Laboratory Skills and Current Events in Biology
Laboratory skills are the foundation of scientific inquiry, enabling you to design experiments, collect data, and draw meaningful conclusions.
Methods Used in Designing a Laboratory Experiment
1. Formulating Questions and Hypotheses
- Experimental Questions: These should be specific and measurable.
* Hypothesis: If the concentration of fertilizer increases, then the height of tomato plants will increase because more nutrients are available for growth.
2. Selecting Appropriate Tools and Materials
- Choose tools based on the experiment's focus:
- Dissecting Instruments: For anatomical studies.
- Chemical Indicators: For biochemical tests.
- Measuring Instruments: For quantitative data collection.
Always consider safety equipment, such as goggles and gloves, when selecting tools.
3. Identifying Variables and Controls
- Independent Variable: The factor you manipulate (e.g., temperature).
- Dependent Variable: The factor you measure (e.g., enzyme activity).
- Controlled Variables: Factors kept constant to ensure a fair test (e.g., pH, volume of solution).
- Control Group: A baseline group not exposed to the independent variable, used for comparison.
Do not confuse the independent and dependent variables. Remember: the independent variable is what you change, and the dependent variable is what you measure.
Techniques Used in Conducting Laboratory Experiments
1. Using the Compound Light Microscope
- Parts and Functions:
- Eyepiece: Magnifies the image (usually 10x).
- Objective Lenses: Provide additional magnification (e.g., 10x, 40x).
- Stage: Holds the slide.
- Coarse and Fine Adjustment Knobs: Focus the image.
Always start with the low-power objective and use the coarse adjustment knob. Switch to high power and use only the fine adjustment knob for precise focusing.
2. Measuring Microscopic Specimens
- Micrometer (\$ \mu \$m): 1 mm = 1,000 \$ \mu \$m.
- Field of View Calculation:
- Measure the diameter of the field of view under low power.
- Use the formula:
$$\text{High-power field diameter} = \frac{\text{Low-power field diameter} \times \text{Low-power magnification}}{\text{High-power magnification}}$$
To stain a specimen without removing the coverslip, add the stain to one edge and use absorbent paper on the opposite edge to draw the stain across.
4. Using Chemical Indicators
- pH Paper: Indicates acidity or alkalinity.
- Bromthymol Blue: Turns yellow in acidic conditions.
- Benedict's Solution: Detects simple sugars (turns from blue to red when heated).
- Iodine Solution: Turns blue-black in the presence of starch.
Always include units in your measurements. For example, "12 mL" instead of just "12."
6. Dissection Techniques
- Specimens: Earthworms, grasshoppers, seeds, flowers.
- Tools: Scalpels, forceps, dissecting pins.
- Safety: Handle sharp instruments carefully and follow dissection protocols.
Dissection helps reveal the internal structures and organ systems of organisms, providing insights into their anatomy and function.
7. Laboratory Safety
- Chemicals: Wear goggles and gloves; never mix unknown substances.
- Heating: Use tongs or heat-resistant gloves; never point a test tube at yourself or others.
- Emergency Protocols: Know the location of safety equipment (e.g., eyewash stations, fire extinguishers).
Never ignore safety warnings. For example, if a beaker is cracked, stop using it immediately and inform your instructor.
Skills Used in Interpreting Experimental Results
1. Organizing and Graphing Data
- Data Tables: Organize data with clear headings and units.
- Graphs:
- Line Graphs: Show trends over time.
- Bar Graphs: Compare discrete categories.
- Axes: Label with variables and units (e.g., "Time (minutes)" on the x-axis).
When plotting a graph, ensure the independent variable is on the x-axis and the dependent variable is on the y-axis.
2. Making Inferences and Predictions
- Inferences: Logical conclusions based on data.
- Predictions: Anticipate outcomes if the experiment is extended or modified.
Recognizing limitations is essential for improving experimental design and ensuring reliable results.
5. Evaluating Accuracy and Repeatability
- Accuracy: Compare results to expected values; calculate percent error if applicable.
- Repeatability: Ensure the experiment can be replicated with consistent results.
Repeating experiments and averaging results can reduce the impact of random errors and increase reliability.
Current Events in Biology
1. Environmental Issues
- Acid Rain: Caused by sulfur and nitrogen pollutants, affecting ecosystems and food webs.
- Climate Change: Impacts biodiversity, habitats, and global weather patterns.
Acid rain with a pH of 3–5 can disrupt aquatic ecosystems by killing sensitive species, leading to cascading effects on terrestrial predators.
2. Advances in Genetic Research
- CRISPR-Cas9: A gene-editing tool with applications in medicine and agriculture.
- Genetic Engineering: Production of insulin by bacteria, reducing reliance on animal sources.
How do ethical considerations shape the use of genetic engineering in medicine and agriculture? Should there be limits on what scientists can modify?
3. Biomedical Research
- Vaccines: Development of mRNA vaccines for diseases like COVID-19.
- Immunology: Advances in understanding autoimmune diseases and cancer therapies.
