50.3 MB (1.7 MB compressed)
5137 x 3425 pixels
43.4 x 29.0 cm ⏐ 17.1 x 11.4 in (300dpi)
HERVE CONGE, ISM / SCIENCE PHOTO LIBRARY HERVE CONGE, ISM / SCIENCE PHOTO LIBRARY
Closed stoma, light micrograph. This structure (oval) is a pore that regulates the exchange of gases and water vapour into and out of a plant. Stomatal closure is a natural response to darkness or drought as a means of conserving water. Each pore is controlled by two guard cells. The pore opens when the guard cells become turgid with water, and close when the guard cells lose water. This stoma is from a tulip plant. Magnification: x445 when printed at 10 centimetres across.
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