D) Stem cells are usually harvested from embryos.
Because you cannot test it or observe it.
A scientific theory are created through the scientific method, in the scientific method you need to be able observe it and experiment.
The pH of stomach secretion is low. This means it is acidic. Too much production can corrode the stomach wall. Therefore in such a situation drinking a basic solution with a higher pH neutralizes some of the stomach acidic secretions hence relieving the effect;
Acid + Base - Salt + Water
Answer:
Dissolved or gaseous substances have to pass through the cell membrane to get into or out of a cell. Diffusion occurs when particles spread. ... They move from a region where they are in high concentration to a region where they are in low concentration.
Explanation:
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