Question

In plant mineral nutrition, elements are called macro or micro-elements depending upon their

• A. relative presence in plant ash
• B. relative importance in plant growth
• C. relative amount required in plants
• D. relative availability in soil

Answer 1

The correct option is C relative amount required in plants

Plants are able to produce their own food through a process called photosynthesis. They absorb mineral nutrients through their roots from the soil and these are transported through the stem to the different plant parts. They require two types of nutrients- macronutrients and micronutrients. Macronutrients, as the name suggests, are the nutrients required by the plants in large amounts. These include carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, calcium and potassium.
Micronutrients are the ones required in very small amounts by the plants. These include iron, zinc, boron, etc.
Plant ash is the residue of burnt plant parts like; bark, wood, sawdust, leaves, woody debris, pulp, husk, hulls, fronds, and other plant debris. Once a plant part is burnt, its organic content is lost as carbon dioxide and water vapours. This is not relevant to define the micro and macronutrients of plants.