Carnivorous plant: Difference between revisions

Revision as of 21:57, 8 November 2005

Revision as of 04:01, 15 November 2005

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In all the studied cases, carnivory allows plants to grow and reproduce using animals as a source of nitrogen, phosphorus and (possibly) potassium, when the usual sources in the soil are absent or limiting. However, there is a spectrum of dependency on animal prey. Pygmy sundews are unable to use nitrate from soil because they lack the necessary enzymes ([[nitrate reductase]] in particular), so they are almost entirely dependent on animal prey. Common butterworts (''Pinguicula vulgaris'') can use inorganic sources of nitrogen better than organic sources, but a mixture of both gives better growth than either alone. European bladderworts seem able to use either source equally well. Animal prey makes up for deficiencies in soil nutrients, but to different extents in different plants.

Plants use their leaves to intercept sunlight. The light energy is used to reduce carbon dioxide from the air with [[electron]]s from water, to make sugars (and other [[biomass]]), and a waste product, [[oxygen]], in the process of [[photosynthesis]]. Leaves also [[Cellular respiration|respire]], in a very similar way to animals, by burning their biomass to generate chemical energy. This energy is temporarily stored in the form of [[ATP]] ([[adenosine]] triphosphate), which acts as an energy currency for metabolism in all living things. As a waste product, respiration produces [[carbon dioxide]].

For a plant to grow, it must photosynthesise more than it respires. If a plant respires more than it photosynthesises, then it will eventually burn up all its available biomass, and die. The potential for plant growth is net photosynthesis. Net photosynthesis is the total gross gain of biomass by photosynthesis, minus the biomass burnt up by respiration. Understanding carnivory requires a [[cost-benefit analysis]] of these factors.