The Question is from neet-zoology animal-kingdom , and it was created by the author T SAILAJA

Question

Leucosolenia and Sycon both belong to the Calcarea class.  What is a key skeletal difference that distinguishes these two genera?

T SAILAJA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Sponge body plans (canal systems)
 **Related Topics**: Calcarea class, spicules, asconoid, syconoid, leuconoid
 **Prerequisites**: Basic understanding of sponge anatomy and classification.
## SOLUTION PATHWAY
**Given Information**:
  Leucosolenia and Sycon are both Calcarea sponges.
  We need to identify a key skeletal difference.
**Method & Steps**:
 1. Understand the different canal systems in sponges.
  Reasoning: Sponges have different body plans based on their canal systems: asconoid, syconoid, and leuconoid. These systems affect the organization of the choanocytes (collar cells) and the overall structure of the sponge.
  Formula/Rule: None directly applicable, but understanding the characteristics of each canal system is key.
 2. Identify the canal system of Leucosolenia and Sycon.
  Working: Leucosolenia has a simple asconoid system, while Sycon has a more complex syconoid system.  This difference in canal system directly impacts the overall skeletal structure and organization of the sponge.
  Key Point: The canal system is directly related to the efficiency of water flow and nutrient uptake, influencing the skeletal arrangement for support and filter feeding.
 3. Determine the key skeletal difference based on canal systems.
  Result: The key difference is the canal system organization: asconoid in Leucosolenia and syconoid in Sycon.
  Verification: This is a fundamental characteristic that distinguishes these two genera within the Calcarea class.  Both have calcareous spicules, but their arrangement differs due to their canal system.
 ## OPTION ANALYSIS
A :x: Leucosolenia does possess spicules, though they may be simpler in arrangement than in Sycon.
B :x: Both Leucosolenia and Sycon have calcareous skeletons; this is a characteristic of the Calcarea class.
C ✓:  This accurately describes the key skeletal difference based on the organization of the canal system and the resulting body structure.
D :x:  The reproductive methods of Leucosolenia and Sycon are not directly related to a key skeletal difference.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing spicule composition with canal system:  Both have calcareous spicules, so focusing only on spicule type is incorrect.
  2.Overlooking the significance of canal system:  The canal system is crucial in determining the overall body plan and skeletal arrangement.
 **Quick Tips**:
  1.Remember the order of complexity of sponge canal systems: asconoid (simplest) → syconoid → leuconoid (most complex).
  2.Visualize the different canal systems to understand how they influence the skeletal structure.

T SAILAJA · Answer

Leucosolenia lacks spicules, while Sycon possesses them.

T SAILAJA · Answer

Leucosolenia has a siliceous skeleton, while Sycon has a calcareous skeleton.

T SAILAJA · Answer

The correct Option is "Leucosolenia has only asconoid organization, while Sycon exhibits syconoid organization."

T SAILAJA · Answer

Leucosolenia reproduces sexually, while Sycon reproduces asexually.

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