Answer:
They are the species which are found only in a particular area. They can be a plant, animal or microorganism. They are at great danger of becoming extinct due to the following reasons: - As they are restricted to a particular area so loss of their habitat is the major reason which could lead to extinction.
Explanation:
His body will react as if he is being starved, this causing his basal metabolic rate to drop.
The SECOND graph represents selection that may lead to reduced variation. It is an example of stabilizing selection.
<h3>What is Stabilizing selection? </h3>
Stabilizing selection is a type of natural selection that leads to a decrease in the genetic variation of the population.
In Stabilizing selection, natural selection tends to favor an average phenotype and then can remove (select) extreme variations.
Stabilizing selection generates a modified bell curve graph in which the central portion is narrower and it is taller than the normal distribution bell shape.
Learn more about Stabilizing selection here:
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Answer:
D. Sami had low birth weight as a lamb but quickly grew into a large sheep.
Explanation:
The Sami lamb is an example of culled because it has the characteristics of quick growth. Culling is the process of separating organisms from a group of same type of organisms due to presence of desired or undesired characteristics. Sami sheep has a unique characteristic of having less weight at time of birth but having quick growth features that make to gain more weight and become large sheep so this sheep is removed from the population for its good traits.
Answer:
Leptin is a protein hormone composed of 167 amino acids of the cytosine family, it is synthesized mainly by white adipose tissue. The leptin receptor is related to that of receptors for cytosines (since it uses Janus or JAK type kinases and STAT-3 proteins as intracellular mediators of transcription pathway), it is predominantly found in the hypothalamus (particularly in the arcuate nucleus and to a lesser extent in the nuclei dorsomedial and ventromedial), hippocampus and cerebellum. There is evidence that leptin acts at the level of the arcuate nucleus, preventing the formation of NPY.
Explanation:
Leptin is produced exclusively in adipose tissue cells in a wide variety of species, including humans, and its concentration is higher in overweight than in lean individuals. The biological actions of leptin can be classified into two groups, those that are exerted in the tissues of the central nervous system, mainly the hypothalamus, and those that are carried out on the peripheral tissues. The former regulate body weight downward, decrease food intake, increase basal energy expenditure and modify some neuroendocrine functions such as reproduction, while the latter have effects on proliferation, differentiation and metabolism of peripheral tissues. The leptin that reaches the hypothalamus, in addition, inhibits protein synthesis and the secretion of neurons producing NPY / AgRP of the arcuate nucleus and stimulates the synthesis and secretion of those containing POMC. NPY (neuropeptide Y) is produced in the hypothalamic arcuate nucleus. This neurotransmitter arrives through the projections of the neurons of said nucleus to the paraventricular nucleus, which is the area where it is released. There are several studies that have shown that an increase in NPY leads to an increase in the sensation of hunger and thus to hyperphagia and obesity. Leptin acts at the level of the arcuate nucleus, preventing the formation of NPY. The leptin receptor lacks enzymatic activity in its intracellular domain. Instead, it is linked to members of the janus kinase family, which belong to a class of tyrosine kinases. The binding of the ligand activates the Jak kinase and leads to the phosphorylation of certain cytoplasmic proteins. Within these proteins there is a class of cytoplasmic transcription factors called signal transducers and activators of transcription (STAT).
