Which tissue is primarily responsible for transporting sugars within a plant?

Which tissue is primarily responsible for transporting sugars within a plant?

• A. Leaves
• B. Xylem
• C. Phloem
• D. Roots

Answer: (C)

Sugars produced by photosynthesis must be moved to where they’re needed or stored, and the tissue that does this long-distance transport is the phloem. Phloem contains sieve tube elements that conduct the sugary sap and companion cells that support them. The process begins when sugars are loaded into the phloem at source tissues (like leaves), which draws water into the phloem by osmosis and creates a pressure that pushes the sap toward sinks (growing tissues, roots, fruits). There, sugars are unloaded and used or stored. Xylem, by contrast, mainly carries water and minerals upward from the roots and is made of cells that are typically dead at maturity, so it doesn’t transport sugars. Leaves generate the sugar, but phloem is the tissue that actually distributes it throughout the plant.

Sugars produced by photosynthesis must be moved to where they’re needed or stored, and the tissue that does this long-distance transport is the phloem. Phloem contains sieve tube elements that conduct the sugary sap and companion cells that support them. The process begins when sugars are loaded into the phloem at source tissues (like leaves), which draws water into the phloem by osmosis and creates a pressure that pushes the sap toward sinks (growing tissues, roots, fruits). There, sugars are unloaded and used or stored. Xylem, by contrast, mainly carries water and minerals upward from the roots and is made of cells that are typically dead at maturity, so it doesn’t transport sugars. Leaves generate the sugar, but phloem is the tissue that actually distributes it throughout the plant.