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 a 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 plants with cytokinins along with a small dose of nitrogenous fertilizer

3. Removal of all yellow leaves and spraying the remaining green leaves with 2, 4, 5 trichloro phenoxy acetic acid

4. Application of iron and magnesium to promote the synthesis of chlorophyll

Sulphur is an important nutrient for optimum growth and productivity in:

1. pulse crops

2. cereals

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

legumes

3. to walk to the sites where oxygen is required

4. to function when haemoglobin is not available.

Hydroponics is

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.

Which of the following is correct set of micronutrient for plants?

1. Mg, Si Fe, Cu Ca

2. Cu, Fe, Zn, B, Mn

3. Mg, Fe, Zn, B, Mn

4. Mo, Zn, Cl, Mg, Ca

Which one of the following is not a microelement for plants?
(1) Cu

(2) B

(3) Zn

(4) Cr

Leghaemoglobin is produced in response to

1. respiration 

2. photosynthesis

3. fatty acid synthesis

4. N₂ fixation.
 

Plants do not get benefit from

(1) N₂ in air

(2) O₂ in air

(3) CO₂ in air

(4) O₃ in air.