Biology 9700 Practical Notes | Patched

You must be ready to perform and interpret the results of standard tests: Benedict’s Test: For reducing sugars (semi-quantitative via color scale). Non-reducing Sugars: Requires hydrolysis with and neutralization with NaHCO sub 3 before re-testing. Biuret Test: For proteins (look for a purple color change). Iodine Test: For starch. Emulsion Test: For lipids using ethanol. 4. Data Presentation and Evaluation

Mastering the Biology 9700 Practical (Paper 3) Scoring an A in AS Level Biology often hinges on . This practical exam tests your ability to follow instructions, collect data, and analyze results under pressure. 🔬 Core Skill 1: Microscopic Techniques

Draw only the tissue layers (e.g., epidermis, xylem, phloem). No shading or sketching allowed. . Ensure units are converted to micrometers ( ) before calculating. 🧪 Core Skill 2: Biochemical Testing

Repeat this process for every objective lens magnification change. The Magnification Formula

Submerge reaction vessels in a thermostatically controlled water bath. Evaporation of liquid during heating. biology 9700 practical notes

) that the difference is due to chance is less than 0.05. Reject the null hypothesis ( H0cap H sub 0

Mastering the 9700 Practical is about consistency. By following the "instructions for use" provided in the paper and maintaining a high level of accuracy in your measurements, you can reliably demonstrate the biological principles learned in the theoretical units. summary table of common sources of error and their specific improvements

How you record your findings is just as important as the experiment itself. 📝 Tables Draw your table you start the experiment. The independent variable goes in the left column . Include headings with units (e.g., ). Do not put units in the body cells. Ensure all readings have the same number of decimal places. 📊 Graphs

Improvement: Test a wider range of intermediate concentrations/temperatures. You must be ready to perform and interpret

Cover the test tubes with a plastic film wrap or use a reflux condenser. Drop sizes vary when using a standard plastic pipette.

Use an calibrated against a stage micrometer to measure actual lengths of tissues or cells. Convert measurements from millimetres ( ) to micrometres ( Standardising Variables : Temperature : Use thermostatically controlled water baths. pH : Use buffer solutions of known concentrations.

: Repeatedly diluting a solution by the same ratio (e.g., factor of 10) to create a range of concentrations. Microscopy & Calibration :

Submerge the tissue in a serial dilution of sucrose solutions (e.g., 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 mol dm-3mol dm to the negative 3 power ) for at least 30 minutes. Remove, gently blot dry again, and record the final mass. Calculate the percentage change in mass: Iodine Test: For starch

Maintain accurate proportions of the tissues (e.g., the cortex should not look thicker than it is relative to the vascular bundles).

Track the disappearance of substrate (e.g., starch using iodine) or the appearance of product (e.g., oxygen gas from hydrogen peroxide breakdown). Serial Dilutions: A critical skill often tested.

Common subjects include catalase, amylase, or protease. Focus on controlling variables like temperature (using a water bath) and pH (using buffers) while measuring the rate of reaction through gas collection or color changes. 2. Microscopic Observation and Calibration

χ2=∑(O−E)2Echi squared equals sum of the fraction with numerator open paren cap O minus cap E close paren squared and denominator cap E end-fraction (Where = Observed values, = Expected values). Calculated as is the number of categories). Student’s t-Test