Prepare for NEET Biology Animal Kingdom (Porifera) with MCQs & PYQs on NEET.GUIDE. Access free practice, previous year questions, and expert insights to study sponges, their canal system, and totipotent cells.
In some Porifera, archaeocytes are totipotent. If an experiment selectively destroyed all archaeocytes within a sponge, which of the following would be the MOST immediate and devastating consequence?
Cessation of water flow through the canal system
Inability to capture food particles
Breakdown of the spongin skeletal structure
Loss of regenerative capacity and inability to differentiate into other cell types
Leucosolenia and Sycon both belong to the Calcarea class. What is a key skeletal difference that distinguishes these two genera?
Leucosolenia lacks spicules, while Sycon possesses them.
Leucosolenia has a siliceous skeleton, while Sycon has a calcareous skeleton.
Leucosolenia has only asconoid organization, while Sycon exhibits syconoid organization.
Leucosolenia reproduces sexually, while Sycon reproduces asexually.
Which of these features is NOT characteristic of the class Hexactinellida?
Six-rayed siliceous spicules
Syncytial body structure with trabecular reticulum
Predominantly found in shallow, warm waters
Often exhibit radial symmetry
The unique 'dermal membrane' observed in some homoscleromorph sponges is primarily composed of which cell type?
Choanocytes
Archaeocytes
Sclerocytes
Pinacocytes
Explain the evolutionary significance of the presence of cellular layers in Porifera despite their lack of true tissues. How does this relate to the potential for more complex body plans in other animal phyla?
The cellular layers in Porifera are analogous to plant tissues, suggesting a common ancestor.
The lack of true tissues limits their complexity, preventing further evolutionary development.
The cellular layers are simply an artifact of their aquatic environment and have no evolutionary significance.
The distinct cell layers, though not forming true tissues, represent a step towards tissue-level organization, foreshadowing the more complex tissue development observed in Eumetazoa.
Which of the following is NOT a characteristic feature of Porifera?
Presence of choanocytes
Presence of a true coelom
Body supported by spicules or spongin fibres
Mostly marine, asymmetrical body
The central cavity in the body of a sponge is called:
Osculum
Spongocoel
Ostia
Gastrovascular cavity
Which type of canal system is considered the most complex in sponges?
Asconoid
Syconoid
Leuconoid
Rhagonoid
Sponges primarily reproduce asexually by:
Binary fission
Budding and gemmule formation
Fragmentation only
Spore formation
The cells responsible for secreting spicules in sponges are called:
Choanocytes
Pinacocytes
Sclerocytes
Archaeocytes