The common nitrogen-fixer in paddy fields is
Which of the folowing is a symbiotic nitrogen fixer?
About 98 percent of the mass of every living organism is composed of just six elements
including carbon, hydrogen, nitrogen, oxygen and:
1. phosphorus and sulphur
2. sulphur and magnesium
3. magnesium and sodium
4. calcium and phosphorus
Which one of the following elements is not an essential micronutrient for plant growth?
A plant requires magnesium for
1. holding cells together
2. protein synthesis
3. chlorophyll synthesis
4. cell wall development
Farmers in a particular region were concerned that pre-mature yellowing of leaves of a pulse crop might cause decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield?
1. Frequent irrigation of the crop
2. Treatment of the palnts with cytokinins alongwith a small dose of nitrogenous fertilizer
3. Removal of all yellow leaves and spraying the remaining green leaves with 2, 4, 5 trichlorophenoxy acetic acid
4. Application of iron and magnesium to promote synthesis of chlorophyll
Sulphur is an important nutrient for optimum growth and productivity in:
1. pulse crops
3. fibre crops
4. oilseed crops
The function of leghaemoglobin is
1. to provide oxygen to leg muscles of nitrogen-fixing
2. to protect oxygen-sensitive enzymes of nitrogen fixing bacteria in the root nodules of
3. to walk to the sites where oxygen is required
4. to function when haemoglobin is not available.
1. cultivation of plants in water
2. growth of plants towards water
3. growth of plants away from water
4. soilless cultivation of plants
The function of leghaemoglobin during biological nitrogen fixation in root nodules of legumes is to
1. convert atmospheric N2 to NH3
2. convert ammonia to nitrite
3. transport oxygen for activity of nitrogenase
4. protect nitrogenase from oxygen.