page 215, number 1 & page 216, number 2

1. Explain the toxic effect of O2 on strict anaerobes.
With the absence of synthesis catalase, peroxidase, or superoxide dimutase, the toxic concentration of H2O2 cannot be degraded when these organisms are cultivated in the absence of O2.

2. Illustrate the chemical reaction involved in the degradation of hydrogen peroxide in the presence of catalase.
2H2O2 ------> catalase ------> 2H2O + O2

Page 216- Questions 3 and 4 Lupe

3. Would catalase be classified as an endoenzyme or an exoenzyme? Explain

it would be an endoenzyme as it does not put out into the environment, it has to have H2O2 added to it to work.

4. Account for the ability if streptococci to tolerate O2 in the absence of catalase activity.

It means that they are facilitative anaerobes that can survive in both environments, aerobic and anaerobic.