A. Fill in the blanks:
1. Microorganisms can be seen with the help of a ………………. .
2. Blue green algae fix ……………. directly from air to enhance fertility of soil.
3. Alcohol is produced with the help of ………………… .
4. Cholera is caused by ……………….. .
5. The female Aedes mosquito is a carrier of the ……………….. virus.
B. Tick (œ“) the correct option:
1. Yeast is used in the production of:
(a) sugar
(b) alcohol
(c) hydrochloric acid
(d) oxygen
2. The following is an antibiotic:
(a) Sodium bicarbonate
(b) Streptomycin
(c) Alcohol
(d) Yeast
3. Carrier of malaria-causing protozoan is:
(a) female Anopheles mosquito
(b) cockroach
(c) housefly
(d) butterfly
4. The most common carrier of Communicable diseases is:
(a) ant
(b) housefly
(c) dragonfly
(d) spider
5. The bread of idli dough rises because of:
(a) heat
(b) grinding
(c) growth of yeast cells
(d) kneading
6. The process of conversion of sugar into alcohol is called:
(a) nitrogen fixation
(b) moulding
(c) fermentation
(d) infection
C. Match the following:
| ‘A’ | ‘B’ |
| 1. Bacteria | a. Fixing nitrogen |
| 2. Rhizobium | b. Setting of curd |
| 3. Lactobacillus | c. Baking of brea |
| 4. Yeast | d. Causing malaria |
| 5. A protozoan | f. Causing cholera |
| 6. A virus | g. Causing AIDS |
| h. Producing antibodies |
D. Answer the following questions in short:
1. Can microorganisms be seen with the naked eye? If not, how can they be seen?
2. What are the major groups of microorganisms?
3. Name the microorganisms which can fix atmospheric nitrogen in the soil.
4. Write 10 lines on the usefulness of microorganisms in our lives.
5. Write a short paragraph on the harms caused by microorganisms.
6. What are antibiotics? What precautions must be taken while taking, antibiotics?
7. What is food preservation?
8. Is it safe to eat infected bread? Why?
9. Why do foods like dry soup mixes remain unspoilt for many days?
E. State True or False:
1. Bacteria possess characteristics of living as well as non-living. ………………..
2. Yeast is used in the preparation of vitamin ‘B’ complex. ……………….
3. All viruses are parasites. …………………
4. All algae can make their own food because they contain chlorophyll. ………………..
5. Microorganism may be unicellular or multicellular. ……………..
F. Classify the following into friendly and harmful microorganisms:
- Yeast
- malarial parasite
- Lactobacillus
- bread mould
- Rhizobium
- Bacillus anthracis
| Friendly | harmful |
G. Visit a doctor. Find out why antibiotics should not be overused. Prepare a short report.
H. Here is a list of food items. Tick (œ“) the food items you think are prone to spoilage from microorganisms:
- Ice creams
- Sandwich
- Sugar
- Milk
- Honey
- Salt
- Uncooked rice
- Salads
- Curd
- Cooked rice
- Dry fruits
- Vegetables
I. Complete the following cycle given as figure by filling the blank boxes:
