Mineral Nutrition · Question 37

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

Sulphur is an important nutrient for optimum growth and productivity in

1. oilseed crops
2. pulse crops
3. cereals
4. fibre crops.

All of the following statements concerning the actinomycetous filamentous soil bacterium Frankia are correct except that Frankia

1. can induce root nodules on many plant species
2. can fix nitrogen in the free-living state
3. forms specialized vesicles in which the nitrogenase is protected from oxygen by a chemical barrier involving triterpene hopanoids
4. like Rhizobium, it usually infects its host plant through root hair deformation and stimulates cell proliferation in the host's cortex.

The deficiencies of micronutrients, not only affect growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, which group of three elements shall affect most, both photosynthetic and mitochondrial electron transport?

1. Co, Ni, Mo
2. Ca, K, Na
3. Mn, Co, Ca
4. Cu, Mn, Fe

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

1. fixation of nitrogen in legumes
2. fixation of atmospheric nitrogen
3. conversion from nitrate to nitrite in legumes
4. conversion from ammonium to nitrate in soil.

Plants deficient of element zinc, show its effect on the biosynthesis of plant growth hormone

1. auxin
2. cytokinin
3. ethylene
4. abscisic acid.

Gray spots of oat are caused by deficiency of

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