Anew cancer fighting agent was discovered in a rare tropical plant. in animals, the substance prevents mitosis by disrupting the formation of microtubules. if the microtubules are not working properly, which of the following is specifically affected?

I believe the answer is The spindle fibers  

Microtubule will form the spindle fibers that will grab the chromosome. The formation of microtubule will be start from prophase and it will have role in moving the chromosome through the metaphase and anaphase. If the substance disrupting the formation of microtubules, then spindle fibers will not be formed.

the principle of segregation describes how pairs of gene variants are separated into reproductive cells. from his data, mendel formulated the principle of segregation. we now know that the segregation of genes occurs during meiosis in eukaryotes, which is a process that produces reproductive cells called gametes.