biology help?

posted by .

In 1857, Louis Pasteur discovered that yeast is a living organism. The
activity of yeast causes fermentation – baker’s yeast, Saccharomyces
cerevisiae, has been used for centuries in the production of bread, beer and
wine. In the absence of oxygen, yeast is able to derive energy from nutrient
carbohydrates by switching from aerobic to anaerobic respiration. In the first
step of anaerobic respiration, known as glycolysis, monosaccharides such as
glucose or fructose are oxidised to form pyruvate, with the net release of
energy in the form of ATP
Step 1 Glycolysis
glucose + ADP + NAD → pyruvate + NAD.2H + ATP
In the second step (alcoholic fermentation) the pyruvate is reduced to form
ethanol and carbon dioxide:
Step 2 Alcoholic fermentation
pyruvate + NAD.2H → ethanol + NAD + CO2
After reading Chapters 5 and 6 of Book 5, an enterprising OU student
decided to investigate the anaerobic respiration of yeast in the presence of
different sources of carbohydrate. The student had a job as a laboratory
technician in a school and so was able to set up the apparatus shown in
Figure 1 and carry out the investigation using each of the mixtures described
in Table 2 in turn. Each experiment was carried out at room temperature
(20 °C).
Table 2 The contents of the reaction mixture in each of the five experiments. You can assume that the
starting concentrations of the carbohydrate solutions were the same (i.e. same mol dm
Experiment A B C D E
A)5 cm3 yeast
suspension +
1 cm3 distilled
B)5 cm3 yeast
suspension +
1 cm3 glucose
C)5 cm3 yeast
suspension +
1 cm3 sucrose
D)5 cm3 yeast
suspension +
1 cm3 starch
E)5 cm3 yeast
suspension +
1 cm3 starch
At the start of each experiment the measuring cylinder was filled with water
and quickly inverted in the trough of water and placed on the beehive shelf
(a platform with holes that allows free movement of water in or out of the
measuring cylinder). The reaction mixture was made up in the bottle and the
stopper quickly replaced so that any gas given off by the yeast mixture
travels through the tube and is collected in the inverted measuring cylinder,
the gas pushing down the water as shown in Figure 1. The volume of gas
produced was measured at 5-minute intervals for 30 minutes. A graph
showing the results of these five experiments is shown in Figure 2.
Q)The experiment could be extended to see how temperature affects the
way the yeast respires. Predict the effect on the results of experiment B
(5 cm3 yeast suspension + 1 cm3 glucose solution) if it was repeated (i)
at 4 °C and (ii) at 60 °C and give a brief explanation for each of your

  • biology help? -

    I would need to see the figures to be able to help.

  • biology help? -

    this is an OU tma question! do the bloody reading you lazy sod- it won t help you in the exam!

  • biology help? -

    i second anonymous and would also like to add that this breaks the plagerism clause of the course...

  • biology help? -

    I would like to know why the first part of the experiment A was done with distilled waetr

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. science

    Does yeast need light to grow? The bread I make using yeast rises in the dark.
  2. science

    For the reproduction of yeast which sugar is best,regular suger,splenda,equal or sweet and low?
  3. Biology

    What fermentation products are made by both yeast and humans?
  4. english

    i need to write a process paragraph about how yeast causes bread to rise. i was wondering if this was good. Yeast is the essential cells of Saccharomyces cervisiae waiting to be activated. Take a half cup of warm water or milk in a …
  5. Biology 205

    Can someone please help me? In 1861, Louis Pasteur observed that when yeasts grow in a sugar and protein medium, completely free of air, they ferment vigorously; and for every gram of yeast that forms, 60 to 80 grams of sugar disappeared.
  6. BIOLOGY GR.12

    What are the differnt conditions for yest fermentation. i have to make a hypothesis and experment based on yeast fermentation. I WANT TO KNOW WHAT EFFECTS THE FERMENTATION. for example using a higher temp to put my yeast in will make …

    Since fermentation occus in the cytoplasm of yeast cells explain the role of mitochondria in yeast cells?
  8. Science

    Saccharomyces Cerevisiae is a fungi, it is used in the production of bread. Rhizopus is a fungus that causes mouldy bread. What is the difference between the structure of the fungi, when looking at Saccharomyces and Rhizopus under …
  9. Biology

    Wine is made by mixing yeast with grapes and allowing the yeast cells to undergo fermentation. Sparkling wine is a type of wine that contains high levels of dissolved carbon dioxide. What is the source of the carbon atoms in the carbon …
  10. chemistry

    Problem 3 A publication this year in the journal Yeast (who’d have thought!) by a Scottish group described their development of a spectrometric procedure to monitor the concentration of glucose, ethanol, biomass, and protein content …

More Similar Questions