Practical techniques in biology
Serial dilution: dilute by the same factor each time (e.g. 1 cm³ + 9 cm³ water = ×10). Colorimetry: measure absorbance or transmission; use a calibration curve of known concentrations to read unknowns. Osmosis practical: measure % change in mass of tissue in different solutions; where the line crosses zero, the solution's ψ equals the tissue's. Enzyme rates: rate = 1/t or gradient of the initial slope; control temperature with a water bath and pH with buffers. Biological drawings: clear lines, no shading, proportions correct, labels with ruled lines. Data processing: means (exclude anomalies), % change, standard deviation (spread around the mean), error bars; overlapping SD bars suggest the difference may not be significant. Aseptic technique for microbes: flame loops, work near a Bunsen, tape lids, incubate at 25 °C.
≈ 50 min