Which tissue carries sugar from leaves to the rest of the tree?

Which tissue carries sugar from leaves to the rest of the tree?

• A. Phloem
• B. Xylem
• C. Heartwood
• D. Branch Collar

Answer: (A)

Phloem is the tissue that moves sugars, produced in the leaves by photosynthesis, to the rest of the tree where they’re used or stored. This transport system works through the phloem’s sieve tubes and companion cells, carrying the “sugar sap” from source tissues (like leaves) to sinks (growing tissues, roots, fruits). The movement is often described as the pressure-flow mechanism: sugars are actively loaded into the phloem at the source, water follows by osmosis, creating pressure that drives sap toward areas where sugars are needed, where they’re unloaded and used or stored. Xylem, on the other hand, carries water and minerals from roots up to the leaves, not sugars. Heartwood is the inner, non-conducting wood, and the branch collar is simply the junction zone at a branch—neither transports sugars.

Phloem is the tissue that moves sugars, produced in the leaves by photosynthesis, to the rest of the tree where they’re used or stored. This transport system works through the phloem’s sieve tubes and companion cells, carrying the “sugar sap” from source tissues (like leaves) to sinks (growing tissues, roots, fruits). The movement is often described as the pressure-flow mechanism: sugars are actively loaded into the phloem at the source, water follows by osmosis, creating pressure that drives sap toward areas where sugars are needed, where they’re unloaded and used or stored.

Xylem, on the other hand, carries water and minerals from roots up to the leaves, not sugars. Heartwood is the inner, non-conducting wood, and the branch collar is simply the junction zone at a branch—neither transports sugars.