F4 EXP01: Practical 2.2

Practical 2.2

Preparation of temporary mounts of

animal cells and tissues

製作動物細胞和組織的臨時裝片

Results: (7 marks)

Make a labelled high power drawing 高倍標註圖of the cornea cells of ox eye in the space below.

Discussion: (9 marks)

1      Why is it necessary to cover the slide with a cover slip in the observation under the microscope?                                                                                                                                                        (2 marks)

Any TWO of the following (1 + 1 = 2):

To flatten the samples;

To focus and observe the samples more easily;

To avoid contamination of the objective by the samples or the liquid on the slide;

To prevent evaporation of water from the samples leading to drying up of the samples;

To prevent the samples from being damaged.

2        What cellular structures can be observed under the light microscope?                                     (3 marks)

Cell membrane, nucleus and cytoplasm (3)

3        What is the general position of the nucleus in animal cell?                                                       (1 marks)

At any positions of the cells (1)

4        Can you find vacuoles in these animal cells?                                                                            (1marks)

No / Only minute vacuoles can be found (1)

5        Describe and explain if there is any change if methylene blue was not added before observation.                                                                                                                                                (2 marks)

The image would become blurred / The nucleus or the cytoplasm could not be observed (1).

This is because the cellular structures are not stained (1).

Practical 2.3

Preparation of temporary mounts of plant cells and tissues

製作植物細胞和組織的臨時裝片

Results: (8 marks)

Make a labelled high power drawing of the plant cells of onion cells in the space below.

Discussion: (11 marks)

1            What cellular structures can be observed under light microscope?                                (4 marks)

Cell wall, cell membrane, nucleus, cytoplasm, (granules) (1@ X 4 = 4)

2      What is the general position of the nucleus in plant cell?                                                 (1 mark)

At the peripheral region of the cell (1).

3      Are all cells under observation green in colour? Why?                                          (2 marks)

No (1). This is because not all plant cells have chloroplasts or chlorophyll / only plant cells with chloroplasts are green under observation (1).

4      State TWO similarities and differences between animal cells and plant cells.               (4 marks)

Any TWO similarities and differences (2@ X 2):

Similarities: Both of them have cell membrane, cytoplasm and nucleus (2).

Differences: Plant cells have cell wall and larger vacuole but animal cells do not (2).