6. ATP epqs Flashcards
Give two ways in which the hydrolysis of ATP is used in cells.
- To provide energy for other reactions/named process;
Reject ‘produce’ energy
- To add phosphate to other substances and make them more
Cells constantly hydrolyse ATP to provide energy.
(a) Describe how ATP is resynthesised in cells.
- From ADP and phosphate;
Reject P/Phosphorus
Reject use of water in the reaction - By ATP synthase;
- During respiration/photosynthesis;
ATP is an energy source used in many cell processes. Give two ways in
which ATP is a suitable energy source for cells to use.
- Releases relatively small amount of energy / little energy lost as
heat;
Key concept is that little danger of thermal death of
cells
- Releases energy instantaneously;
Key concept is that energy is readily available
- Phosphorylates other compounds, making them more reactive;
- Can be rapidly re-synthesised;
- Is not lost from / does not leave cells.
The new antibiotic is safe to use in humans because it does not inhibit the
ATP synthase found in human cells.
Suggest why human ATP synthase is not inhibited and bacterial synthase
is inhibited.
Human ATP synthase has a different tertiary structure to
bacterial ATP synthase
OR
Human ATP synthase has a different shape active site to
bacterial ATP synthase
OR
Antibiotic cannot enter human cells/mitochondria
OR
Antibiotic not complementary (to human ATP synthase);
the equation which
represents the reaction catalysed by ATP synthase.
ADP + Pi ⟶ ATP + H2O
4.88 × 10–6 ;;;
If answer incorrect
EITHER
Allow 1 mark for 0.244
Allow 1 mark for 1.22 × 10–5
OR
Allow 1mark for 12200 / 1.525
Allow 1 mark for 0.61
Describe and explain the pattern shown by the data in the table.
Description
- As concentration of ATP increases, length of muscle decreases;
Accept negative correlation
Explanation
2. More ATP (hydrolysed by ATP hydrolase), so more energy
released, so more muscle contraction / shortening of muscle;
Hydrolysis of ATP is catalysed by the enzyme ATP hydrolase.
A student investigated the effect of ATP concentration on the activity of ATP
hydrolase. She used shortening of strips of muscle tissue caused by contraction
as evidence that ATP was being hydrolysed.
* She took four slides A, B, C and D, and added strips of muscle tissue of
the same length to each slide.
* She then added the same volume of ATP solutions of different
concentrations to the four slides and left each slide for five minutes.
* She then recorded the final length of each strip of muscle tissue.
Other than those given, name two variables the student should have
controlled.
- Species / organism the muscle tissue came from;
OR
Thickness / type / source of the muscle tissue;
Ignore surface area of muscle tissue
- Temperature of the muscle tissue / ATP solution / slides;
Need to be qualified
3. pH of the ATP solution;
Water is used to hydrolyse ATP.
Name the two products of ATP hydrolysis.
Adenosine diphosphate and (inorganic) phosphate;
Describe how an ATP molecule is formed from its component molecules. (4)
- and 2. Accept for 2 marks correct names of three components adenine,
ribose/pentose, three phosphates;;
Accept for 1 mark, correct name of two components
Accept for 1 mark, ADP and phosphate/Pi
Ignore adenosine
Accept suitably labelled diagram
- Condensation (reaction);
Ignore phosphodiester - ATP synthase;
Give two advantages of ATP as an energy-storage molecule within a cell.
Cannot pass out of cell;
Quickly / easily broken down (hydrolysed) / broken
down in a on-step reaction / immediate source of energy;
Stores / releases small amounts of energy;
Describe how NAD is regenerated in anaerobic respiration in yeast cells.
Formed when reduced NAD used to reduce / donate H ions
to pyruvate / convert pyruvate to ethanol;
Describe the part played by the inner membrane of a mitochondrion in
producing ATP. (3)
Electrons transferred down electron transport chain;
Provide energy to take protons / H+ into space between membranes;
Protons / H+ pass back, through membrane / into matrix / through ATPase;
Energy used to combine ADP and phosphate / to produce ATP;
A scientist investigated ATP production in a preparation of isolated mitochondria.
He suspended the mitochondria in an isotonic solution and added a suitable
respiratory substrate together with ADP and phosphate. He bubbled oxygen through
the preparation.
(i) Why was the solution in which the mitochondria were suspended isotonic?
(ii) Explain why the scientist did not use glucose as the respiratory substrate.
(iii) Explain why the oxygen concentration would change during this investigation.
(i) Prevent damage to mitochondria caused by
water / osmosis / differences in water potential;
Accept: other terms that imply damage e.g. shrink / burst
1
(ii) Glucose is used / broken down during glycolysis in cytoplasm / not in
mitochondria;
Accept: ‘glucose is converted to pyruvate’ for description of
breakdown
Glucose cannot cross mitochondrial membrane / does not
enter mitochondria;
Accept: only pyruvate can
2
(iii) Terminal / final acceptor (in electron transport chain) / used to
make water; (1)
Humans synthesise more than their body mass of ATP each day. Explain why it is
necessary for them to synthesise such a large amount of ATP.
Give two ways in which the properties of ATP make it a suitable source of energy in
biological processes.
- Energy released in small / suitable amounts;
- Soluble;
- Involves a single / simple reaction;
Write a simple equation to show how ATP is synthesised from ADP.
ADP + Pi → ATP;
