What do you call to the leaf surface that can be opened or closed by the plant to regulate the rates at which co2 enters the leaf and water is lost?

Agrios, G. N. Plant Pathology. New York, NY: Academic Press, 1997.

Beerling, D. J. & Franks, P. J. Plant science: The hidden cost of transpiration. Nature 464, 495-496 (2010).

Brodersen, C. R. et al. The dynamics of embolism repair in xylem: In vivo visualizations using high-resolution computed tomography Plant Physiology 154, 1088-1095 (2010).

Brodribb, T. J. & Holbrook, N. M. Water stress deforms tracheids peripheral to the leaf vein of a tropical conifer. Plant Physiology 137, 1139-1146 (2005)

Canadell, J. et al. Maximum rooting depth of vegetation types at the global scale. Oecologia 108, 583-595 (1996).

Choat, B., Cobb, A. R. & Jansen, S. Structure and function of bordered pits: New discoveries and impacts on whole-plant hydraulic function. New Phytologist 177, 608-626 (2008).

Chung, H. H. & Kramer, P. J. Absorption of water and "P through suberized and unsuberized roots of loblolly pine. Canadian Journal of Forest Research 5, 229-235 (1975).

Eapen, D. et al. Hydrotropism: Root growth responses to water. Trends in Plant Science 10, 44-50 (2005).

Hetherington, A. M. & Woodward, F. I. The role of stomata in sensing and driving environmental change. Nature 424, 901-908 (2003).

Holbrook, N. M. & Zwieniecki, M. A. Vascular Transport in Plants. San Diego, CA: Elsevier Academic Press, 2005.

Javot, H. & Maurel, C. The role of aquaporins in root water uptake. Annals of Botany 90, 1-13 (2002).

Kramer, P. J. & Boyer, J. S. Water Relations of Plants and Soils. New York, NY: Academic Press, 1995.

Kramer, P. J. & Bullock, H. C. Seasonal variations in the proportions of suberized and unsuberized roots of trees in relation to the absorption of water. American Journal of Botany 53, 200-204 (1966).

MacFall, J. S., Johnson, G. A. & Kramer, P. J. Observation of a water-depletion region surrounding loblolly pine roots by magnetic resonance imaging. Proceedings of the National Academy of Sciences of the United States of America 87, 1203-1207 (1990).

McCully, M. E. Roots in Soil: Unearthing the complexities of roots and their rhizospheres. Annual Review of Plant Physiology and Plant Molecular Biology 50, 695-718 (1999).

McDowell, N. G. et al. Mechanisms of plant survival and mortality during drought: Why do some plants survive while others succumb to drought? New Phytologist 178, 719-739 (2008).

Nardini, A., Lo Gullo, M. A. & Salleo, S. Refilling embolized xylem conduits: Is it a matter of phloem unloading? Plant Science 180, 604-611 (2011).

Pittermann, J. et al. Torus-margo pits help conifers compete with angiosperms. Science 310, 1924 (2005).

Sack, L. & Holbrook, N. M. Leaf hydraulics. Annual Review of Plant Biology 57, 361-381 (2006).

Sack, L. & Tyree, M. T. "Leaf hydraulics and its implications in plant structure and function," in Vascular Transport in Plants, eds. N. M. Holbrook & M. A. Zwieniecki. (San Diego, CA: Elsevier Academic Press, 2005) 93-114.

Schenk, H. J. & Jackson, R. B. Rooting depths, lateral root spreads, and belowground/aboveground allometries of plants in water-limited environments. Journal of Ecology 90, 480-494 (2002).

Sperry, J. S. & Tyree, M. T. Mechanism of water-stress induced xylem embolism. Plant Physiology 88, 581-587 (1988).

Steudle, E. The cohesion-tension mechanism and the acquisition of water by plants roots. Annual Review of Plant Physiological and Molecular Biology 52, 847-875 (2001).

Steudle, E. Transport of water in plants. Environmental Control in Biology 40, 29-37 (2002).

Takahashi, H. Hydrotropism and its interaction with gravitropism in roots. Plant Soil 165, 301-308 (1994).

Tyree, M. T. & Ewers, F. W. The hydraulic architecture of trees and other woody plants. New Phytologist 119, 345-360 (1991).

Tyree, M. T. & Sperry, J. S. Vulnerability of xylem to cavitation and embolism. Annual Review of Plant Physiology and Molecular Biology 40, 19-38 (1989).

Tyree, M. T. & Zimmerman, M. H. Xylem Structure and the Ascent of Sap. 2nd ed. New York, NY: Springer-Verlag, 2002.

Tyree, M. T. & Ewers, F. The hydraulic architecture of trees and other woody plants. New Phytologist 119, 345-360 (1991).

Wheeler, T. D. & Stroock, A. D. The transpiration of water at negative pressures in a synthetic tree. Nature 455, 208-212 (2008).

Wullschleger, S. D., Meinzer, F. C. & Vertessy, R. A. A review of whole-plant water use studies in trees. Tree Physiology 18, 499-512 (1998).

Zimmerman, M. H. Xylem Structure and the Ascent of Sap. 1st ed. Berlin, Germany: Springer-Verlag, 1983.

Included among the rate-limiting steps of the dark stage of photosynthesis are the chemical reactions by which organic compounds are formed by using carbon dioxide as a carbon source. The rates of these reactions can be increased somewhat by increasing the carbon dioxide concentration. Since the middle of the 19th century, the level of carbon dioxide in the atmosphere has been rising because of the extensive combustion of fossil fuels, cement production, and land-use changes associated with deforestation. The atmospheric level of carbon dioxide climbed from about 0.028 percent in 1860 to 0.032 percent by 1958 (when improved measurements began) and to 0.041 percent by 2020. This increase in carbon dioxide directly increases plant photosynthesis up to a point, but the size of the increase depends on the species and physiological condition of the plant. Furthermore, most scientists maintain that increasing levels of atmospheric carbon dioxide affect climate, increasing global temperatures and changing rainfall patterns. Such changes will also affect photosynthesis rates.

For land plants, water availability can function as a limiting factor in photosynthesis and plant growth. Besides the requirement for a small amount of water in the photosynthetic reaction itself, large amounts of water are transpired from the leaves; that is, water evaporates from the leaves to the atmosphere via the stomata. Stomata are small openings through the leaf epidermis, or outer skin; they permit the entry of carbon dioxide but inevitably also allow the exit of water vapour. The stomata open and close according to the physiological needs of the leaf. In hot and arid climates the stomata may close to conserve water, but this closure limits the entry of carbon dioxide and hence the rate of photosynthesis. The decreased transpiration means there is less cooling of the leaves and hence leaf temperatures rise. The decreased carbon dioxide concentration inside the leaves and the increased leaf temperatures favour the wasteful process of photorespiration. If the level of carbon dioxide in the atmosphere increases, more carbon dioxide could enter through a smaller opening of the stomata, so more photosynthesis could occur with a given supply of water.

Several minerals are required for healthy plant growth and for maximum rates of photosynthesis. Nitrogen, sulfate, phosphate, iron, magnesium, calcium, and potassium are required in substantial amounts for the synthesis of amino acids, proteins, coenzymes, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), chlorophyll and other pigments, and other essential plant constituents. Smaller amounts of such elements as manganese, copper, and chloride are required in photosynthesis. Some other trace elements are needed for various nonphotosynthetic functions in plants.

Each plant species is adapted to a range of environmental factors. Within this normal range of conditions, complex regulatory mechanisms in the plant’s cells adjust the activities of enzymes (i.e., organic catalysts). These adjustments maintain a balance in the overall photosynthetic process and control it in accordance with the needs of the whole plant. With a given plant species, for example, doubling the carbon dioxide level might cause a temporary increase of nearly twofold in the rate of photosynthesis; a few hours or days later, however, the rate might fall to the original level because photosynthesis produced more sucrose than the rest of the plant could use. By contrast, another plant species provided with such carbon dioxide enrichment might be able to use more sucrose, because it had more carbon-demanding organs, and would continue to photosynthesize and to grow faster throughout most of its life cycle.

What does the word "migration" mean? How many sets of legs does a shrimp have? From poisonous fish to biodiversity, learn more about the study of living things in this quiz.