The main reason that most farmers use stem cuttings rather than just planting a seed is that a tree's genetic variation will occur. The seeds of many fruit trees tend to vary differently from the parent, because seeds themselves are produced by sexual reproduction (i.e they receive genes from a male and female to form). As they are a cross from two sets of genes, many fruit trees are not “true to seed”. Their seeds will produce a generally different variety of tree from the parent. When using stem cuttings, it's almost like a cloning process.
Answer:
1. The physiological changes that will occur when someone lives at altitude for an extended period include increased production of more red blood cells.
2. The changes are advantageous as the person can survive lower altitude better and strenuous activities that interferes with breathing.
3. The specific physiological pathway that results in the changes described involves decrease in pulmonary ventilation at high altitude leading to hypoxia then hypoxemia. The body then produces more red blood cells to counteract the lower oxygen saturation in blood in high altitudes.
A. is the answer. DNA forms genes. The codons in the DNA make the phenotype.
Je ne peux pas vraiment expliquer la réponse en raison de votre question confuse, mais voici une note pour faire des questions non confuses la prochaine fois
The second one due to the fact that pioneer plants come in much later
