画图解释一下---**题目** 现建立“动物精原细胞 (2n=4) 有丝分裂和减数分裂过程”模型。1个精原细胞 (假定DNA中的P元素都为³²P, 其它分子不含³²P) 在不含³²P的培养液中正常培养, 分裂为2个子细胞, 其中1个子细胞发育成细胞 ①。细胞 ①和②的染色体组成如图所示, H (h) 、R (r) 是其中的两对基因, 细胞 ②和③处于相同的分裂时期。下列叙述正确的是 ( ) *(Translation of Stem: Now establish a model of "animal spermatogonium (2n=4) mitosis and meiosis process". 1 spermatogonium (assuming all P elements in DNA are ³²P, other molecules do not contain ³²P) is cultured normally in a ³²P-free culture medium, dividing into 2 daughter cells, one of which develops into cell ①. The chromosome composition of cell ① and ② are shown in the figure, H (h) and R (r) are two pairs of genes among them, cell ② and ③ are in the same division phase. Which of the following statements is correct?)* **Options** A. 细胞 ①形成过程中没有发生基因重组 *(Translation: A. Gene recombination did not occur during the formation of cell ①)* B. 细胞 ②中最多有两条染色体含有³²P *(Translation: B. At most two chromosomes in cell ② contain ³²P)* C. 细胞 ②和细胞 ③中含有³²P的染色体数相等 *(Translation: C. The number of chromosomes containing ³²P in cell ② and cell ③ is equal)* D. 细胞 ④～⑦中含³²P的核DNA分子数可能分别为2、1、1、1 *(Translation: D. The number of nuclear DNA molecules containing ³²P in cells ④~⑦ could possibly be 2, 1, 1, 1 respectively)* **Chart/Diagram Description** * **Type:** Biological diagram illustrating stages of cell division (likely meiosis) starting from a cell labeled "细胞 ①" and leading to cells labeled "细胞 ②" and "细胞 ③", which further divide into cells labeled "细胞 ④" through "细胞 ⑦". * **Main Elements:** * **Cell ①:** An oval representing a cell. Inside, four condensed chromosomes are shown, each consisting of two sister chromatids. The chromosomes are arranged as two homologous pairs. One pair is labeled with alleles H/h (H on one chromosome/both chromatids, h on the homologous chromosome/both chromatids). The other pair is labeled R/r (R on one chromosome/both chromatids, r on the homologous chromosome/both chromatids). This represents a diploid cell (2n=4) after DNA replication, likely a primary spermatocyte in Prophase I or Metaphase I. * **Cell ②:** An oval representing a cell, originating from Cell ① via an arrow. Inside, two condensed chromosomes are shown, each consisting of two sister chromatids. One chromosome is labeled with allele H (on both chromatids). The other chromosome is labeled with allele R (on both chromatids). The two chromosomes appear aligned, possibly in Metaphase II. This represents a haploid cell (n=2) with replicated chromosomes, likely a secondary spermatocyte. * **Cell ③:** An oval representing a cell, originating from Cell ① via an arrow, positioned beside Cell ②. Inside, two condensed chromosomes are shown, each consisting of two sister chromatids. One chromosome is labeled with allele h (on both chromatids). The other chromosome is labeled with allele r (on both chromatids). The two chromosomes appear aligned, similar to Cell ②. This represents a haploid cell (n=2) with replicated chromosomes, likely a secondary spermatocyte. * **Cells ④, ⑤:** Labels indicating daughter cells originating from Cell ② via arrows. No internal structure shown. * **Cells ⑥, ⑦:** Labels indicating daughter cells originating from Cell ③ via arrows. No internal structure shown. * **Arrows:** Arrows indicate the progression of cell division: from Cell ① to Cells ② and ③, and from Cell ② to Cells ④ and ⑤, and from Cell ③ to Cells ⑥ and ⑦. * **Labels:** "细胞 ①", "细胞 ②", "细胞 ③", "细胞 ④", "细胞 ⑤", "细胞 ⑥", "细胞 ⑦" are labels for the cells. Gene/allele labels H, h, R, r are shown on the chromosomes within Cells ①, ②, and ③.