Question

25 8. using the following terms, explain the process of cell wall growth and cellulose deposition in elongating cells: cellulose microfibrils, cellulose synthase complexes (rosettes), cortical microtubules, secretory vesicles, matrix substances, plasma membrane.
26 in the typical cell cycle, there are checkpoints. what are these checkpoints? what purpose do they serve?
27 what is the preprophase band? what role does it play in plant cell division?

Explanation:

Question 25:

Cellulose synthase complexes (rosettes) in the plasma membrane synthesize cellulose microfibrils. Cortical microtubules guide the orientation of microfibril deposition. Secretory vesicles transport matrix substances to the cell - wall. These components work together for cell - wall growth and cellulose deposition in elongating cells.

Question 26:

Checkpoints in the cell cycle include G1/S, G2/M, and M - phase checkpoints. They ensure DNA integrity, proper DNA replication, and correct chromosome segregation, preventing the propagation of damaged or abnormal cells.

Question 27:

The preprophase band is a ring of microtubules and actin filaments that forms before prophase in plant cells. It predicts the plane of cell division and helps in the proper orientation of the cell - division machinery.

Answer:

Question 25:

Cellulose synthase complexes in the plasma membrane produce cellulose microfibrils. Cortical microtubules direct microfibril orientation. Secretory vesicles supply matrix substances for cell - wall growth and cellulose deposition.

Question 26:

Checkpoints are G1/S, G2/M, and M - phase checkpoints. They maintain DNA integrity, ensure proper replication and chromosome segregation.

Question 27:

The preprophase band is a microtubule - actin ring. It predicts the cell - division plane and aids in division machinery orientation.