Azotobacter and Bacillus polymyxa are

1. Decomposers

2. Nonsymbiotic nitrogen fixer

3. Symbiotic nitrogen fixer

4. Pathogenic bacteria

Nitrogen fixation usually refers to the biological process by which:

(1) Ammonia is converted into nitrogen

(2) Nitrates are converted to nitrites

(3) Nitrogen in the atmosphere is converted into ammonia

(4) Nitrites are converted into nitrates

The formula for BNF is:
${\mathrm{N}}_2+ 6 {\mathrm{H}}^{+} +6 {\mathrm{e}}^{-} \to 2 {\mathrm{NH}}_3$
The process is coupled to the hydrolysis of $\mathrm{\_\_\_\_\_\_\_\_\_\_}$ equivalents of ATP and is accompanied by the coformation of $\mathrm{\_\_\_\_\_\_\_\_\_\_}$ molecules of ${\mathrm{H}}_2$

(1) 8, 2

(2) 16, 1

(3) 4, 1

(4) 6, 2

Conversion of nitrate to nitrogen gas and nitrous oxide is called:

(1) nitrogen fixation

(2) ammonification

(3) denitrification

(4) eutrophication

Which of the following minerals required by a plant is not a ‘macronutrient’?
1. Iron
2. Sulfur
3. Potassium
4. Calcium

Match each item in Column I with one in Column II and select the best match from the codes given:

    Codes:

Match each item in Column I with one in Column II and select the best match from the codes given:

    Codes:

Consider the two statements:
I. Excess of manganese in plants may induce deficiencies of iron, magnesium and calcium.
II. Manganese inhibits translocation of iron and magnesium at apex and competes with calcium for uptake.
1. Both I and II are correct and II explains I
2. Both I and II are correct but II does not explain I
3. I is correct and II is incorrect
4. Both I and II are incorrect

Nitrogen fixing bacteria live in the nodules in a plant root. These nodules are formed by the cells of:
1. Epidermis
2. Cortex
3. Endodermis
4. Vascular cylinder

For each NH₃ produced, the number of ATP molecules required by the nitrogenase enzyme is:
1. 4
2. 8
3. 12
4. 16