SO1BI Chapter 2 PDF

## Chapter Two: Scientific Processes in Biology **Introduction** 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, measur...

## Chapter Two: Scientific Processes in Biology **Introduction** 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. **Think** - Studying Biology without conducting experiments **Common Biology laboratory apparati, equipment and other resources** **Task 2.1** Search from reliable internet sources the video or images showing biology apparati and equipment and their uses. Note down what you have observed. **Biology laboratory** 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 which open outwards, adequate space for carrying out experiments, proper lighting, good ventilation, a source of water, a source of heating, and adequate space for storing apparati, chemicals, models, and specimens. **Apparati and equipment** A wide variety of apparati and equipment are needed in order to conduct Biology practical. ### Common biological apparati and equipment | Apparati and Equipment | Description | Figure | Magnification | |---|---|---|---| | Hand lens | Used to magnify specimens that are under observation. | 2.1 | Size of drawing / Size of actual object | | Sweep net | Used for catching small organisms, such as butterflies and grasshoppers. | 2.2 | | | Scoop net | Used for catching fish and other aquatic animals. | 2.3 | | | Pooter | Used for picking up small organisms, such as insects, without hurting them. | 2.4 | | | Quadrat | Used to estimate the number of organisms in an area. | 2.5 | | | Specimen bottle | Used to keep specimens for storage. | 2.6 | | | Dissecting kit | Contains tools for dissection of specimens. | 2.7 | | | Thermometer | Used for measuring temperature. | 2.8 | | | Heat sources | Bunsen burner, kerosene stove, and spirit burner are used for heating in the laboratory. | 2.9 | | | Mounting needle | Used to lift small delicate specimens. | 2.10 | | | Microscope slide | A small flat piece of glass used to hold specimens under observation. | 2.11 | | | Coverslip | A small piece of glass used to cover specimens on a microscope slide. | 2.11 | | | Microscope | An instrument used to magnify very small specimens. | 2.12 | | **Parts of the Light Microscope** | Part | Function | |---|---| | Eyepiece | Has a lens that magnifies the specimen five times (5x), ten times (10x), or fifteen times (15x). | | 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. | | Coarse adjustment knob | Rises or lowers the body tube in order to bring the image into focus. | | Fine adjustment knob | Rises or lowers body tube in order to bring the image into sharp focus. | | Arm | Supports the body tube, knobs, stage, diaphragm and mirror. It is one of the parts that is held when moving the microscope. | | Ocular tube | Allows light to pass straight from the objective lens to the eyepiece lens. | | Stage | Surface on which the specimen is placed. | | Stage clip | Holds the slide containing the specimen in place. | | Mirror | Reflects and directs light to the specimen under observation. | | Condenser | Concentrates light onto the specimen that is placed on the stage. | | Diaphragm | Regulates the amount of light passing from the mirror to the condenser. | | Hinge screw | Rises and lowers the stage to keep the specimen in the correct position for observation. | | Base | Provides firm support for the microscope. | **How to use the Light Microscope** 1. 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. 2. Mount the specimen on the microscope slide. Cover it with a coverslip. 3. Make sure that the low objective lens is in line with the eyepiece lens. 4. Place the slide with the specimen on the stage. Hold it in place with the stage clip. 5. 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. 6. Adjust the coarse adjustment knob to bring the specimen into focus. 7. Adjust the fine adjustment knob to bring the specimen into a sharp focus. **Total magnification = eyepiece magnification * objective lens magnification** For example: If the eyepiece magnification is 5x and the objective lens magnification is 40x, then the total magnification is 5 * 40 = 200x. **How to care for the Light Microscope** 1. Always start with the coarse adjustment knob. 2. When the microscope is not in use for a long time, remove the lenses and put them in a desiccator. 3. Do not touch the microscope with wet hands. 4. Do not touch the surface of the mirror or the lenses with your fingers. 5. Lubricate the moving parts regularly. 6. Always use the coverslip in order to protect the lenses of the microscope from getting into contact with the specimen. 7. Remove the slides from the stage immediately after use. 8. Move the objective lenses up when storing the microscope. 9. When storing the microscope, rotate the rotating nosepiece so that the low magnification lens is in line with the eyepiece lens. **Activity 2.1: 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. 2. Place one of the pieces on the slide with a drop of water. 3. Cover the specimen with a cover slip and observe it under the microscope. 4. Draw your observations in your notebook. **Safety Precautions** 1. Take precautions when using sharp objects, such as knife and razor blade. 2. Do not taste anything in the laboratory. They may be contaminated with poisonous materials or they may be poisonous themselves. **Basic Skills in Scientific Studies** **Task 2.2** Search from library and reliable internet sources the information on basic skills in scientific studies. Write short notes. **Observation** Observation is one of the methods of studying Biology. Through observation. One can study living things in many ways. Observation is done by using sense organs. An example of using sense organs in making observations is shown in Figure 2.21. **Activity 2.2: 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. 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 (√) 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. **Measurement** 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 and their units** | Measurement | SI unit | Symbol | Other common units | |---|---|---|---| | Mass | Kilogram | kg | Grams (g) | | Length | Meter | m | Millimetre (mm), Centimetre (cm), Kilometer (km) | | Temperature | Kelvin | K | Degrees Celsius (°C), Degrees Fahrenheit (°F) | | Time | Second | s | Minutes (min), Hour (hr) | **Mass** Mass is the quantity of matter of an object. Everything in the world is made up of matter. Mass is measured using a weighing balance or a weighing scale. It is often expressed in grams (g) or kilograms (kg), whereby 1000 g = 1 kg. The weighing balance can be manual or digital. Examples of weighing scales are shown in figure 2.22 and 2.23. **Activity 2.3: Measuring the mass of objects.** Materials: Weighing Balance, weights (0.5 kg, 1 kg, 2 kg, and 5 kg), stones, flour, sugar, notebook, coins, textbook, and pencil or pen Procedure: 1. Put a weighing scale on a flat surface, such as a table. 2. Put half a kilogram weight on the platform. 3. Add a small amount of flour until the weighing scale balances. What is the mass of the flour you have measured? 4. Record your results in your notebook. 5. Repeat procedures 2, 3, and 4 above using different weights to measure the different materials you have collected. 6. 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. Figure 2.24 shows examples of instruments for measuring length and Figure 2.25 shows how to use one of the length measuring instruments. **Activity 2.4: Measuring the length of objects** Materials: Ruler, paper, a small dried fish, notebook, and a pen or pencil. Procedure: 1. Take a leaf and lay it on a piece of paper. Trace the outline of the leaf and mark at the extreme points of the leaf outline. 2. Join the two points by a straight line. 3. Put the zero mark of the ruler at the first mark and read the length at the second point. 4. Record the measurement in your notebook. 5. Compare your findings with those of your classmates. Did you get similar measurements? **Table 2.4: Conversion of some measurements** * 10 mm = 1 cm * 100 cm = 1 m * 1000 m = 1 km * 100 000 cm = 1 km **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 = [(x*°C] + 32 * °C = (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. **Activity 2.5: Measuring the temperature of different things** Materials: Thermometer, beakers, hot water, cold water, and ice cubes Procedure: 1. Carefully take a thermometer from its case and hold it at the top. Do not touch the bulb. 2. Shake it for a few seconds, then read the number that corresponds to the mark. 3. Put the thermometer bulb under your armpit and wait for two minutes. 4. Read the number that corresponds to the mark. 5. What is your body temperature? 6. Use the thermometer to measure the temperature of hot water, cold water, and the 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. 7. Record the temperature in degrees Celsius in your notebook. 8. Compare your results with those of your classmates. Are they similar? **Scientific methods** **Task 2.3** 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. **Steps of the scientific method** 1. **Identifying the problem:** This is where a scientist makes a puzzling observation. The observation can be made in the environment or from the work of other scientists. 2. **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. 3. **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. 4. **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. 5. **Data analysis and interpretation:** At the end of the experiment, the scientist analyses the observations and data recorded to identify trends, patterns, or anomalies in the data. 6. **Conclusion:** A conclusion is a statement that summarizes what a scientist has learnt from an experiment. When scientists reach a conclusion, they state whether the data or information collected supports their hypothesis or not. Conclusions often lead scientists to pose new questions and plan new experiments to answer them. 7. **Reporting results:** Scientists communicate their results to others in a final report. They can present the results to the scientific community by publishing their final report in a journal or at seminars, conferences, workshops, and meetings. **Key Terms:** * **Dependent variable:** 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 factor that the researcher changes systematically to obtain different results * **Controlled variable:** This is the condition or a factor that is kept constant during the experiment. For example, if we are trying to test the effect of different amount of water on the growth of earthworms, the controlled variable should be the amount of sunlight provided to each tray. **Activity 2.6: Observing different types of plant leaves** Materials: Different types of plant leaves, hand lens, notebook, and a pen or pencil Procedure: 1. Collect different types of leaves from plants in the school or home environment. 2. Examine each leaf closely. Look at the size, shape, and color. Feel the texture of the leaf. 3. Using a hand lens, observe the patterns on each leaf. 4. Note down what you have observed. 5. Examine the leaves you have caught then use hand lens to observe the details of the same features. The features include number of legs, eyes, and the way they move. **Caution:** Avoid collecting hairy or thorny plants and those known to be poisonous. **Activity 2.7: Collecting and observing the characteristics of animals** Materials: Preserved specimens of insects and other small animals, sweep nets, a pen or pencil, notebook, bottles, and hand lenses Procedure: 1. Use sweep nets to catch insects such as grasshoppers, termites, cockroaches, and butterflies around school compound. Sweep nets can also be used to catch small animals, such as millipedes and frogs. 2. Put the collected insects and other small animals in specimen bottles. 3. Carefully observe the external features of the organisms you have caught. 4. Record your observations in a notebook. 5. Release or preserve the organisms you have used in your observation. **Safety Precaution:** Care should be taken when collecting dangerous organisms such as wasps, scorpions, centipedes, and bees. **Chapter Summary** Biological apparati are instruments and equipment needed for effective studying of Biology. 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. A microscope is an instrument that is used during scientific studies to magnify very small specimens so that their details can be seen clearly. There are two types of microscopes: light microscope and electron microscope. The total magnification in a microscope is calculated using the following formula: Eyepiece magnification * Objective lens magnification. Observation, measuring, and experimentation are skills needed when studying Biology. The scientific method is a set of steps that scientists use to study things systematically. It involves: Identifying the problem, Formulating a hypothesis, Experimentation, Observation and recording data, Data interpretation, Conclusion, Reporting results. Simple biological experiments are performed to study different features of living things. **Revision Exercise 2** 1. **Identify the apparatus or equipment you can use to perform each of the following biological activities:** * Catch a frog from a pond in order to study its external features. * Collect insects and small animals from the school compound. * Estimate the number of small organisms per square meter. 2. **As a biology student, how would you help your friend to label and state the functions of the parts of the microscope labeled 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:** * The slide containing specimen did not settle on the stage for observation. * He was unable to achieve sharp focus. * The image was too bright, making it difficult to see the detail of specimen. * 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 external features of a variety of preserved specimens.** * Mention the sense organ that the students would primarily use, and explain its function. * 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.** * Time * Mass * Temperature * Length 8. **Convert the following temperatures into degrees Fahrenheit** * 36 °C * 40 °C 9. **Imagine you are a student. Your Biology teacher has tasked you to measure the length and width of a leaf.** * What instruments would you use to ensure accurate measurements? * 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 a control experiment when testing a given hypothesis?** 13. **Identify the step of the scientific method in each of the following situations:** * John is not feeling well, he goes to see a medical doctor at a nearby hospital. * The doctor asks John several questions about how he feels. * The doctor orders John's body temperature, blood, and urine samples to be measured and diagnosed in the laboratory. * The laboratory technician diagnoses malaria parasites in John's blood. * 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.**