Certain unicellular eukaryotes, including diatoms and some yeasts, have mechanisms of nuclear division that resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?
A) They reproduce by binary fission in their early stages of development and by mitosis when they are mature.
B) They have circular chromosomes that are segregated by a mitotic spindle.
C) Chromosomes are segregated by a mitotic spindle, but the nuclear envelope remains intact during division.
D) Chromosomes are segregated by attachment to the plasma membrane.

Question

Quizplus · Accepted Answer

Chromosomes being segregated by a mitotic spindle while the nuclear envelope remains intact during division is a characteristic feature of nuclear division in certain unicellular eukaryotes, like diatoms and some yeasts. This process is an intermediate step in the evolution of mitosis, differing from the complete breakdown of the nuclear envelope seen in most eukaryotic cells.

Certain Unicellular Eukaryotes, Including Diatoms and Some Yeasts, Have Mechanisms