The statement is true. Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange. It may effect part or all of a lung. An airway blockage also can cause Atelectasis. A blockage may be due to a foreign object, a mucus plug, lung cancer, or a poorly placed breathing tube from a ventilator. When a blockage occurs, the air that's already in the air sacs is absorbed into the bloodstream.
The Brain region that is believed to play a critical role in OCD, is the orbital frontal cortex. Obsessive compulsive and related disorders are a group of overlapping disorders that generally involve intrusive, unpleasant thoughts and repetitive behaviors. An individual experiences thoughts and urgents that are intrusive and unwanted and/or the need to engage in repetitive behaviors or mental acts.
Come into existence and develop
Answer;
Gene flow
Gene flow is the most important factor that holds a gene pool of a species together and prevents speciation.
Explanation;
-Evolution may occur as a result of genes being transferred from one population to another. This gene flow occurs when there is migration. The loss or addition of people can easily change gene pool frequencies even if there are no other evolutionary mechanisms operating.
-Gene flow may also occur without migration, for instance, when people travel to another area and successfully mate with people in the population there, a transfer of genes occurs between the populations even though the traveler returns home.
-Additionally, gene flow may flow between species. A good example is when segments of DNA are transferred from one species to another by viruses as they invade the cells of animals or plants.
<span>It would be replaced in cases where new information and evidence would be discovered that completely contradicts the old information and evidence. Then you couldn't revise it because revision incorporates the old evidence that would now be obsolete. Then you would make a completely new theory.</span>
