Question

Which one of the following element is essential for the growth of pollen tube?
A. Ca
B. B
C. Mg
D. Mo

Answer 1

Hint: Plants use nutrients to create their bodies and maintain their physiological processes. Along with non-mineral elements like carbon, oxygen, and hydrogen, it also contains mineral elements like potassium, phosphorus, magnesium, and zinc.

Step by step solution:
A.. Ca is necessary for the development of plant tissues and for promoting plant growth. Cell walls in plants are kept together by calcium. Additionally, it plays a crucial role in signalling the coordination of cellular processes and activating enzymes.
B. In soil, boron can be found in both soluble and non-soluble forms. It is a component of silicates and can be found as boric acid, calcium, and magnesium borates. Salts of calcium and magnesium are soluble in it. Boron is necessary for plants' leaves and seeds. It is necessary for the absorption and usage of calcium, pollen germination, cell differentiation, and the transfer of carbohydrates. Additionally, it is critical for the metabolism of fat, hormones, and nitrogen. It controls cellular development and differentiation.
C. Plants use magnesium as their primary energy source during photosynthesis. Chlorophyll cannot absorb the solar energy required for photosynthesis without magnesium. The enzymes involved in the production of chlorophyll contain magnesium. In other words, magnesium gives the plant its green hue. Magnesium is also necessary for the synthesis of nucleic acid, the metabolism of carbohydrates, and the stabilisation of cell membranes.
D. Molybdate ions, which are molybdenum's absorbed form, are taken up by plants. It can also be absorbed as di, tri, or pentoxides. It is necessary throughout the plant, but is especially needed by the roots in the form of molybdate ions. The main purposes of this are nitrogen fixation and nitrate reduction.

So, option B is correct.

Note: The critical concentration of an essential element is the level at which plant growth is inhibited. When an element is present in less than its concentration, it is said to be deficient. The growth of the plant is slowed down because critical nutrients are not as readily available.