Lab 1_ex 1-3 PDF

**Exercise 1 -- Lab Safety** ---------------------------- Overview -------- During this lab, you will become familiar with the laboratory safety rules as well as the location of safety equipment in the room. Following good laboratory practices is a fundamental component of any investigation as it...

**Exercise 1 -- Lab Safety** ---------------------------- Overview -------- During this lab, you will become familiar with the laboratory safety rules as well as the location of safety equipment in the room. Following good laboratory practices is a fundamental component of any investigation as it ensures everyone's safety as well as the ability to perform experiments and collect data using the principles of proper scientific research. General Laboratory Safety Guidelines ------------------------------------ 1. Turn off cell phones 2. Be serious and alert while working in the laboratory 3. Tie back long hair and remove excessively large jewelry 4. Wear close-toed shoes and casual clothes to the lab. Wear a lab coat, gloves and safety goggles when instructed. 5. Be prepared to work when you arrive in the laboratory. Familiarize yourself with the exercises by reading through them before coming to lab. Be sure that you understand the procedure to be employed in any laboratory investigation and the possible hazards associated with it. This will help ensure that you are able to complete the exercise efficiently and get the most out of the lab exercise. 6. When performing an exercise, read all directions for an investigation several times. Follow the directions exactly as they are written. If you are in doubt about any part of the investigation, ask your lab instructor for assistance. 7. Only perform activities authorized by the lab instructor. Focus only on the assigned exercises. 8. Pay attention while the lab instructor reviews the basic content ideas and the specific procedures for the day\'s lab. Make note of any procedural changes or additional directions announced by the lab instructor. 9. When working with blood, body fluids, or other biohazardous wastes, including animals for dissection, dispose all materials that come in contact with waste (i.e., gloves, slides, coverslips, toothpicks, etc.), in the proper biohazardous waste container. 10. Any glassware or apparatus that has come into contact with biohazardous waste must be washed with 10% bleach solution or placed in location indicated by instructor for sterilization later. 11. If a glass is broken, do not pick it up. Notify the lab\'s instructor who will instruct you on a clean-up procedure. 12. Never handle any equipment unless you have specific permission. 13. When heating a test tube, make sure it is pointed away from yourself and those around you. 14. Always use test tube holders, tongs, or padded gloves when handling hot glassware. 15. Dispose of all used sharp objects (such as needles and scalpel blades) in puncture-resistant containers. 16. Use the proper techniques and protection when handling chemicals. Dispose of all chemicals as instructed by the lab instructor. Wear rubber gloves and safety goggles if handling chemicals. 17. Take extreme care not to spill any material in the laboratory. If a spill occurs, ask your instructor immediately about the proper cleanup procedure. Never pour chemicals or other substances into the sink or trash container. 18. Do not directly smell or mouth pipette any chemicals. Never eat or taste anything or apply cosmetics in the laboratory. This includes food, drinks, candy, gum, and chemicals. Wash your hands before and after performing every investigation. 19. Know the location and proper use of safety equipment, such as the fire extinguisher, fire blanket, first-aid kit, safety shower, and eyewash station. Questions -- Exercise 1 ----------------------- 1. What should you do if chemicals splash onto your skin or into your eyes during a lab? -- -- 2. Why is it important to know the location of safety equipment like fire extinguishers, fire blankets, and eyewash stations before starting a lab? -- -- 3. What steps should you take when handling chemicals in the lab, especially if you accidentally spill them? -- -- 4. How should you dispose of sharp objects or biohazardous waste materials in the lab? -- -- 5. Why is it important to never eat, drink, or apply cosmetics in the laboratory? What precautions should you take before and after performing lab investigations? -- -- **Exercise 2 -- Introduction to Biology and The Scientific Method** ------------------------------------------------------------------- Objectives ---------- Upon completion of this laboratory, students should be able to - - - Introduction ------------ Biology is the study of life. Biologists are scientists who observe life, ask questions about what they see, design experiments to answer those questions, and ultimately try to explain what they observe. Biology is not simply a collection of facts, but a systematic study of living phenomena. The scientific method is used by many scientists, including biologists, to augment the body of scientific knowledge. This method is a somewhat different approach than the way other disciplines, such as history, music or art, answer questions and add to the knowledge in those domains. The scientific method uses the following four steps to attempt to understand natural phenomena. A black arrow pointing to the right Description automatically generated In order to answer a scientific question, it is only necessary to observe; for example, "How do dogs and cats look different?" For other questions, you want explanations for what you observed. To do that you propose a **hypothesis**: a tentative answer to the question. A "good" hypothesis is one that restates a question with a possible explanation for what was observed. Hypotheses state possible causes and reflect past experience with similar questions. Sometimes they are referred to as guesses; but, at the very least, they must be "educated" guesses. One of the most important characteristics of a good hypothesis is that it is testable by an observation or an experiment. A hypothesis that states "DNA was brought to the planet by aliens" is not a testable hypothesis. The scientist designs an experiment to test the hypothesis in a controlled way, meaning that the design must contrast an **experimental group** with a **control group** (where nothing is manipulated). The two groups are treated exactly alike except for the one variable (characteristic) being tested (called the **independent variable**). The independent variable is the manipulated variable, and we measure the effect of this manipulation on the **dependent variable**. Finally, the results of the experiment must be interpreted and compared to the hypothesis. If the hypothesis is eliminated, one should propose an alternative hypothesis that is also testable and is compatible with the observed results. A. Using the Scientific Method to make a Conclusion  ---------------------------------------------------- You will learn that not all observations can be made directly. Instead, scientists often must rely on instrumentation and other indirect alternatives. You will need to draw conclusions about information you cannot see. You'll be following the link below to test the growth of bacteria in a (virtual) petri dish following the scientific method. You can test: --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- A. the effects of antibacterial agents 1 or 2 on bacterial growth, or ------------------------------------------------------------------ B. the effects of temperature on bacterial growth ----------------------------------------------------------------------------- Pre-Lab questions ----------------- 1. What question do you want to answer about bacteria growth? -- -- 2. Based on your question, what is your **hypothesis**? -- -- 3. What will be your **independent variable**? -- -- 4. What will be your **dependent variable**? -- -- 5. What variables will you need to **control**? -- -- Protocol: ------------------------------- 1. 2. 3. 4. 5. 6. 7. 8. Control Test: Temperature °C ---------------------------------- ------ Amount Substance A mL Amount Substance B mL Duration of Experiment days Controlled Variables (constant ) Results: How much bacteria (estimate a percentage) grew in this dish? Test \#2: Temperature °C ---------------------------------- ------ Amount Substance A mL Amount Substance B mL Duration of Experiment days Controlled Variables (constant ) Results: How much bacteria (estimate a percentage) grew in this dish? Test \#3: Temperature °C ---------------------------------- ------ Amount Substance A mL Amount Substance B mL Duration of Experiment days Controlled Variables (constant ) Results: How much bacteria (estimate a percentage) grew in this dish? Interpret: Post-Lab Questions ----------------------------- Conclusions: Which dish had the least bacterial growth? What can you deduce (infer) about this experiment? -- -- In the future, what variables would you suggest be controlled (held constant) so that the outcome of the experiment is more reliable? Would you change the experiment to gain more reliable results? -- -- **Exercise 3 -- Scientific Measurements** ----------------------------------------- ### Objectives Upon completion of this laboratory, students should be able to - - - ### Introduction When conducting experiments, measurement is a basic technique to determine differences and similarities. For some time the **metric system** has been the system of measurement used in the sciences. In the late 1700s in France, a system was created that was simple, easy to use, and based on scientific features. No longer would length be based on some varying distance between someone's nose and their fingertips. The metric system is based on consistent, quantifiable measures. In addition, the units created were in multiples of ten, which allow for easy calculations. The metric system is referred to as a decimal system because of this power of ten. When conducting experiments, correct measurements are crucial, so it is important that you know how to make and interpret them. The metric system uses prefixes that relate to a specific power of ten. With each prefix a stem is added to indicate length, weight, or volume. For length the base unit is **meter (m)**, for weight or mass the base unit is **gram (g)**, and for volume the base unit is **liter (l)**. Now you are ready to combine prefixes with each base unit. **Table 3.1** **Property** **Description** **Unit** **Unit symbol** **Measuring device or instrument** -------------- -------------------------------- ------------------- ----------------- ------------------------------------ Mass How much do I have? grams **g** Electronic balance Volume How much space does it occupy? liters **L** Graduated cylinder Volume milliliters **mL** Pipet Volume H cubic centimeters **cm^3^** Burette Temperature How hot? Degrees Celsius **˚C** Thermometer **Table 3.2:** Commonly used prefixes for length, weight, and volume.  **How to Measure Length** There are several instruments that can be used to measure length. Probably the most familiar is the ruler. It is usually better not to use the ends of the ruler as your starting point because many times the ends have been worn down or dented, which makes the measurement imprecise. **Figure 3.1:** Making measurements of length on a ruler. **How to Measure Weight/Mass** A balance is the most common instrument used to measure weight or mass; there are many different types of balances. Biologists often use a triple-beam balance or a top loading scale to measure mass. To weigh an item, place it on the pan and move the riders until the pointer is at the balance mark. It is best to move the largest slider first. Original Size  **Figure 3.2:** Triple-beam balance. ©bluedoor, LLC **How to Measure Volume** Volume of a liquid is usually measured with a graduated cylinder or pipette. Depending on the size and material, you will need to be aware of the meniscus. To accurately measure the volume of a liquid, read the volume at the bottom of the curve of the meniscus, with your eye level at the surface of the liquid. See ***Figure 3.3*.** Original Size **Figure 3.3:** How to read a graduated cylinder. ©bluedoor, LLC The volume of solid objects can be calculated by a variety of formulas. For example, a wooden block's volume can be calculated by multiplying length × width × depth. **How to Measure Temperature** Scientific thermometers are calibrated in Celsius (°C). This is a base 100 scale in which water boils at 100 degrees and freezes at 0 degrees.  **Figure 3.4:** Celsius temperature scale. You can convert between °C and degrees Fahrenheit (°F). Formulas for conversions between the Celsius and Fahrenheit scales are shown in ***Table 3.3*.** **Table 3.3:** Temperature conversion formulas. A table of maths Description automatically generated with medium confidence **Taking Measurements** A. **Measuring length and width of different geometric shapes** 1. Obtain two different geometric shape cutouts from your instructor. 2. Using the metric ruler provided in your workspace, measure the length and width of each one of the shapes. 3. Record your measurements in the table below. Make sure you use significant figures, so in the example below (Figure 1), the ruler markings are every 0.1 cm. The correct reading is 4.58 cm, the two first digits, **[4.5]**8 are known exactly, the 4.5**** is uncertain. When measuring, you record all the digits that are known exactly, plus the first one that is uncertain. 4. Using the values you obtained, [calculate the area] of the geometric shapes. You calculate the area of a square or a rectangle, by multiplying width X length. Record your results in the following table and *[don't forget the units!\ ]*If multiplying or dividing measured values, the result should be reported with the lowest number of significant figures used in the calculation. -- -- -- -- -- -- -- -- B. Measuring the Volume of a sample of water 1. Obtain your water sample from your instructor. 2. Pour your water sample into the 100 ml beaker. 3. Measure the volume of water in the beaker and record this measurement in the table below. *[Remember to write the numerical value and the units, as well as the significant figures.]* 4. Carefully transfer the water in the beaker into the 100 ml graduated cylinder. 5. Measure the volume of water in the 100 ml graduated cylinder and record your measurement in the table below. *[Remember to write the numerical value and the units, as well as the significant figures.]* **Table 4. Volume measurement** -- -- -- -- 6. Do the measured values have the same number of significant figures? Explain your answer (why yes, or why no) C. Measuring Mass 1. Use a double-beam (Figure 2) balance to obtain the mass of a 250-mL beaker. Record the mass in the table below. *[Remember to write the numerical value and the units.]* 2. Remove the beaker from the balance and add three scoops of sugar to the beaker. 3. Obtain the new combined mass of the beaker and the sugar. Record this new mass in the table below. *[Remember to write the numerical value and the units.]* 4. Use your two measurements to determine the mass of the sugar and record it in the table below. *[Remember to write the numerical value and the units.]* **Table 5. Mass measurement** -- -- -- -- D. Measuring Temperature 1. Obtain a thermometer from your instructor. Before making your measurements, examine the markings on the thermometer. 2. Obtain three 500 ml beakers. 3. Fill one beaker with tap water 4. Half fill another beaker with tap water, the add ice to fill beaker. 5. Obtain hot water from your instructor. \*\*\*Handle the beaker with insulating gloves\*\*\* 6. Measure the temperature in each one of the beakers and record your results below. *[Remember to write the numerical value and the units.]* -- -- -- -- -- -- Compare your results of each measurement with those of your other group members. Are the measurements close in value? What does this tell you about the precision of your measurements as a group? Questions 1. What are some potential sources of error in your measurements? 2. What is longer: 1 inch or 1 centimeter? 3. Which is larger: 1 gallon or 1 liter? 4. Human body temperature is 98 °F. What temperature is this on the Celsius scale? 5. Briefly explain how the metric system is useful to scientists.