Biology Lab Fundamentals and Metric Conversions

Metric Conversions and Temperature

Metric Units

• 1 m = 100 cm = 1000 mm
• 1 kg = 1000 g
• 1 L = 1000 mL

Conversion Direction:

• Right: Moving the decimal to convert from bigger to smaller units.
• Left: Moving the decimal to convert from smaller to bigger units.

Temperature Standards

• Water freezes at 0°C.
• Water boils at 100°C.

Biomolecule Identification Tests

Protein Test (Biuret)

• Positive: Pink or purple
• Negative: Blue

Starch Test (Iodine)

• Positive: Black or purple
• Negative: Yellow or brown

Sugar Test (Benedict’s)

• Green: Low concentration
• Yellow: Medium concentration
• Red/Orange: High concentration
• Blue: None

Lipid Test (Brown Paper)

• Positive: Greasy or translucent
• Negative: Opaque

Cellular Processes and Enzymes

Diffusion and Osmosis

• Hypertonic: Water moves out; the cell shrinks. In plants, this is called plasmolysis.
• Hypotonic: Water moves in; the cell swells. In plants, this creates turgor pressure.
• Rule: Water follows the solute.

Microscope Usage

• Total magnification = ocular × objective.
• Always start with the lowest power, then increase.

Enzyme Function

• Enzymes lower activation energy.
• They work best at optimal temperature and pH.
• High heat causes denaturation.

Energy Production

Photosynthesis

• Main pigment: chlorophyll.
• Produces oxygen (O2).
• Light reactions occur in the thylakoid.
• Dark reactions occur in the stroma.
• Blue and red light are the most effective.

Cellular Respiration and Fermentation

• Glucose is used to produce ATP.
• Fermentation occurs in the absence of oxygen.
• Simple sugars are utilized most easily.

Key Laboratory Experiments

Dialysis Tubing

• Small molecules (glucose, iodine) can cross the membrane.
• Large molecules (starch) cannot cross.
• Selective permeability depends on molecular size.

Catalase Activity

• More bubbles indicate higher enzyme activity.
• Extreme pH or temperature decreases activity.
• Experiments require a control.

Photosynthesis Lab

• More bubbles indicate higher oxygen production.
• Blue light produces the most; yellow light produces the least.

Yeast Fermentation

• Higher gas production indicates better sugar utilization.
• Starch is not fermented because the molecule is too large.

Scientific Method and Measurements

Experiment Basics

• Independent variable: What you change.
• Dependent variable: What you measure.
• Positive control: Expected result.
• Negative control: No result.

Volume by Displacement

• Volume = final volume - initial volume.
• 1 mL = 1 cm³.

Diffusion Lab Observations

Higher temperatures increase the diffusion rate because molecules move faster.

Common Biology Exam Traps

• Greasy paper indicates lipids.
• A pink Biuret test indicates protein.
• Cell shrinks = hypertonic environment.
• Cell swells = hypotonic environment.
• More bubbles = higher enzyme activity.