practical 9 Flashcards
Investigation into the effect of a named variable on the rate of respiration of cultures of yeast.
An investigation of the effect of temperature on respiration in yeast.
Yeast is a single-celled fungus. It can respire aerobically and anaerobically. During aerobic respiration, the transport of electrons is linked to the synthesis of ATP. In this investigation these electrons will be accepted by a substance called methylene blue. When methylene blue accepts electrons, it changes from blue to colourless.
Q)what is the function of methylene blue
During respiration, electrons are transferred to synthesise ATP. Respiration can be
measured using a redox indicator dye such as methylene blue, which accepts these
electrons and undergoes a colour change from blue to colourless.
Investigation into the effect of a named variable on the rate of respiration of cultures of yeast.
An investigation of the effect of temperature on respiration in yeast.
Yeast is a single-celled fungus. It can respire aerobically and anaerobically. During aerobic respiration, the transport of electrons is linked to the synthesis of ATP. In this investigation these electrons will be accepted by a substance called methylene blue. When methylene blue accepts electrons, it changes from blue to colourless.
Q)You were told to leave the tubes in the water bath for 5 minutes (step 5). Explain why.
To equilibrate the yeast and glucose mixture/ so the yeast reaches the required temperature
You were told to make sure that the water bath temperature stayed at 35oC (step 6).
Describe how you monitored the water bath temperature and kept it constant at 35oC. 2
use thermometer to measure at regular intervals throughout investigation (every 30 sec)
2. heat/remove bunsen burner/add cold/hot water
Investigation into the effect of a named variable on the rate of respiration of cultures of yeast.
An investigation of the effect of temperature on respiration in yeast.
Yeast is a single-celled fungus. It can respire aerobically and anaerobically. During aerobic respiration, the transport of electrons is linked to the synthesis of ATP. In this investigation these electrons will be accepted by a substance called methylene blue. When methylene blue accepts electrons, it changes from blue to colourless.
Q. There was no control experiment in this investigation. Describe the control experiment
you would set up. Explain why this control experiment would be important 2
1.methylene blue and glucose/methylene blue, boiled, yeast and glucose
2.to show that glucose did not cause methylene blue to go colourless/to show that colour change was produced by respiration/yeast
Investigation into the effect of a named variable on the rate of respiration of cultures of yeast.
An investigation of the effect of temperature on respiration in yeast.
Yeast is a single-celled fungus. It can respire aerobically and anaerobically. During aerobic respiration, the transport of electrons is linked to the synthesis of ATP. In this investigation these electrons will be accepted by a substance called methylene blue. When methylene blue accepts electrons, it changes from blue to colourless.
Q)You were told not to shake the tubes again (step 9). Shaking the tubes would have
caused the methylene blue to go blue again. Suggest why
mixing with air/oxygen
2. oxygen oxidises methylene blue /causes methylene blue to give up electrons
Investigation into the effect of a named variable on the rate of respiration of cultures of yeast.
An investigation of the effect of temperature on respiration in yeast.
Yeast is a single-celled fungus. It can respire aerobically and anaerobically. During aerobic respiration, the transport of electrons is linked to the synthesis of ATP. In this investigation these electrons will be accepted by a substance called methylene blue. When methylene blue accepts electrons, it changes from blue to colourless.
Q)Respiration by the yeast caused the methylene blue to go colourless. Explain how.
methylene blue accepts electrons
2. electrons from glucose/reduced coenzyme/substrate
Why does the yeast and glucose solution s be buffered
should be buffered to maintain a constant pH.
what happens to to the rate of respiration and in terms of methylene blue at high temperature
at high
temperatures denaturation may occur.
● As enzymes are crucial to respiration, as their activity decreases, so does the
rate of respiration. This means that the methylene blue will take longer to turn
colourless when the temperature is further from the optimum
