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 cell cycle is the final answer! : )

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs