Answer: In humans, meiosis is the process by which sperm cells and egg cells are produced. In the male, meiosis takes place after puberty. Diploid cells within the testes undergo meiosis to produce haploid sperm cells with 23 chromosomes. A single diploid cell yields four haploid sperm cells through meiosis. In females, meiosis begins during the fetal stage when a series of diploid cells enter meiosis I. At the conclusion of meiosis I, the process comes to a halt, and the cells gather in the ovaries. At puberty, meiosis resumes. One cell at the end of meiosis I enters meiosis II each month. The result of meiosis II is a single egg cell per cycle (the other meiotic cells disintegrate). Each egg cell contains 23 chromosomes and is haploid. The union of the egg cell and the sperm cell leads to the formation of a fertilized egg cell with 46 chromosomes, or 23 pairs. Fertilization restores the diploid number of chromosomes. The fertilized egg cell, a diploid, is a zygote. Further divisions of the zygote by mitosis eventually yield a complete human being.
Natural selection is the process through which species adapt to their environments
natural selection is the method through which populations of dwelling organisms and species adapt and exchange. individuals in a population are obviously variable, that means that they will be all unique in a few methods. this variation approach that some humans have trends higher suited to the environment than others. people with adaptive tendencies—traits that supply them a few advantage—are more likely to live to tell the tale and reproduce. those humans then pass the adaptive developments directly to their offspring. over the years, the ones powerful trends come to be more not unusual within the populace. through this machine of natural selection, favorable trends are transmitted through generations.
natural selection can cause speciation, in which one species offers rise to a brand new and rather precise species. it is one of the processes that drives evolution and permits to provide an cause of the sort of existence inside the world
Darwin selected the decision natural choice to contrast with “artificia selection,” or selective breeding that is controlled via human beings..
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To answer your question, the major reservoir for
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Hey! here is your answer
passive refilling of the heart occurs During ventricular systole, the blood pressure
Answer:
down syndrome
Explanation:
people with down syndrome have an extra chromosome in the twenty-first pair
