Activity Book

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Activity Book
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2.1
Practical
Observation with a microscope
2 When using the high power objective for
observation, we should not focus with the coarse
adjustment knob. Why?
ANS ?
The coarse adjustment knob leads to a larger
degree of movement of the body tube. (To be
continued.)
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3
2.1
Practical
Observation with a microscope
continued from previous page
This may damage the objective or the slide
because the distance between the objective and
the slide is very small.
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4
2.1
Practical
Observation with a microscope
3 Which magnification is more suitable for
counting the number of cells in a specimen, a low
power or a high power magnification?
ANS ?
A low power magnification.
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2.2
Practical
Preparation of temporary mounts of plant cells
and tissues
Questions
1 Why is iodine solution, but not water, added to
the cells?
To increase the contrast and make some of the
structures more easily seen.
ANS ?
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2.2
Practical
Preparation of temporary mounts of plant cells
and tissues ANS ?
1.To prevent the objective lens from getting wet.
2.To prevent the specimen from drying out
because of evaporation. 3.To protect the
specimen from being damaged. (To be continued.)
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2.2
Practical
Preparation of temporary mounts of plant cells
and tissues
2 Why is a cover slip put over the cells for
observation with a microscope?
continued from previous page 4.To flatten the
specimen so that they can be seen easily in one
plane of focus for the objective lens.
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2.2
Practical
Preparation of temporary mounts of plant cells
and tissues
4 Where does the nucleus usually lie inside a
plant cell?
ANS ?
Near the side of the cell.
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2.2
Practical
Preparation of temporary mounts of plant cells
and tissues
5 Are all the plant cells you observed green in
colour? Explain.
No. Not all of them contain chloroplasts or
chlorophyll. Only those with chloroplasts are
green.
ANS ?
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2.3
Practical
Preparation of temporary mounts of animal cells
and tissues
4 What are the similarities and differences
between plant cells and animal cells?
Similarities Both of them have a nucleus
(except mature red blood cells), cell membrane
and cytoplasm. (To be continued.)
ANS ?
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2.3
Practical
Preparation of temporary mounts of animal cells
and tissues
continued from previous page
Differences 1 Plant cells have a thick cell wall
and some have chloroplasts. Animal cells do not
have cell walls or chloroplasts. 2 Plant cells
usually have a large vacuole while animal cells
do not. (to be continued.)
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2.3
Practical
Preparation of temporary mounts of animal cells
and tissues
continued from previous page
3 Plant cells are often larger than animal
cells. 4 Plant cells have a definite shape while
the animal cells do not.
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Exercise 2
Multiple-choice questions no.11 C
C
C
C
C
C
C
D
B
B
A
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Exercise 2
Structured questions
1a Name two structures that are present in cell
X but not in cell Y.
Chloroplast (1m) Cell wall (1m)
ANS ?
1b Describe the functions of each of the
structure stated in a.
Chloroplast contains chlorophyll for carrying
out photosynthesis. (1m) Cell wall supports (1m)
and protects the cell (1m).
ANS ?
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Exercise 2
1c State two importance of water to cell X and
cell Y.
Water acts as a medium for chemical reactions / a
medium of transport / provides support and give
shape to the cells / a cooling agent. (Any 2,1m
each)
ANS ?
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Exercise 2
1d Cell Y is a very active cell. What organelle
will be found in it more than in other cells?
Suggest a reason for your answer.
Mitochondria (1m). Active cells require more
energy, thus they usually contain more
mitochondria to release more energy (1m).
ANS ?
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Exercise 2
1e From the scales provided above, try to find
out the magnifications of cell X and cell Y.
Magnification of cell X 15/0.01 1500 (1m)
Magnification of cell Y 20/0.01 2000 (1m)
ANS ?
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Exercise 2
3a Describe the steps in preparing the slide.
Peel off the inner epidermis from an onion scale
fleshy leaf (1m). Place a small part of the
epidermis on the central of a slide (1m). Add a
drop of stain / water to the specimen (1m).
Finally cover it with a cover slip (1m).
ANS ?
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Exercise 2
3b What precaution should the student take when
mounting the slide?
The student should make sure that there are no
bubbles trapped between the slide and cover slip.
(1m)
ANS ?
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20
Exercise 2
3c i Suggest a stain that the student may use.
Iodine solution (1m)
ANS ?
3c ii Give one advantage and one disadvantage
of using stain.
ANS ?
Advantage It gives a better contrast.(1m)
Disadvantage It may kill the cells. (1m)
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Exercise 2
3d i Name parts P and Q.
P eyepiece (1m) Q objectives (1m)
ANS ?
3d ii How is the total magnification of the
microscope related to the magnifications of P
and Q?
The total magnification is the product of the
magnifications of P and Q. (1m)
ANS ?
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22
Exercise 2
3e Draw a fully labelled diagram of an epidermal
cell observed under the light microscope. title
of diagram (0.5m)
ANS ?
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23
Exercise 2
3f i What is the function of chloroplasts?
Chloroplasts contain chlorophyll which can
absorb light energy for photosynthesis. (1m)
ANS ?
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Exercise 2
3f ii Explain why chloroplast is absent in
cells of onion bulb.
Onion bulb grows underground (1m). It is not
necessary to have chloroplast for photosynthesis
as light is not available (1m).
ANS ?
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