The hypothesis by Coleman was that the product of the ob+ gene was the appetite suppressing hormone. Hence, the homozygous ob/ob mutant are in a position to synthesize that hormone, and its circulating level would be zero. He also hypothesized that the product of the db+ gene was the receptor for the appetite-suppressing hormone. Thus, the homozygous db/db mutant would be able to synthesize the hormone but would not be in a position to respond to it. It would eat excessively and produce large amounts of body fat, which in turn would produce large amounts of appetite-suppressing hormone . In the absence of a receptor, the db/db mutant's hormone level would remain abnormally high.
Coleman's hypothesis were confirmed when the precise functions of the ob+ and db+ genes were determined. The peptide hormone encoded by the ob+ gene was named Leptin.
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uneed to read and work this out
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In biology, a cladogram can be described as a diagram which shows evolutionary relationships among different organisms. A cladogram shows which organisms share evolutionary history and which organisms are more closely related to one another.
<em>The cladogram in the above picture shows that the limbs originated after the jaws. </em>
The cladogram shows that amoeba was a common ancestor to sponges, earthworms, salmon, lizards, kangroo and cats.
The correct answer is - 1) inverted pyramid, with a narrow base representing a small number of young individuals.
The populations that are decreasing are usually population in countries that are highly developed. The conditions for living are excellent, the medical care on high level, life expectancy very high, but the birth rates very low.
In this type of conditions, there's smaller and smaller number of young individuals, with the middle aged population being much bigger, and the older population being constantly on the rise. This will give the age-structure histogram a reverse shape than what it is supposed to have, it will be similar in appearance like a inverted pyramid, meaning that the population is aging and that it will be constantly on a decline in the future.
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science is the study of the physical world by observation for the purpose of understanding the world
