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.
1. Regulation of glucose blood levels is an example of negative feedback mechanism.
Negative feedback mechanism is a control mechanism involved in homeostasis maintain, in this case maintenance of glucose blood levels in normal range.
Negative feedback mechanism contains sensory system that detects the changes, control system that responds to change and activates mechanisms of effector system that reverse the changes in order to restore conditions to their normal levels.
• Pancreatic cells-sensors
• Insulin-control system
• Body cells- effector cells
2. Blood glucose levels change throughout the day because of the food consumption, but in healthy individuals levels of glucose are successfully regulated via the mechanism of hormones such as insulin and glucagon in a process called glucose blood regulation.
This tight regulation of pancreatic hormones is referred to as glucose homeostasis. Insulin lowers blood sugar and glucagon raises it.
3. If the beta cells are destroyed by an autoimmune disease (immune system attacks its own cells), there would be no insulin release, and consequently, the glucose blood levels would be increased.
Diabetes type I is a metabolic disorder caused by the destruction of insulin-producing pancreatic beta cells.
Polyoma vaccine does the Polyomavirus. It’s recommend that parrots get this vaccine yearly.
Prophase is a Triangular Square Telophase is a Circle with cylinders
Considering answers;
-fever
-constricted veins
-swollen veins
-confusion
Answer;
Swollen veins
Swollen veins might be a symptom of a person whose vein valves are not functioning properly and are causing fluid it flow away from the heart.
Explanation;
Valves are structures that are found in the circulatory system both in the heart and the veins.
They function to prevent the back flow of blood.
They do so by ensuring the continuous flow of blood in one direction.
If the valves are not functioning properly it may lead to various effects such as swollen veins due to the back flow of blood which may lead to the pooling of blood in the extremities.
