Scientific Processes in Biology | Biology Form One Notes New Syllabus

Chapter Two: Scientific Processes in Biology

Biology laboratory is a special room or building designed for carrying out biological experiments.

A laboratory should have good qualities and facilities which include large door for opening outwards, adequate space for carrying out experiments, proper lighting, good ventilation, a source of water, a source of heating, and adequate space for storing apparatus, chemicals, models, and specimens.

Common Biology laboratory apparatus, equipment and resources

A hand lens

This is mainly used to magnify specimens that are under observation.

A hand lens enables a scientist to magnify small organisms or their parts in order to observe them clearly.

Scientists usually make drawings of objects which they observe using a hand lens. The size of the drawing that they make is usually larger or smaller than the actual object.

Magnification

Magnification is calculated as follows:

Formula for magnification

$\textbf{Magnification} = \frac{\text{Size of image}}{\text{Actual size of object}}$

Example 1: Cell under a microscope

Actual size of a cell = 20 μm (micrometres)
Size of the image in a textbook = 4 cm

Step 1: Convert units (very important!)

4 cm = 40 mm
40 mm = 40,000 μm

Step 2: Apply the formula

$\text{Magnification} = \frac{40{,}000\ \mu m}{20\ \mu m} = 2000$

✅ Answer:

The magnification is ×2000

Sweep nets

A sweep net is used for catching small flying organisms, such as butterflies, grasshoppers and other small animals.

Scoop nets

These are used for catching fish and other aquatic animals.

Pooter

This is a device that scientists use to pick up small organisms, such as insects without hurting them.

The pooter has two tubes. The scientist sucks through one tube and the organism is drawn into the pooter through the other tube.

Quadrat

A quadrat is a wooden square or metallic grid which is used to estimate the number of organisms in an area.

Specimen bottle

A specimen bottle is a glass or plastic container in which specimens are kept for storage.

A dissecting kit

A dissecting kit contains tools for dissection of specimens.

Some of the items included in the dissecting kit are:

(a) Forceps for holding specimens.

(b) A pair of scissors for cutting specimens or objects.

(d) A needle for loosening internal parts.

(e) Pins for holding specimens in place.

(f) Hand lens for magnifying small specimens or their parts.

Thermometer

A thermometer is an instrument used to measure temperature.

Heat sources

Heat sources are used for heating various things in the laboratory.

Examples of heat sources in the laboratory are:

Bunsen burner,

kerosene stove,

and spirit burner,

Mounting needle

A mounting needle is used to lift small delicate specimens.

Microscope slide and coverslip

The microscope slide is a small flat piece of glass that is used to hold specimen under observation.

A specimen to be observed under a microscope is placed on a slide with a drop of a liquid and covered with a coverslip.

Microscope3

A microscope is an instrument that is used during scientific studies to magnify very small specimens so that their details can be seen.

The smallest structures of cells, tissues, and organs of organisms can be studied well if magnified by the microscope.

Types of microscopes

Electron microscope

Light microscope

The electron microscope

The electron microscope uses beams of electrons to magnify specimens.

The maximum useful magnification of most electron microscopes is about a million times.

These microscopes are very expensive.

They are mostly found in research centres or research institutions.

The light microscope

The light microscope is the type of microscope that depends on light to illuminate and magnify tiny specimens.

For this matter, it differs from the electron microscope by having lower magnification.

The maximum useful magnification of most light microscopes is about one thousand times.

This type of microscope is commonly used in schools and health facilities.

Parts of the Light Microscope

Table 2.1: Parts of the light microscope and their functions

Part	Function
Eyepiece	Has a lens that magnifies the specimen five times, ten times, or fifteen times.
Body tube	Supports the eyepiece and the rotating nosepiece.
Rotating nosepiece	Supports the objective lenses. Rotates to allow changes from one lens to another.
Objective lenses	Magnify the object under observation. Light microscope usually has three objective lenses: low power, medium power, and high power. A high-power lens reveals more details of the specimen.
Coarse adjustment knob	Rises or lowers the body tube in order to bring the image into focus.

How to use the light microscope

(a) Place the microscope on the laboratory bench or table. Make sure it is not too close to the edge. Position the microscope such that the arm faces you and the stage faces away from you.

(b) Mount the specimen on the microscope slide. Cover it with a coverslip.

(d) Place the slide with the specimen on the stage. Hold it in place with the stage clip.

(e) 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 the eyepiece.

(f) Adjust the coarse adjustment knob to bring the specimen into focus. (g) Adjust the fine adjustment knob to bring the specimen into a sharp focus.

How to care for the light microscope

(a) Lift the microscope using both hands, one hand holding the arm and the other holding the base.

(b) When not in use, cover the microscope with clean cloth and store it in a dry, dust-free place.

(d) Do not place the microscope at the edge of the table or bench as it could be knocked over.

(e) When the microscope is not in use for a long time, remove the lenses and put them in a desiccator.

(f) Do not touch the microscope with wet hands.

(g) Do not touch the surface of the mirror or the lenses with your fingers.

(h) Lubricate the moving parts regularly.

(i) Always use the coverslip in order to protect the lenses of the microscope from getting into contact with the specimen.

(j) Remove the slides from the stage immediately after use.

(k) Move the objective lenses up when storing the microscope.

(l) When storing the microscope, rotate the rotating nosepiece so that the low magnification lens is in line with the eyepiece lens.

Activity: Using the light microscope

Materials: Light microscope, microscope slide and coverslip, razor blade, knife or scalpel, onion bulb, forceps, mounting needle or glass rod, iodine solution, and blotting paper

Procedure

Use the knife to cut the onion bulb vertically or lengthwise into four pieces.

Observing a Specimen

Safety Precaution

Take precautions when using sharp objects, such as a knife and razor blade.

Obtain a fresh leaf from one of the quarters.

Trim the thin layer to approximately 5 mm times 5 mm.

Put a drop of water on the microscope slide. Place the trimmed thin layer of onion leaf in the drop of water using a glass rod or a mounting needle, as shown in Figure 2.15.

Gently cover the specimen with a coverslip making sure that no air bubbles are trapped inside.

Dry any excess water from the sides of the coverslip using a blotting paper.

Mount the slide on the stage of the light microscope. Hold it in place with the stage clips.

Observe the specimen under the low power objective lens, then observe under the medium power objective lens.

Remove the specimen from the microscope stage. Remove the specimen from the slide and put a new specimen. Put a drop of iodine on the specimen. Repeat the procedures. Iodine makes the specimen clear. Use blotting paper to eliminate any excess iodine.

Biological Models and Preserved Specimens

Biological Models

Biological models are sculptures that represent a particular organ or system of an organism. They are usually made in three dimensions, which helps to represent the real part of an organism.

Purpose and Examples

Models are used during teaching and learning to help reinforce concepts.

Most models used in Biology are made of plastic materials.

Common examples include models of the human eye, lungs, heart, ear, and skeleton.

(a) The human ear.

(b) (b) The human skeleton.

Preserved Specimens

Preserved specimens are collected organisms or parts of organisms that are maintained for learning purposes.

Examples

Organisms or parts of organisms that are usually preserved include:

Plant leaves

Roots

Fruits

Insects

Small animals

Final Steps of Observation (from previous context)

Observe the specimen again under low power and medium power objective lenses.

What did you observe? (This is a question for the student to answer based on their experiment).

Scientific Tools and Basic Skills

Biological Models and Preserved Specimens

Biological models are three-dimensional sculptures that represent a particular organ or system of an organism, used during teaching to reinforce concepts. They are mostly made of plastic materials.

Examples include models of the human eye, lungs, heart, ear, and skeleton. Preserved specimens are collected organisms or parts of organisms that are maintained for learning purposes.

Examples include plant leaves, roots, fruits, insects, and small animals.

Containers for Living Organisms

Cages are enclosures often made of wire mesh or bars where living organisms like birds, mice, rabbits, or other small animals are kept. Aquariums are special vessels used in the laboratory for keeping live aquatic organisms, such as fish. They can be of different shapes and sizes.

Basic Skills in Scientific Studies

There are essential skills needed in studying Biology, including observation, measurement, and experimentation.

Observation

Observation is one of the methods of studying Biology. Through observation, one can study living things in many ways, including by using their sense organs.

An example is using sense organs in making observations.

Observation and Sense Organs in Biology

Observation is a key method of studying Biology, allowing one to study living things in many ways, including by using their sense organs.

We have five sense organs

the eyes, ears, skin, nose, and tongue.

The observation process, with the help of these sense organs, enables you to study living organisms.

Examples of Observation Using Sense Organs

If you have a coconut, you can use your sense organs to determine the following about it:

Seeing (Eyes): It is round.

Hearing (Ears): It contains a liquid by hearing the sound when shaken.

Touching (Skin): It has a rough husk.

Smelling (Nose): It has a good smell (after breaking the coconut).

Tasting (Tongue): It has a sweet taste (after breaking the coconut).

Materials

Colourful pictures

Insects

Preserved specimens

Flowers

Perfume

Whistle

Bell

Stones

Wooden objects

Pieces of cloth

Ice

Hot water

Lukewarm water

Procedure

Carefully observe the specimens provided using your sense organs.

Note down the features of each specimen you have observed.

Record the observations by putting a tick on each object.

Safety Precautions

Do not taste anything in the laboratory. They may be contaminated with poisonous materials or they may be poisonous themselves.

The use of sense organs to make observations has many advantages in everyday life

For example, when you see dark clouds, you know that it is likely to rain.

When you hear the school bell ringing in the morning, you know it is time to begin the school routine.

You like to wear a perfume because it smells nice.

When you get near fire, you feel the heat and move away.

When cooking, you taste food to ensure it is delicious.

The following are the Disadvantages of observations made using the senses

They are often subjective. This means that they are based on a person's interests, opinions, or situation rather than facts. For instance, one may feel a bowl of water lukewarm, while another may feel it warm and yet another person may feel it hot.

For this reason, scientists use standard units of measurement when carrying out scientific investigations.

These units remain constant everywhere.

Measurements

Scientists use specific instruments and units of measurement in their investigations.

The standard system of measurement used by scientists all over the world is called the International System of Units (SI units).

This system ensures precision in the presentation of scientific results and the uniformity of data presentation internationally. It also enables scientists to confirm results from other parts of the world.

Table 2.3: Fundamental quantities

Measurement	SI unit	Symbol	Other common units
Mass	Kilogram	kg	Grams (g)
Length	Metre	m	Millimetre (mm), Centimetre (cm), Kilometre (km)
Temperature	Kelvin	K	Degrees Celsius, Degrees Fahrenheit
Time	Second	s	Minutes (min), Hour (hr)

Mass is the quantity of matter of an object.

The thing in the world is made up of matter.

Mass is measured using for out less and reliable weighing scale weighing balance can the patient. Lot of examples. 1000g = 1kg

Activity: Measuring the mass of objects

Materials:

Weighing balance, weights (0.5 kg, 1 kg, 2 kg, and 5 kg), stones, flour, sugar, notebooks, coins, textbook, plant, and pencil pen.

Procedure:

Put a weighing scale on a flat surface, such as a table.

Put half a kilogram weight on the platform.

Add a small amount of flour until the weighing scale balances.

What is the mass of the flour you have measured?

Record your results in your notebook.

Repeat procedures 2, 3, and 4 above using different weights to measure the different materials you have collected.

Prepare a short report of your results.

Length

Length is a measurement of the distance or dimension from one point to another.

For example, you can measure the height of a human being, and plant, as well as the length of a leaf and fish.

Length can be measured using a ruler or tape measure.

Common units of expressing length are millimetres (mm), centimetres (cm), metres (m), and kilometres (km).

These units of length can be converted into other units.

10 mm = 1 cm

100 cm = 1 m

1000 m = 1 km

100 000 cm = 1 km

(a) Ruler

(b) Tape measures

Activity: Measuring length of objects

Materials:

Ruler, paper, a leaf, a small dried fish, notebook, and a pen or pencil.

Procedure:

Take a leaf and put it on a piece of paper. Trace the outline of the leaf.

Put two marks at the extreme points of the leaf outline.

Join the two points by a straight line.

Put the zero mark of the ruler at the first mark and read the length at the second point.

Record the measurement in your notebook.

Compare your findings with those of your classmates. Did you get similar measurements?

Temperature

Temperature is the degree of hotness or coldness of a substance.

It is a physical property that explains the common notions of hot and cold.

The common units for measuring temperature are:

Kelvin (K),

Degrees Celsius (°C),

and degrees Fahrenheit (°F).

These units relate as follows:

K = °C + 273.15

°F = (9/5 × °C) + 32

°C = 5/9 (°F − 32)

The normal human body temperature is between 36 °C and 37 °C.

A thermometer is used to measure temperature.

It can measure human body temperature and temperature of liquids, such as water.

The boiling temperature of water is 100 °C.

Activity: Measuring the temperature of different things

Materials:

Thermometer, beakers, hot water, cold water, and ice cubes.

Procedure:

Carefully take a thermometer from its case and hold it at the top. Do not touch the bulb.

Shake it for a few seconds and read the number that corresponds to the mark.

Put the thermometer bulb under your armpit and wait for two minutes.

Read the number that corresponds to the mark.

What is your body temperature?

Use the thermometer to measure the temperature of hot water, cold water, and ice cubes by dipping the bulb into a container with the substance you want to measure. Observe the movement of the mark inside the thermometer until it stops moving. Record the number that corresponds to the mark.

Record the temperature in degrees Celsius in your notebook.

Compare your results with those of your classmates. Are they similar?

Scientific methods

Search from library and reliable internet sources the information on scientific methods.

Science is the knowledge and systematic study of the structure and behaviour of the natural and physical world.

It is based on facts that can be proven through observation and experiments.

In order to study situations and come up with solutions to the problems, scientists follow a set of steps called the scientific method.

The scientific method is a way of studying things by testing facts systematically.

Scientific method steps

It follows seven steps which are:

Identifying the problem,

Formulating a hypothesis,

Experimentation,

Observation and recording data,

Analysis and interpretation,

Conclusion,

and reporting results.

Identifying the problem

This is where a scientist makes a puzzling observation. The observation can be made in the environment or in the work of other scientists. An example of such an observation is: “Earthworms are mostly found in well-shaded soil.” After making an observation, the scientist asks questions that can be answered by gathering evidence. For example: “What conditions make earthworms prefer cool shaded areas to open well-lit areas?”

Formulating a hypothesis

A hypothesis (plural is hypotheses) is a suggestion of the answer to the question asked. It is an intelligent guess that tries to explain an observation. For example: “Earthworms prefer cool well-shaded areas because these areas have higher moisture than open well-lit areas.”

Experimentation

An experiment is a scientific procedure carried out under controlled conditions to determine whether a hypothesis is correct or not. In an experiment, a scientist uses variables to test a hypothesis. Variables are conditions or factors that can change or can be changed. Examples of variables include temperature, speed, and light. They can be classified as dependent, independent, and controlled variables.

Dependent variable

This is the condition or factor that is measured or tested to obtain the results of the experiment.

Independent or manipulated variable

This is a condition or a factor that the researcher changes systematically to obtain different results.

Controlled variable

This is the condition or factor that is kept constant during the experiment. For example,

(a) Set-up A

Tray

Moist paper towel

Dry paper towel

Earthworm

(b) Set-up B

Tray

Dry paper towel

Earthworm

In set-up A:

(a) The direction in which the earthworms move is the factor under investigation. This is the dependent variable.

(b) The moisture content of the paper towels is varied. This is the independent variable.

Set-up B: Control experiment

In this set-up, the paper towels are not moistened. The independent variable is not changed. The control experiment proves that the independent variable determines the direction of movement of earthworms.

Observation and data recording

The scientist observes what happens from the time the experiment is set up to the time it ends. It is important to note all the changes made in the independent variable and the resulting changes in the dependent variable.

Scientific Method Example: Earthworms and Water Drops

Problem Identification

Hypothesis

Experimentation

Test Experiment

Control Experiment

Observation and Recording Data

Data Analysis and Interpretation

Conclusion

Reject

Modify

Reporting

Data Analysis and Interpretation

Scientists analyze observations and data collected during experiments. They look for patterns or trends that help them understand the results and determine whether the hypothesis is supported.

Conclusion

A conclusion is a statement that summarizes what a scientist has learned from an experiment. It indicates whether the hypothesis was supported by the data.

Reporting Results

Scientists communicate their findings in final reports. These reports include the problem, hypothesis, methods, results, and conclusions, allowing others to understand and replicate the experiment.

Simple Biological Experiments

Biological experiments can be done to study different features of living things. As you learn Biology, you can carry out experiments to test hypotheses or to learn more about organisms.

Note: If your results do not support the hypothesis:

(a) Do not stop to repeat the experiment.

(b) Give possible reasons for the difference between your hypothesis and the experimental results.

Activity 2.6: Observing Different Types of Plant Leaves

Materials:

Different types of plant leaves

Hand lens

Notebook

Pen or pencil

Procedure:

Collect different types of leaves from plants in the school or home environment.

Examine each leaf closely as follows:

(a) Look at the size, shape, and colour.

(b) Feel the texture of the leaf.

Using a hand lens, observe the pattern on each leaf.

Note down what you have observed.

Caution:

Avoid collecting hairy or thorny plants and those known to be poisonous.

Questions:

How are the leaves similar?

How are the leaves different?

Activity 2.7: Collecting and Observing the Characteristics of Animals

Materials:

Preserved specimens of insects and other small animals

Sweep nets

Pen or pencil

Notebook

Books

Hand lens

Procedure:

Use sweep nets to catch insects such as grasshoppers, termites, cockroaches, and butterflies around the school compound, as shown in Figure 2.29.

Sweep nets can also be used to catch small animals such as millipedes and frogs.

Using Sweep Nets to Collect Insects and Other Small Animals

Put the collected insects and other small animals in specimen bottles.

Safety Precaution:

Care should be taken when collecting dangerous organisms such as wasps, scorpions, centipedes, and bees.

Carefully observe the external features of the organisms you have caught.

Then use a hand lens to observe the details of the same features.

The features include number of legs, eyes, and the way they move.

Record your observations in a notebook.

Release or preserve the organisms you have used in your observation.

Revision Exercise

1. Identify the apparatus or equipment you can use to perform each of the following biological activities:

(a) Catch a frog from a pond in order to study its external features.

(b) Collect insects and small animals from the school compound.

2. As a biology student, how would you help your friend to label and state the functions of the parts of the microscope labelled A–E

3. Amina was performing an experiment. Some of her specimens were very delicate and small. Which apparatus was she supposed to use in order to lift these specimens from the specimen bottle?

John attempted to observe plant cells using a prepared slide under a light microscope, but he was unable to obtain a clear image due to the following challenges:

(a) The slide containing specimen did not settle on the stage for observation.

(b) He was unable to achieve sharp focus.

5. Observation of Preserved Specimens

(a) Mention the sense organ that the students would primarily use, and explain its function.

(b) Give one disadvantage of using sense organs to make observations.

6. Measurement Systems

Why is it important for scientists to use a standard system of measurement?

7. Instruments and SI Units

Name the instrument you would use to measure the following and state their corresponding SI units:

(a) Time

(b) Mass

(d) Length

8. Temperature Conversions

(a) Convert the following temperatures into degrees Fahrenheit:

(i) 36°C

(ii) 40°C

(b) Convert the following temperatures into kelvin:

(i) 100°C

(ii) 0°C

(i) 57 K

(ii) 273 K

(iii) 142°F

(iv) 43°F

9. Volume Conversion

How many millilitres are in:

(i) 1 cm³

(ii) 1 m³

10. Length Conversion

Convert the following into meters:

(i) 300 mm

(ii) 500 cm

11. Measuring a Leaf

Imagine you are a student. Your Biology teacher has tasked you to measure the length and width of a leaf.

(a) What instruments would you use to ensure accurate measurements?

(b) What steps would you follow to obtain reliable data?

12. Health Scenario

Recently, you have observed that children in your village are getting frequent fever accompanied with vomiting and headaches. This is not observed in a neighbouring village where there is wide use of mosquito

11. Variables in Experiments

During an experiment, a scientist noticed that some of the factors can be manipulated. What is the general term or name used to refer to such factors?

12. Control Experiment

What is the importance of a control experiment when testing a given hypothesis?

13. Identifying Scientific Method Steps

Identify the step of the scientific method in each of the following situations:

(a) John is not feeling well, he goes to see a medical doctor at a nearby hospital.

(b) The doctor asks John several questions about how he feels.

(d) The laboratory technician diagnoses malaria parasites in John’s blood.

(e) The doctor confirms that John has malaria and prescribes medicine for him.

14. Scientific Research Reflection

A Form One student was presenting his research findings to fellow students. He made a concluding statement that “Scientific research is a never-ending process.” Give possible reasons for his statement.