domingo, 22 de febrero de 2009
NUCLEAR ENERGY
It's called nuclear energy to that which is obtained by exploiting the nuclear reactions caused by spontaneous or man. These reactions occur in certain isotopes of some chemical elements, the most famous of this type of energy fission of uranium-235 (235 U), with operating nuclear reactors. However, to produce this type of drawing energy nuclear reactions can be used many other isotopes of various chemical elements such as thorium, plutonium, strontium, or polonium.
lunes, 16 de febrero de 2009
tropism is a response produced by a plant by the action of hormones, compared to an external stimulus. The plants have no sense organs. Nor can move to change the environment that surrounds them. However, as animals, plants can detect changes in the environment and respond to them. The most frequent response in plants is to grow slowly in one direction defined by the stimulus. These may include: Positive when the plant grows toward the stimulus
Phototropic reaction is the ability or by hormones, a plant to change the direction of its normal growth occurs when the light changes, as in growth, the light is very important and also in carrying out photosynthesis, rioja which leads us to conclude that in response to this stimulus, the plant grows toward the light source. This change occurs because some plants have specialized receptors, called fototropinas that activate the plant hormone auxin.
Geotropismo or gravitropismo is one response to a stimulus on the gravitational force of the bodies. Ie, the stems always grow up to find the necessary light for photosynthesis, the roots into the soil, there you will find water and minerals.
Hidrotropismo corresponds to a movement to plant wetlands, where the water. Given this root stimulation a clear positive response, thus spoke of a positive hidrotropismo.
Nastia is a transient response in certain areas of a plant compared to an external stimulus and diffuse, based on processes of growth or change in the turgidity of groups of cells that vary in volume by controlling the entry and exit water, the resulting movement is not influenced by the direction of the stimulus.
Phototropic reaction is the ability or by hormones, a plant to change the direction of its normal growth occurs when the light changes, as in growth, the light is very important and also in carrying out photosynthesis, rioja which leads us to conclude that in response to this stimulus, the plant grows toward the light source. This change occurs because some plants have specialized receptors, called fototropinas that activate the plant hormone auxin.
Geotropismo or gravitropismo is one response to a stimulus on the gravitational force of the bodies. Ie, the stems always grow up to find the necessary light for photosynthesis, the roots into the soil, there you will find water and minerals.
Hidrotropismo corresponds to a movement to plant wetlands, where the water. Given this root stimulation a clear positive response, thus spoke of a positive hidrotropismo.
Nastia is a transient response in certain areas of a plant compared to an external stimulus and diffuse, based on processes of growth or change in the turgidity of groups of cells that vary in volume by controlling the entry and exit water, the resulting movement is not influenced by the direction of the stimulus.
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