在减数分裂的双线期，同源染色体通过下列哪种结构连接在一起？（1分）

Question

BlackTom AI · Accepted Answer

Chiasmata (the visible “crossing” points) physically hold homologous chromosomes together during prophase I (the diplotene stage) of meiosis.

1) Relevant concepts
- Homologous chromosomes pair (synapsis) during prophase I to form a tetrad (bivalent).
- The synaptonemal complex promotes close pairing and facilitates crossing‑over between non‑sister chromatids.
- After crossing‑over, the sites where non‑sister chromatids have exchanged genetic material appear as chiasmata (singular: chiasma). Cohesin proteins maintain sister chromatid cohesion so homologs remain associated until anaphase I.

2) Step‑by‑step reasoning
- During leptotene/zygotene the homologs begin pairing; at pachytene crossing‑over occurs guided by the synaptonemal complex.
- Recombination leaves physical links between homologs; when the synaptonemal complex disassembles at diplotene, those links remain as chiasmata.
- Chiasmata are the only persistent physical connections that keep homologous chromosomes paired on the meiotic spindle until they separate at anaphase I.

3) (No numerical calculations required.)

4) Why the correct answer is correct
- The chiasma is the structural manifestation of crossing‑over and is the actual physical connection between homologous chromosomes in prophase I/diplotene, ensuring correct alignment and promoting genetic recombination.

5) Why other choices are incorrect
- Centromere (a): Centromeres connect sister chromatids to each other and serve as attachment sites for kinetochores; they do not by themselves join homologous chromosomes.
- Spindle/main axis (c): The spindle apparatus attaches to chromosomes later (metaphase/anaphase) and does not create the inter‑homolog connection during prophase I.
- Any repeat of “centromere” (d) is likewise incorrect for the same reason.

6) Conclusion
Therefore the homologous chromosomes in meiotic prophase I (diplotene) are connected by chiasmata (option b: 交叉), which matches the provided correct answer.

在减数分裂的双线期，同源染色体通过下列哪种结构连接在一起？（1分）Single choice

Similar Questions

23. A special kind of cellular division, it occurs only in the sex cells (sex cells: sperm and eggs) and produces gametes.

During which phase of cell division do homologous chromosomes first separate and move to opposite sides of the cell?

A diploid (2n) cell undergoes meiosis. How many chromosomes will each gamete contain?

Question at position 73 Crossing over between homologous chromosomes occurs during and homologous chromosomes separate from each other during .prophase I; anaphase IIprophase II, telophase Iprophase I; anaphase Iprophase II; telophase II

Question at position 62 If a diploid cell (2n = 16) undergoes meiosis I and II, the result is:2 cells; each with 2n = 82 cells; each with 2n = 164 cells; each with n = 84 cells; each with 2n = 322 cells; each with 2n = 32

Question at position 5 Crossing over occurs in Printed Blank[input]Question Blank 1 of 1[input] 1.anaphasecytokinesistelophaseinterphasemetaphaseprophase

In the ovule each megaspore mother cell undergoes _____ to produce four megaspores.

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler