Page 95 - Photosynthesis: The Green Miracle

Harun Yahya

Leaf cross-section

Every leaf consists of very dif-
ferent parts shown here, and
every part has its own task
of vital importance to the
plant as a whole.

Upper epidermis

Palisade mes-
ophyll (the
leaf’s soft in-
ternal tissue)

Spongiform
mesophyll

Lower epidermis
Observer cell
Chloroplast
Pore (stoma)
Perspiration Packet Phloem Xylem (woody tis-
(lowest water sheath (veinous sue – highest water
potential) potential)
tissue
meshed
tubes)

and heat. When the weather is very hot and dry, the pores remain only
ajar, but when moisture increases, the guard cells begin to open. In cold

and rainy weather, the pores open up entirely; thus there is more moisture
for the chloroplast to evaporate in. By the help of the solar light, the chlo-
roplast obtains the carbon dioxide it needs by absorbing the carbon diox-
ide through the pores.
There may be 100 to 300 pores in 1 square millimeter of leaf surface,
and the total number of pores in the whole leaf may reach millions. Every
one of these millions of windows is opened and closed by cells acting in-

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