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AP Intermediate 2nd Year Microorganisms: Friend and Foe — practice questions

Explore 10 free Microorganisms: Friend and Foe questions in AP Intermediate 2nd Year Science. Open each question or exercise to read its content, reference answers and available explanation.

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Microorganisms: Friend and Foe questions and exercises with answers

Showing questions 1–10 of 10.

CLASS8 · Biology · Microbe ↔ UseRead the answer and worked solution →Curd is formed from milk by the action ofRead the answer and worked solution →The puffed-up appearance of dosa/idli batter is due to production ofRead the answer and worked solution →The characteristic large holes in Swiss cheese are due to a large amount of CO₂ produced byRead the answer and worked solution →Penicillin was discovered byRead the answer and worked solution →Which yeast is used to ferment cereals and fruit juices to produce ethanol (also used for bread-making)?Read the answer and worked solution →The gas biogas is composed predominantly ofRead the answer and worked solution →A common bacterium among the methanogens producing biogas from cattle dung isRead the answer and worked solution →Statins, blood-cholesterol lowering agents, are produced byRead the answer and worked solution →Cyclosporin A, used as an immunosuppressive agent in organ transplant patients, is produced byRead the answer and worked solution →

Worked practice questions

CLASS8 · Biology · Microbe ↔ Use

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Matching pairs
  1. Left
    Yeast
    Right
    Makes bread rise
  2. Left
    Lactobacillus
    Right
    Turns milk to curd
  3. Left
    Rhizobium
    Right
    Fixes nitrogen in roots
Instructions
Match each microbe to its useful role.

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Curd is formed from milk by the action of

  1. Lactic acid bacteria (Lactobacillus)
  2. Yeast (Saccharomyces cerevisiae)
  3. Rhizobium
  4. Streptococcus
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Correct answer: A. Lactic acid bacteria (Lactobacillus)

1. Curd formation is a microbial fermentation of milk. 2. syllabus names Lactobacillus and related lactic acid bacteria (LAB) as the agents. 3. They produce lactic acid that coagulates milk protein and gives the sour taste. 4. Vitamin B₁₂ content also increases during LAB fermentation. _Source: syllabus Biology, Ch 8 "Microbes in Human Welfare", §8.1_

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The puffed-up appearance of dosa/idli batter is due to production of

  1. O₂ during aerobic fermentation
  2. CO₂ during bacterial fermentation
  3. H₂ during hydrolysis
  4. NH₃ during protein breakdown
Show answer and solution

Correct answer: B. CO₂ during bacterial fermentation

1. Dosa/idli batter is fermented by bacteria naturally present in the flour. 2. Microbial fermentation releases CO₂ gas. 3. The CO₂ gas gets trapped in the batter, causing the puffed-up appearance. 4. Bread dough shows the same phenomenon with baker's yeast producing CO₂. _Source: syllabus Biology, Ch 8 "Microbes in Human Welfare", §8.1_

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