Drosophila has four pairs of homologous chromosomes, and the probability of producing gametes with t

Half of the homologous chromosomes of Drosophila come from the father, and three of the gametes it produces come from its father, and if the fourth one comes from the mother, then the probability that the first chromosome comes from the father, the probability that the second one comes from the father, the probability that the third one comes from the father, the probability that the fourth one does not come from the father, and the probability from the mother is But the one from the mother can also be the first, second, and third ones, so there are four cases, so the probability is.

The probability of producing a gamete with 3 paternal chromosomes is (1 2) 3*1 2*c(4,3)=(1 2) 4*4=

In addition, the probability of producing a gamete with 1 paternal chromosome is (1 2) 1*(1 2) 3*c(4,1)=(1 2) 4*4=

The probability of producing a gamete with 2 paternal chromosomes is (1 2) 2*(1 2) 2*c(4,2)=(1 2) 4*6=

The probability of producing a gamete with 4 paternal chromosomes is (1 2) 4*c(4,4)=(1 2) 4*1=

The probability of producing a gamete with 0 paternal chromosomes is (1 2) 4*c(4,0)=(1 2) 4*1=

Test Center: The Relationship between Genes and Traits Special Topic: Analysis:

The somatic cells of Drosophila contain 4 pairs of homologous chromosomes, including 3 pairs of autosomes and 1 pair of sex chromosomes, the sex chromosomes of female Drosophila are composed of XX, and the sex chromosomes of male Drosophila are XY; The Y chromosome of Drosophila is longer than the X chromosome a, and the somatic cells of Drosophila contain 4 pairs of homologous chromosomes, including 3 pairs of autosomes and 1 pair of sex chromosomes, and a is correct; b. The sex chromosome composition of female Drosophila is xx, and the sex chromosomes are homotyped, and b is correct; c. The sex chromosome composition of male Drosophila is XY, in which the X-stained mortal body is longer than the Y chromosome, and the sex chromosome is heterosexual, C is correct; D. Although the X chromosome and the Y chromosome of Drosophila are a pair of homologous chromosomes, they have non-homologous segments, so the genes located on the X chromosome in the somatic cells of male Drosophila may not be able to find the corresponding allele on the Y chromosome

First, four pairs of homologous chromosomes. Second, gametes with two chromosome combinations are produced. Thirdly, it is impossible to write without a diagram that the w gene of one somatic sex chromosome of Drosophila forms 2 W genes when replicated in interphase.

(1) Observing the sex chromosomes of the fruit fly shows that its two sex chromosomes are atypic XY, so the fruit fly is a male fruit fly (2) The analysis of the graph shows that the fruit fly has 8 chromosomes and 4 pairs of homologous chromosomes, of which 3 pairs are autosomes, which are two, two and two respectively1 pair is a sex chromosome, which is the X and Y chromosome sets, which refer to a group of chromosomes with different morphologies and sizes, and there are no homologous chromosomes in the same chromosome group, so a chromosome set in the diagram can be , x or , y So the answer is: (1) The male sex chromosomes are xy (2) 42, x or , y

Three pairs are the same, only xy is different.

There are four pairs in pairs, and the lowest morphology is different, indicating that it is a sex chromosome.

1 different 2 standard type c type c type.

3 Different types of the second chromosome of Drosophila have different viability in different degrees of warmth.