Page 27 - Innovator's Science-8

Ans. • A bread slice near the sink will show fungal growth (mold).
• Slices in the refrigerator will likely have no or slower growth.
The warm and damp area near the sink helps germs and microorganisms grow easily, while the cold air
inside the refrigerator slows down or stops their growth.

8. Observe the set-up given in the figure and answer the
following ques ons. Warm sugar
i. What happens to the sugar solu on in flask A? solution + Yeast
Lime
ii. What do you observe in test tube B a er four hours? water
Why do you think this happened?
A B
iii. What would happen if yeast were not added to flask
Experimental set-up
A?
Ans. i. The yeast ferments the sugar in the warm solu on, producing carbon dioxide gas and a small amount
of alcohol.
ii. Lime water in test tube B turns milky. This happens because CO produced in flask A travels through
2
the delivery tube into flask B and reacts with lime water, confirming the presence of carbon dioxide.
iii. Fermenta on would not occur, so no carbon dioxide would be produced. As a result, lime water
would remain clear in test tube B.

Put on your
Thinking cap
Problem Solving Skills
A. Darken the correct options in the OMR Sheet: OMR Sheet
1. The human eye can only see objects that are above a ___________ size.
a. certain b. same

c. small d. none of these
2. The letters appear ___________ when seem through the flask. Wrong Methods

a. smaller b. larger Correct Method
c. stronger d. weaker

3. What type of microorganism is yeast? 1. a b c d
a. algae b. protozoa
2. a b c d
c. fungi d. bacteria
4. Which microorganism helps in curd formation?
3. a b c d
a. Mould b. Spirulina
c. Lactobacillus d. Rhizobium
4. a b c d
5. Which of the following is unicellular?
a. Human b. Yeast
5. a b c d
c. Tree d. Mould

B. Fill in the blanks. Observational Skills

1. Yeast converts sugar into alcohol and _____________ gas during the process of fermentation.

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Science-8