bio practical yay (1)

Module 1: Lab Safety

• The goal of lab safety is to understand how to work safely in the laboratory environment.
• Proper lab behavior, equipment use, and safety response are key learning outcomes.
• A lab safety contract typically covers PPE (goggles, gloves, coat), chemical handling, emergency equipment use (eyewash/shower), proper waste disposal, and general behavior (no food/drinks, hair tied back).
• Emergency response, spill handling, broken glass disposal, labeling and identifying safety equipment are key lab safety topics.

Module 2: Scientific Method

• A good scientific question is specific, testable, and measurable, often starting with "how," "what," or "why."
• A scientifically useful hypothesis is a clear, testable statement predicting a relationship between variables.
• A null hypothesis is a default statement indicating no effect or no difference (e.g., "X has no effect on Y").
• Predictions from a hypothesis use an "If..., then..." format to predict the expected outcome.
• Good experimental design includes independent/dependent variables, a control group, replication, and controlled variables.
• On graphs, the x-axis represents the independent variable, and the y-axis represents the dependent variable; always label units and provide a title.
• Tables should include descriptive titles, column/row headers, and units.

Module 3: Measurement

• Accuracy indicates closeness to the true value, while precision indicates consistency of repeated measurements.
• Only one digit of uncertainty should be included in a measurement, as part of the estimation rule.
• When multiplying or dividing significant figures, use the lowest number of significant figures; when adding or subtracting, round to the least precise decimal place.
• Metric units of measure include:
  • Length in meters (m)
  • Area in square meters (m²)
  • Volume in liters (L)
  • Mass in grams (g)
  • Density in g/mL or g/cm³
  • Temperature in Celsius (°C)
• Common metric prefixes with their values
  • Kilo- (10³)
  • Centi- (10⁻²)
  • Milli- (10⁻³)
  • Micro- (10⁻⁶)
  • Nano- (10⁻⁹)
• To perform conversions, use conversion factors or move the decimal accordingly.
• Water displacement calculates an object's volume as the final volume minus the initial volume of water.
• Density is calculated as mass divided by volume.
• Micropipettes require selecting the correct range, attaching a tip, avoiding air bubbles, and measuring in μL.
• Key statistical measures include:
  • Mean (average value)
  • Median (middle value in ordered list)
  • Range (difference between maximum and minimum values)

Module 4: Scientific Literature

• A scientific manuscript includes parts such as the abstract, introduction, methods, results, discussion, and references.
• Different types of literature include:
  • Primary literature is original research articles (peer-reviewed)
  • Secondary literature consists of reviews and analyses that may or may not be peer-reviewed
  • Tertiary literature includes encyclopedias and textbooks, which are not peer-reviewed
  • Gray literature includes reports, theses, and white papers that are not peer-reviewed
• Only primary literature is always peer-reviewed.

Module 5: Spectrophotometry

• Spectrophotometry terms include absorbance, transmittance, wavelength, standard curve, blank, and spectrum.
• Spectrophotometry measures the concentration of light-absorbing substances, such as dyes or proteins.
• A spectrophotometer passes light at a specific wavelength through a sample, and a detector measures the absorbance.
• A blank is a solution without the analyte and is used to zero the machine.
• Measuring absorbance at two wavelengths is useful for differentiating substances or improving accuracy.
• A standard curve is a graph of known concentrations versus absorbance and finds unknowns.
• An absorption spectrum is a graph showing how a substance absorbs across a range of wavelengths.

Module 6: pH and Buffers

• Decimals and scientific notation example: 0.0001 = 1 × 10⁻⁴
• pH can be measured using pH paper (approximate) or a pH meter (precise).
• Key pH terms:
  • Acids release H⁺ ions
  • Bases accept H⁺ ions
  • Neutralization: Acid + base → water + salt
  • Alkalinity is a basic property
• A buffer resists pH change when small amounts of acid or base are added.
• Buffers are important for maintaining pH stability in biological systems (e.g., blood).
• Key pH conversions:
  • pH = -log[H⁺]
  • pOH = -log[OH⁻]
  • pH + pOH = 14
• The log scale defines that a difference of 1 pH = 10x difference in [H⁺]
• Practice problems include calculating pH, pOH, and H⁺/OH⁻ concentrations from given values.

Module 7: Properties of an Enzyme

• Enzymes lower activation energy and speed up reactions without being consumed.
• Environmental factors like temperature, pH, and substrate concentration affect enzyme activity.
• Denaturation is a structural change in an enzyme that causes loss of function.
• Horseradish Peroxidase (HRP):
  • Catalyzes the breakdown of hydrogen peroxide (H₂O₂).
  • Guaiacol turns brown when oxidized and is used to measure activity by absorbance.
• Absorbance readings are taken with a spectrophotometer to track reaction progress.
• Null hypotheses tested include each tested variable (temperature, pH, enzyme concentration, etc.) had a null hypothesis stating it had no effect on enzyme activity.