Mineral Nutrition · Question 31

Leguminous plants are able to fix atmospheric nitrogen through the process of symbiotic nitrogen fixation. Which one of the following statements is not correct during this process of nitrogen fixation?

1. Leghaemoglobin scavenges oxygen and is pinkish in colour.
2. Nodules act as sites for nitrogen fixation.
3. The enzyme nitrogenase catalyses the conversion of atmospheric N2 to NH3.
4. Nitrogenase is insensitive to oxygen.

Study the cycle shown below and select the option which gives correct words for all the four blanks A, B, C and D. [figure]

1. array|l|l|l|l| A & B & C & D \ Nitrification & Ammonification & Animals & Plants \ array
2. array|l|l|l|l| A & B & C & D \ Denitrification & Ammonification & Plants & Animals \ array
3. array|l|l|l|l| A & B & C & D \ Nitrification & Denitrification & Animals & Plants \ array
4. array|l|l|l|l| A & B & C & D \ Denitrification & Nitrification & Plants & Animals \ array

One of the free-living, anaerobic nitrogen-fixer is

1. Beijerinckia
2. Rhodospirillum
3. Rhizobium
4. Azotobacter

An element playing important role in nitrogen fixation is

1. molybdenum
2. copper
3. manganese
4. zinc

Which one of the following is not a micronutrient?

1. Molybdenum
2. Magnesium
3. Zinc
4. Boron

Manganese is required in

1. plant cell wall formation
2. photolysis of water during photosynthesis
3. chlorophyll synthesis
4. nucleic acid synthesis

Nitrogen fixation in root nodules of Alnus is brought about by:

1. Bradyrhizobium
2. Frankia
3. Clostridium
4. Azorhizobium

Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing micro-organism?

1. Crotalaria juncea
2. Cycas revoluta
3. Cicer arietinum
4. Casuarina equisetifolia

Which one of the following elements is not an essential micronutrient for plant growth?

1. Zn
2. Cu
3. Ca
4. Mn

A plant requires magnesium for

1. protein synthesis
2. chlorophyll synthesis
3. cell wall development
4. holding cells together