Master GCSE Biology

MS1:

- Aseptic technique: Sterile technique used to prevent contamination with microorganisms (1)

- Importance:

- Prevents contamination of cultures/samples (1)

- Ensures reliable and valid results (1)

MS2:

- Place a drop of pond water on a slide (1)

- Add a coverslip (1)

- Place the slide on the microscope stage (1)

- Focus using the coarse and then fine focus (1)

- Observe using different magnifications (1)

MS3:

- Independent variable: Solute concentration in solutions (1)

- Dependent variable: Change in mass/length of potato cylinders (1)

- Control variables:

- Temperature (1)

- Time (1)

- Surface area of potato cylinders (1)

- Procedure:

- Cut potato cylinders of equal size (1)

- Weigh/measure initial mass/length (1)

- Place cylinders in solutions of different concentrations (1)

- Weigh/measure mass/length after a set time (1)

MS4:

- From blue to green, yellow, orange, or red (depending on sugar concentration) (2)

MS5:

- Glucose (reducing sugar):

- Benedicts' reagent turns blue to green, yellow, orange, or red (1)

- Starch (non-reducing sugar):

- Benedicts' reagent remains blue (1)

- Procedure:

- Add Benedicts' reagent to samples of both glucose and starch (1)

- Heat both samples (1)

- Observe color changes (1)

MS6:

- Independent variable: pH of catalase-containing solutions (1)

- Dependent variable: Rate of oxygen production (1)

- Control variables:

- Temperature (1)

- Volume of catalase solution (1)

- Amount of hydrogen peroxide (1)

- Procedure:

- Prepare catalase solutions at different pHs (1)

- Add equal volumes of solutions to hydrogen peroxide (1)

- Measure rate of oxygen production using a gas syringe (1)

MS7:

- Iodine solution (1)

MS8:

- Leaf exposed to light:

- Iodine turns blue-black due to the presence of starch (1)

- Leaf kept in the dark:

- Iodine remains orange-brown due to the absence of starch (1)

- Procedure:

- Take leaf sections from both plants (1)

- Boil in water to inactivate enzymes (1)

- Add iodine solution (1)

- Observe color changes (1)

MS9:

- Reliability: Consistency of results (1)

- To ensure results can be replicated by others (1)

- Validity: Measuring what is intended to be measured (1)

- To ensure data is meaningful (1)

- Accuracy: Closeness of results to the true value (1)

- To minimize errors (1)

MS10:

- Unexpected/unusual result that does not fit the pattern of the other data (2)

- Can be due to:

- Experimental error (1)

- Variation within samples (1)

- Outlying data (1)