Which tissue transports sugars from sources to sinks within the plant?

Which tissue transports sugars from sources to sinks within the plant?

• A. Phloem
• B. Xylem
• C. Cambium
• D. Pith

Answer: (A)

Sugars are moved within the plant by phloem, the transport tissue for photosynthates. Phloem carries organic nutrients produced in photosynthetic tissues (sources) to parts that need them or store them (sinks) such as developing leaves, roots, fruits, and growing shoots. The process involves loading sugar into sieve tubes near the source, often with the help of companion cells, which creates an osmotic gradient that draws in water from the xylem. This generates turgor pressure that pushes the phloem sap through the sieve tubes toward regions of unloading at the sink. Once unloaded, the sugars are used or stored by the sink tissues. In contrast, xylem mainly moves water and minerals from roots to shoots, driven by transpiration, cambium is a growth tissue that forms xylem and phloem, and pith is storage tissue—not a transport conduit for sugars.

Sugars are moved within the plant by phloem, the transport tissue for photosynthates. Phloem carries organic nutrients produced in photosynthetic tissues (sources) to parts that need them or store them (sinks) such as developing leaves, roots, fruits, and growing shoots. The process involves loading sugar into sieve tubes near the source, often with the help of companion cells, which creates an osmotic gradient that draws in water from the xylem. This generates turgor pressure that pushes the phloem sap through the sieve tubes toward regions of unloading at the sink. Once unloaded, the sugars are used or stored by the sink tissues. In contrast, xylem mainly moves water and minerals from roots to shoots, driven by transpiration, cambium is a growth tissue that forms xylem and phloem, and pith is storage tissue—not a transport conduit for sugars.