Question

organelle that produces fibers responsible for nuclear division; not present in plant cells
each half of the x (chromosome) containing identical copies of dna
spindle fibers, centrioles, and the centromere they attach to
center of the chromosome that hold sister chromatids together and the site where spindle fibers attach
spindle apparatus
centrioles
centromere
sister chromatid

Explanation:

1. Centrioles are organelles that produce fibers for nuclear division and are absent in plant cells.
2. Sister chromatids are each half of the X - shaped chromosome with identical DNA copies.
3. The spindle apparatus includes spindle fibers, centrioles, and the centromere they attach to.
4. The centromere is the center of the chromosome holding sister chromatids together and the attachment site for spindle fibers.

Answer:

1. centrioles
2. sister chromatid
3. spindle apparatus
4. centromere