Page 28 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

Table 2.2: Observation of objects using sense organs
Sense
Object
Sight Hearing Smell Touch
1. Flower
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2. Perfume
3. Whistle
4. Cloth

The use of sense organs to make another person may feel it hot. For this
observations has many advantages reason, scientists use standard units
in everyday life. For example, when of measurement when carrying out
you see dark clouds, you know that scientific investigations. These units
it is likely to rain. When you hear the remain constant everywhere.
school bell ringing in the morning,
you know it is time to begin the school Measurements
routine. You like to wear a perfume Scientists use specific instruments
because it smells nice. When you get and units of measurement in their
near fire, you feel the heat and move investigations. The standard system of
away. When cooking you taste food to measurement used by scientists all over
ensure it is delicious. the world is called the International

However, one of the disadvantages of System of Units (SI units). This system
observations made using the senses ensures precision in the presentation of
is that they are often subjective. This scientific results and the uniformity of
means that they are based on a person’s data presentation internationally. It also
interests, opinions, or situation rather enables scientists to confirm results
than facts. For instance, one may feel from other parts of the world. Table 2.3
a bowl of water lukewarm, while shows some common measurements in
another may feel it warm and yet Biology and their units.
Table 2.3: Fundamental quantities
Measurement SI unit Symbol Other common units

Mass Kilogram kg Grams (g)
Length Metre m Millimetre (mm), Centimetre (cm) Ki-
lometre (km)

Temperature kelvin K Degrees Celsius (˚C), Degrees Fahrenheit
(˚F)

Time Second s Minutes (min), Hour (hr)

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