Kinetochores: choose all that apply.
a. they are complex structures attached to the centromeres of chromosomes that bind to spindle microtubules. b. b. they are important for maintaining homologous chromosome pairing and plays a role in recombination.
c. they catalyze the phosphorylation of specific proteins.
d. they are enzymes that control progression through the cell cycle.
e. they are required for the segregation of chromosomes during anaphase of mitosis or meiosis.

a. They are complex structures attached to the centromeres of chromosomes that bind to spindle microtubules.

d. They are enzymes that control progression through the cell cycle.

Explanation:

In the eukaryotes during cell division, the spindle apparatus gets attached to the chromatid in a structure called kinetochore. It is present in the centromere. It supervises, control and starts the striking movement of chromosome during division. For chromosome editing its protein helps in holding the sister chromatid. Every chromatid have there own kinetochore that faces in the opposite direction, and are also attached to the opposite pole of the mitotic spindle apparatus .

i believe the answer is a or 1

b. the carbon cycle ensures living things have a source of hydrogen