Which of the following elements is responsible for maintaining turgor in cells?

1. Magnesium
2. Sodium
3. Potassium
4. Calcium

During biological nitrogen fixation, inactivation of nitrogenase by oxygen poisoning is prevented by?

1. Leghaemoglobin

2. Xanthophylls

3. Carotene

4. Cytochrome

The oxygen evolved during photosynthesis comes from water molecules. Which one of the following pairs of elements are involved in this reaction?

1. Manganese and chlorine

2. Manganese and potassium

3. Magnesium and molybdenum

4. Magnesium and chlorine

Minerals known to be required in large amounts for plant growth include:
1. phosphorus, potassium, sulphur, calcium
2. calcium, magnesium, manganese, copper
3. potassium, phosphorus, selenium, boron
4. magnesium, sulphur, iron, zinc

Deficiency symptoms of nitrogen and potassium are visible first in:

1. Senescent leaves

2. Young leaves

3. Roots

4. Buds

The most abundant intracellular cation is:
1. Ca²⁺
2. H⁺
3. K⁺
4. Na⁺

Best defined function of manganese in green plants is :

1. Photolysis of water

2. Calvin cycle

3. Nitrogen fixation

4. Water absorption

Which one of the following is a wrong statement?

An element playing important role in nitrogen fixation is:

1. molybdenum

2. copper

3. manganese

4. zinc

The function of leghemoglobin in the root nodules of legumes is:
1. oxygen removal
2. nodule differentiation
3. expression of nif gene
4. inhibition of nitrogenase activity