Unit 1 - ATP, Water + Inorganic Ions

Question 1

During respiration what happens to the energy?

Answer 1

During respiration, the energy stored in glucose is not released directly, instead the energy released is used to form adenosine triphosphate (ATP). ATP is then hydrolysed providing energy for processes in the cell.

Question 2

Structure of ATP?

Answer 2

It is made up of adenine (same base as found in DNA), ribose sugar and 3 phosphate groups.

Question 3

Structure of ATP diagram?

Question 4

ATP is a nucleotide derivative. What is a nucleotide derivative?

Answer 4

It is a modified version of a nucleotide.

Question 5

What are the differences between A DNA nucleotide and ATP?

Answer 5

ATP has a ribose sugar, A DNA nucleotide has deoxyribose.
ATP has 3 phosphates, A DNA nucleotide has 1 phosphate.
ATP always has adenine as the base, A DNA nucleotide can have adenine, thymine, guanine and cytosine.

Question 6

Examples of what energy is used for in the cell?

Answer 6

Active transport
Synthesising molecules
Mitosis - contraction of spindle fibres
Muscle contraction

Question 7

Why does the hydrolysis of ATP release energy?

Answer 7

ATP is NOT energy. It contains stored energy in the bond between the 2nd and 3rd phosphate. This high energy bond is broken using hydrolysis and the energy is released.

Question 8

Equation for the hydrolysis of ATP?

Answer 8

ATP + Water = ADP + Pi+ Energy

Question 9

What can the released Pi in the hydrolysis of ATP do?

Answer 9

It can be added to other compounds to make them more reactive, this is known as phosphorylation.

Question 10

What is the enzyme called that carries out a phosphorylation?

Answer 10

A kinase

Question 11

What are the 2 processes where ATP is made?

Answer 11

Respiration and photosynthesis.

Question 12

What type of reaction is used to make ATP?

Answer 12

A condensation reaction.

Question 13

Equation for the making of ATP?

Answer 13

ADP + Pi = ATP + Water

Question 14

The condensation of ATP requires what enzyme?

Answer 14

ATP synthase.

Question 15

What does ADP stand for?

Answer 15

Adenosine diphosphate.

Question 16

Definition of an inorganic ion?

Answer 16

Inorganic-means that it does NOT contain carbon.
Ion-and atom or a compound which has a positive or negative electrical charge.

Question 17

Iron (Fe2+) ions?

Answer 17

They’re found in the protein haemoglobin, in red blood cells. They oxygen binds to the ion and transports oxygen to respiring cells. Haemoglobin has a quaternary structure with 4 polypeptide chains, each with 1Fe2+, so each haemoglobin can carry 4 oxygen molecules.

Question 18

Hydrogen (H+) ions?

Answer 18

They determine the pH of a solution. The higher the concentration of H+ ions, the lower the pH of the solution (more acidic). A high or low concentration of H+can denature proteins including enzymes and so affect enzyme rate of reactions. H+ ions are also used in photosynthesis and respiration, along with ATP synthase, for the formation of ADP and Pi.

Question 19

Sodium ions?

Answer 19

They’re involved in the absorption of glucose into the blood. They’re co-transported along with glucose into the epithelial cells of the small intestine down a Na+ concentration gradient. Na+ are also involved with the production of electrical impulses in neurones. Na+ are also involved with water reabsorprion in the kidneys.

Question 20

Phosphate (PO4 3+) ions?

Answer 20

Phosphate ions are added to ADP to produce ATP in a condensation reaction during photosynthesis and respiration. They can also be added to other molecules (phosphorylation) to make them more reactive. It is also used to join DNA and RNA nucleotides together via phosphodiester bonds in the sugar phosphate backbone. They also make up the hydrophilic part of the phospholipid bilayer.

Question 21

Chemical structure of water?

Answer 21

Water contains bonds between the hydrogen and oxygen atoms. The negative electrons in the bond are pulled towards the oxygen and away from the hydrogen. This makes the oxygen slightly negative and the hydrogen slightly positive. Water is therefore polar as it has an opposite charge each end of the molecule.

Question 22

What is the bonding like between water molecules?

Answer 22

Weak hydrogen bonds are formed between molecules where the slightly negative oxygen on 1 water molecule is attracted to the slightly positive hydrogen on a different water molecule. This gives water its useful properties.

Question 23

What properties does hydrogen bonding give water?

Answer 23

The hydrogen bonds between water molecules means they show cohesion. Cohesion allows water to be pulled in a continuous column in the xylem of plants. Cohesion also gives water surface tension which can support small organisms such as pond skaters and form droplets on skin for sweating.

Question 24

What is waters use in reactions?

Answer 24

It is a metabolite in hydrolysis reactions, condensation reactions, photosynthesis and respiration.

Question 25

What is waters use as a solvent?

Answer 25

Water acts as a solvent which allows:
-chemical reactions to occur in solution
-the transport of substances

Question 26

Why does water act as a solvent?

Answer 26

Because water is polar.

Question 27

Definition of a solvent?

Answer 27

A solvent is a substance which allows other substances to dissolve into it forming a solution.

Question 28

Definition of latent heat of vaporisation?

Answer 28

It is the energy required for a liquid to turn into a gas.

Question 29

Use of water in cooling body temp?

Answer 29

Water has a large latent heat of vaporisation. This means that for water to turn from a liquid into a gas the hydrogen bonds must be broken which requires a lot of energy. This is useful in cooling body temp with sweating/panting as a lot of heat energy can be removed through evaporation of water without losing too much water, reducing dehydration.

Question 30

Definition of specific heat capacity?

Answer 30

It is the energy needed to raise the temp of 1g of a substance by 1•C.

Question 31

What is waters use in preventing large changes in body temp?

Answer 31

Water has a high specific heat capacity. It takes a lot of energy to increase the temp of water as most energy is used to break the hydrogen bonds rather than release heat to increase the temperature. This is useful to organisms as:
-buffers the change in body temp (preventing denaturing of enzymes if too hot or reducing enzyme activity if too cold).
-makes water a good habitat as the temperature does not change.

Question 32

In summary, what is waters properties and how do they relate to its function?

Answer 32

1) metabolite-used in condensation and hydrolysis reactions.
2) solvent-allows reactions to occur in the cell and for the transport of substances.
3)high heat capacity-buffers changes in body temperature.
4) large latent heat of vaporisation-provided a cooling effect with little loss of water through evaporation.
5) cohesion between water molecules due to hydrogen bonding-supports columns of water during the transport of water in the xylem of plants and produces surface tension to support small organisms.