atp&water

Question 1

what does atp stand for

Answer 1

adenine triphosphate

Question 2

structure of atp

Answer 2

three phosphate groups
ribose
nitrogenous base

Question 3

how is the energy in atp stored

Answer 3

in high energy bonds between the phosphate groups

Question 4

how is energy in atp released

Answer 4

via hydrolysis

Question 5

atp hydrolysis reaction

Answer 5

1. when energy is needed by a cell, atp is broken down into adp (adenine diphosphate) and p (inorganic phosphate).
2. a phosphate bond is broken and energy is released. this reaction is catalysed by the enzyme atp hydrolase.

Question 6

atp condensation reaction

Answer 6

atp can be resynthesised in a condenstaion reaction between adp and p . it is catalysed by atp synthase.
this occurs during respiration and photosynthesis.

Question 7

what can atp hydrolysis be used for

Answer 7

the energy released in atp hydrolysis reaction can coupled to other energy requiring reactions occur, rather than being lost as heat.

Question 8

what can inorganic phosphate do

Answer 8

it can be added to another compound, making the compound more reactive (phosphorylation).

Question 9

four water functions

Answer 9

1. water is a metabolite in lots of metabolic reactions (condensation and hydrolysis reactions)
2. water is a solvent, helpful as most metabolic reactions occur in solution (cytoplasm)
3. water helps with temperature control as it has a high latent heat of vaporisation and high specific heat capacity.
4. water molecules are very cohesive which helps transport in organisms.

Question 10

structure of water

Answer 10

1. a molecule of water is one atom of oxygen joined to two molecules of hydrogen by shared electrons.
2. bc the shared negative hydrogen electrons are pulled towards the oxygen atom, the other side of each hydrogen atom is left w a slight positive charge.
3. the unshared negative electrons on the oxygen atom gives it a slight negative charge.

Question 11

why is water a polar molecule

Answer 11

it has a partial negative charge on one side and a partial positive charge on the other side

Question 12

hydrogen bonding

Answer 12

when the slightly negatively charged oxygen atoms attract the slightly positive hydrogen atoms of other water molecules.

Question 13

water is an important metabolite

Answer 13

1. many metabolic reactions involve a condensation or hydrolysis reaction.
2. hydrolysis reaction requires a molecule of water to break a bond. e.g. energy from atp is released via hydrolysis.
3. condensation reaction releases a molecule of water as a new bond is formed. e.g. amino acids are joined together to form polypeptides by condensation reaction.

Question 14

water has a high latent heat of vaporisation

Answer 14

1. since it takes a lot of energy to break the hydrogen bonds between water molecules, it takes a lot of energy for water to evaporate.
2. this is useful for living organisms bc it means they can use water loss through evaporation to cool down without losing too much water e.g. sweating.

Question 15

water can resist changes in temperature

Answer 15

1. the hydrogen bonds between water molecules can absorb a lot of energy so it takes a lot of energy to heat it up.
2. this is useful for living organisms because it means that water doesn’t experience temperature changes, making it a good habitat as the temperature under water is more stable than on land.
3. water inside organisms also remain at a fairly stable temperature to help maintain a constant internal body temperature.

Question 16

water is a good solvent

Answer 16

1. a lot of important substance in metabolic reactions are ionic. because water is polar, the positive end of a water molecule will be attracted to the negative ion and the negative end will be attracted to the positive ion.
2. this means that ions will get totally surrounded by water molecules and dissolve.

Question 17

there is strong cohesion between water molecules

Answer 17

1. water molecules are cohesive because they are polar.
2. strong cohesion helps water flow, good for transporting substances e.g. xylem.
3. strong cohesion also means that water has a high surface tension when in contact with air. e.g. sweat forms droplets, some insects can “walk on water”