Author: Philip Colls
Document comments: Created by the \'abHTML to RTF .Net\'bb 5.8.2.9

Respiration Booklet revision questions                  NAME:
Q1. Some plant seeds can respire aerobically and anaerobically. A summary of the process of anaerobic respiration is shown below.
 
(a)     (i)      Where in a cell does stage 1 occur?
_________________________________________________________________(1)
(ii)      Explain how stage 2 enables stage 1 to continue.
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(b)     The Respiratory Quotient (RQ) can provide information on the type of respiration taking place in an organism. The following equation is used to calculate the RQ.
 
(i)      What would be the RQ for aerobic respiration of glucose?
 
(1)
(ii)      A student calculated that the RQ of germinating seeds was 1.8. Use the information provided to explain this result.
______________________________________________________________
______________________________________________________________
______________________________________________________________
____________________________________________________________(2)
(c)     Aerobic respiration produces more ATP per molecule of glucose than anaerobic respiration. Explain why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
 (2)   (Total 8 marks)
Q2. The diagram represents two of the stages of aerobic respiration that take place in a mitochondrion.
 
(a)     Name substance X.
_________________________________________________________________(1)
(b)     Which stage of aerobic respiration takes place inside a mitochondrion and is not represented on the diagram?
_________________________________________________________________(1)
(c)     Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________(3)  (Total 5 marks)
Q3. (a)     The table contains statements about three biological processes. Complete the table with a tick if the statement in the first column is true, for each process.
 
| | Photosynthesis | Anaerobic respiration | Aerobic respiration
| ATP produced | | |
| Occurs in organelles | | |
| Electron transport chain involved | | |
(3)
(b)     Write a simple equation to show how ATP is synthesised from ADP.
_________________________________________________________________(1)
(c)     Give two ways in which the properties of ATP make it a suitable source of energy in biological processes.
1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
_________________________________________________________________(2)
(d)     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.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
__________________________________________________(2)  (Total 8 marks)
Q4. (a)     Describe how acetylcoenzyme A is formed in the link reaction.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
________________________________________________________________(2)
(b)     In the Krebs cycle, acetylcoenzyme A combines with four-carbon oxaloacetate to form six-carbon citrate. This reaction is catalysed by the enzyme citrate synthase.
(i)      Oxaloacetate is the first substrate to bind with the enzyme citrate synthase. This induces a change in the enzyme, which enables the acetylcoenzyme A to bind.
Explain how oxaloacetate enables the acetylcoenzyme A to then bind to the enzyme.
______________________________________________________________
______________________________________________________________
______________________________________________________________
____________________________________________________________ (2)
(ii)     Another substance in the Krebs cycle is called succinyl coenzyme A. This substance has a very similar shape to acetylcoenzyme A. Suggest how production of succinyl coenzyme A could control the rate of the reaction catalysed by citrate synthase.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
____________________________________________________________(2)
(c)     In muscles, pyruvate is converted to lactate during anaerobic respiration.
(i)      Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
____________________________________________________________(2)
(ii)     In muscles, some of the lactate is converted back to pyruvate when they are well supplied with oxygen. Suggest one advantage of this.
______________________________________________________________
______________________________________________________________
______________________________________________________________
_______________________________________________(1)  (Total 9 marks)
Q5. Yeast cells can respire aerobically or anaerobically. A student used the apparatus shown in Figure 1 to measure the rate of respiration in yeast.
She:
•        positioned the flask in a water bath so that the yeast culture reached a constant temperature
•        then left the apparatus for one hour before starting her investigation.
Figure 1

(a)     Suggest one reason why it was important that the student left the apparatus for one hour after the yeast culture reached a constant temperature.
___________________________________________________________________
________________________________________________________________(1)
(b)     During her investigation, the coloured liquid moved to the right. Explain why it moved to the right.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(c)     The student found that the coloured liquid moved 1.5 cm in 24 hours. The diameter of the lumen (hole) of the capillary tubing was 1 mm.
The volume of a capillary tubing is given by πr^2l, where π is 3.14 and l = length. Calculate the volume of gas produced in cm^3 hour^–1. Show your working.
Answer = ____________________ cm^3 hour^–1     (2)
Figure 2 shows a typical population growth curve for yeast under laboratory conditions.
Figure 2

(d)     Explain why a log scale is used to record the number of cells.
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(1)
(e)     Many yeast cells die during the death phase. Suggest one reason why.
___________________________________________________________________
___________________________________________________________________
________________________________________________________________(1)
(f)      The following equation can be used to make predictions of the growth in the population of yeast cells under ideal laboratory conditions.
X_t = X_0 e^rt
X_t = the population after a certain time
X_0 = the population at the start
e = 2.72 (base of natural logarithm)
r = growth rate
t = time period in hours over which r applies
A population of 2000 yeast cells was left for 10 hours. The value for the growth rate was 0.5  Assuming no yeast cells died, calculate the predicted size of the population after 10 hours. Show your working.

Answer = ____________________ 
(2)   (Total 9 marks)
Q6. Scientists measured the rate of carbon dioxide release by three groups of insects of the same species at 10 °C, 20 °C and 30 °C. They also determined the mean mass of each group of insects.
The scientists results are shown in the table.

Temperature / °C

Mean mass / g

Rate of carbon dioxide release / µdm^3 minute^−1

Rate of carbon dioxide
release per gram /
µdm^3 g^−1 minute^−1

10 | 0.047 | 0.12 |
20 | 0.046 | 0.33 |
30 | 0.048 | 0.56 |
(a)     Complete the table above and plot a graph of your calculated values against temperature on the graph paper. Express your calculated rates with the appropriate number of significant figures.
 
(3)
The body temperature of the insects was largely determined by the temperature they were kept at. At each temperature, the scientists recorded rate of carbon dioxide release by individual insects over time. This rate depends upon spiracles opening or closing.

The graphs below show results for three insects.
 
(b)     Calculate the change in the rate per hour of opening of the spiracles between 10 °C and 20 °C.
___________________________________________________________________
_________________________________________________________________(1)
(c)     Explain how you could determine the total amount of carbon dioxide secreted at 30 °C during the period of recording.
___________________________________________________________________
_________________________________________________________________(1)
(d)     Suggest an explanation for the effect of temperature on the rate of carbon dioxide release.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
________________________________________________(3)   (Total 8 marks)
Q7. The figure below shows the apparatus used for measuring the rate of oxygen consumption in aerobic respiration by seeds.
 
(a)     For the first 10 minutes, the tap attached to tube A was left open and the syringe from tube B was removed.
Suggest three reasons why the apparatus was left for 10 minutes.
1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
___________________________________________________________________
3. _________________________________________________________________
_________________________________________________________________(3)
(b)     Suggest and explain why the chosen temperature was 20 °C for this experiment.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
After 10 minutes, the tap attached to tube A was closed and the syringe was attached to tube B. Every minute, the syringe plunger was moved until the levels in the U-tube were the same. The reading on the syringe volume scale was then recorded.
The results are shown in the table below.

Time / minutes

Reading on syringe 
volume scale / cm^3

0 | 0.84
1 | 0.81
2 | 0.79
3 | 0.76
4 | 0.73
5 | 0.70
6 | 0.68
7 | 0.66
8 | 0.63
9 | 0.62
10 | 0.58
(c)     During the experiment, the coloured liquid in the tubing moved towards tube B.
Explain what caused this.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
________________________________________________________________ (3)
(d)     The mass of the seeds was 1.6 g. Use the information in the table above to calculate the rate of oxygen consumption in cm^3 g^–1 hour^–1 by the seeds.
Show your working.

 
Rate = ____________________ cm^3 g^–1 hour^–1
(2)
(Total 10 marks)
Q8.
A scientist investigated the use of a new source of carbohydrate in the production of ethanol for biofuel. He wanted to find the optimum time to leave a mixture of yeast and this carbohydrate to produce ethanol. The scientist set up an airtight container containing yeast and this carbohydrate. He then measured the oxygen, carbon dioxide and ethanol concentrations over 8 hours.
The results of his investigation are shown in the graph below.

(a)     The scientist used a container that was airtight. Give two explanations why the container had to be airtight.
1. _________________________________________________________________
___________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
___________________________________________________________________
_________________________________________________________________(4)
(b)     Explain the relationship between the concentration of oxygen and the concentration of carbon dioxide between 0 and 3 hours.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(c)     The scientist concluded that yeast starts to respire anaerobically when the oxygen concentration falls below a certain concentration. What is the oxygen concentration when the yeast starts to respire anaerobically? Explain your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(d)     (i)      The scientist worked for a biofuel company. Give two suggestions for further work he should do to make sure that the results he presented to the company were reliable. Explain how each of your suggestions would make the results more reliable.
Suggestion_____________________________________________________
______________________________________________________________
Explanation ____________________________________________________
______________________________________________________________
Suggestion_____________________________________________________
______________________________________________________________
Explanation ____________________________________________________
____________________________________________________________(4)
(ii)     The scientist recommended that when the ethanol is produced commercially as biofuel the reaction should be stopped at 6 hours. Use the graph to suggest why.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(iii)    The scientist’s work was funded by a biofuel company. Explain why the source of funding can cause problems with scientific work.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 16 marks)

Mark schemes
Q1.
(a)     (i)      Cytoplasm/cytosol;
1
(ii)     1.      Regenerates/produces NAD / oxidises reduced NAD;
2.       NAD reduced in stage 1/glycolysis / NAD accepts hydrogen in stage 1/glycolysis;
Note: penalise use of NADP for first marking point obtained.
Do not accept NAD accepts only protons but allow accepts protons and electrons.
2
(b)     (i)     1/one/1.0;
1
(ii)     1.      Aerobic and anaerobic respiration occurring;
Accept: some/mainly anaerobic respiration occurring.
2.      More carbon dioxide produced than oxygen uptake;
2
(c)     1.      Oxygen is final/terminal (electron) acceptor / oxygen combines with electrons and protons;
2.      (Aerobic respiration) oxidative phosphorylation / electron transfer chain;
3.      Anaerobic (respiration) only glycolysis occurs / no Krebs / no link reaction;
Ignore: number of ATP produced.
3. Accept: without oxygen.
3. Ignore: converse.
2 max
[8]
Q2.
(a)     pyruvate;
1
(b)     Krebs cycle;
1
(c)     ATP formed as electrons pass along transport chain;
oxygen is terminal electron acceptor / accepts electrons from electron
transport chain / electrons cannot be passed along electron transport 
chain if no O_2 to accept them;
forms H_2O / accepts H^+ from reduced NAD / FAD / oxidises reduced 
NAD / FAD;
3
[5]
Q3.
(a)
| Photosynthesis | Anaerobic respiration | Aerobic respiration
ATP produced | | |
Occurs in organelles | | |
Electron transport chain involved | | |
1 mark per column
Mark ticks only. Ignore anything else if different symbols such as crosses are used as well.
If crosses are used instead of ticks allow cross as equivalent to a tick.
Reject tick with a line through
3
(b)     ADP + P_i → ATP;
Both sides correct, but allow other recognised symbols or words for phosphate ion. Reject P unless in a circle.
Accept = as equivalent to arrow
Accept reversible arrow
Ignore any reference to kJ / water
1
(c)     1.      Energy released in small / suitable amounts;
2.      Soluble;
3.      Involves a single / simple reaction;
1. In context of release, not storage. Ignore producing energy / manageable amounts.
2. Reject "broken down easily / readily". Reject "quickly / easily resynthesised".
2 max
(d)     1.      ATP cannot be stored / is an immediate source of energy;
2.      ATP only releases a small amount of energy at a time;
2
[8]
Q4.
(a)     1.      Oxidation of / hydrogen removed from pyruvate and carbon dioxide released;
2.      Addition of coenzyme A.
Accept: NAD reduced for oxidation
2
(b)     (i)      1.      Change (in shape) of active site / active site moulds around the substrate;
Reject: reference to inhibitor
Accept: change in tertiary structure affecting active site
2.      (Substrate / active site) now complementary.
Neutral: references to two active sites
2
(ii)     1.      Is a competitive inhibitor / attaches to active site;
Neutral: reference to inhibitor forming an enzyme-substrate complex
2.      Reduces / prevents enzyme-substrate / E-S complex forming.
Accept: Reduces / prevents acetylcoenzyme A binding to enzyme / citrate synthase
2
(c)     (i)      1.      Regenerates / produces NAD / oxidises reduced NAD;
2.      (NAD used) in glycolysis.
Accept: description of glycolysis
Accept: glycolysis can continue / begin
2
(ii)     (Pyruvate used) in aerobic respiration / (lactate / lactic acid) is toxic / harmful / causes cramp / (muscle) fatigue.
Accept: (pyruvate) can enter link reaction
Accept: reduces cramp / (muscle) fatigue
Neutral: ‘reduces muscle aches’
1
[9]
Q5.
(a)     (So the) oxygen is used/absorbed/respired;
1
(b)     1.      Anaerobic respiration produces carbon dioxide;
2.      Increase in pressure/volume (of gas);
Reference to either volume or pressure required for the mark
2
(c)     1.      Correct answer in range of
4.9 × 10^–4 to 4.91 × 10^–4 = 2 marks;;
Accept any equivalent mathematical representation of this answer
2.      Incorrect answer buts shows division by 24 = 1 mark
OR
Incorrect answer but shows a number from 1175 to 1178 (ignore position of decimal point, standard form and any numbers that follow) = 1 mark;
OR
Incorrect answer but show the number 49 (ignore position of decimal point, standard form and any numbers after 49) = 1 mark;
2
(d)     Large range/difference/increase in numbers;
Accept reference to exponential (increase)
Ignore if the answer only refers to numbers being high
Ignore to ‘fit on the scale’
1
(e)     Decrease/no glucose/substrate
OR
Increase in ethanol/carbon dioxide/acidity;
Accept decrease/no oxygen as Figure 2 is not linked to Figure 1.
Accept competition for glucose/oxygen.
Accept any named sugar
Accept decrease in pH
Accept increase in toxins
Ignore food/nutrients
1
(f)      1.      Correct answer of 298000 or 297766 or 297765.59 or 296826 = 2 marks;;
Accept: any equivalent answer with appropriate rounding
e.g. 2.98 × 10^5,
29.78 × 10^4 etc.
2.      Incorrect answer but working shows 2000 × 2.72 = 1 mark;
OR
Incorrect answer but working shows 2.72^0.5 ^× ^10 / 2.72^5 / e^0.5 ^× ^10 / = 1 mark
2
[9]
Q6.
(a)     1.      Line graph with rate on y axis and temperature on x axis and linear scales;
2.      Values calculated to appropriate sf;
3.      Rates correctly calculated and plotted, with ruled line connecting points and no extrapolation;
3
(b)     8 or 9;
1
(c)     1.      Determine the area under the curve;
1
(d)     1.      Enzymes / metabolism faster;
2.      Higher rate of respiration and carbon dioxide production / release;
3.      Spiracles open more often / remain open to excrete / get rid of carbon dioxide / get more oxygen;
Note – explanation required
3
[8]
Q7.
(a)     1.      Equilibrium reached.
Accept equilibrate
2.      Allow for expansion / pressure change in apparatus;
3.      Allow respiration rate of seeds to stabilise.
Ignore seeds acclimatise
3
(b)     1.      Optimum temperature / temperature for normal growth of seeds;
2.      (Optimum temperature) for enzymes involved in respiration.
2
(c)     1.      Oxygen taken up / used by seeds;
2.      CO_2 given out is absorbed by KOH (solution);
3.      Volume / pressure (in B) decreases.
3
(d)     0.975 / 0.98.
If incorrect,
0.26 × 6 / or incorrect numbers divided by 1.6 for 1 mark
2
[10]
Q8.
(a)     1.      No oxygen can enter;
2.      Ethanol produced during anaerobic respiration;
OR
3.      No ethanol / carbon dioxide can escape;
4.      Allows accuracy of measuring;
OR
5.      To prevent entry of / contamination with microorganisms;
6.      Prevent competition with yeast;
Any two pairs of answers
Second mark of each pair must be related to the first point of the pair.
4 max
(b)     1.      Yeast respiring aerobically;
2.      Oxygen used equal to carbon dioxide produced;
2
(c)     1.      7.0 / 7;
2.      Ethanol production starts;
2
(d)     (i)      1.      Repeat;
2.      Identify anomalies / see if results are similar / enough results for statistical test / give more reliable mean;
3.      Carry out statistical test / statistical analysis;
4.      Ensure results are significant / find probability of results being due to chance;
5.      Peer review;
6.      Allows procedure to be checked / see if other scientists get similar results;
Two pairs of linked points, each pair a suggestion and an explanation. The explanation must relate to the suggestion to gain the second point of the pair.
4
(ii)     1.      Curve levelling off / rate of increase is decreasing / very little extra ethanol produced;
2.      Becomes less cost effective / less profit;
2. Accept a description of cost effectiveness
2
(iii)    1.      (Funding agency) might want particular results;
2.      Results may be withheld / results may not be published / results may be confidential;
2 max
[16]