Which is essential for the growth of root tip?
(1) Zn

(2) Fe

(3) Ca

(4) Mn

In which of the following, all three are macronutrients?
(1) Iron, copper, molybdenum

(2) Molybdenum, magnesium, manganese

(3) Nitrogen, magnesium, phosphorus

(4) Boron, zinc, manganese

Select the mismatch.

(1) Frankia                      Alnus

(2) Rhodospirillium            Mycorrhiza

(3) Anabaena                   Nitrogen fixer

(4) Rhizobium                 Alfa-fa

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⁺