Biology 9700 Practical Notes [hot] -

Examiners frequently ask candidates to prepare a specific concentration range from a stock solution. You must master both proportional and serial dilution techniques. Proportional (Simple) Dilution

Improvement: Seal test tubes with Parafilm or rubber bungs during incubation. Understanding Uncertainty

Draw either a smooth, continuous curve or a straight line using a ruler, depending on the trend. Alternatively, connect the points dot-to-dot with straight lines if instructed or if the intermediate values cannot be confidently predicted. Never extrapolate your line beyond the first or last data point. 2. Essential Biochemical Tests biology 9700 practical notes

: Used when you need specific concentrations at regular intervals (e.g., 2%, 4%, 6%). You calculate the volume of stock and distilled water for each. Serial Dilution

Draw complete enclosed boxes with clear gridlines using a ruler. Examiners frequently ask candidates to prepare a specific

Cover test tubes with foil or rubber bungs to prevent evaporation loss.

Plot a line graph of percentage change against sucrose concentration. The point where the line crosses the x-axis (zero change in mass) represents the point where the water potential of the solution equals the internal water potential of the potato tissue. Method 2: Incipient Plasmolysis neutralize with NaHCO3NaHCO sub 3

You must memorize the reagents, procedures, positive results, and negative results for the standard biochemical tests. Reagent / Test Hot Water Bath Needed? Positive Result Negative Result Benedict's Solution for 5 mins) Green, Yellow, Orange, or Brick-Red ppt Clear Blue Non-Reducing Sugars Acid Hydrolysis + Benedict's Yes (Boil with , neutralize with NaHCO3NaHCO sub 3 , then heat with Benedict's) Brick-Red precipitate Clear Blue Starch Iodine in KI Solution Blue-Black Yellow-Brown Proteins Biuret Reagent Purple / Violet Lipids Ethanol Emulsion Test No (Mix with ethanol, pour into water) Cloudy White Emulsion Clear / No layer 3. Enzyme Kinetics Experiments

Dissolve lipid in absolute ethanol first, then pour the mixture into cold water. Semi-Quantitative Benedict’s Test

: The one you change (e.g., enzyme concentration). Decide on at least 5 different values (range and interval).