Water & Inorganic Ions

Question 1

What is the structure of water?

Answer 1

• dipolar (oxygen=negative, hydrogen=positive)
• hydrogen bonds

Question 2

What is the function of water as a metabolite?

Answer 2

• involved in lots of reactions (photosynthesis, hydrolysis, condensation)
• product of respiration (advantageous for organisms in dry habitats)

Question 3

What is the function of water as a solvent?

Answer 3

• many polar substances dissolve in it
• can be easily transported around animals/plants (in blood/xylem)
• removes excretory products e.g urea
• used as medium for metabolic reactions to occur

Question 4

What is the advantage of water having a high specific heat capacity?

Answer 4

• lots of energy required to raise temp of water (needed to break hydrogen bonds)
• means temp remains relatively stable even if surrounding temp fluctuates
• provides stable environment for aquatic organisms

Question 5

What is the advantage of water having a large latent heat of vaporisation?

Answer 5

• lots of energy required to convert water from liquid to gas (due to hydrogen bonds)
• advantageous to organisms as water provides cooling effect (e.g. sweating)

Question 6

What is the function of water having strong cohesion?

Answer 6

• water molecules ‘stick’ together by hydrogen bonds
• internal support: continuous column of transport (e.g. transpiration), not easily compressed
• external support: provide surface tension where water meets air - enables insects to walk on surface (e.g. pond skaters), also provides buoyancy for aquatic organisms

Question 7

What is the function of sodium?

Answer 7

Co-transport of glucose + amino acids across cell membranes

Question 8

What is the function of Iron?

Answer 8

Component of haemoglobin which transports oxygen

Question 9

What is the function of hydrogen?

Answer 9

Determining pH and thus affecting protein structure/enzyme activity

Question 10

What is the function of phosphate?

Answer 10

Structural component of DNA, RNA and ATP