PRACTICE EXAM QUESTIONS
1 The diagram below shows some of the stages
in anaerobic respiration in a muscle.
Hexose
(b). i. Name the process shown by stages A to
C.
[1]
ii. State where in a cell this process
occurs.
[1]
(c). i. Give two uses of ATP in cells.
[2]
ii. At which of the stages shown in the
diagram is ATP used?
[1]
(d). NADH + H is a reduced coenzyme which
is involved in anaerobic respiration
At which of the stages shown is NADH +
H+ oxidised?
[1]Total 6 marks
LONDON
Stage A
Hexose bisphosphate
Stage B
Glycerate 3-phosphate
Stage C
Pyruvate
+
2
Stage D
Lactic acid
(a). The inner membrane of a mitochondrion is folded to form cristae. Suggest how this
folding is a adaptation to the function of a mitochondrion.[2]
(b). The equation represents oxidation of a lipid.
C57H104O6 + 80O2 → 57CO2 + 52H2O + Energy
Use the equation to calculate the Respiratory. Quotient (R.Q.) of this lipid. Show
your working
[1]
(c). Suggest an explain for each of the following:
i. the R.Q. of germinating maize grains is 1;
[1]
ii. the R.Q. of a normal, healthy person varies over a 24 hour period.
[1]
[Total 5 marks]
3
Copy and complete the table with a tick if the statement is true about the particular
stage of respiration.
Statement
Stage of respiration
ATP produced
Carbon dioxide
produced
Reduced NAD
converted to
NAD
Glucose → pyruvate
Pyruvate→
acetylcoenzyme
Krebs cycle
Electron carrier chain
[4]
(b). The graph shows the volume of oxygen consumed and the volume of carbon
dioxide released by a small animal over a 15 minute period.
Showing your working in each case, use the graph to calculate:
i. the rate of oxygen consumptions;
ii. the respiratory quotient (R.Q). of this animal over the 15 minute period.
4
[1]
[2]
Mitochondria are organelles that are thought to have entered into a mutualistic existence
with cells many millions of years ago. They are surrounded by a double membrane
system and are usually 0.5 µm – 1.0 µm in length. The inner membrane is folded into
structures called cristae and the space inside is called the matrix. Mitochondria possess
proteins called cytochromes. They also contain small circle of DNA which code for a few
of the mitochondrial proteins. Mitochondria have the biochemical machinery needed for
carrying out some protein synthesis.
Liver cells have between 1000 and 2000 mitochondria which can occupy up to 20% of
the cell volume.
a)Use information in the passage to answer the following.
i.
Outline two pieces of evidence
suggesting that mitochondria
originally existed outside
eukaryotic cells as free living organisms.[2]
ii.
Suggest why mitochondria can no longer
exist as free living organisms.[1]
iii.
Suggest why liver has so many mitochondria.[1]
iv. Explain the significance of the folding of the
inner mitochondrial membrane.[2]
(b). The figure below represents the main
stages of aerobic respiration.
State precisely where the reactions in boxes
A, B and C occur in the cell. [3]
c)iWhat substance is X?[1]
ii)A total of 38 molecules of ATP is formed during
the complete breakdown of one molecule of glucose.
State how many molecules are formed at each of
the stages A, B and
C.[2]``````````````````````````````````````````````````````````````````````````````````````````````````````````````
`````````````````````````````````````````````````````````````````````````````````
iii)If glucose is burned, the energy transferred as heat and light is 2881 kJ mol-1. In the
reactions described above, some of the energy is retained in the form of ATP. The energy
‘trapped’ in ATP is 50 kJ mol – 1. Calculate the percentage of the energy made available from
the breakdown of one molecule of glucose which is retained for biological reactions in the
cell. Show your working
[3]
5
(a). The diagram below shows a section through
electron microscope
i.
ii.
a mitochondrion as seen using an
Name the parts labelled A, B and C.
[3]
On the diagram, by means of an arrows, show the location of the electron
transport system.
[1]
iii.
The magnification of this diagram is ×70 000. Calculate the actual length of
the mitochondrion, giving your answer in suitable units. Show your working
[2]
(b). Active mitochondria can be isolated from liver cells. If these mitochondria are than
incubated in a buffer solution containing a substrate, such as succinate, dissolved
oxygen will be used by the mitochondria. The concentration of dissolved oxygen in
the buffer solution can be measured using the electrode. An experiment was carried
out in which a suspension of active mitochondria was incubated in a buffer solution
containing succinate, an intermediate of the Krebs cycle. The concentration of
dissolved oxygen was measured every minute for five minutes. A solution
containing sodium azide was then added to this preparation and the concentration
of dissolved oxygen was measured for a further five minutes. Sodium azide
combines with cytochromes and prevents electron transport. The results are shown
in the graph below.
i.
ii.
Explain why the concentration of oxygen decreased during the first five
minutes.[2]
Suggest what effect the addition of sodium azide will have on the production of
ATP and give an explanation for your answer.
[3]
[Total 11 marks]