Plants that live in extremely hot and arid
climates often keep their stomata closed during
the day, to reduce the amount of water that is
lost in transpiration, and open it during the
cooler and more humid nighttime. This system is
called Crassulacean acid metabolism (CAM), or CAM
photosynthesis, and the plants that use it are
referred to as CAM plants. These plants fix
CO2 at night, avoiding water loss by
not opening their stomata during the day, and
release the CO2 during the day. CAM
plants include succulents, cacti, bromeliads,
orchids, and others.
In contrast to CAM
photosynthesis, most plants on Earth (making up
95% of the Earth's plant biomass) undergo
C3 carbon fixation, living in areas
with moderate sunlight, moderate temperature, and
plenty of ground water. They lose approximately
97% of the water taken up by their roots to
transpiration -- the cost of having stomata open
during the day, something the arid-dwelling CAM
plants cannot afford to do.Hope this helps!
Hi, thanks for the question! As you may know,
plants have pores or openings on their leaves and
stems called stomata. This name comes from Greek
for "mouth". These pores allow carbon dioxide to
enter the leaves and oxygen water to escape.
Plants can respond to light and heat and humidity
and even the wind by altering how open the pores
are. The pore size is regulated by specialized
cells called "guard cells" which become more of
less swollen as the conditions require.In hot, dry
areas, such as the desert, plants have evolved
ways to avoid losing a lot of water during the
day. They perform "Crassulacean Acid Metabolism"
or CAM, photosynthesis. In these plants, the
stomata are closed during the day and open during
night to allow for CO2 and water
transfer. Hope this answers your question!
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