Answer:
Selection is a directional process that leads to an increase or a decrease in the frequency of genes or genotypes. Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles.
Selection occurs in response to a specific environmental factor. It is a central topic of population and evolutionary biology. The consequence of natural selection on the genetic structure and evolution of organisms is complicated. Natural selection can decrease the genetic variation in populations of organisms by selecting for or against a specific gene or gene combination (leading to directional selection). It can increase the genetic variation in populations by selecting for or against several genes or gene combinations (leading to disruptive selection or balancing selection). Natural selection might lead to speciation through the accumulation of adaptive genetic differences among reproductively isolated populations. Selection can also prevent speciation by homogenizing the population genetic structure across all locations.
Selection in plant pathology is mainly considered in the framework of gene-for-gene coevolution. Plant pathologists often think in terms of Van der Plank and his concept of "stabilizing selection" that would operate against pathogen strains with unnecessary virulence. As we will see shortly, Van der Plank used the wrong term, as he was actually referring to directional selection against unneeded virulence alleles.
Answer:
Una variable de control (o constante científica) en la experimentación científica es un elemento experimental que es constante y sin cambios durante el curso de la investigación. ... Las variables de control en sí mismas no son de interés primario para el experimentador.
Explanation:
I believe it gives you the answer. It should be one fifth or 20%. #TeamAlvaxic
the autonomic (involuntary) nervous system controls the rate at which the heartbeats. sympathetic (fight or flight) signals speed up the heart’s rate while parasympathetic (rest and digest) signals slow it down. The part or parts of the heart that forms sympathetic and parasympathetic neurons form synapses is called cardiac plexus.
Cardiac plexus is a plexus of the nerves that are present at the base of the heart and is divided into superficial and deep part. The sympathetic and the parasympathetic nerves form synapses with heart in the form of cardiac plexus.
The sympathetic nerves are responsible for activating flight or fight mode while parasympathetic nerves are responsible for restoring the normal body state.
To learn more about sympathetic nerves here
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Answer:
the 4rd one
Explanation:
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