Among plant-like protists, which mode of reproduction is common for diatoms and euglenoids?

• A. Sexual reproduction only
• B. Asexual reproduction
• C. Reproduction by spores
• D. Budding

Answer: (B)

Asexual reproduction is the usual mode for diatoms and euglenoids. Diatoms reproduce mainly by mitotic cell division: a parent cell splits its silica shell (frustule) to form two new cells, allowing rapid population growth. With each division, the cells gradually get smaller, so sexual processes that restore size and introduce genetic variation occur less frequently. Euglenoids typically reproduce by binary fission, simply duplicating their contents and dividing into two identical offspring. While sexual reproduction can occur in some circumstances, it is not the common pattern for these groups, and spores or budding are not typical modes for diatoms or euglenoids.