Topic 2: Scientific Processes in Biology - Biology Form One Notes New Syllabus

Topic 2: Scientific Processes in Biology – Biology Form One Notes New Syllabus

Science is studied through a procedure that follows systematic processes, which require the use of a variety of apparati and equipment. Among the processes that are conducted to carry out scientific studies include observation, measurement, and experimentation.

In this chapter, you will learn about different biological apparati and equipment, and the use of sense organs to make correct observation. You will also learn how to measure mass, length, and temperature.

Likewise, you will learn the steps for carrying out scientific studies, commonly known as the scientific methods. The competencies developed will enable you to apply scientific methods, appropriately use biological apparati, make accurate observations using sense organs, and perform accurate measurements in various daily life situations.

COMMON BIOLOGY LABORATORY APPARATI, EQUIPMENT AND OTHER RESOURCES

The biology Laboratory: Is a special room designed for conducting biological experiments.

Qualities and facilities of a good biology laboratory

i. Large door which open outwards

ii. Adequate space for conducting experiments

iii. Proper lighting

iv. Good ventilation

v. Source of water

vi. Source of heat

vii. Storage room for keeping chemicals, models and apparatus.

THE MICROSCOPE

The microscope is an instrument used to magnify small objects which cannot be seen by the naked eye.

TYPES OF MICROSCOPE

There are two types of microscope:

i. Light microscope (compound)

ii. Electron microscope

Electron microscope is a microscope that can magnify a specimen up to 1,000,000 times.

Light microscope is a microscope that can magnify object up to 1,000 times by using lenses and light. Light microscope is commonly used in school laboratory.

PARTS OF A LIGHT MICROSCOPE AND THEIR FUNCTIONS

i. Eye piece – It has lenses, it increases magnification

ii. Body tube – It holds lenses of the ocular and objectives, it connects the eye piece lens to the object lens

iii. Coarse adjustment knob – It lowers and raises the body tube to obtain a clear image

iv. Fine adjustment knob – It brings sharp focusing by moving stages or body tube up or down

v. Arm / Limb – It supports the body tube and connects it to the base, it helps to handle microscope

vi. Revolving Nose Piece – It holds two or more objective lenses

vii. Objective Lenses – It brings image into focus and magnify it. The total magnification in a microscope is calculated using the following formula.

Eyepiece magnification × Objective lens magnification

viii. Stage Clip – It holds the slides firmly in place

ix. Stage – It is a place where slides of specimens are kept

x. Condenser – It concentrates the light which passes through the specimen.

xi. Hinge Screw – They lower or raise the stage to keep the specimen in position

xii. Mirror – It reflects light upward through diaphragm to specimen

xiii. Base – It supports the microscope

xiv. Diaphragm – It is a hole that regulate the amount of light that passes through specimen.

HOW TO USE THE MICROSCOPE

The following procedures should be followed when using a microscope;

i. Mount the object (specimen) on a microscope slide.

ii. Place the microscope on a flat platform (bench) in such a way that its near limb is near you.

iii. Remove the eye piece and then rotate the nose piece so that the objective with the lower magnification power is in the body tube.

iv. As you look into the body tube, move the mirror until the back of the object is brightly and evenly illuminated.

v. Place the slide on the stage so that the specimen is over the hole.

vi. While looking at the microscope from the slide, operate the course adjustment knob to lower the body tube until you obtain a clear image of the specimen.

vii. If a clear image is not seen, operate the fine adjustment knob to get it.

viii. After using the microscope, make sure that the stage and the objectives are clean before returning the microscope to its place.

HANDLING AND CARE FOR THE LIGHT/COMPOUND MICROSCOPE

A microscope is a delicate and expensive instrument; hence it should be handled with great care as follows;

i. Always use both hands when carrying the microscope. One hand holds the limb and the other holds the base.

ii. Always place a microscope at the center of the table

iii. Avoid wetting any party of the microscope

iv. The surface of the mirror, eye pieces and objectives should be cleaned with a soft cloth or tissue to avoid scratching them, they must be protected from dust, corrosive substances, corrosive fumes and liquids.

v. Do not touch the mirror or the lenses with your fingers.

vi. The fine and course adjustment knobs should always be Turned slowly.

vii. When it is not in use, the microscope should be kept in any place where it is not likely to come into contact with corrosive substances or fumes.

viii. When it is not used for long time, the eye pieces and objectives should be removed and kept in desiccators with a drying agent.

ix. All moving parts should be lubricated with special grease every now and then.

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

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

BASIC SKILLS IN SCIENTIFIC STUDIES

There are three basic skills that are needed in studying biology (scientific studies)

Observation
Measurements
Experimentation

1. OBSERVATIONS

This method is done by using sense organs

All scientific investigations involve observation using sense organs. here are five sense organs used in observation, namely;

i. Eyes

ii. Ears

iii. Nose

iv. Tongue

v. Skin

The observation process with the help of sense organs enables to study living organism, for example if you have a coconut, you can use your sense organs to determine that:

a. It is round by seeing

b. It contains liquid by hearing the sound when shaken

c. It has rough husk by touching

d. It has a good smell by smelling (after breaking the coconut)

e. It has sweet taste by tasting (after breaking the coconut)

Activity

Making observations using sense organs

Materials: Colourful pictures, insects, preserved specimens, flowers, perfume, whistle, bell, stones, wooden objects, pieces of cloth, ice, hot water, and lukewarm water

Procedure

1. Carefully observe the specimens provided using your sense organs.

Safety precautions

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

2. Note down the features of each specimen you have observed.

3. Draw a table similar to Table 2.2 in your exercise book. Record the observations by putting a tick (V) on each object.

ADVANTAGE OF USING SENSE ORGANS TO MAKE OBSERVATION

i. Eyes- when you see clouds it is likely to rain

ii. Ears- when you hear the school bell at school your supposed to be somewhere

iii. Smell- You like perfume because it smells nicely

iv. Skin- When you get near fire you fell heat and move away

v. Nose- When cooking you taste food to ensure it is delicious

DISADVANTAGES 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

2. MEASURMENTS

Measurement is the system of using specific instruments and units to make investigations. 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 measurements in Biology and their uses

LENGTH (l)

Length the distance between any two points. The instrument used to measure length is called ruler or tape measure. It is expressed in millimeters (mm), centimeters (cm), meters (m), and kilometers (km)

Conversions of some measurement

Instruments For Measuring Lenght

MASS (m)

Mass is the quantity (amount) of matter in the object. The instrument that can be used to measure mass is called weighing balance such as beam balance, digital balance. It is expressed in grams (g) or kilograms (kg), Where, 1kg = 1000g.

Instruments used for measuring mass

TEMPERATURE

Temperature is the measure of relative hotness and coldness of a body. 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.

Under Teachers Guide Student Should Perfom Activity 2.3, 2.4 and 2.5 which is Found In The Student TIE Text Book Page 24-26

SCIENTIFIC METHODS

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

Steps of scientific methods

The scientific method involves seven steps as follows.

Identifying a problem
Formulating a hypothesis
Experimentation
Observation and recording data
data Analysis and interpretation
Conclusion
Report results

1. IDENTIFYING A 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.

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 questions asked is suggested.

Hypothesis is an intelligent guess which tries to answer the observed problem.

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

By careful observation in a natural setting
By conducting experiment

3. EXPERIMENTATION

Experiment is the test done or 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:

Test experiment
Control experiment

(a) Test experiment is the one that receives treatment  Example: addition of fertilizers

(b) Control experiment is the one that does not receive treatment  Example: no addition of fertilizers

Note
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 then 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

4. OBSERVATION AND RECORDING DATA

Observation and recording 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.

5. DATA ANALYSIS AND INTERPRETATION

Data analysis and interpretation s 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

6. CONCLUSION

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

7. REPORT RESULTS

After the experiment the report should be written to easy communication to other scientists.

Note: If your results do not support the hypothesis:

(a) Do not stop to repeat them experiment.

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

Under Teachers Guide Student Should Perfom Activity 2.6 and 2.7 Which Is Found In The Student TIE Text Book Page 30-30

Chapter summary

1 Biological apparati are instruments and equipment needed for effective studying of Biology.

2. Some of the apparati used in studying Biology are hand lens, sweep nets, scoop nets, pooters, specimen bottles, quadrats, dissecting kits, mounting needles, slides, coverslips, and microscopes.

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

4. There are two types of microscopes: light microscope and electron microscope.

5. The total magnification in a microscope is calculated using the following formula.

Eyepiece magnification × Objective lens magnification

6. Observation, measuring, and experimentation are skills needed when studying Biology.

7. Sense organs used to make observations are:

(a) Eyes for seeing.

(b) Nose for smelling.

(d) Tongue for tasting.

(e) Skin for feeling.

8. Scientific measurements are taken using specific instruments and are expressed in specific units. Some basic biological measures are:

9. The scientific method is a set of steps that scientists use to study things

Identifying the problem
Formulating a hypothesis
Experimentation
Observation and recording data
Data interpretation.
Conclusion.
Reporting results

10. Simple biological experiments are performed to study different features of living things.

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 extemal 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 in Figure 2.31?

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?

4. 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.

Educate your friend on how to address the challenges faced in order to obtain a clear image of the plant cells.

5. Biology students were assigned to observe the extemal features of a variety 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. Why is it important for scientists to use a standard system of measurement?

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

(a) Time

(b) Mass

(d) Length

8. (a) Convert the following temperatures into degrees Fahrenheit

(i) 36 C

(ii) 40 ℃

(b) Convert the following temperatures into kelvin

(i) 57 K (ii) 273 K

(ii) 142 °F (iv) 43 °F

(d) How many millimetres are in R Convert the following into metres
(i) 300 mm (ii) 5500 cm

9. 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?

10. As a biologist, 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 nets. You are supposed to address this problem using scientific method. Explain the steps that you would follow to address this problem.

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

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

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