Causes of speciation
<span>Geographic isolation
In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.
</span>Reduction of gene flow
<span>However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random. Individuals in the far west would have zero chance of mating with individuals in the far eastern end of the range. So we have reduced gene flow, but not total isolation. This may or may not be sufficient to cause speciation. Speciation would probably also require different selective pressures at opposite ends of the range, which would alter gene frequencies in groups at different ends of the range so much that they would not be able to mate if they were reunited.</span>
Sheep, goats, toads, and octopus
Answer:
Genetic engineering is deliberate modification of genome to gain desired traits.
The main steps of genetic engineering:
Restriction enzymes are used to isolate the required gene leaving it with sticky ends. Sticky ends are a short section of unpaired bases A vector, which is usually a bacterial plasmid or a virus, is cut by the same restriction enzyme leaving it with corresponding sticky ends. The vector and the isolated gene are joined together by ligase enzyme. The vector inserts the gene into required cells. The genes are transferred to animal, plant or microorganism cells, during early development, which allows them to develop with the desired characteristics.
Answer:
The correct answer is 1: In Waters´ method, the head is rested on the extended chin.
Explanation:
The parietoacanthial projection (Waters' method) is a widely used radiography method that demonstrates if there are any facial bone fractures, inflammation, or foreign body in the patient skull.
The patient must be in an erect position or prone. They must rest their head on the tip of the <u>extended chin</u> against the table surface. The neck must be hyperextended so that the orbitomeatal line (OML) forms a 37-degrees angle with the plane of the image receptor (IR). This is<u> not perpendicular to IR</u>, as <u>perpendicular means</u> that a <u>90-degree angle</u> must be formed. The mentomeatal line (MML) must be perpendicular to the image receptor plane. Finally, the midsagittal plane must be perpendicular to the plane of the image receptor.
