15. The cytokinetic organelle in plant cells is

(A) centriole
(B) phragmoplast
(C) proplastid
(D) chromoplast

The cytokinetic organelle in plant cells is the phragmoplast. This structure facilitates cytokinesis by guiding vesicles to form the cell plate, unlike animal cells that use a cleavage furrow. The correct answer is (B) phragmoplast.​

Option Analysis

(A) Centriole: Centrioles organize the mitotic spindle in animal cells but are absent in plant cells, playing no role in cytokinesis.​
(B) Phragmoplast: Correct. This microtubule array forms during telophase in plant cells, directing Golgi-derived vesicles to the cell center for cell plate formation.​
(C) Proplastid: Proplastids are precursors to chloroplasts and other plastids, involved in photosynthesis, not cell division.​
(D) Chromoplast: Chromoplasts store pigments for coloration in fruits and flowers, unrelated to cytokinesis.​

The cytokinetic organelle in plant cells, known as the phragmoplast, is essential for dividing the cytoplasm during mitosis. Unlike animal cells, plant cells lack centrioles and use this structure to form a new cell wall.​

Phragmoplast Structure

Phragmoplast consists of interzonal microtubules and Golgi vesicles that assemble at the cell equator in telophase. These guide cell wall materials to create the cell plate, which expands and fuses with the parent wall.​

Cytokinesis Process

Vesicles fuse centrally, forming the cell plate that matures into a middle lamella and primary walls. This ensures rigid separation due to existing cell walls.​

Why Not Other Options?

• Centriole: Animal-specific for spindle formation; plants use microtubule organizing centers.​

• Proplastid: Immature plastid for chloroplast development, not division-related.​

• Chromoplast: Pigment storage organelle, irrelevant to cytokinesis.​