Question

In which of the following forms is iron absorbed by plants ?

• A. Ferric
• B. Free element
• C. Ferrous
• D. Both ferric and ferrous

Answer 1

The Correct Option is D

To understand how plants absorb iron, we must examine the various forms of iron available in the soil and how plants utilize them. Iron is an essential micronutrient for plants and plays a crucial role in photosynthesis. It is absorbed by plants primarily in two forms: ferric (Fe³⁺) and ferrous (Fe²⁺). Let's explore why both forms are important:

1. Ferric (Fe³⁺) Form:
   • In aerobic soil conditions, iron mainly exists in the ferric form due to its stability in oxygen-rich environments.
   • Plants absorb ferric iron through specific transport mechanisms. However, ferric ions are not very soluble, which can limit their availability to plants.
   • To increase solubility, plants release organic compounds, known as siderophores, to chelate ferric ions, enhancing absorption.
2. Ferrous (Fe²⁺) Form:
   • In anoxic or waterlogged conditions, iron is reduced to the ferrous form, which is more soluble than ferric iron.
   • Plants can readily absorb ferrous iron due to its high solubility. Some plants have developed mechanisms to directly uptake ferrous ions using specialized transport proteins.

Considering these mechanisms and environmental conditions, plants can utilize both ferric and ferrous forms of iron to meet their nutritional needs. Thus, the correct answer is "Both ferric and ferrous."

Given the options:

• Ferric - Although correct, it is not the only form absorbed.
• Free element - Iron is never absorbed as a free element due to its reactivity.
• Ferrous - Also correct, but inadequate alone.
• Both ferric and ferrous - This option correctly includes both primary forms by which iron is absorbed by plants.

In conclusion, the correct answer is Both ferric and ferrous, as this reflects the adaptability and necessity for plants to absorb iron in different forms depending on environmental conditions.