Question 2 โ€” Yeast and the balloon - Questions at the end of the chapter - Chapter 2 Class 8 - The Invisible Living World: Beyond our (Curiosity)

Last updated at June 7, 2026 by

Q 2
Question

Yeast is added to sugar solution in test tube B, with balloons on both tubes. (i) Why does the balloon on B inflate? (ii) The balloon's gas is then shaken into lime water — what is she trying to find out?

๐Ÿ”— Concept: 2.4.2 Microorganisms and Food

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(i) Option (c): yeast produced a gas. (ii) She wants to test if the gas is carbon dioxide.

Explanation

  • (i) Yeast in tube B feeds on sugar and releases carbon dioxide gas.
  • This gas fills the balloon, so it inflates.
  • (ii) Carbon dioxide turns lime water milky.
  • So shaking the gas into lime water tests whether it is carbon dioxide.
Yeast makes carbon dioxide, which inflates the balloon and turns lime water milky.
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