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Basically because your skin has several layers to it (see link, below), and the layer that has the blood vessels capable of bleeding in it is further down than a superficial scrape would affect.
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Answer:Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly. Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly.Semipermeable membranes, also termed selectively permeable membranes or partially permeable membranes, allow certain molecules or ions to pass through by diffusion.
Explanation: hope that helps
I believe it is B i took this test last year.
The mRNA will attach to the small ribosomal unit and then the large ribosomal unit. Then the mRNA will be decoded with its codon's tRNA. ... The tRNA will come in at the A site and a peptide bond will form between amino acids at the A and P sites.
Limiting factors are resources or other factors in the environment that can lower the population growth rate. Limiting factors include a low food supply and lack of space. Limiting factors can lower birth rates, increase death rates, or lead to emigration.