Page 7 - Focus PT3 2020 Science ( BI Version )

Science PT3 Chapter 2 Cell as the Basic Unit of Life
Structures of Animal Cell and Plant Cell

1. Cells are very tiny and can only be clearly seen under a microscope.

2. A microscope is used to observe the structures of animal and plant cells in Activities 2.1 and 2.2.
Steps
Form
Form
1 Eyepiece magnifies the image of the specimen Place the microscope in
to about ten times (10x) magnification.
Tube connects the eyepiece to the objective 1 a bright place.
lenses.
Coarse focus knob is used to move the Crank the low power
low power objective lens. 2 objective lens down so
Fine focus knob is used to move the that it is clicked into
position.
high power objective lens to bring the
specimen into better focus.

Low power objective lens Adjust the diaphragm
magnifies the image of the 3 and mirror so that there
specimen to 4x. is sufficient light to view
the specimen through
Medium power objective the microscope.
lens magnifies the image
of the specimen to 10x.
4 Place the slide on the
High power stage and use the clips
objective lens to hold the slide.
magnifies the image
of the specimen to
40x.
5 Turn the coarse focus
Diaphragm controls knob to lower the body
the amount of tube as close to the
light reaching the specimen as possible
specimen. without touching it.

Mirror reflects 6 Look through the
eyepiece, and turn
light towards the coarse focus knob
the diaphragm. anticlockwise to move
the body tube up until
the image comes into
focus.
Stage is the
platform to place the
slides.

Clips hold the slides 7 Turn the fine focus
knob for fine focusing.
in place.

Figure 2.4 The structure of a microscope and the way to use it

30

02 Fokus Science F1.indd 30 11/19/19 11:41 AM