Leaf Structure of C3 and C4 Plants

Leaf Structure of C3 and C4 Plants - 2 at lower...

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Leaf Structure of C 3 and C 4 Plants The leaves of C 4 plants are structured differently than those of C 3 plants. Photosynthesis occurs within the mesophyll cells in C 3 plants, which form a dense layer on the upper surface of the leaf and a spongy layer on the lower surface. Bundle-sheath cells surrounding the veins are not photosynthetic. Below: A cross-section of a C 3 leaf. Dense layers of mesophyll cells surround the bundle-sheath cells of C 4 plants. Both the bundle- sheath cells and the rings of mesophyll cells are photosynthetic. Below: A cross-section of a C 4 leaf. The Calvin Cycle in C 4 Leaves C 4 plants have a pathway that allows them to fix CO
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Unformatted text preview: 2 at lower concentration than C 3 plants. This gives them an advantage during hot, dry conditions because they can keep the stomata closed for longer periods of time to prevent dehydration before photorespiration occurs. In C 4 plants, CO 2 is fixed in the mesophyll cells by PEP carboxylase, an enzyme that is more efficient than rubisco. The resulting organic compound is transported to the mesophyll cells where the CO 2 is released for the Calvin Cycle. The movement of CO 2 into the bundle sheath cells maintains a higher concentration than would otherwise be possible....
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