Water and Inorganic Ions

Question 1

why is water dipolar?

Answer 1

it has an unevenly distributed charge due to the oxygen being slightly negative and the hydrogen being slightly positive

Question 2

what bonds form between the water molecules between the H and the O?

Answer 2

hydrogen bonds

Question 3

how is water a metabolite?

Answer 3

It’s used in many reactions
-approximately 90% of the plasma in the blood is water
-cytoplasm in cells is mainly water too

Question 4

how is water a good solvent?

Answer 4

polar molecules dissolve in water because it’s dipolar, they’re hydrophilic
- positive hydrogen atoms attract negative solutes
- negative oxygen atoms attract positive solutes

Question 5

what does it mean when water has a high specific heat capacity?

Answer 5

a lot of energy is required to raise the temperature of water by breaking the H bonds
- temperature of water remains stable for enzymes to work optimally

Question 6

what does it mean when water has a large latent heat of vaporisation?

Answer 6

a lot of energy is required to convert water into a gas
- heat energy from the skin is transferred to the water to evaporate it
- provides a cooling effect (eg. sweating)
- due to H bonds needing to be broken

Question 7

why is the fact that water is cohesive and advantage?

Answer 7

water molecules stick together to produce a continuous column of water up the xylem
-easier to draw up a column rather than individual molecules
provides surface tension to water
-allows smaller animals to move and live on the surface away from predators

Question 8

what bonds form between the O and H within a water molecule?

Answer 8

covalent

Question 9

where do inorganic ions occur in an organism?

Answer 9

the cytoplasm

Question 10

what is ATP composed of?

Answer 10

3 phosphate ions, a ribose molecule and an adenine molecule

Question 11

why is ATP a good source of energy?

Answer 11

• releases energy in small manageable amounts so none is wasted
• small and soluble so can be easily transported around the cytoplasm
• only 1 bond is broken to release energy immediately
• energy can be transferred to another molecule by transferring a Pi group (phosphorylation - making other compounds more reactive)
• can’t pass out the cell so the cell always has a supply of energy

Question 12

why is the phosphate group described as inorganic?

Answer 12

because it doesn’t contain carbon

Question 13

how is ATP made?

Answer 13

• in respiration
• from ADP by adding a Pi via a condensation reaction using ATP synthase

Question 14

how is ATP hydrolysed?

Answer 14

by removing water using the enzyme ATP hydrolase