INTRODUCTION TO BIOLOGY
The word Biology is delivered from two
Greek words, namely:
(i) Bios – means life
(ii) Logos – means study
Therefore,
Biology
Is the study of life
OR
Biology: is a branch of science which
deals with the study of living things.
A person who studies biology is called
Biologist.
TERMINOLOGIES OF BIOLOGY
1. LIFE
Is the ability of living things to
feed, reproduce, sense, respire, grow and develop, move and excrete.
2. CELL
Is a basic unit of life.
- Some living things have one cell
hence called unicellular organisms while others have many cells hence called
multicellular organisms
3. LIVING THING
Is anything which has life.
- Living things are also called
organisms or animate things - All living things are made up of very small units called
cells.
Examples of living things
-Animals such as human being, cows,
frogs, snakes
-Plants such as maize plants, bean
plants
-Fungi such as mushrooms
-Microorganisms such as bacteria and
viruses
- Protozoans such as amoeba, euglena,
plasmodium and paramecium
BRANCHES OF BIOLOGY
There are two main branches of
biology, namely
(i) Zoology
(ii) Botany
(i) ZOOLOGY
Is the study of animals.
Examples of animals
-Human beings
-Lizards
-Fish
-Cow
∆A person who study zoology is called Zoologist
(ii) BOTANY
Is the study of plants
Examples of plants
- Maize plants
-Bean plants
-Moss plants
- A person who study botany is called
Botanist
OTHER BRACHES OF BIOLOGY
The following are other branches of
biology:
1. MICROBIOLOGY
Is the study of microorganism
- Fern plants
- Pines, cypress and
- Christmas tree
Microorganisms are very small
organisms that cannot be seen with naked eyes.
Examples of microorganisms
-Bacteria
-Viruses
∆ A person who studies microbiology is
called microbiologist
2. BACTERIOLOGY
Is the study bacteria
Examples of bacteria
- Salmonella typhi
-Vibrio cholera
∆A person who studies bacteriology is
called bacteriologist
3. VIROLOGY
Is the study of viruses Example of
fungi
-HIV (Human Immunodeficiency Virus)
-Corona virus
-A person who studies virology is
called virologist
4. MYCOLOGY
Is the study of fungi
Examples of fungi
- Yeast
-Mushroom
-A person who studies mycology is
called mycologist
5. GENETICS
Is the study of inheritance
- A person who studies genetics is
called geneticist
6. CYTOLOGY
Is the study of cells
- A person who studies cytology is
called cytologist
7. ANATOMY
Is the study of internal structures of
living things.
Example of internal structures of
living things
- Heart
- Brain
- Kidneys -
Lungs
- A person who studies anatomy is
called anatomist
8. ENTOMOLOGY
Is the study of insects
Example of insects
-Locust -
- Grasshoppers
- Butterflies
- Butterflies
- A person who studies entomology is
called entomologist
9. PHYSIOLGY
Is the study of how body structures of
an organism function
- A person who studies physiology is
called physiologist
10. HOLTICULTURE
Is the science and art of growing
fruits, vegetables, flowers or ornamental plants.
11. IMMUNOLOGY
Is the study of body immune system
- A person who studies immunology is
called immunologist
12. PARASITOLOGY
Is the study of parasites
Example of parasites
-Plasmodium
- Some fungi
-Viruses
- Some bacteria
- A person who studies parasitology is
called parasitologist
13. TAXONOMY
Is the study of classification
- A person who studies taxonomy is
called taxonomist
14. ECOLOGY
Is the study of relationship between
organisms and their environment
- A person who studies ecology is
called ecologist
15. ORNITHOLOGY
Is the study of birds Examples of
birds
- Hen
- Hawk
- Penguin
- Vulture
- A person who studies ornithology is
called ornithologist.
16. ICHTHYOLOGY
Is the study of fish.
17. MORPHOLOGY
Is the study of external forms and
structures of organisms
THE IMPORTANCE OF STUDYING BIOLOGY
The following is an outline of why the
study of biology is important:
(i) It helps us
to understand ourselves better.
(ii) Biology
helps us to understand our environment better and how to conserve it
(iii) Biology
helps us to know the causes, transmissions, signs and symptoms of diseases.
(iv) Biology
enables scientists to come up with ways of preventing, treating and curing
diseases.
(v) Biology
enables researchers to come up with improved breeds of crops and animals.
(vi) It is a
foundation for getting into careers such as medicine and agriculture.
(vii) Biology
helps us to answer some fundamental questions such as, what do we need to
survive?
(viii) Biology
helps us to get professional people like doctors, pharmacists and teachers.
(ix) It
encourages international cooperation.
(x) It helps us
to acquire research skills such as measuring, observing, analysis and making
conclusions.
QUESTION
1. Form one students in a certain
secondary school were interested to know why it is necessary to study biology.
Assume you are a Biology teacher: educate these students on the importance of
studying Biology by giving six (6) points.
2. Outline six reasons why it is
important to study Biology?
3. Biology is more than a study of
animals and plants. Explain
4. Distinguish between unicellular
organisms from multicellular organisms giving an example in each case.
5. How Botany differs from Zoology?
CHARACTERISTICS OF LIVING THINGS
There are seven (7) characteristics
(life processes) that distinguish living things from nonliving things. These
are: -
(i) Movement
and locomotion
(ii) Respiration
(iii) Nutrition
(iv) Irritability
or sensitivity
(v) Growth
(vi) Excretion
(vii) Reproduction
NB: For easy study of these
characteristics the word MR NIGER can be used
(i) MOVEMENT
Is the act of changing position or
postures by the whole organism or part of an organism.
- Living things moves in order to
search for food, water, mate, light and to escape from dangers.
- It can occur at a cellular level
e.g. cytoplasmic streaming in amoeba and it can also occur in an organ level.
E.g. Closing and opening of leaves, folding of leaves in plants.
Example of movement
- Singing
- Closing and opening
- Yawning of leaves
- Clapping hands
LOCOMOTION
Is the change in position by the whole
body of an organism from one place and another. Example of locomotion
- Walking -
Swimming
- Running -
Crawling
(ii) RESPIRATION
Is the process of breaking down of
food materials within the cells to release energy.
- Living things need energy for
movement, growth and development, and functioning of body organs.
(iii) IRRITABILITY (SENSITIVITY)
Is the ability of an organism to
detect and respond to a stimulus.
Stimulus
Is a change in the external and
internal environment of an organism.
Examples of stimulus
- Light
- Temperature
- Cold
- Wind
-An alarm clocks
- A smell of food
- A fly landing on your eye.
Response
Is the change shown by an organism in
reaction to a stimulus
Example of response
- Salivation when food smells
- Blinking when a fly landing on the
eye
- Picking up a phone after hearing it
ringing
(iv) NUTRITION (FEEDING)
Is the process of taking in food,
absorb and assimilate nutrients
- Nutrition is the characteristic of
living things which is the basic difference between plants and animals.
- Plants make their own food through
photosynthesis process hence called autotrophs
- Animals get their food by eating
other living things hence called heterotrophs.
- All living things need food to provide
energy for such activities such as growth, repair and health.
(v) GROWTH AND DEVELOPMENT
Growth: Is an irreversible and
permanent increase in size and dry mass of an organism.
- All living things grow and build up
their bodies.
- Animals grow until they reach
certain adult size, but most plants can grow continuously throughout their
lives.
Example of growth
- Increase in body weight
- Increase in body height
- Increase in body size and shape
DEVELOPMENT
Is the change in the complexity of an
organism.
Example of development
- Emergence of a new structure
- Ripening of fruits.
(vi) REPRODUCTION
Is the process by which living things
produce new individuals of their kind.
- All living things reproduce, to
replace organisms lost by death.
- Human beings bear babies; birds
hatch chicks; and plants produce seedlings as new organisms, which eventually
grow to mature organisms to replace those lost by deaths.
(vii) EXCRETION
Is the process of removing metabolic
waste products from the body of living organisms.
- Excretion is shown by both animals
and plants
Example of waste products
- Carbon dioxide
-Urea
- Excess water
-Ammonia
- Waste products are removed from the
body by excretory organs such skin, kidneys, lungs and liver
DIFFERENCES BETWEEN LIVING THINGS AND
NON-LIVING THINGS
|
Living things |
Non-living things |
|
They respire |
Do not respire |
|
They grow |
Do not grow |
|
They respond to stimuli |
Do not respond to stimuli |
|
They reproduce |
Do not reproduce |
|
They excrete |
Do not excrete |
|
They feed |
Do not feed |
|
They move |
Do not move |
|
|
|
QUESTIONS
1. A scientific
space craft brought a material to earth from outer space. Explain how you would
establish if the material is living or non –living thing. Give four points.
Your answer should be in tabular form as shown below:
2. By giving
example distinguish the following terms:
(a) Nutrition
and respiration
(b) Growth and
development
(c) Movement
and locomotion
3. Excretion is
the process of removing metabolic by-products from the body of an organism.
Give four examples of excretory products eliminated by the living things.
4. Write seven
processes that take place in the bodies of living things.
5. State
whether it is movement or locomotion.
(a) Singing
(e) Hopping
(b) Yawning
(f) Leaping
(c) Clapping
hands (g) Flying
(d) Walking
RELATIONSHIP BETWEEN BIOLOGY AND OTHER RELATED FIELDS
Biology relates with many other
fields, some of them are:
(i) Agriculture
(ii) Medicine
(iii) Pharmacy
(iv) Nutrition
(v) Forestry
(vi) Veterinary
science
THE TABLE BELOW SHOW HOW BIOLOGY RELATES WITH OTHER FIELDS
|
FIELD |
MEANING |
HOW IT RELATES TO BIOLOGY |
|
AGRICULTURE |
Is the practice of growing crops and keeping animals An expert person in agriculture who gives advice to farmers is called agriculturist |
Knowledge of Biology enables researchers to come up with improved breeds of crops and animals in order
to increase animal products such as
meat, milk and eggs.. |
|
MEDICINE |
Is the science of diagnosing, treating and preventing diseases in humans |
(i) Doctors, surgeons and nurses
apply knowledge of biology to diagnose, treat and prescribe the right
medicine Page 8 of 135 to cure the disease. (ii) Doctors apply knowledge of
biology to offer education to the patients
on how to prevent themselves from the
diseases |
|
NUTRITION |
Is the study of how food is taken in
and used in the human body in relation to the needs of the body. à A person who studies nutrition is called nutritionist. |
Knowledge of biology enables us to know the suitable diet that should
be taken in order to maintain good
health |
|
PHARMACY |
|
|
|
VETERINARY SCIENCE |
Is the study concerned with the
health of animals and treatment of diseases that affect them. A person who treats and taking care of the health of animals is called veterinarian |
Veterinarians apply knowledge of
biology to diagnose, treat and prevent illness in large and small animals |
|
FORESTRY |
Is the science or practice of
planting and taking care of trees and forests. - A forest is a large area of land covered with trees. A person who takes care of forests is called a forester. |
Knowledge of biology helps to know how to plant trees, the importance
of planting trees and the danger of
cutting down of trees Knowledge of biology is applied to determine the type of plants the
type of plants to be grown related to the
climate, soil and water availability. |
|
|
|
|
SCIENTIFIC PROCESSES IN BIOLOGY
The study of biology involves
scientific processes.
- Scientific processes are conducted
in order to solve different life problems and help us to understand well our
environment.
WAYS USED IN CARRYING OUT SCIENTIFIC
PROCESSES IN BIOLOGY
There are three basic skills that are
needed in studying biology (scientific studies)
(a) Observation
(b) Measurement
(c) Scientific
method
(a) OBSERVATION
This method is done by using sense
organs
- All scientific investigations
involve observation using sense organs
SENSE ORGANS USED IN OBSERVATION
There are five sense organs used in
observation, namely;
(i) Eyes
(ii) Ears
(iii) Nose
(iv) Tongue
(v) Skin
THE FUNCTION OF EACH SENSE ORGAN
EYES
Used for seeing or vision.
Example: shape, colour and size of the
object
SKIN
Used for touch
Used to detect pain, heat, cold and
pressure
Example: texture of an object,
temperature and sharpness of an object.
NOSE
Used for smelling.
Example: smell of chemicals or foods
EARS
Used for hearing.
Example: sounds of living and
non-living things
TONGUE
Used for tasting.
Example: tastes of different specimens
such as sugar and salt.
Example: If you have a coconut, you
can use sense organs to determine that:
(i) It is round – by seeing
(ii) It contains a liquid – by hearing
the sound when shaken
(iii) It has rough husk (surface) – by
touching
(iv) It has good smell – by smelling
(v) It has good taste – by tasting
after breaking the coconut
WEAKNESS OF USING SENSE
ORGANS IN MAKING OBSERVATION
(i) Sense organs are based on person's
ideas rather than facts.
(ii) Sense organs alone cannot be
enough to give out all the details in accuracy way.
ADVANTAGE OF USING SENSE ORGANS IN
OBSERVATION
- Enables us to study living things.
PRECAUTIONS WHEN USING SENSE ORGANS IN
OBSERVATION
(i) Avoid smelling everything in the
laboratory without permission from your teacher or laboratory technician.
(ii) Avoid tasting anything in the
laboratory unless you are told do so by the teacher or laboratory technician.
(b) MEASUREMENT
Is the system of using specific
instruments and units to make investigations. Or is the process of assigning
numerical values to different things in order to find their size or magnitude.
- For any meaningful measurement in
Biology, we need to state the physical quantity (parameter) to be measured and
its units.
- The units applied in measurement are
International System of units (SI-Units).
COMMON PHYSICAL QUANTITIES
(PARAMETERS) MEASURED IN BIOLOGY
The following are common physical
quantities (parameters) measured in biology with their standard units and
instrument used for measuring each parameter:
|
PHYSICAL QUANTINTY |
Instrument used |
SI unit |
|
(i) Mass |
Weighing balance |
kilogram (kg) or gram (g) |
|
(ii) Length |
Ruler or tape measure |
Metre (m) or centimetre (cm) |
|
(iii)Temperature |
Thermometer |
Celsius (0C) or Kelvin (K) |
|
(iv) Time |
Stopwatch |
Seconds (s) |
|
(v) Pulse rate |
Stethoscope |
Numbers of beats per minutes |
1. LENGTH (l)
Is the distance between any two points
- The instrument used to measure
length is called ruler or tape measure
- It is expressed in millimetres (mm),
centimetres (cm), metres (m), and kilometers (km)
Where:
1cm = 10 mm
1m = 100 cm
1km = 1000 m
WORKED EXAMPLES
1. Convert the
following units into millimeter
(i) 10 cm
(ii) 10 km
(iii) 50 m
2. Change the
following units as directed
(i) 1000km to
cm
(ii) 320 to km
(iii) 200mm to km
(iv) 900km to m
2. MASS (m)
Is the quantity (amount) of matter in
the object
à The instrument that can be used to measure mass is called
weighing balance such as beam balance, electronic balance
à It is expressed in grams (g) or kilograms (kg)
Where
1kg = 1000g
WORKED EXAMPLES
1. Convert the
following units as directed
(i) 70g into kg
(ii) 40g into
kg
(iii) 10kg into g
3. TEMPERATURE
Is the measure of relative hotness and
coldness of a body or object
- The instrument used to measure
temperature is called thermometer
- It is expressed in Kelvin (K),
degrees Celsius (℃)
and degrees Fahrenheit (℉)
- The normal body temperature is
between 36℃
to 37℃
Temperature in different units can be
calculated by using the following formula
(i) K = ℃ + 273
(ii) ℉ = ( × ℃) + 32
(iii) ℃ = × (℉ − 32)
WORKED EXAMPLES
1. Convert the following units into
Kelvin (K)
(i) 85℃
Solution
From: K = ℃ + 273
Where: ℃ = 85
K = 85 + 273 = 358
Therefore: 85℃ = 𝟑𝟓𝟖K
(ii) −450℃
Solution
From: K = ℃ + 273
Where: ℃ = −450
K = −450 + 273 = −177
Therefore: −𝟒𝟓𝟎℃
= −𝟏𝟕𝟕K
(iii)115℃
(iv) 40℉
2. Convert the
following units into degrees Celcius (℃)
(i) 20K
(ii) 40℉
(iii)100℉
3. Convert the
following temperature into degrees Fahrenheit (℉)
(i) 85℃ (iii)100℃
(ii) 115℃ (iv) 20K
4. PULSE RATE
Is the number of times the heart beats
per minute.
- The instrument used to measure pulse
rate is called stethoscope
- It is expressed in number of heart
beats per minute.
NB:
For a person in normal health, the pulse rate occurs 72 times per minute but
for the embryo of human being aged about 60 days, the pulse rates is 150 beats
per minute
Parts of the body where Pulse is felt
Pulse is felt in any artery by placing
the index and middle fingers on:
- The neck
- Behind the knee,
- The wrist
- On the side of elbow
- Below ears
- Near the ankle joint.
NB: Do not use the thumb to make pulse
because it has its own pulse.
(c) SCIENTIFIC METHOD
Is a set of steps that a scientist
follows to solve a problem about nature.
OR is an organized set of guidelines
used to solve scientific problem
- The scientific method is also called
scientific process or scientific procedure
IMPORTANCE OF SCIENTIFIC
METHOD
(i) It helps us
to solve scientific problem
(ii) It helps
us to gain new knowledge
(iii) It helps us to conduct project
work or carry out field work
STEPS OF THE SCIENTIFIC METHOD
The scientific method involves the
following steps;
1. Identifying
a problem
2. Formulating
a hypothesis
3. Conducting
experiment
4. Collecting
data
5. Analysing
data
6. Interpreting
data
7. Conclusion
1. IDENTIFYING THE PROBLEM
This is the first step in the
scientific method where a problem is recognized or identified.
- In our day to day life one often
comes across questions which require explanations or answers.
PROBLEM
Is a specific event observed in the
environment.
For example
In a certain region of Tanzania,
Agricultural officers observed tomatoes yield was low despite frequent
irrigation, correct planting techniques, timely planting and adequate sunlight.
Question (problem could be)
What could have caused poor yield of
tomatoes in Jama's garden despite all the efforts made?"
2. FORMULATING A HYPOTHESIS
This is the second step in the
scientific method where a possible answer to a question is suggested.
Hypothesis
Is an intelligent guess which tries to
answer the observed problem.
Or is a tentative explanation for the
observation made.
- A hypothesis from the above problem
could be that the low yield of tomatoes is caused by poor soil fertility."
- Therefore, the agricultural officers
suggested that application of fertilizer could increase the tomatoes yield.
Ways used to test hypothesis
(i) By careful observation in a
natural setting
Example: Behaviour of a certain type
of wild animal can be studied by carefully observing the animal in the field
they live
(ii) By conducting experiment
3. EXPERIMENTATION
In this step, scientists plan and
conduct an experiment
- In planning an experiment
- Scientists collect necessary
information concerning the problem, determine which apparatus will be used,
which materials will be required and what procedures will be followed to prove
or reject the hypothesis.
Experiment
Is a test done to confirm or reject
the hypothesis
- Experiment is conducted to determine
if the hypothesis is correct or not.
- Experiment is repeated more times to
obtain more accurate results
NB: In conducting experiment, two sets
of subjects are involved:
(a) Experimental group or test
experiment
(b) Control group or control
experiment
(a) Test experiment
Is the one that receives treatment
Or is the experiment which is done by
changing variables or factors from time to time
Example: addition of fertilizers (b) Control experiment
Is the one that does not receive
treatment
Or is the experiment which is done
without changing variables or factors.
Example: no addition of fertilizers
- Control experiment is usually set in
order to compare it with the test experiment and to prove the hypothesis.
From our example of low tomatoes
yield, a plan for investigation could be as follows: Aim of the experiment: To
observe if low yield is due to poor soil fertility Requirements: Tomato seed
from affected area, fertilizer Instructions:
(i) Set aside two plots and name them
as: Plot A and Plot B
(ii) Subject all the two plots to the
same ecological conditions
(iii) In plot A apply fertilizer as
recommended by the agricultural officers
(iv) In plot B fertilizer should not
be added.
(v) Harvest and compare the yields of
the two plots
NB: In the above planned experiment,
the plot B is not applied with fertilizer, this is a control experiment. The
controlled experiment proves that the fertilizer is the one that determines the
tomatoes yield.
The experiment is conducted by using
variables
VARIABLES
Are conditions or factors that can
change or be changed during an experiment
TYPES OF VARIABLES
There are three types of variables,
namely;
(a) Dependent variable
Is the condition or factor that is investigated
or observed to obtain the results of the experiment
(b) Independent variable (manipulated)
Is the condition or factor that is
changed systematically to obtain different results
(c) Controlled variable
Is the condition that is kept constant
during the experiment. Example light
4. COLLECTING DATA
Is the process of recording and
presenting all the changes or information observed during experiment
- In this step, all changes observed
during the experiment are collected and recorded.
Data
Is the information gathered during the
experiment.
Or is unprocessed information that is
collected from the experiment by observation or measurement.
5. DATA ANALYSIS
Is the process of translating
information observed during an experiment.
- Data analysis involves comparing the
results obtained and hypothesis
- Data are organized and analyzed in
order to test the hypothesis, to see trends and patterns
- To enable one to see the results in
an organized manner, data should be presented using different methods such as
tables, bar charts, pie charts, histograms drawings or line graphs.
Example
A table below presents the data
analyzed from our tomato experiment
PLOT TOMATO
YIELD
A
2,300 kg
B
150 kg
6. DATA INTERPRETATION
Is the process of giving meaning of
the collected data.
- In our tomato yield experiment, the
data in the table above shows that there is a difference in tomato yield from
the two plots.
- The yield of plot A was higher than
of the plot B. this mean that, the amount of fertilizer has effect on the
amount of tomato yield.
7. CONCLUSION
Is the statement that summarizes the
results of the experiment conducted.
- In conclusion, a hypothesis can be
accepted or rejected based on the data collected and analyzed. Example
- In our tomato yield experiment, the
results have shown that the application of the right amount of fertilizer
increased crop yield.
- Therefore, low tomato yield was a
result of poor soil fertility.
- The results support the hypothesis
that low crop yield was caused by poor soil fertility
- In this case, the hypothesis was
accepted or confirmed.
- In some cases, when the hypothesis
selected and involved for experiment is rejected another hypothesis is formed
and an experiment is conducted again.
- Conclusion results to the formation
of law, theory and principle. The steps for scientific method are summarized in
the figure below.
The steps for scientific method are
summarized in the figure below.
THE BIOLOGY LABORATORY
The word 'laboratory' originates from
Latin name 'laborare' which means "a place for work"
Laboratory is a room or building designed for carrying out scientific
experiments.
There are various types of laboratory
such as;
(i) Biology
laboratory
(ii) Chemistry
laboratory
(iii) Physics
laboratory
(iv) Clinical
laboratory
(v) Industrial
laboratory
BIOLOGY LABORATORY
Biology laboratory is a special room
or building where biological experiments are conducted.
The biology laboratory differs from
other scientific laboratories in the following ways;
(i) Biology
laboratory has preserved specimens
(ii) Biology
laboratory has models of organs
(iii) Biology laboratory has
microscope
(iv) Biology
laboratory has dissecting kit
(v) Biology
laboratory has charts showing different body systems and organs
(vi) Biology
laboratory has cages Cage is an enclosure made to hold animals
(vii) Biology
laboratory has aquaria (single–aquarium) Aquarium is tank made for keeping live
aquatic animals
QUALITIES OF A GOOD LABORATORY
(i) Laboratory
has doors which exit outwards. This is for easy escape when accident occurs.
(ii) Laboratory
should have source of water. Water help in boiling, mounting specimens and
cleaning.
(iii) Laboratory
should have source of heat. Heat is needed for experiments
(iv) Laboratory
should have electricity supply. Electricity is for lighting and electronic
devices.
(v) Laboratory
should have adequate apparatus for conducting experiments
(vi) Laboratory
should have adequate storage room and cupboards. For storing apparatus and
specimens
(vii) Laboratory
should have adequate space for carrying out experiments.
(viii) Laboratory
should have emergency facilities placed in area where can be reached easily.
Example fire extinguishers and sand buckets
LABORATORY SAFETY RULES
Laboratory can be a dangerous place if
the safety rules are not observed.
The following are some rules to ensure
safety in a laboratory.
(i) Do not
enter the laboratory or do an experiment without permission from a teacher.
(ii) Do not
run, play or make noise in the laboratory. (iii) Do not eat any food or drink
in the laboratory
(iv) Do not use
broken apparatus or unlabeled chemicals.
(v) Do not take
any laboratory tool or specimen out of the laboratory.
(vi) Do not
taste anything without being instructed
(vii) Do not
put laboratory equipment at the edge of benches or tables.
(viii) Do not leave
water and gas taps open
(ix) Do not
block the emergency facilities and passage ways.
(x) Follow all
instructions before starting any experiment.
(xi) Wash your
hands with clean water and soap after the experiment.
(xii) Wash the
apparatus and benches at the end of the experiment
(xiii) Wear
safety tools before you start the experiment
(xiv) Read and
understand all the warning signs on the container.
(xv) Report all
accidents occurred to your teacher or laboratory technician.
COMMON APPARATUS AND EQUIPMENT USED IN THE BIOLOGY
LABORATORY
APPARATUS
Is a tool used for carrying out
experiments in laboratory.
Some common biology laboratory
apparatus and equipment include:
1. TEST TUBE
It is used to hold, mix or heating
small amounts of substance
2. TEST TUBE
HOLDER
It is used to hold test-tubes during
heating
3. TEST TUBE
RACK
Used to hold and support test tubes
4. PETRI DISH
- Used for putting specimens
- Used for growing small organisms
5. BUNSEN
BURNER
Used to heat materials in the
laboratory
6. THERMOMETER
Used to measure temperature
7. DROPPER
à Used for adding liquids drop by drop
8. BEAM BALANCE
Used to measure mass of substances
9. MORTOR AND
PESTLE
Used for crushing and grinding substances
10. MICROSCOPE
Used to magnify micro-organisms
11. HAND LENS
Used to magnify small organism/objects
for observation.
12. POOTER
Used for catching up small organisms
without hurting them
It is made with two tubes where one is
for sucking organisms and another for drawing in the apparatus
13. FISH NET
Used for catching organisms living in
water Example fishes and tadpoles
14. SWEEP NET
Used for catching flying insects
15. SPECIMEN BOTTLE
Used for keeping preserved organism
16. DISSECTING KIT
It carries tools used for dissection
THE MICROSCOPE
MICROSCOPE
Is an instrument used to magnify
micro-organism.
Micro-organisms are very smallest
organism which cannot be seen by our naked eyes.eg bacteria.
TYPES OF MICROSCOPE
There are two types of microscope
(i) Light
microscope (compound)
(ii) Electron
microscope
1. ELECTRON MICROSCOPE
Is a microscope that uses beams of
electrons to magnify specimen.
The maximum useful magnification of
most electrons microscope is one million times (100, 0000×)
Electron microscope is very expensive.
It is mostly found in research
centres.
2. LIGHT MICROSCOPE
Is a microscope that uses light to
illuminate and magnify small specimen. - Light microscope is also called
compound microscope
It has low magnification compared to
that of electron microscope
Maximum useful magnification of most
light microscope is about one thousand time (1000×).
Light microscope is commonly found in
school laboratories and health centres.
DIFFERENCES BETWEEN ELECTRON AND LIGHT
MICROSCOPE
|
LIGHT MICROSCOPE |
ELECTRON MICROSCOPE |
|
(i) It is less expensive |
It is more expensive |
|
(ii) Uses light to illuminate object |
Uses electron beam to illuminate object |
|
(iii)It has low magnification |
It has high magnification |
|
(iv) It has low resolution |
It has high resolution |
|
(v) It uses glass lenses |
It uses magnetic deflector |
A WELL LABELLED DIAGRAM OF
A LIGHT MICROSCOPE
PARTS OF THE LIGHT MICROSCOPE AND
THEIR FUNCTION
Light microscope has the following
parts:
(i) Eyepiece
lens (ocular lens)
(ii) Eyepiece
(ocular)
(iii) Body tube
(iv) Coarse
adjustment knob
(v) Fine adjustment
knob
(vi) Rotating
nose piece
(vii) Objective
lens
(viii) Stage
(ix) Stage clip
(x) Condenser
(xi) Diaphragm
(xii) Mirror
(xiii) Arm
(xiv) Hinge
screw
(xv) Base
|
PART OF THE MICROSCOPE |
FUNCTION |
|
|
1. Eye piece lens |
Used to increase magnification |
|
|
2. Ocular tube |
Allow light to pass from the
objective lens to the eyepiece. It has a lens that magnifies the
specimen |
|
|
3. Body tube |
It holds the ocular lens and
objective lenses at the proper working distance from each other. It supports the eyepiece and
rotating nose piece It connects the eyepiece to the
objective lens |
|
|
4. Coarse adjustment knob |
It raises or lowers the body tube in order to bring
the image into focus. |
|
|
5. Fine adjustment knob |
It raises or lowers the body tube in order to bring
the image into sharp focus |
|
|
6. Rotating nose piece |
It holds two or more objective lenses |
|
|
7. Objective lens |
It brings s image into focus and magnify it |
|
|
8. Stage |
It is a place where slides of specimen are kept |
|
|
9. Stage clip |
It holds the slides firmly in place. |
|
|
10. Condenser |
It concentrates the light which passes through the
specimen. |
|
|
11. Diaphragm |
It regulates the amount of light that passes through
the specimen. |
|
|
12. Mirror |
It reflects and directs light to the specimen under
observation. |
|
|
13. Hinge screw |
|
It raises or lowers the stage to keep the specimen in
right position for observation. |
|
14. Arm/limb |
|
Supports the body tube, knobs, stages, diaphragm and
mirror |
|
|
|
It helps to handle microscope when moving it. |
|
15. Base |
|
It provides firm support for the microscope. |
HOW TO USE LIGHT MICROSCOPE
(i) Place the
microscope on the laboratory bench or table. Position the microscope such that
the arm faces you and the stage faces away from you.
(ii) Mount the
specimen on slide and cover it with a cover slip.
(iii) Make sure
that the low objective lens is in line with the eye piece lens.
(iv) Place the
slide with the specimen on the stage and hold it in place with the stage clip.
(v) While
looking through the eyepiece use your hand to adjust the mirror so that the
light is directed to the specimen on the stage. Always keep both eyes open when
looking through eyepiece
(vi) Adjust the
coarse adjustment knob to bring the specimen into focus (vii) Adjust the fine
adjustment knob to bring the specimen into a sharp focus.
(viii) Rotate the nose piece to a
higher power objective lens if you want to observe more details of the
specimen.
PRECAUTIONS WHEN HANDLING
AND CARING OF A LIGHT MICROSCOPE
(i) Always use
two hands when carrying a light microscope. One hand holding the arm and the
other holding the base.
(ii) Never
place the microscope at the edge of the bench or table. This is because it
could be knocked over.
(iii) Do not
touch the surface of the mirror or lenses with your fingers.
(iv) Clean
dirty lenses using lens tissue or a soft cloth
(v) Lubricates
the moving parts regularly
(vi) Always use
the cover slip in order to protect the lenses of the microscope from getting
into contact with the specimen
(vii) Remove
the slides from the stage immediately after use.
(viii) Turn the
adjustment knob slowly. Always start with the course adjustment knob.
(ix) When not
in use, cover the microscope with clean cloth and store it in dry and dustless
place.
(x) When not in
use for a long time, remove the lenses and put them in a desiccator (xi) Move
the objective lenses up when storing the microscope.
(xii) When storing the microscope
rotate the nose piece so that the low magnification lens is in line with the
eyepiece lens.
NB: SLIDE
Is a flat rectangular piece of glass
used to hold a specimen for microscopic observation
SLIDE COVER (COVER SLIP)
Is a small glass used to cover the
specimen on slide
MAGNIFICATION
Is the number of times the image has
been enlarged
- In microscope, magnification is
determined (calculated) by multiplying the eye piece lens magnification by the
objective lens magnification.
|
Total magnification = Eyepiece lens magnification × Objective lens
magnification |
Worked Example
1. Calculate the total magnification
of the image seen by ×5 of eyepiece lens and by ×10 of the objective lenses
Solution
Data given
Total magnification =Asked
Eyepiece lens magnification = 5
Objective lens magnification =10
Total magnification = eyepiece lens
magnification × objective lens magnification
Total magnification = 5 ×10 =50
Therefore, the total magnification of
the image is ×50
2. Calculate the objective lens
magnification of the object, if the total magnification is ×250 and the
eyepiece lens is ×10
Solution
Data given
Total magnification =250
Eyepiece lens magnification = 10
Objective lens magnification =Asked
From:
Total magnification = eyepiece lens
magnification × objective lens magnification
250 = 10 × objective lens
magnification
Objective lens magnification = = 25
Therefore, the objective lens
magnification is ×25
REVISION QUESTIONS
1. Calculate the total magnification
of image, if the objective lens magnification is ×20 and eyepiece lens
magnification lens is ×10.
2. If the magnification power of
eyepiece lens of a compound microscope is ×10 and that of the high-power
objective lens is ×50, what is the total magnification of the specimen under
observation?
3. Calculate the objective lens
magnification of object. If the total magnification of the object is ×300 and
the eyepiece lens magnification is ×5.
4. Calculate the eyepiece lens
magnification of an object. If the objective lens magnification of the object
is ×15 and the total magnification of an object is ×120.
HAND LENS
Is an instrument composed of a convex
lens used for magnifying small objects.
The
Diagram of hand lens
PARTS OF HAND LENS
Hand lens has three main parts,
namely:
(i) Convex lens: used for magnifying
small objects.
(ii) Frame: gives support to the
convex lens
(iii)Handle: helps to handle the hand
lens when moving it.
HOW TO USE A HANDLENS
In order to magnify an object by using
a hand lens, the following procedures should be followed:
(i) Place the
object or specimen under observation on the bench or table.
(ii) Move the
hand lens with one hand from the object or specimen to the eye
(iii)As the object or specimen comes
into focus an enlarged image will be observed
How to determine magnification of an
object or specimen viewed under a hand lens Magnification of an object or
specimen viewed under a hand lens is determined (calculated) by dividing the
length of a drawing by the length of the actual object. As follows:
𝐋𝐞𝐧𝐠𝐭𝐡
𝐨𝐟
𝐚
𝐝𝐫𝐚𝐰𝐢𝐧𝐠(𝐢𝐦𝐚𝐠𝐞)
Drawing magnification =
𝐋𝐞𝐧𝐠𝐭𝐡
𝐨𝐟
𝐭𝐡𝐞
𝐚𝐜𝐭𝐮𝐚𝐥
𝐨𝐛𝐣𝐞𝐜𝐭
OR
𝐒𝐢𝐳𝐞
𝐨𝐟
𝐚
𝐝𝐫𝐚𝐰𝐢𝐧𝐠(𝐢𝐦𝐚𝐠𝐞)
Magnification of a drawing =
𝐒𝐢𝐳𝐞
𝐨𝐟
𝐭𝐡𝐞
𝐚𝐜𝐭𝐮𝐚𝐥
𝐨𝐛𝐣𝐞𝐜𝐭
WORKED EXAMPLES
1. A drawing of 10cm in length was
made of Bee of 5cm in length. Calculate the magnification of drawing.
Solution
Data given
Length of a drawing =10
Length of the actual object = 5
Magnification of a drawing =Asked
From:
Length of a drawing
Magnification of a drawing =
Length of the actual object
10cm Magnification of a drawing = = 2
5cm
Therefore, Magnification of a drawing
is ×2
REVISION QUESTIONS
1. If the
length of the drawing is 8cm and the actual length of the object is 2cm. What
will be the magnification of a drawing?
2. (a)How do
you determine the magnification of an object viewed under a hand lens?
3. Basically,
there are two types of microscope, name them:
4. Compare and
contrast a light microscope and an electron microscope.
5. How do you
determine the magnification of an object viewed under a light microscope
6. Mention
three parts of a hand lens
7. (a) Draw a
well labelled diagram of a light microscope.
(b) State the function of each part
labelled in the diagram 7 (a) above.
8. Draw a well
labelled diagram of a hand lens.
The following are warning signs that are found on apparatus
and chemical containers in the laboratory or on the boxes in which chemicals
and apparatus are kept.
(i) Toxic
(ii) Corrosive
(iii) Flammable
(iv) Oxidant
(v) Explosive
(vi) Harmful
(vii) Irritant
(viii) Fragile
(ix) Radioactive
(x) Biohazard
1. TOXIC
Is a poison substance which may cause
death when touched, swallowed or inhaled.
Examples of toxic substances
- Pesticides
- medicine
A diagram of toxic warning sign
2. CORROSIVE
Is a substance that can burn the skin
or a surface.
= It can cause body wounds or burn
various things such as a clothes and furniture
Examples of corrosive substances
- Concentrated acids e.g. sulphuric
acid,
- Concentrated alkaline e.g. Sodium
hydroxide.
A diagram of corrosive warning sign
3. FLAMMABLE
Is a substance which can catch fire
easily.
- The substances should never be
brought near open flame
Examples of flammable materials
- Alcohol
- Petrol
- Kerosene
- Diesel
A diagram of flammable warning sign
4. OXIDANT
These are chemical that can accelerate
burning of materials.
Example of oxidant substances
- Potassium permanganate
- Potassium hydroxide
A diagram of oxidant warning sign
5. EXPLOSIVE
An explosion is a forceful rapid
reaction, which involves throwing off of particles at high speed.
Example of explosive substances
- Gunpowder
- Mosquito spray
6. HARMFUL
Is the substance which can cause
illness.
This substance may not kill
immediately but may have effects when used for a long period.
Examples of harmful substances
-Alcohol
- Cigarettes
DIAGRAM OF HARMFUL
7. RADIOACTIVE
Is the substance that emits harmful
radiations.
- Radioactive substances are elements
that emit radiations either alpha, beta, gamma or neutrons.
- Radioactive substances can cause
dangerous effects such as skin damage, skin diseases, disabilities, death,
blindness and various types of cancer ases Example of radioactive
- X- rays
- Uranium splits to emit neurons
- Radium emits alpha and gamma rays
- Tritium emit beta rays
- Cesium emit gamma rays
A diagram of radioactive warning sign
BIOHAZARD
Is a biological substance that can
cause disease or threat to the health of humans.
- Biohazard contains microbes
- Biohazard is a short form of
biological hazard
Example of biohazards substances
- Medical waste e.g. wound dressings
- Sludge waste
DIAGRAM OF BIOHAZARDS
REVISION QUESTIOS
1. Write TRUE
or FALSE
(i) A
laboratory is a special room designed for scientific investigation
(ii) Thermometers
and burners are only found in the biology laboratory
(iii) Laboratory safety rules are
formulated to frighten students
(iv) Corrosive
chemicals can burn books and clothes because they catch fire easily
(v) Using
microscope, biologists have been able to observe very small organisms.
2. Name the
laboratory apparatus used in the following activities
(i) Magnifying
substance
(ii) Catching
flying insects
(iii) Keeping specimens
(iv) Crushing
things
(v) Measuring
mass
3. State the
function of the following parts of microscope
(i) Base
(ii) Diaphragm
(iii) Condenser
(iv) Mirror
(v) Stage
(vi) Objective
lens
4. List four
features that make biology laboratory different from other facilities.
5. Explain how
the following substances should be handled.
(i) Harmful
(ii) Explosive
(iii) Oxidant
