Which of the following enzyme is secreted by yeast, responsible for fermentation

Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society. Give reasons for your answer.

Biogas, Citric acid, Penicillin and Curd

Identify the blank spaces $a, b, c$ and $d$ given inthe following table and select the correct answer.

Commercial extraction of penicillin was done by

For the manufacture of gluconic acid and citric acid, which of the following micro-organism is used