7. Fill in the blanks:
(a) Micro-organisms can be seen with the help
of a ____________.
(b) Typhoid is caused by __________.
(c) Micro-organisms may be single-celled like
bacteria, some algae and protozoa, or _______
like algae or fungi.
10. • Yeast reproduces rapidly and produces carbon dioxide
during respiration. Bubbles of the gas fill the dough and
increase its volume.
• This is the basis of the use of yeast in the baking industry
for making breads, pastries and cakes.
11. • Yeast is used for commercial
production of alcohol and
wine.
• yeast is grown on natural
sugars present in grains like
barley, wheat, rice, crushed
fruit juices, etc.
• The smell of alcohol as sugar
has been converted into
alcohol by yeast comes
because of the process of
conversion of sugar into
alcohol known as
fermentation.
13. Poll
1. Yeast is used in the production of:
(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen
2. The bread or idli dough rises because of:
(i) heat (ii) grinding (iii) growth of yeast cells (iv) kneading
3.The process of conversion of sugar into alcohol is called:
(i) nitrogen fixation (ii) moulding (iii) fermentation (iv) infection
14. HOMEWORK
Q1. List some of the diseases caused by different micro-organisms that are
not mentioned in the book.
Q2. Observe at your home and explain the process of how does your mother
bake a cake and explain the reason behind it.
Q3. As done earlier in an activity of adding sugar and yeast in water and
keeping it like that for the next 4-5 hours, explain what had happened during
this whole process.
Q4. Watch video on you tube and tell about how did Louis Pasteur discover
the process of fermentation.
