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SAI International School
Subject- Biology, Class-VIII
Topic- Microorganisms: Friend and Foe
Subtopic- Nitrogen Fixation and Nitrogen Cycle
Module- 17

Home Assignment- I

OBJECTIVE (MCQ)

Q1. Which of the following symbiotic bacterium fixes atmospheric nitrogen?
(a) Blue-green algae
(b)Rhizobium
(c)Pseudomonas
(d)Nitrobacter

Q2. Which of the following free-living bacteria fixes atmospheric nitrogen?
(a) Blue-green algae
(b)Rhizobium
(c)Pseudomonas
(d)Nitrobacter

Q3. Conversion of ammonia to nitrates is -
(a) Denitrification
(b)Nitrogen fixation
(c)Nitrification
(d)Nitrogen assimilation

Q4. Conversion of nitrates to atmospheric nitrogen is -
(a) Denitrification
(b)Nitrogen fixation
(c)Nitrification
(d)Nitrogen assimilation

Q5. Nitrogen cycle is important because it -
(a) Ensures survival of life
(b)Helps to maintain ratio of nitrogen in air
(c)Both (a) and (b)
(d)For synthesis of carbon

Q6. Nitrogen accounts nearly 79% of the air. Still nitrogen is the most limiting
nutrient for plant growth because -
(a) Atmospheric nitrogen cannot be directly utilized by plants.
(b) For growth, plants do not require nitrogen.
(c) Animal consume all nitrogen before it reaches to plants