Question

During what phases of Meiosis does the spindle fiber form, chromo condense, nuclear envelope fragment, nucleolus disappear, homogenous chromo pair off, crossing-over occur?

1) prophase 1
2) telophase 1
3) metaphase 1
4) anaphase 1

Answer 1

Spindle fiber formation, chromosome condensation, nucleolus disappearance, and crossing-over all occur during prophase I of Meiosis I.

Step-by-step explanation:

The events of spindle fiber formation, chromosome condensation, nuclear envelope fragmentation, nucleolus disappearance, pairing off of homologous chromosomes, and crossing-over all occur during prophase I of Meiosis I. During this phase, the nuclear envelope begins to break down, chromosomes condense, spindle fibers start to form, and homologous chromosomes pair up, which is key to this stage. Prophase I is unique in allowing crossing-over, a process not present in prophase of mitosis or meiosis II.