Microorganisms

Samacheer Book Back Questions And Answers For Science Standard 8 “Microorganisms“

I. Choose the best answer:
1. Microorganisms are measured in _____.
a) cm
b) mm
c) micron 
d) meter

2. _____ shows both living and nonliving characteristics.
a) Protozoa
b) Virus
c) Bacteria
d) Fungi

3. _____ is a prokaryotic microorganisms.
a) Virus
b) Algae
c) Fungi
d) Bacteria

4. Based on shape, the bacteria are classified into _____ types.
a) two
b) three
c) four 
d) five

5. Common cold in human is caused by _____.
a) plasmodium
b) influenza
c) vibrio cholera
d) aphthovirus

II. Fill in the blanks:
1. _____ is prepared from a mould called penicillium.
2. _____ are the infectious protein particles.
3. The infecting virus particle found outside the host cell is _____.
4. Microorganism can be seen with the help of a _____.
5. Bacteria, which has a flagellum at one end is classified as _____.

Answers:
1. Penicillin
2. Prions
3. virion
4. microscope
5. monotrichous

III. State true or false. If false, correct the statement:
1. Disease causing microorganisms are called pathogens
2. Female anopheles mosquito is a carrier of dengue virus
3. Chicken pox is a communicable disease.
4. Citrus canker is transmitted by insects.
5. Yeast is used in the large-scale production of alcohol.

Answers:
1. True
2. False (Female Anopheles mosquito is a carrier of malaria parasite)
3. True
4. False (Citrus canker is transmitted by air and water)
5. True

IV. Match the following:
1. Nitrogen fixing bacteria      A. Vaccine
2. Tuberculosis                        B. Prion
3. Kuru                                    C. Lactobacillus acidophilus
4. Probiotics                            D. Bacteria
5. Edward Jenner                     E. Rhizobium

Answers:
1. E
2. D
3. B
4. C
5. A

V. Answer the following questions:
1. Assertion: Malaria is caused by Protozoa.
Reason: The disease is transmitted by mosquito.
a. If both assertion and reason are true and reason is the correct explanation of assertion.
b. If both assertion and reason are true and reason is not the correct explanation of assertion.
c. If assertion is true but reason is false.
d. If both assertion and reason are false.

2. Assertion: Algae are heterotrophic.
Reason: They do not have chlorophyll.
a. If both assertion and reason are true and reason is the correct explanation of assertion.
b. If both assertion and reason are true and reason is not the correct explanation of assertion.
c. If assertion is true but reason is false.
d. If both assertion and reason are false.

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