Yr 12 AS Biology Revision Questions1. The table below refers to three organic compounds found in cell organelles.

If the compound is found in the organelle, place a tick (√) in the appropriate box and if the compound is not found in the organelle, place a cross (x) in the appropriate box.

O r g a n e l l e

R i b o s o m e

C h l o r o p l a s t

S m o o t h e n d o p l a s m i cr e t i c u l u m

M i t o c h o n d r i o n

P h o s p h o l i p i d D N A R N A

(Total 4 marks)

2.(a) The diagram below shows a section through a mitochondrion as seen using an electron microscope.

(i) Name the parts labelled A, B and C.

A …………………………………………………………………………….

B …………………………………………………………………………….

C …………………………………………………………………………….(3)

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(ii) On the diagram, by means of an arrow, 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 .

Answer ........................................................(2)

(b) Active mitochondria can be isolated from liver cells. If these mitochondria are then 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 an 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.

S o d i u m a z i d e a d d e d

00

5 1 0

1

2

3

4

5

6

7

C o n c e n t r a t i o no f d i s s o l v e do x y g e n/ a r b i t r a r y u n i t s

T i m e / m i n s

(i) Explain why the concentration of oxygen decreased during the first five minutes.

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Yr 12 AS Biology Revision Questions(ii) Suggest what effect the addition of sodium azide will have on the production of

ATP and give an explanation for your answer.

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(Total 11 marks)

3. The table below refers to features of prokaryotic and eukaryotic cells.

If the feature is present place a tick (√) in the appropriate box and if the feature is absent, place a cross (X) in the appropriate box.

Feature Prokaryotic cell Eukaryotic

Endoplasmic reticulum

Mesosome

Ribosomes

Golgi apparatus

(Total 4 marks)

4. The photograph below shows a section through a mitochondrion as seen using an electron microscope.

A

C B

Prof. R. Bellairs/Wellcome Photo Library

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(a) Name the parts labelled A, B and C.

A ................................................................................................................................

B ................................................................................................................................

C ................................................................................................................................(3)

(b) Describe the role of mitochondria.

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(Total 5 marks)

5. An experiment was carried out to determine what happens to amino acids after they are absorbed by animal cells. The cells were incubated for 5 minutes in a medium containing radioactively labelled amino acids. The radioactive amino acids were then washed off and the cells were incubated in a medium containing only non-radioactive amino acids.

Samples of the cells were taken at 5, 10 and 45 minutes after the start of the experiment and the sites of radioactivity in the cells were determined.

The results are given in the table below. The figures show radioactivity in certain cell organelles expressed as a percentage of the total radioactivity within the cells.

O r g a n e l l eP e r c e n t a g e o f t o t a l r a d i o a c t i v i t y

A t 5 m i n u t e s A t 1 0 m i n u t e s A t 4 5 m i n u t e s

R o u g h e n d o p l a s m i cr e t i c u l u m

G o l g i a p p a r a t u s

S e c r e t o r y v e s i c l e s

8 0

1 0

0

1 0

8 0

5

5

3 0

6 0

(a) Name ONE type of molecule synthesised from amino acids in cells.

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Yr 12 AS Biology Revision Questions(b) Explain why the radioactivity is associated mainly with the rough endoplasmic reticulum

after the first 5 minutes of the experiment.

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(c) Explain the changes in the pattern of radioactivity in the cell during the remaining 40 minutes of the experiment.

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(d) Suggest why the figures in the tables total less than 100%.

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(e) If the experiment is continued for a further period of time, most of the radioactivity will be found outside the cell.

Name and describe the process which brings about this result.

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(Total 11 marks)

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6. The diagram below shows the structure of a bacterium, a typical prokaryotic cell.

A

B

C

(a) Name A, B and C as labelled on the diagram.

A ...............................................................................................................................

B ...............................................................................................................................

C ...............................................................................................................................(3)

(b) Complete the table below to show three differences between a prokaryotic cell and a eukaryotic cell.

Prokaryotic cell Eukaryotic cell

1

2

3

(3)(Total 6 marks)

Yr 12 AS Biology Revision Questions7. The photograph below shows human cells as seen using a light microscope. It has been

magnified 800 times.

B

A

(a) Calculate the actual diameter of the cell labelled A, expressing your answer in µm (micrometres). Show your working.

Answer ……………………… µm(3)

(b) In the space below, make an accurate drawing of the cells labelled A and B,

enlarge 2 ×. Do not label your drawing.

(4)(Total 7 marks)

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8. The photograph below-shows part of an animal cell, as seen using an electron microscope. The magnification is ×5000.

(a) Name the structures labelled A and B.

A............................................................................................................................................

B............................................................................................................................................(2)

(b) Calculate the actual length of the structure labelled B in µm. Show your working.

Actual length of B .................. µm(3)

Yr 12 AS Biology Revision Questions(c) Describe how proteins synthesised on the rough endoplasmic reticulum are processed and

transported out of the cell.

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(Total 10 marks)

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9. The following table refers to organelles found in eukaryotic cells. Complete the table by writing the name of the organelle, two features of its structure or one function of the organelle in each of the four empty boxes as appropriate.

Name of organelle Two features of structure One function

1. Stack of curved cisternae

2. Surrounded by many vesicles

Modificationof proteins

Rough endoplasmicreticulum

1.

2.

Chloroplast

1.

2.

Site ofphotosynthesis

(Total 6 marks)

Yr 12 AS Biology Revision Questions10. The diagram below shows the structure of a bacterial cell as seen using an electron

microscope.

C e l l w a l l S t o r a g e g r a n u l e B

A

X Y

(a) (i) Name the parts labelled A and B.

A ............................................................................................................................

B ............................................................................................................................(2)

(ii) Name the carbohydrate present in the storage granules.

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(iii) Describe how the cell wall in this bacterial cell differs from that in a plant cell.

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(b) The diagram has been magnified 6000 times. Calculate the actual length of thebacterial cell between X and Y. Show your working, and give your answer inmicrometres.

Answer ............................. µm(3)

(Total 7 marks)

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11. (a) Draw and label a diagram to show the structure of the Golgi apparatus as seen using an electron microscope.

(3)

Yr 12 AS Biology Revision Questions(b) The process of protein synthesis in cells and the secretion of proteins from the cells was

investigated using radioactively labelled amino acids.

The cells were incubated with radioactive amino acids for 30 minutes. The cells were then removed and washed thoroughly to remove any radioactive amino acids on the cell surfaces.

The washed cells were then incubated with non-radioactive amino acids for 120 minutes. Every 20 minutes a sample of cells was removed and the level of radioactivity in the rough endoplasmic reticulum and in the secretory vesicles was determined.

The graph below shows the levels of radioactivity in the rough endoplasmic reticulum and the secretory vesicles.

8 0

7 0

6 0

5 0

4 0

3 0

2 0

1 0

00 2 0 4 0 6 0 8 0 1 0 0 1 2 0

I n c u b a t i o n t i m e / m i n

L e v e l o fr a d i o a c t i v i t y/ a r b i t r a r yu n i t s

S e c r e t o r yv e s i c l e s

R o u g he n d o p l a s m i cr e t i c u l u m

(i) Describe and explain the changes in the level of radioactivity in the rough endoplasmic reticulum during the first 40 minutes of the incubation period.

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(ii) Explain the shape of the curve for the secretory vesicles between 0 and 40 minutes.

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(Total 8 marks)

12. Eukaryotic cells contain organelles, many of which are bound by a membrane. Some organelles have a double membrane, often called an envelope.

(a) (i) Describe two structural differences between the double membrane surrounding a mitochondrion and the double membrane surrounding a nucleus.

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(ii) Name one other organelle that has a double membrane.

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Yr 12 AS Biology Revision Questions(b) Centrioles are an example of organelles that are not membrane-bound. Describe the

structure and function of centrioles.

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(Total 6 marks)

13. The diagram below shows some of the stages in protein synthesis and secretion in a mammalian cell.

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(a) (i) Name the processes taking place during stages A and B.

A ….................................................................................................................

B .....................................................................................................................(2)

(ii) Name the process by which protein is secreted in stage F.(1)

(b) Describe the part played by transfer RNA in the formation of the polypeptide chain during stage B.

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(Total 6 marks)