2015年10月23日 星期五

F4 Biology WS 04 ans

2 The cell II
WS 04
Suggested Answers

Textbook exercise
M.C.       
4
5
6
7
8
C
C
C
D
B
(5 marks)

Q. 9                                                                                                                                         (2 marks)
(a)    Cell membrane (1) and cytoplasm (1)
Con: Nucleus is not correct because many living cells such as differentiated sieve cells in plants and red blood cells in human do not have nucleus.

Q. 11
(a)    Mitochondria (1)
        (Rough) endoplasmic reticulum (1)
(b)    EM can give out an image with higher magnification and resolution (1)
          The EM technology enables the scientists to discover the structures of organelles inside cells, so that they can investigate the functions of organelles (1).                                  (4 marks)

Q.13
(a)    A large vacuole / chloroplasts / cell wall (any 2) (2)
(b)    (i)
Description of function
Cell part

Controls the passage of nutrients into the cell
B
1
Increase in volume when the cell is placed in water
E
1
Contains genetic material
F
1
Prevents the cell bursting
A
1
Produces glucose during photosynthesis
D
1
(ii)    The magnification = 6.4 cm / 0.1 mm                                                                                   1
                                        = 6.4 cm / 0.01 cm
                                        = 640                                                                                                       1
Con: Many students don’t know how to calculate the magnification. Also some of them
         even cannot convert the unit “mm” into “cm”.



Q.14
a      i       The magnification = 2.8 cm / 2 mm                                                                              1
                                               = 0.028 m / 2 X 10-6 m OR 28000 mm / 2 mm                               1
                                               = 14000                                                                                         1
Con: Many students don’t know how to calculate the magnification. Also some of them
         even cannot convert the unit “cm” into “m” or “mm”.

        ii      Mitochondrion                                                                                                             1
        iii     Mitochondria release energy by respiration.                                                                1
                Muscle cells require much energy                                                                                1
                for contraction.                                                                                                             1
Rel:   Many students just copy irrelevant information of mitochondria from teaching notes (e.g. liver cells have many mitochondria) but cannot give an answer corresponding to the question.
Exp: Some students explain well why muscle cells need much energy.

        b      Muscle cells have a nucleus / nuclear membrane while bacterial cells do not.             1
            Muscle cells have membrane-bounded organelles while bacterial cells do not.           1
                Muscle cells have no cell wall while some bacterial cells have a cell wall.                  1
Rel:   Again, many students cannot give an answer corresponding to the question. They just give a comparison of eukaryotic cells with prokaryotic cells without the mention of muscle cells and bacterial cells.

Q.15
    Similarities:
    Both prokaryotic cells and eukaryotic cells are bounded by a cell membrane.                    1
        Both have DNA as genetic material.                                                                                   1
        Differences:
        Prokaryotic cells have no true nucleus while eukaryotic cells have a true nucleus.
        / DNA of prokaryotic cells is lying free in the cytoplasm while DNA of eukaryotic cells is enclosed in the nucleus.
        / Prokaryotic cells are usually smaller than eukaryotic cells.
        / The cell wall of prokaryotic cells does not contain cellulose while the cell wall of eukaryotic cells contains cellulose.
        / Prokaryotic cells do not have organelles bounded by a double membrane while eukaryotic cells have organelles bounded by a double membrane.
        / Prokaryotic cells do not have endoplasmic reticulum while eukaryotic cells have endoplasmic reticulum.
        / In prokaryotic cells, ribosomes are lying free in the cytoplasm while in eukaryotic cells, some ribosomes are attached to endoplasmic reticulum and some are lying free in the cytoplasm.
                                                                                                                                            (any 5) 1 x 5
        Communication                                                                                                                      3
Con: Many students give up to answer question. Actually, it is easy for them to write something by converting the table of comparison in the teaching notes into paragraphs.

Rel:   Some students only state the differences between prokaryotic cells and eukaryotic cells without comparing their similarities.

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