood vessels.
• Adhesion of water molecules to the cell wall of xylem vessels helps water move against gravity from the roots to the leaves.

Question 5

Thermal properties

Answer 5

• Evaporation of sweat from body surfaces involves heat loss, which brings about a cooling effect.
• The high specific heat capacity of water makes aquatic ecosystems more stable than terrestrial.

Question 6

Solvent properties

Answer 6

• Water dissolves mineral ions in the soil and transports it along xylem vessels from the roots to all parts of the plant.
• Water in blood plasma dissolves a range of solutes and gases, which makes it possible for blood to transport nutrients and gases around the body
• Water’s versatility (its ability to exist as a liquid, solid and vapour) makes water a universal solvent and medium for numerous biochemical reactions.

Question 7

high latent heat of vaporisation

Answer 7

which can be defined as the amount of heat 1 g of a liquid absorbs to change its state, from liquid to gaseous.

Question 8

Water is a __

Answer 8

Water is also a great coolant. A large amount of energy is needed to turn liquid water into water vapour. This means that water has a high latent heat of vaporisation

Question 9

Specific heat

Answer 9

Specific heat is the amount of heat that must be absorbed or released for 1   g of a substance to change its temperature by 1   °C.

Question 10

Glucose

Answer 10

As a polar molecule, glucose is soluble in water so it can be transported in the blood. Blood glucose concentration needs to be strictly maintained between certain levels because of its effect on osmotic potential

Question 11

Amino acids

Answer 11

These are both negatively and positively charged. Most of them are soluble in water. However, their solubility varies depending on their size and the R group. Amino acids with a hydrophilic R group will be easily dissolved in water and transported in the blood. If amino acids contain a hydrophobic R group, they will not be easily dissolved in water and will be transported in lower concentrations in the blood.

Question 12

Fats

Answer 12

As they are nonpolar, fats are generally insoluble in water and therefore are transported in structures called lipoproteins (a single layer of phospholipids with proteins embedded among the molecules surrounding the fat).

Question 13

Cholesterol

Answer 13

Cholesterol is required for the synthesis of many biologically important molecules and is a component of membranes. It requires the help of transport lipoproteins to be transported in blood because it is hydrophobic.

Question 14

Oxygen

Answer 14

Oxygen is nonpolar, however, due to its small size it is soluble in water to a limited extent. This is why oxygen transported in the blood is bound to the protein called hemoglobin.

Question 15

Sodium chlorid

Answer 15

As an ionic compound, sodium chloride is transported in blood in the form of Na + and Cl - ions . These ions are easily dissolved in water