Question

$100$ zygospores, alternate with empty cells in Spirogyra are under __________ conjugation and the total number of daughter filaments formed will be ___________.

• A. Scalariform, $400$
• B. Lateral, $100$
• C. Lateral, $400$
• D. Scalariform, $100$

Answer 1

Answer: (A)

Scalariform, $400$

Spirogyra is a member of a genus of some 400 species of free-floating green algae (division Chlorophyta) found in freshwater environments around the world. spirogyras are filamentous algae that consist of thin unbranched chains of cylindrical cells. They can form masses that float near the surface of streams and ponds, buoyed by oxygen bubbles released during photosynthesis. They are commonly used in laboratory demonstrations. Scalariform conjugation is most common method in most heterothallic species of Spirogyra. It takes place in the night when two filaments come close and lie opposite and parallel to each other. opposite cells develop outgrowths or protuberances called conjugation processes. At the point of contact, the tips of these processes dissolve (bycytase) to form conjugation tube between opposite cells. The decay of female gametangia causes the liberation of zygospore which remains dormant in the pond bottom till the favorable conditions return. Zygospore undergoes meiosis to form four haploid nuclei.

So the correct option is 'scalariform, 400'.