Question

Number of essential nutrients needed by plants is
A) 5
B) 8
C) 16
D) 4

Answer 1

Hint: Plants are producers and use light energy to synthesise food molecules. In order to do this they need access to all the atoms required for the building blocks of food and their structures, as well as for the machinery of synthesis.

Complete Answer:
- The nutrients needed by plants are obtained from various sources in nature. These are in the form of basic atoms and molecules, which are then used to build a mature plant.
- The sources of these nutrients come from the air, which includes carbon, hydrogen, and oxygen; from the soil, including iron, nitrogen, and calcium; and from water which includes soluble forms of other elements like chlorine.
- The same nutrients can be obtained from different sources. Since everything is synthesised by the plant from the elemental building blocks, the number of nutrients is large.
- Nutrients may be micro like boron, copper, and manganese, which are needed in very small amounts, or macro like nitrogen, carbon, and phosphorus.
- Many plants have symbiotic relations with microorganisms like fungi and bacteria, which help them convert unusable molecules into usable sources of nutrition. For example, mycorrhizal fungi increase the range from which a plant can obtain water and nutrition.

Hence the correct answer is option C.

Note: Animals can synthesise some essential molecules like non-essential amino acids, but they obtain others like vitamins and minerals from plant sources. We balance our diets to ensure that all essential plant nutrients are available.