Answer:
Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium.
Explanation:
Explained in greater detail, each gene resides at a specific locus (location on a chromosome) in two copies, one copy of the gene inherited from each parent. The copies, however, are not necessarily the same. When the copies of a gene differ from each other, they are known as alleles.
For you to understand the process we can say that the weak will die. If the animal or organism can't get food or find any it is naturally "selected" to die.So a Cuticle could have evolved like that. Hope tgis is useful
Reproductive isolating mechanisms are barriers which impeded mating (prezygotic) or prevent the hybrid from developing properly (postzygotic) but the overall effect is to cause speciation by making it difficult for two diverging species to share genes. So one kind of mechanical isolation could be the usage of contraceptives. As of temporal isolation, or behavioral isolation could be exemplified by people who suffer from diseases that cause separation (such as HIV or cancer). I hope that this is the answer that you were looking for and it has helped you.
