IB Biology  -  Questions on Sizes of cells

1.	If a red blood cell has a diameter of 8 mm and a student shows it with a diameter of 40 mm in a drawing, what is the magnification of the drawing?
A.	× 0.0002
B.	× 0.2
C.	× 5
D.	× 5000
(Total 1 mark)

2.	The drawing below shows the structure of a virus.

(a)	Identify structures labelled I and II.
I:	...........................................................................................................................
II:	...........................................................................................................................
(2)
 
(b)	Use the scale bar to calculate the maximum diameter of the virus. Show your working.

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

(c)	Explain briefly why antibiotics are effective against bacteria but not viruses.
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(3)
 
(d)	Explain how antibiotic resistance develops in bacteria.
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(3)
(Total 10 marks)
3.	The diagram below shows the structure of a cell.

(a)	State the names of I and II.
I:	...........................................................................................................................
II:	...........................................................................................................................
(2)
 
(b)	Calculate the actual length of the cell, showing your working.

Answer:	...................................................................................................................
(2)
 
(c)	State the function of the structure labelled III.
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(1)
 
(d)	Deduce which type of cell is shown in the diagram, giving reasons for your answer.
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(2)
(Total 7 marks)

4.	The width of a human hair is 0.1 mm. What is the width in mm?
A.	10 mm
B.	100 mm
C.	1000 mm
D.	10 000 mm
(Total 1 mark)

5.	Which ratio limits the size of cells?
A.	The rate of metabolism to mass
B.	The surface area to volume
C.	The mass to volume
D.	The surface area to mass
(Total 1 mark)

6.	A student observes and draws an Amoeba, using the high power lens of a microscope. The diameter of the drawing is 100 mm. The actual diameter of the Amoeba is 100 µm. What is the magnification of the drawing?
A.	0.001
B.	100
C.	400
D.	1000
(Total 1 mark)