First of all, what is photosynthesis? Well, it's how plants get their food. When you get hungry you probably just sit down and have something to eat. Plants, however, don't have it so easy, they have to make their own food. Plants use water (H2
O), carbon dioxide (CO2
), and sunlight to make glucose (C6
), also known as sugar. The process follows the chemical equation: 6CO2
O+light -> C6
. The light has a special role. Just like your car needs gas in order for it to run, photosynthesis needs some kind of energy source for the reaction to occur, because the product has more energy than the starting materials. That fuel is sunlight. Plants have special little chemical machines based on the light-absorbing molecule chlorophyll to conduct the photosynthesis. Most plants and many bacteria get their food by photosynthesis.
So chemically, the photosynthetic process that land and aquatic plants use to produce food is identical. Both types of plants require carbon dioxide, water, and energy to produce glucose (their food). The only difference between photosynthesis in aquatic and land plants is where in their environments they get these nutrients. Land plants get water from the ground through their extensive root system, carbon dioxide from the air through their stomata (tiny holes in a plant's leaves), and energy from the sun. Aquatic plants get water and carbon dioxide from their aquatic environment and, like the land plants, light energy from the sun. Even though the plant is underwater, it still gets its energy from the sun because sunlight can pass through water.
To understand where aquatic plants find this CO2
think about your favorite kind of pop. Those bubbles that give the pop its fizzy nature come from CO2
that's dissolved in the liquid.
If you would like more information on sunlight passing through water and how CO2
is dissolved in water and taken up by plants, try the following site: http://www.thekrib.com/Plants/phisio.html
-KH (w small changes by Mike W,)
(republished on 07/18/06)