Required practical 9 A level bio

What is the main variable investigated in the required practical 9 for the 2022 exams?

• Sugar concentration

• Light intensity

• pH level

• Temperature

Which organism is primarily used in the practical to study respiration?

• Plant cells

• Human cells

• Bacteria

• Yeast

What is the role of methylene blue in the practical?

• Catalyst for respiration

• Redox indicator dye

• Nutrient for yeast

• Source of glucose

Why should the test tubes not be shaken during the experiment?

• To maintain temperature

• To keep the yeast dormant

• To avoid breaking the tubes

• To prevent oxygen introduction

What does the change from blue to colorless in methylene blue indicate?

• Glucose depletion

• Yeast death

• Electron transfer during respiration

• Oxygen production

What is the optimum temperature for respiration as indicated in the practical?

• 55 degrees Celsius

• 35 degrees Celsius

• 65 degrees Celsius

• 45 degrees Celsius

Why is it important to equilibrate the test tubes before starting the experiment?

• To allow the yeast to adapt

• To achieve uniform temperature

• To mix the methylene blue thoroughly

• To ensure accurate volume measurement

What happens to the rate of respiration when the temperature deviates from the optimum?

• It increases due to faster molecular movement

• It increases indefinitely

• It decreases due to enzyme denaturation

• It remains constant

How is the rate of respiration calculated in the practical?

• Change in color intensity of methylene blue

• Glucose concentration over time

• One divided by the mean time

• Volume of gas produced per minute

What safety precaution is necessary due to the use of methylene blue?

• Avoiding ingestion

• Wearing gloves

• Using a fume hood

• Wearing eye protection