Nodule Formation

Q.

What is the function of leghemoglobin in the root nodules of legumes?

Q.

The correct sequence of events in nodule formation is:

1. Curling of root hairs - rapid division of cortical cells - production of infection thread - bacteria enters polyploidy cells - colonization of surrounding areas of roots

2. Rapid division of cortical cells - production of infection thread - curling of root hairs - colonization of surrounding areas of roots - bacteria enters polyploidy cells

3. Colonization of surrounding areas of roots - curling of root hairs - production of infection thread - rapid division of cortical cells - bacteria enters polyploidy cells

4. Colonization of surrounding areas of roots - rapid division of cortical cells - bacteria enters polyploidy cells - curling of root hairs - production of infection thread

Q.

What are the advantages of nitrogen fixation?

Q.

What are the steps involved in the formation of a root nodule?

Q.

What are root nodules? How are they helpful?

Q. Nodule formation of legume roots is reduced due to the deficiency of

1. sulphur
2. boron
3. chlorine
4. both a and b

Q.

The correct sequence of events related to nodule formation of legumes is

A. Formation of bacteroids

B. Growth of infection thread

C. Secretion of sugars, amino acids and flavonoids by roots

D. Chemotactic movement of Rhizobia towards legume roots

1. DCBA

2. ABCD

3. CDBA

4. CDAB

Q. If the nitrogenase enzyme has been inactivated by radiation, there will be no

1. fixation of atmospheric nitrogen
2. fixation of nitrogen by microorganisms
3. conversion of nitrite to nitrate
4. conversion of ammonia into nitrite

Q.

Identify the correct option related to the given figure regarding root nodule formation in legumes.

1. B-Inner Cortex and pericycle cells under division

2. Both A & B

3. A-Infection thread containing bacteria

4. B - Mature nodule

Q. Plants compete with __ for the limited nitrogen available in soil.

Q.

If by radiation all nitrogenase enzyme are inactivated, then there will be no

1. Fixation of nitrogen in legumes

2. Conversion from nitrate to nitrite in legumes

3. Conversion from ammonium to nitrate in soil

4. Fixation of atmospheric nitrogen

Q.

What are the steps involved in formation of a root nodule?

Q. If by radiation, all nitrogenase enzymes are inactivated, then there will be no

1. Fixation of nitrogen in legumes
2. Conversion from ammonia to nitrate in soil
   
3. Conversion from nitrate to nitrite in legumes
4. None of the above

Q. Bacteria present in root nodules of the leguminous plants are

1. Rhizobium
2. Lactobacillus
3. Cyanobacteria
4. Azotobacter

Q. From the options given below, identify the gene responsible for nitrogen fixation.

1. Leg-haemoglobin
2. None of the above
3. Nif
4. Nitrogenase

Q.

The conversion of N₂ gas to form nitrogen that can be used by plants is called

1. Nitrogen fixation

2. Nitrogen assimilation

3. Nitrogen cycling

4. Nitrogen uptake

Q. Why are leguminous plants useful for maintaining soil fertility?

Q. Rhizobium lives as an aerobic microbe under free living conditions but gets adapted to anaerobic conditions during nitrogen fixation.

1. True

2. False

Q. Consider the following steps involved in nodule formation in the root of a legume.
(i) Bacteria release chemicals and enzymes.
(ii) Bacteria stop dividing and form baceroides.
(iii) Roots secrete chemical attractants.
(iv) Formation of infection thread.
(v) Formation of nodules.
(vi) Division of infected cortical cells.
(vii) Curling of root hair and degradation of their cell wall.
(viii) infection thread grows along with multiplication of bacteria.
Arrange the steps in the right sequence and mark the correct option.

1. (iii), (i), (vii), (iv), (viii), (vi), (v), (ii)
2. (iii), (iv), (viii), (i), (vi), (vii), (ii), (v)
3. (i), (iv), (iii), (vi), (v), (vii), (viii), (ii)
4. (i), (iii), (vi), (iv), (viii), (ii), (v), (vii)

Q. Explain the steps involved in the formation of root nodule.

Q. Identify the bacteria found in root nodules of leguminous plants

1. Escherichia Coli
2. Granulobacter
3. Rhizobium
4. Azotobacter

Q. Explain the inter relationship between organic farming and biofertilizers, with the help of any three suitable examples.
[5 marks]

Q. Coralloid roots help the plant

1. Absorb and fix nitrogen better
2. Absorb water more efficiently
3. Respiration
4. Anchorage to the soil

Q. The pigment protein present in nodulated roots inhabited by Rhizobium is

1. leg-haemoglobin
2. nitrate reductase
3. hydrogenase
4. plastocyanin

Q.

Pigment betacyanin is found in

1. beet roots

2. brinjal

3. carrot

4. urine

Q.

Q. Why the plants do not take nitrogen directly and want to perform nitrogen fixation?

Q. Root nodules are not formed in non-leguminous plants because they grow in

1. All the above
2. Soils having bacteria for converting nitrogen into usable form
3. Nitrogen deficient soils
4. Soils rich in nitrogen

Q. What are the steps involved information of root nodule?

Q. Why are leguminous plants cultivated as green manure crop?

Q. Name the pigment found in the root nodules of the leguminous plant .