Unit 1 Chapter 3 Revision Questions

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Chapter 3 ­ cells and movement in and out of them
1. Define resolution.
Minimum distance apart that two objects can be in order for them to appear as separate
2. What is the resolution of an electron microscope like and why?
Better resolution due to the shorter wavelength of a beam of electrons
3. What is the resolution of a light microscope like and why?
Poor resolution due to the long wavelength of light
4. Disadvantages of TEM and SEM
TEM has to be stained
Has to be done in a vacuum
Cannot examine living cells
Specimen must be very thing
May alter appearance
5. Advantages of TEM
Better resolution than light and SEM
6. Advantages of SEM
Better resolution than light
Image is 3D
Can be made in colour
7. How do electron microscopes work?
Beam of electrons passed through. Some absorbed -> dark. Some passes through -> light.
8. 1mm = how many micrometres?
1000 micrometres
9. 1mm = how many nanometres?
1,000,000 nanometres
10. How do you work out magnification?
Size of image/ size of object
Parts of the cell
11. Function of the nucleus
Acts as a control centre of the cell, using mRNA (hence regularly protein synthesis)
Manufactures ribosomes + ribosomal RNA
12. Name five parts of the nucleus:
Nuclear envelope
Nuclear pores

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Chapter 3 ­ cells and movement in and out of them
13. What are the nuclear pore function?
Allows passage of molecules
14. What is the nuclear envelope?
Double membrane that surrounds the nucleus
15. What is chromatin?
DNA in nucleoplasm
16. What is the function of the double membrane of the mitochondrion?
Outer ­ controls entry/exit
Inner ­ folded and forms cristae
17. Why do cristae have a large SA?
For enzyme attachment in respiration
18.…read more

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Chapter 3 ­ cells and movement in and out of them
25. Which processes are passive?
Facilitated diffusion
Cell Fractionation
26. What is cell fractionation?
The process of breaking apart cells and separating/isolating their organelles
27. Three stages of cell fractionation
1) Place tissue in isotonic, buffered, cold solution
2) Homogenation
3) Ultracentrifugation
28. Why is the solution cold?
To reduce enzyme activity that might break down organelles
29. Why is the solution buffered?
To maintain a constant pH
30.…read more

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Chapter 3 ­ cells and movement in and out of them
36. Uses of lipids
Water proofing
Energy source
Phospholipids in plasma membrane
37. Test for lipids
Emulsion test -> ethanol and water -> cloudy white emulsion
38. What are the differences between triglycerides and phospholipids
Triglycerides Phospholipids
Not polar Polar (two poles
3 fatty acids 2 fatty acids
No phosphate group Phosphate group
39.…read more

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Chapter 3 ­ cells and movement in and out of them
43. Define diffusion
The net movement of molecules or ions from a region of high concentration to a region of
low concentration (down a conc gradient)
44. What is diffusion proportional to?
Surface area x conc diff/ diffusion diff
45. What molecules diffuse through the phospholipid layer?
Non-polar molecules
Small molecules
46. Factors affecting diffusion:
Surface area
Size of conc grad
Diffusion distance
Composition of membrane
Size/nature of diffusing molecule
47.…read more

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Chapter 3 ­ cells and movement in and out of them
52. What is an isotonic solution?
Concentration inside cells is equal to that of the solution
No net movement of water across a semi-permeable membrane (although there is
53. When is a plant cell described as turgid?
When water enters the cell because the WP of the solution compared to the cell solution
is higher.
Therefore the water enters the cells.
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Chapter 3 ­ cells and movement in and out of them
60. Explain how cholera bacteria works
1) Most `vibrio cholerae' bacteria are killed by stomach acid. Some may survive if pH above
4.5.…read more


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