Search results
Results From The WOW.Com Content Network
For example, when the stomata are closed to prevent water loss during drought: this limits the CO 2 supply, while O 2 production within the leaf will continue. In algae (and plants which photosynthesise underwater); gases have to diffuse significant distances through water, which results in a decrease in the availability of CO 2 relative to O 2.
Marine plants can be found in intertidal zones and shallow waters, such as seagrasses like eelgrass and turtle grass, Thalassia. These plants have adapted to the high salinity of the ocean environment. Light is only able to penetrate the top 200 metres (660 ft) so this is the only part of the sea where plants can grow. [77]
The term "plants" is taken here to mean the Archaeplastida, i.e. the glaucophytes, red and green algae and land plants. Alternation of generations occurs in almost all multicellular red and green algae, both freshwater forms (such as Cladophora) and seaweeds (such as Ulva). In most, the generations are homomorphic (isomorphic) and free-living.
The spores of freshwater algae are dispersed mainly by running water and wind, as well as by living carriers. [83] However, not all bodies of water can carry all species of algae, as the chemical composition of certain water bodies limits the algae that can survive within them. [83] Marine spores are often spread by ocean currents.
Countercurrent flow occurs when deoxygenated blood moves through the gill in one direction while oxygenated water moves through the gill in the opposite direction. This mechanism maintains the concentration gradient thus increasing the efficiency of the respiration process as well and prevents the oxygen levels from reaching an equilibrium ...
[189] [190] After some years of debate, [191] it is now generally accepted that the three major groups of primary endosymbiotic eukaryotes (i.e. green plants, red algae and glaucophytes) form one large monophyletic group called Archaeplastida, which evolved after one unique endosymbiotic event. [192] [193] [194] [195]
Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow). An autotroph is an organism that can convert abiotic sources of energy into energy stored in organic compounds, which can be used by other organisms.
Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. [1] They are unicellular species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few ...