SSC CGL 2024 Tier-I · 9 September 2024, Shift 1 · General Awareness · Question 16 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 6 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

Which of the following pairs is INCORRECT regarding the grade of organisation and its example?

(a)Cell-tissue grade organisation - Jellyfish
(b)Cellular grade organisation - Sycon
(c)Protoplasmic grade organisation - Paramecium
(d)Tissue-organ grade organisation - Euplectella

Answer

Why

Correct — D. Euplectella, the Venus flower basket, is a glass sponge and belongs to Porifera.

Sponges never reach the tissue-organ grade. Their cells are specialised but loosely bound, with no true tissues and no organs, which places them at the cellular grade.

The tissue-organ grade begins with flatworms such as Planaria, where tissues are assembled into organs like the pharynx.

So the pair that does not hold is the one filing Euplectella under tissue-organ grade, and finding the broken pair is what the stem asks.

Why the others are wrong

(a)
Cell-tissue grade organisation - Jellyfish — Jellyfish are Cnidaria, which have true tissues but no organs - the cell-tissue grade. The pairing is correct, so it cannot be the one the stem wants.
(b)
Cellular grade organisation - Sycon — Sycon is a sponge, and sponges sit at the cellular grade, with cells doing separate jobs without forming tissues. Another correct pairing.
(c)
Protoplasmic grade organisation - Paramecium — Paramecium is a single-celled protozoan in which one cell carries out every function - the protoplasmic grade. Correctly paired, so not the answer.

Concept

Grades of organisation rank animals by how far their cells are organised.

Protoplasmic grade: one cell does everything, as in Amoeba and Paramecium.

Cellular grade: many cells divide the labour but form no tissues, as in sponges.

Cell-tissue grade: true tissues appear, as in Cnidaria.

Tissue-organ grade: tissues combine into organs, as in flatworms.

Organ-system grade: organs are linked into working systems, first in roundworms such as Ascaris and then in annelids, arthropods and chordates.

Euplectella is the standard exam name for a glass sponge, so it appears in Porifera questions as often as Sycon and Spongilla do.

Key facts

Euplectella, the Venus flower basket, is a glass sponge and belongs to Porifera.
Sponges show the cellular grade of organisation and have no true tissues.
Cnidaria such as jellyfish and Hydra show the cell-tissue grade.
The tissue-organ grade first appears in flatworms such as Planaria.

Study next

Phylum Porifera - canal system, spicules, and the examples Sycon, Spongilla and EuplectellaPhylum Cnidaria - polyp and medusa forms and the stinging cnidoblastsLevels of organisation across the animal kingdom up to the organ-system grade

Common traps

Assuming a glassy skeleton means a complex animal, when the spicules of Euplectella are secreted by loose cells.
Marking the pair you recognise instead of the pair that is wrong, on an INCORRECT-pair stem.

The same animals recur under different labels - also asked 17 Sep 2024, 12:30, GA Q.25, which lists Spongilla, Hydra, Euplectella and Sycon and asks which one is not a poriferan.

Related PYQs

No directly related past PYQ was found.