Answer:
Secondary succession
Explanation:
A secondary succession is when a type of disturbance happens when there is <em>already </em>soil present. In this case, it has already started out with a forest (including plants, trees, and wildlife). Other examples of a secondary succession include a wildfire, hurricane, flood, or human destruction.
This is different from a <em>primary succession</em>. A primary succession occurs when there is <em>no</em> soil present.
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.
P(t) = 2500(0.86) Find the initial population size. Does the function represent growth or decay? growth decay By what percent does the population size change each hour? 1%
DNA model given by Watson and Creek in the year of 1953 gave a very detailed study regarding the structure of B DNA which is valid till date and is essentially corroborating with Chargaff's data and Xray diffraction pattern.
<h3><u>Explanation:</u></h3>
The DNA is the most common nucleic acid found in the living organisms as a genetic material. As stated by Watson and Creek, this DNA contains a double helical structure with two sugar phosphate backbones and the nitrogen bases getting projected from it inwards. The backbones are formed of ribose sugar and phosphate and joined together with a phosphodiester bond. The ribose sugar is attached to phosphates at its 3' and 5' Carbon atoms. The nitrogen bases found in DNA are Adenine, Guanine, Thymine and Cytosine. The Adenine has two hydrogen bonds with thymine and guanine has 3 hydrogen bonds with cytosine.
Each full turn of a helix is 34A and each base pair is 3.4A apart. The distance between two strands of DNA is 20A.
Chargaff's rule regarding the equal amount of adenine and thymine as well as guanine and cytosine is matching with this structure. All the other rules also do match with this DNA structure.
