This, though a broad statement, is true as far as I can tell.
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.
The answer is Brachial Plexus. Brachial Plexus Injury is the result of pulling or stretching the arm forcibly. Sudden damage to the nerves, weakness, loss of sensation and movement are the most common symptoms of a brachial plexus injury.
Answer:
there are two types of cell one eukaryotic cell that have true nucleus (genetic material enclosed in membrane) and membrane bounded organelles and other is prokaryotic cell that donot have have true nucleus (genetic material dispersed in cytoplasm) and membrane bounded organelles.
similarities between PC and EC is that both contains cell membrane, ribosomes (not a membrane bounded organelle) .
examples of PC are bacteria , paramecium,fungi etc
examples of EC are plant and animal cells
there are two names for cell membrane i.e plasmalemma, cell surface membrane,
selectively permeable or semipermeable means cell only allows those material to pass through its cell membrane which it needs.this cell'ability is important because to protection against the poisonous substance and to maintain cell needs .
