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>
Answer:
Thyrocalcitonin or TCT
Explanation:
Thyrocalcitonin or TCT is a non-iodinated calcium lowering hormone. It is originating from the parafollicular cells or C cells (C for calcium).
The thyroid gland consists of follicles of cuboidal epithelial cells. These cuboidal cells have a nucleus at the base. These are principal cells responsible for the synthesis of thyroid hormones.
In between these follicular cells, other high cuboidal cells are present, known as parafollicular cells / C cells. These cells synthesise the hormone TCT. When there is high levels of calcium ions in the serum, TCT will release. This lowers the high level of calcium ions in the blood and plasma to normal level. This is done due to the deposition of calcium in the bone.
Answer:
Oxygen is reduced, gaining electrons and hydrogen ions. -second choice
Answer:
1. Carbohydrates - It serves several key functions in your body. They provide you with energy for daily tasks and are the primary fuel source for your brain's high energy demands. Fiber is a special type of carb that helps promote good digestive health and may lower your risk of heart disease and diabetes.
2. Protein- You use protein to make enzymes, hormones, and other body chemicals. Your body also uses protein to build and repair tissues. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
3. Lipids - This is essential for all life on Earth. They play many important roles in maintaining the health of an organism. Arguably the most important function lipids perform is as the building blocks of cellular membranes. Other functions include energy storage, insulation, cellular communication and protection
4. Nucleic acids are very important for cell functioning, and therefore for life. There are two types of nucleic acids, DNA and RNA. Together, they keep track of hereditary information in a cell so that the cell can maintain itself, grow, create offspring and perform any specialized functions it's meant to do.
Answer: While active transport requires energy and work, passive transport does not.
Explanation:
