MEDIUM
8th CBSE
IMPORTANT
Earn 100

Manoj adds some yeast to two test tubes containing sugar solution. One test tube is kept in ice and the other at room temperature. The picture shows what happens after three hours.

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What should Manoj keep the same in both the test tubes for a fair experiment?

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Important Questions on Microorganisms: Friend and Foe

EASY
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 8
What type of organism is yeast?
MEDIUM
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 9
How do plants take up nitrogen?
MEDIUM
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 10
Plants and animals are continuously using nitrogen. Will there be a depletion of nitrogen in the environment due to this continuous use? Explain your answer.
HARD
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 11
Paheli dug two pits, A and B, in her garden. In pit A, she put a polythene bag packed with some agricultural waste. In pit B, she dumped the same kind of waste but without packing it in a polythene bag. She then covered both the pits with soil. What did she observe after a month?
HARD
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 12

Curd is formed only in

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HARD
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 13

Refer to the given diseases.
(i) Athlete's foot
(ii) Amoebic dysentery
(iii) Polio
(iv) Cholera
(v) Malaria
(vi) Measles
(vii) Pyorrhea
(viii) Ringworm
(ix) Typhoid
(x) Tuberculosis
Select the option which correctly identifies bacterial diseases (P), viral diseases (Q), protozoan diseases (R) and fungal diseases (S).

HARD
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 14
Consider the following statements and select the option which correctly identifies true (T) and false (F) ones.
(i) Diatoms float in water due to the presence of light stored fats with silica.
(ii) AIDS virus kills WBC and reduces the immunity of the body.
(iii) Escherichia coli is present in the intestine of humans where they help in the digestion of food.
(iv) A virus always consists of double strands of DNA or RNA surrounded by a protein coat.
MEDIUM
8th CBSE
IMPORTANT
Science Textbook of Competency Based Questions for Class VIII>Chapter 2 - Microorganisms: Friend and Foe>Exercise>Q 15
Which of the following is a correct pair of bacterial disease and its causal agent?
I. Citrus canker — Xanthomonas citri.
II. Tundu of wheat — Corynebacterium tritici.
III. Blight of rice — Xanthomonas oryzae.
IV. Angular leaf spot of cotton — X. malvacearum.
V. Anthrax of cattle — Bacillus anthracis.
VI. Whooping cough — Bordetella pertussis.