Plants need to move (transport) various types of substances over short (within the cell, across the membranes, and from
cell to cell within the tissue), as well as very long distances. Water taken up by the roots has to reach all parts of the
plant, upto the very tip of the growing stem. The photosynthates or food synthesized by the leaves have also to be
moved to all parts, including the root tips, embedded deep inside the soil. However, plants lack both interstitial fluid as
well as regular circulation system.
Substances move over short distances mainly by diffusion
and active transport, supplemented by cytoplasmic streaming.
Long distance transport occurs through vascular systems,
xylem and phloem. This transport of substances over longer
distances through the vascular tissue, i.e., xylem and phloem,
is called translocation. The direction of translocation is
essentially unidirectional, in case of water (from root to stem,
leaves, flowers and fruits) and multi-directional in case of
minerals and organic solutes.
Organic compounds synthesized in the photosynthetic leaves are exported to all other parts of the plant including
storage organs. from the storage organs they are later re-exported. The mineral nutrients are taken up by the roots
and transported upwards into the stem, leaves and the growing regions. Hormones or plant growth regulators and other
TransporT in planTs -i
The content for PMT Biology is
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students to engage in inquiry
and develop meaningful
knowledge. An essential topic
for PMT is presented here to
enable students grasp the
topic, analyse the type of
questions appearing in PMTs,
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