If A and B are a pair, because female sex chromosomes are X and X, and male sex chromosomes are X and Y; The eggs produced by women only contain X, and the sperm produced by men contain X or Y. When the fertilized egg combined with egg X and sperm Y is XY, the fertilized egg develops into a boy. When the fertilized egg combined with egg X and sperm X is XX, the fertilized egg will develop into a girl. Sperm containing X and sperm containing Y are random, so the chances of a mother having another child are 50% and 50% respectively.
(2) Of the 23 pairs of chromosomes in human somatic cells, 22 pairs are basically the same in shape and size as men and women, while one pair is obviously different in shape and size. Male is XY chromosome and female is XX chromosome. Therefore, in the "Human Genome Project", it is necessary to determine 22 autosomes, 1 X chromosome and 1 Y chromosome, accounting for 24 chromosomes.
(3) The Human Genome Project aims to accurately sequence the human genome, find all human genes and find out their positions on chromosomes. Decode all human genetic information. The purpose is to decode life, understand the origin of life, understand the law of life growth and development, understand the reasons for the differences between species and individuals, understand the occurrence mechanism of diseases and life phenomena such as longevity and aging, and provide scientific basis for the diagnosis and treatment of diseases. The number of chromosomes in human somatic cells is 23 pairs, of which 22 pairs are autosomes, and the 23rd pair is related to sex determination. This is a sex chromosome. Each of the 22 pairs of autosomes has the same gene. X and y chromosomes have different genes. So the sequence of base pairs on human chromosomes has been determined, so B is correct.
(4) The chromosome composition in male somatic cells is 22 pairs of autosomes +XY, in which XY is a pair of sex chromosomes. When men form germ cell sperm, the paired chromosomes should be separated, so the sperm formed has two kinds of chromosomes: 22 autosomes +X and 22 autosomes+Y; The chromosome composition of female somatic cells is 22 pairs of autosomes +XX. When forming germ cell eggs, the paired chromosomes should be separated, and the chromosome set of the formed egg becomes one: 22 autosomal +X, so the chromosome composition of male germ cells is 22 autosomal +Y or X.
(5) After the completion of the human genome project, it will have the following effects on human life: it will be beneficial to the diagnosis and treatment of diseases; Help citizens choose a healthy lifestyle; Conducive to the study of biological evolution; Conducive to the cultivation of excellent higher animal and plant varieties; It is beneficial to study the regulation mechanism of gene expression. While the human genome project brings benefits to mankind, we should also consider how to protect the privacy of citizens' genetic information and avoid the phenomenon that companies discriminate against employees on the grounds of genetic test results.
So, the answer is: (1) b; 50%?
(2)24
(3)B？
(4) Article 22 +X or Article 22 +Y?
(5) Conducive to the diagnosis and treatment of diseases; Help citizens choose a healthy lifestyle; Conducive to the study of biological evolution; Conducive to the cultivation of excellent higher animal and plant varieties; It is beneficial to study the regulation mechanism of gene expression. While the human genome project brings benefits to mankind, we should also consider how to protect the privacy of citizens' genetic information and avoid the phenomenon that companies discriminate against employees on the grounds of genetic test results.