Which of the following statements are correct regarding Spirogyra algae ?
a. It is commonly called as Pond scum.
b. It grows in Marine water.
c. Its cell consist spiral shaped chloroplast.
d. It belon

Question

Which of the following statements are correct regarding Spirogyra algae ?
a. It is commonly called as Pond scum.
b. It grows in Marine water.
c. Its cell consist spiral shaped chloroplast.
d. It belong in family Zygnemataceae.

UnlockIAS · Accepted Answer

Correct — option (3), a, c and d (statements a, c and d). Spirogyra is a filamentous green alga (Chlorophyta) common in still or slow-moving freshwater bodies — ponds, ditches and lake margins — where its filaments form the slimy, bright-green floating mats popularly known as 'pond scum' or 'pond silk', which is exactly what statement a describes. Statement c is Spirogyra's single most distinctive diagnostic feature: each cylindrical cell contains one or more ribbon-like chloroplasts arranged in a spiral, helical path along the length of the cell, studded with pyrenoids (starch-storing bodies) — this spiral chloroplast is what gives the genus its name (from the Greek 'speira', a coil) and is the feature most exam questions use to identify it. Statement d is also correct: Spirogyra is classified in the family Zygnemataceae, order Zygnematales, within the class Charophyceae/Zygnematophyceae of green algae — a family defined by exactly this kind of filamentous, unbranched, sexually-reproducing-by-conjugation algal body plan. Statement b is the one false claim: Spirogyra is a strictly freshwater genus, not a marine one, and its cell walls and osmoregulation are adapted to freshwater conditions rather than the higher salinity of seawater.

Why the other options are wrong — (a) This bundle keeps the false statement b (that Spirogyra grows in marine water) alongside the two true statements a and c, but drops the true statement d. Spirogyra is a freshwater alga, and any option that includes b as correct is including a factually wrong claim, while also incorrectly excluding its correct family classification.  (b) This bundle again includes the false statement b (marine growth) while dropping the true statement a (the 'pond scum' common name). Spirogyra's freshwater, still-water habitat is exactly why it earns the popular name 'pond scum', so omitting a while including the false marine claim gets both parts of the option wrong.  (d) This bundle keeps the two true statements a and d but again includes the false statement b, and in doing so drops the true statement c — Spirogyra's defining spiral chloroplast, the feature the genus is named for. An option that both admits a false claim and excludes the genus's single most diagnostic true feature cannot be the fully correct set.

Concept: Spirogyra is a genus of unbranched, filamentous freshwater green algae in the family Zygnemataceae (order Zygnematales), instantly recognisable under a microscope by its one or more ribbon-shaped, spirally coiled chloroplasts running the length of each cylindrical cell, each chloroplast bearing pyrenoids that store starch. It reproduces asexually by simple fragmentation of the filament and sexually by conjugation, in which two parallel filaments form connecting tubes and the protoplast of one cell migrates through the tube into a cell of the other filament to form a zygospore — a process with no motile gametes, unlike many other green algae. Because it thrives in nutrient-rich still or slow freshwater, dense Spirogyra mats are a common, visually obvious sign of a pond or ditch, giving rise to its everyday name, pond scum or pond silk.

State PCS 2025 Q59 — Science & Technology PYQ with Answer

State PCS 2025 Q59 — Science & Technology PYQ with Answer