What role did the dust bowl have on the history of soil conversion

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

Everything in the universe originated from a single point. how was it possible for everything in the universe to have occupied a single point in space?