Which nutrient is mobile and can be moved from older to newer tissue in plants?

The correct choice is that both nitrogen and sulfur are considered mobile nutrients in plants. Mobile nutrients are those that can be easily relocated within the plant from older tissues to newer tissues as the plant grows.

Nitrogen plays a crucial role in plant growth because it is a key component of amino acids, proteins, and nucleic acids. When plants experience a shortage of nitrogen in the soil, they can remobilize stored nitrogen from older leaves to support new growth, thus demonstrating its mobility.

Similarly, sulfur is also mobile and can be transferred from older leaves to younger ones. It is essential for the synthesis of amino acids and proteins, as well as for various physiological functions in plants. When sulfur is limited, older tissues can provide the necessary sulfur to support developing tissues, which highlights its function as a mobile nutrient.

Calcium, on the other hand, is considered an immobile nutrient. It primarily functions in the cell walls and membranes and cannot be easily moved from older to newer tissues when the plant is deficient. That's why the correct response is that both nitrogen and sulfur are mobile, allowing them to be effectively redistributed throughout the plant to promote healthy growth.