. Advanced biology. Biology; Physiology; Reproduction. When peas are rolled down an inclined plane through a small opening against nails, they line up in pens in a very definite order. When this experiment is performed, a sorting out, known as a normal distribution, occurs. Few peas are found in the end pens, many in the center. This illustrates the law of chance, discussed on p. 317. from each other. Some are tall and some are short, some are blue-eyed and some are brown-eyed. This will be explained later. We have learned that a process called matura- tion or ripening occurs in the developmen
. Advanced biology. Biology; Physiology; Reproduction. When peas are rolled down an inclined plane through a small opening against nails, they line up in pens in a very definite order. When this experiment is performed, a sorting out, known as a normal distribution, occurs. Few peas are found in the end pens, many in the center. This illustrates the law of chance, discussed on p. 317. from each other. Some are tall and some are short, some are blue-eyed and some are brown-eyed. This will be explained later. We have learned that a process called matura- tion or ripening occurs in the development of mature germ cells in the parent organism. This maturation of the germ cells accounts for the differences among off- spring. Chromosomes are thought to possess combinations of char- acter-determiners called genes. These genes are found to be in pairs in the primary sex cells. During the matu- ration process, reduction takes place. In reduction, one member of each pair goes to a given germ cell. Consequently, each germ cell has one half the number of chromosomes found in the pri- mary sex cell. If the primary sex cell had a pair of character- determiners for eye color, one of this pair carries blue and the other brown, the chromosome containing the gene for blue eyes would go to one germ cell and the chromosome containing the gene for brown eyes would go to another germ cell. A primary sex cell may have two characters for a particular trait, but a germ cell only has one and is pure in regard to any particular trait. Consequently, the same organism may produce germ cells with unlike characters. The sperm cells of the male are not identical; eggs, too, have different character-determiners or genes in them. When the sperm and egg meet in the process of fertilization, the characters of the fertilized egg depend upon the characters in the genes in the combined chromosomes of both the sperm and Please note that these images are extracted from scanned page images that may hav
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Keywords: ., bookcentury1900, bookdecade1920, booksubje, booksubjectphysiology
