Answer: Aristotle and Ptolemy had both assumed each planet is attached to a single sphere, but geometers and astronomers could employ a number of such spheres to generate the observed motions of the planets.
Explanation:
Explanation:
In the early days of development, in an embryo, the cells are pluripotent and can differentiate into any kind of cell of the organism. As the embryo develops, autocrine and paracrine signaling between the cells of the embryo causes the cells to migrate to particular regions of the embryo and begin differentiating into respective parts of the organism. This signaling causes differential silencing of particular genes of the cells depending on the type of cells they will differentiate into. As the embryo develops into a fully grown organism, these cells lose potency (except for stem cells) and become fully differentiated into respective limbs or organs of the organism.
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The disadvantages of the pyramid of productivity as a representation: The rate of biomass production of an organism is required, which involves measuring growth and reproduction through time. There is still the difficulty of assigning the organisms to a specific trophic level.
Reactants are the molecules that begin cellular respiration, in this case that would be oxygen<span> and </span>glucose<span>. Hope this helps. </span>
