The centromere is a region in which...

chromatids remain attached to one another until anaphase.

Why do neurons and some other specialized cells divide infrequently?

They have been shunted into G₀.

Which of the following is released by platelets in the vicinity of an injury?

PDGF

Several organisms, primarily protists, have what are called intermediate mitotic organization.

What is the most probable hypothesis about these intermediate forms of cell division?

They show some but not all of the evolutionary steps toward complete mitosis.

Using which of the following techniques would enable your lab group to distinguish between a cell in G₂ and a cell from the same organism in G₁?

Radioactive-labeled nucleotides

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle are called...

cyclins

A plant-derived protein know as colchicine can be used to poison cells by blocking the formation of the spindle.

Which of the following would result if colchicine is added to a sample of cells in G₂?

The chromosomes would coil and shorten but have no spindle to which to attach

Several organisms, primarily protists, have what are called intermediate mitotic organization.

These protists are intermediate in what sense?

They maintain a nuclear envelope during division.

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

Two long strands of DNA plus proteins.

Which of the following investigations might be most productive to show what the data on the teenagers might indicate?

Test female teens at different times in their menstrual cycles.