Nitrogen Fixation in Legumes

Q. How many ATP are required for the formation of one molecule of NH${}_3$ by the nitrogenase enzyme?

1. Six
2. Eight
3. Twelve
4. Sixteen

Q. A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called:

1. Strip farming
2. Shifting agriculture
3. Contour farming
4. Ley farming

Q.

What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium? What is their role in $N_2$ - fixation?

Q. Which is not true for nitrogenase enzyme in root nodules in legumes?

1. Associated with Rhizobium
2. Site of reduction of $N_2$ into $N{H}_3$
3. It is a Mo-Fe protein
4. Resistant to $O_2$ concentration

Q.

What is the role of nitrogenase and leghemoglobin in root nodules of legumes?

Q.

Assertion (A) Nitrogen-fixing enzyme in legume root nodules functions at low oxygen concentration.
Reason (R) Low oxygen concentration is provided by leghaemoglobin.

1. Both A and R are correct, but R is not the correct explanation of A

2. A is correct, but R is incorrect

3. Both A and R are incorrect

4. Both A and R are correct and R is the correct explanation of A

Q. Which is not true for nitrogenase enzyme in root nodules in legumes?

1. Associated with Rhizobium
2. Site of reduction of $N_2$ into $N{H}_3$
3. It is a Mo-Fe protein
4. Resistant to $O_2$ concentration

Q. The function of leghaemoglobin during biological Nitrogen fixation in root nodules of legume is to

1. Convert atmospheric $N_{2}toN{H}_3$
2. Transport oxygen to the enzyme nitrogenase
3. Protect nitrogenase from excessive oxygen supply
4. Convert $N{H}_3$ to nitrite

Q.

What are the conditions necessary for fixation of atmospheric nitrogen by Rhizobium. What is their role in N₂ -fixation?

Q. Assertion: Nitrogen-fixing enzyme in legume root nodules functions at low oxygen concentration Reason: Low oxygen concentration is provided by legheamoglobin

1. Both assertion and reason are true and the reason is the correct explanation for the assertion
2. Both assertion and reason are true but the reason is not the correct explanation for the assertion
3. Assertion is true but the reason is false
4. Both assertion and reason are false

Q. Function of leghaemoglobin during biological nitrogen fixation in root nodules of legumes is to

1. Convert ammonia to nitrite
2. Transport oxygen for activity of nitrogenase
3. Convert atmospheric nitrogen to ammonia
4. Protect nitrogenase from oxygen

Q. The common nitrogen-fixer in paddy fields is

1. Frankia
2. Rhizobium
3. Oscillatoria
4. Azospirillum

Q. Which of the following can fix atmospheric nitrogen directly?

1. Pea
2. Brassica
3. Castor
4. Petunia

Q. Assertion :Nitrogen fixing bacteria of legume root nodules survive in oxygen depleted cells. Reason: Leghaemoglobin completely removes oxygen from nodule cells.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. In soyabean, fixed nitrogen is exported in the form of:

1. Ureides
2. $\alpha$-ketoglutaric acid
3. Pyruvate
4. Ammonia

Q. Which of the following plants have red pigment in their roots?

1. Radish
2. Soybean
3. Mustard
4. Maize

Q. Which one of the following is wrong statement.

1. Anabaena and Nostoc are capable of fixing nitrogen- in
   free living state also
2. Root nodule forming nitrogen fixers live as aerobes
3. Phosphours is a constituent of all members , certain
   nucleic acids and all proteins
4. Nitrosomonas and Nitrobacter are chemoautotrophs

Q. Which one of the following is not a free living nitrogen fixing bacterium?

1. Azotobacter
2. Anabaena azollae
3. Pseudomonas
4. Cyanobacterium

Q. The function of leghemoglobin in the root nodules of legumes is

1. Oxygen removal
2. Inhibition of nitrogenase activity
3. Expression of nif gene
4. Nodule differentiation

Q. A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called:

1. Ley farming
2. Contour farming
3. Strip farming
4. Shifting agriculture

Q. In nodular plant leghaemoglobin helps in

1. Scavanging of oxygen
2. Help reduction of nitrite
3. Nodule formation
4. None of the above

Q. Assertion :Nitrogen-fixing bacteria in legume root nodules survive in oxygen-depleted cells of nodules Reason: Leghaemolobin completely removes oxygen from the nodule cells

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

Assertion (A) Nitrogen-fixing enzyme in legume root nodules functions at low oxygen concentration.
Reason (R) Low oxygen concentration is provided by leghaemoglobin.

1. Both A and R are correct and R is the correct explanation of A

2. Both A and R are correct, but R is not the correct explanation of A

3. A is correct, but R is incorrect

4. Both A and R are incorrect

Q. Refer the given figure showing the bacteriods in the section of root nodule of a leguminous plant. Select the correct statement regarding A?

1. It is leghaemoglobin, which protects nitrogenase from oxygen
2. It protects bacteriods from nitrogenase
3. It secretes chemical attractants that cause curling of root hair around nitrogen-fixing bacteria
4. None of the above

Q.

A system of rotating crops with legumes or grass pasture to improve soil structure and fertility is called:

1. Contour farming
2. Strip farming
3. Shifting agriculture

4. Ley farming

Q. A farmer adds Azotobacter culture to soil before sowing maize. Which mineral element will be replenished by doing so?

1. N
2. P
3. K
4. S

Q. Assertion :Nitrogen-fixing bacteria in legume root nodules survive in oxygen-depleted cells of nodules. Reason: Leghaemoglobin completely removes oxygen from the nodule cells.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct