Name the following:
The organelle that forms the aster during cell division.
Topic: Centrosome
Answer
CENTROSOME.
Read the word ORGANELLE carefully — it decides the answer. The CENTROSOME is the organelle; the CENTRIOLES are the pair of cylindrical structures INSIDE it. So the organelle that forms the aster is the centrosome, and answering "centriole" names a part rather than the organelle asked for.
The centrosome lies near the nucleus in an ANIMAL cell. At the start of division its halves move to opposite poles, and radiating fibres appear around each — the star-shaped ASTER (aster = star).
It organises the SPINDLE, the apparatus that separates the chromatids.
THE POINT WORTH KNOWING: higher plants have NO centrioles and therefore form NO aster, yet they still build a spindle. This is one of the differences between plant and animal mitosis, the other being cytokinesis by cell plate rather than by furrowing.
THREE SIMILAR WORDS to keep apart: CENTROSOME — the ORGANELLE near the nucleus CENTRIOLE — the cylindrical structures within it CENTROMERE — the point joining two chromatids ON a chromosome The question wording tells you which is wanted: "organelle" points to the centrosome.