The circulatory system - hemoglobin in the blood transports oxygen :)
<span>Alleles are each of two or more alternative forms of a gene that are found at the same position in a chromosome. Traits on the other hand, are the characteristics that are defined by genes. So the combination of alleles for a gene is what manifests itself into a trait.</span>
Answer:
Although humans can sometimes influence natural disasters (for example when poor levee design results in a flood), other disasters that are directly generated by humans, such as oil and toxic material spills, pollution, massive automobile or train wrecks, airplane crashes, and human induced explosions, are considered.