Which tissue would you examine to study the transport of sugars from leaves to roots?

Which tissue would you examine to study the transport of sugars from leaves to roots?

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

Answer: (B)

Sugars move through the phloem, the plant tissue specialized for distributing photosynthates from where they’re made (the leaves) to where they’re used or stored (like roots, buds, or fruits). In the phloem, living sieve tube elements work with companion cells to load sugars, mainly sucrose, into the vessels. This loading draws in water by osmosis, creating a high hydrostatic pressure that pushes the sugary fluid down the plant toward areas of lower pressure where the sugars are unloaded for use or storage. This source-to-sink movement is known as translocation. Xylem, by contrast, is the tissue that carries water and mineral nutrients from roots upward to the leaves; it’s not the route used for moving sugars downward. Cambium is a growth tissue that produces new xylem and phloem, not a transport pathway. Phytoplankton are not plant tissues within a plant at all—they’re microscopic photosynthetic organisms. So, to study the transport of sugars from leaves to roots, you’d examine the phloem.

Sugars move through the phloem, the plant tissue specialized for distributing photosynthates from where they’re made (the leaves) to where they’re used or stored (like roots, buds, or fruits). In the phloem, living sieve tube elements work with companion cells to load sugars, mainly sucrose, into the vessels. This loading draws in water by osmosis, creating a high hydrostatic pressure that pushes the sugary fluid down the plant toward areas of lower pressure where the sugars are unloaded for use or storage. This source-to-sink movement is known as translocation.

Xylem, by contrast, is the tissue that carries water and mineral nutrients from roots upward to the leaves; it’s not the route used for moving sugars downward. Cambium is a growth tissue that produces new xylem and phloem, not a transport pathway. Phytoplankton are not plant tissues within a plant at all—they’re microscopic photosynthetic organisms.

So, to study the transport of sugars from leaves to roots, you’d examine the phloem.