Author: Philip Colls
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Cells booklet Revision questions             NAME:
Q1. The photograph shows part of the cytoplasm of a cell.
 
(a)     (i)      Organelle X is a mitochondrion.
What is the function of this organelle?
______________________________________________________________
______________________________________________________________
(1)
(ii)     Name organelle Y.
______________________________________________________________
(1)
(b)     This photograph was taken using a transmission electron microscope. The structure of the organelles visible in the photograph could not have been seen using an optical(light) microscope. Explain why.
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(2)
(Total 4 marks)
Q2. An amoeba is a single-celled, eukaryotic organism. Scientists used a transmission electron microscope to study an amoeba. The diagram shows its structure. 
 
(a)     (i)      Name organelle Y.
____________________________________________________________(1)
(ii)     Name two other structures in the diagram which show that the amoeba is a eukaryotic cell.
1. ____________________________________________________________
2. __________________________________________________________(2)
(b)     What is the function of organelle Z?
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(1)
(c)     The scientists used a transmission electron microscope to study the structure of the amoeba. Explain why.

(2)
(Total 6 marks)
 
Q3. The diagram shows a eukaryotic cell.
 
(a)     Complete the table by giving the letter labelling the organelle that matches the function.
 
Function of organelle | Letter
Protein synthesis |
Modifies protein (for example, adds carbohydrate to protein) |
Aerobic respiration |
(3)
(b)     Use the scale bar in the diagram above to calculate the magnification of the drawing.
Show your working.

 
 
Answer = ____________________
(2)
(Total 5 marks)
Q4. The diagram shows how some organelles may be distinguished from each other.
 
Organelle found in prokaryotic           Organelle found only in
and eukaryotic cells                         eukaryotic cells
Organelle A
 
Organelle found in                    Organelle found in
animal cells and in                 plant cells. Contains
 plant cells. Does not                  inner membranes
  contain membranes                 arranged in stacks.
 arranged in stacks.                      Organelle B
 
Larger organelle surrounded             Smaller organelle surrounded
 by an envelope through which        by an outer membrane. Has an inner
 there are pores. usually one           membrane, folded to form cristae.
per cell.                                          Many in the cell.
Organelle C                                            Organelle D
(a)     (i)      Name organelle B.
____________________________________________________________(1)
(ii)     Describe the function of organelle B.
______________________________________________________________
______________________________________________________________
____________________________________________________________(2)
(b)     Which of organelles A, B, C or D
(i)      is a ribosome;
____________________________________________________________(1)
(ii)     contains most of the DNA found in a plant cell?
____________________________________________________________(1)
(c)     Some liver tissue was ground, filtered and centrifuged to make a suspension of organelle D.
(i)      Explain why the solution in which the liver tissue was ground should be ice-cold.
______________________________________________________________
______________________________________________________________
(1)
(ii)     The ground liver was centrifuged at low speed. The pellet that formed at the bottom of the centrifuge tube was thrown away and the supernatant centrifuged again at higher speed. Explain why it was necessary to first centrifuge the ground liver at low speed in order to obtain a suspension of organelle D.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 8 marks)
Q5. The diagram shows a cholera bacterium. It has been magnified 50 000 times.
 
(a)     Name A.
_________________________________________________________________(1)
(b)     Name two structures present in an epithelial cell from the small intestine that are not present in a cholera bacterium.
1. _________________________________________________________________
2. _______________________________________________________________(2)
(c)     Cholera bacteria can be viewed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM).
(i)      Give one advantage of using a TEM rather than a SEM.
______________________________________________________________
____________________________________________________________(1)
(ii)     Give one advantage of using a SEM rather than a TEM.
______________________________________________________________
______________________________________________________________
____________________________________________________________(1)
(d)     Calculate the actual width of the cholera bacterium between points B and C.
Give your answer in micrometres and show your working.

 
____________________ µm
(2)
(e)     An outbreak of cholera occurred in London in 1849. The graph shows the relationship between the number of deaths from cholera and the height at which people lived above sea level.
 
Describe the relationship between the number of deaths from cholera and the height at which people lived above sea level.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(Total 9 marks)
 
Q6.  (a)     Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope.
___________________________________________________________________
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___________________________________________________________________
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(4)
The figure below shows a microscopic image of a plant cell.
 
© Science Photo Library

(b)     Give the name and function of the structures labelled W and Z.
Name of W__________________________________________________________
Function of W________________________________________________________
Name of Z __________________________________________________________
Function of Z ________________________________________________________
(2)

(c)     A transmission electron microscope was used to produce the image in the figure above.  Explain why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(d)     Calculate the magnification of the image shown in the figure in part (a).

 
Answer = ___________________(1)
(Total 9 marks)
Q7. Below is a diagram of an animal cell.
 
(a)     Name the organelles labelled:
B _________________________________
C _________________________________                                  (2)
(b)     Name two structures present in plant cells that are not present in animal cells.
1. _________________________________________________________________
2. _______________________________________________________________(1)
A biologist prepared a sample of organelles labelled C from liver. He used the following method.
1.      Added to the liver tissues an ice-cold, buffered solution with the same water potential as the liver tissue.
2.      Mixed the liver and solution in a blender.
3.      Filtered the mixture from the blender.
4.      Spun the filtered liquid in a centrifuge at a low speed. A pellet appeared in the bottom of the centrifuge tube.
5.      Poured off the liquid above the pellet into a second centrifuge tube and spun this at a higher speed to obtain the sample of organelles labelled C.
(c)     Explain why the solution the biologist used was ice-cold, buffered and the same water potential as the liver tissue (step 1).
Ice-cold____________________________________________________________
___________________________________________________________________
Buffered____________________________________________________________
___________________________________________________________________
Same water potential__________________________________________________
_________________________________________________________________(3)
(d)     Explain why the biologist used a blender and then filtered the mixture (steps 2 and 3).
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(2)
(e)     Name the organelle that made up most of the first pellet after centrifuging at a low speed (step 4).
_________________________________________________________________(1)
(f)     The second centrifuge tube was spun at a higher speed to obtain the sample of organelles labelled C in the diagram (step 5). Suggest why.
___________________________________________________________________
___________________________________________________________________
_________________________________________________________________(1)
(Total 10 marks)

Mark schemes
Q1.
(a)     (i)      (Aerobic) respiration;
Accept ATP production / energy release
Reject anaerobic respiration
Reject energy production
1
(ii)     Golgi (apparatus / body);
Ignore smooth ER
1
(b)     (‘It’ = Optical microscope)
Ignore reference to magnification
1.      Has low resolution / not high enough resolution;
Accept converse relating to EM
2.      (Because) wavelength of light not short enough / too long;
Accept larger wavelength
Accept statements that microscopes have a wavelength
2
[4]
Q2.
(a)     (i)     Golgi (apparatus / body);
1
(ii)     1.      Nucleus;
Accept: nucleolus / nuclear envelope / nuclear membranes
2.      Mitochondrion;
Accept cristae / mitochondrial membranes
3.      Endoplasmic reticulum / ER;
Ignore reference to rough / smooth
4.      Lysosome;
Reject lysozyme
2 max
(b)     (Aerobic) respiration / ATP production / provide energy;
Accept Krebs cycle / electron transport.
Ignore 'produces energy'
Reject anaerobic respiration
Ignore what energy is used for
1
(c)     1.      High / better resolution;
2.      Shorter wavelength;
3.      To see internal structures / organelles / named organelles;
Accept ultrastructure
2 max
[6]
Q3.
(a)
| Protein synthesis | L;
| Modifies protein | H;
| Aerobic respiration | N;
3
(b)     1800−2200;
1.8, 2.0 or 2.2 in working or answer = 1 mark.
Ignore units in answer.
1 mark for an incorrect answer in which student clearly divides measured length by actual length (of scale).
Accept I / A or I / O for 1 mark but ignore triangle.
Accept approx 60mm divided by 30μm for 1 mark
2
[5]
Q4.
(a)     (i)      Chloroplast;
1
(ii)     Photosynthesis;
Uses light (energy);
To produce carbohydrates / starch / glucose / sugars / ATP / 
reduced NADP;
Note that candidates cannot be expected to have a detailed knowledge of photosynthesis.
max 2
(b)     (i)      A;
1
(ii)     C;
1
(c)     (i)      Slows enzymes / prevents enzymes being denatured / 
prevents / stops self-digestion;
Ignore references to bacteria. Reject enzymes not working
1
(ii)     To remove organelle C / nuclei;
Which are larger / more dense;
2
[8]
Q5.
(a)     (Plasma / cell) membrane;
Reject: nuclear membrane
1
(b)     Nucleus / nuclear envelope / nuclear membrane / nucleolus;
Accept: membrane-bound organelles only if an example has not been given
Mitochondrion;
(Smooth / rough) ER;
Lysosome;
Microvillus / brush border;
Neutral: villi
Golgi;
Linear / non-circular DNA / chromosome;
Neutral: DNA strands
80S / denser / heavier / larger ribosomes;
Neutral: ribosomes
2 max
(c)     (i)      Higher resolution / higher (maximum) magnification / higher detail (of image);
OR
Allows internal details / structures within (cells) to be seen / cross section to be taken;
Accept: ‘better’ instead of ‘higher’
Neutral: shorter wavelength
Reject: longer wavelength
Reject: can be used on living specimens
Q Do not accept ‘clearer’ image
1
(ii)     Thin sections do not need to be prepared / shows surface of specimen / can have 3-D images;
Accept: can be used on thick(er) specimens
Reject: can be used on living specimens
Neutral: refs. to staining / preparation / artefacts / colour
1
(d)     Two marks for correct answer of 0.42 – 0.46;;
One mark for incorrect answers in which candidate clearly divides measured width by magnification;
Correct answer = 2 marks outright
Accept: 0.4 or 0.5 only if working is correct for 2 marks
Do not award a mark for 0.4 or 0.5 if there is no working out
Ignore rounding up
2
(e)     As height increases, the number of deaths decrease / inversely proportional / negative correlation;
Correct reference to increase / decrease at 14-30m;
Accept: converse statement
Must give a trend and not simply give individual points
Do not penalise for ‘more likely to get cholera’
2
[9]
Q6.
(a)     1.      Add drop of water to (glass) slide;
2.      Obtain thin section (of plant tissue) and place on slide / float on drop of water;
3.      Stain with / add iodine in potassium iodide.
3.    Allow any appropriate method that avoids trapping air bubbles
4.      Lower cover slip using mounted needle.
4
(b)     1.      W – chloroplast, photosynthesis;
2.      Z – nucleus, contains DNA / chromosomes / holds genetic information of cell.
2
(c)     1.      High resolution;
2.      Can see internal structure of organelles.
2
(d)     Length of bar in mm × 1000.
1
[9]
Q7.
(a)     B Golgi (body / apparatus);
C Mitochondria / mitochondrion;
2
(b)     1.      Chloroplasts / plastids
2.      Cell wall
3.      Cell vacuole
4.      Starch grains / amyloplasts;
Any 2 for 1 mark
1 max
(c)     1.      Ice-cold – Slows / stops enzyme activity to prevent digestion of organelles / mitochondria;
2.      Buffered – Maintains pH so that enzymes / proteins are not denatured;
Reject reference to cells
3.      Same water potential – Prevents osmosis so no lysis / shrinkage of organelles / mitochondria / C;
Ignore damage
For each mark must link reason to relevant property
3
(d)     1.      Break open cells / homogenise / produce homogenate;
2.      Remove unbroken cells / larger debris;
2
(e)     Nucleus / nuclei;
1
(f)     Mitochondria / organelle C less dense than nucleus / organelle in first pellet;
Accept ‘lighter’ for less dense
1
[10]