Phylum-Porifera Questions in English

(A) Sponges are multicellular organisms, but they exhibit a "cellular level" of body organization, meaning they do not possess true tissues, organs, or organ systems.
Although sponges lack tissues, there is a degree of physiological division of labour among the various types of cells (e.g., choanocytes, amoebocytes) present in their body.
These cells perform specific functions such as digestion, respiration, and reproduction, but they are not organized into permanent layers or masses to form tissues.
Therefore, both the Assertion and the Reason are correct, and the Reason provides a valid explanation for why the organization is considered "cellular level" despite the presence of functional specialization.

(A) Sponges are multicellular organisms that belong to the phylum $Porifera$.
They possess a unique water transport or canal system,which is a defining characteristic of this phylum.
Water enters through minute pores called $ostia$ in the body wall into a central cavity,the $spongocoel$,and goes out through the $osculum$.
This pathway of water transport is helpful in food gathering,respiratory exchange,and removal of waste.
Since the canal system is a diagnostic feature that defines the phylum $Porifera$,the Reason correctly explains the Assertion.

(A) The members of Phylum $Porifera$ are commonly known as sponges.
They are primitive multicellular animals with a cellular level of organization.
They have a water transport or canal system.
Water enters through minute pores called $ostia$ in the body wall into a central cavity,$spongocoel$,from where it goes out through the $osculum$.
This pathway of water transport is helpful in food gathering,respiratory exchange,and removal of waste.
$Choanocytes$ or collar cells line the spongocoel and the canals.
Digestion is intracellular.
The body is supported by a skeleton made up of $spicules$ or $spongin$ fibers.
They are hermaphrodite,i.e.,eggs and sperm are produced by the same individual.

(N/A) $(i)$
Location: In Protozoa (e.g.,Amoeba).
Function: Osmoregulation and excretion.
$(ii)$
Location: In Porifera (sponges).
Function: These are minute pores on the body wall through which water enters the body cavity (spongocoel).

(N/A) $\rightarrow$ Phylum Porifera (Latin: porus = pore, ferre = to bear) includes the first and most primitive group of multicellular animals, commonly referred to as sponges.
$\rightarrow$ They are primitive, multicellular animals with a cellular level of organization.
$\rightarrow$ They are generally marine and mostly asymmetrical.
$\rightarrow$ Sponges possess a unique water transport or canal system.
$\rightarrow$ Water enters through minute pores (ostia) in the body wall into a central cavity, the spongocoel, from where it exits through the osculum.
$\rightarrow$ This pathway of water transport is essential for food gathering, respiratory exchange, and the removal of waste products.
$\rightarrow$ Choanocytes or collar cells line the spongocoel and the canals.
$\rightarrow$ Digestion is intracellular.
$\rightarrow$ The body is supported by a skeleton made up of spicules or spongin fibres.
$\rightarrow$ They are hermaphrodite (sexes are not separate), and reproduction occurs both asexually (by fragmentation) and sexually (by formation of gametes).

(N/A) $\Rightarrow$ Sponges exhibit cellular level of organization,meaning their cells are not organized into tissues.
$\Rightarrow$ Although they consist of thousands of cells,these cells function relatively independently or in loose aggregates.
$\Rightarrow$ There is a division of labor among the cells,where different types of cells perform specific functions,but they do not form complex,integrated tissue layers.

(A) Archaeocytes are undifferentiated embryonic amoebocytes of sponges with blunt pseudopodia and a large nucleus. These cells exhibit totipotency,meaning they have the ability to differentiate into any other type of cell required by the sponge body.

(D) The ascon type of canal system is the simplest form found in sponges,such as $Leucosolenia$.
In this system,the water enters through the ostia into the central cavity known as the spongocoel.
The spongocoel is lined by flagellated collar cells called choanocytes.
From the spongocoel,water exits through the osculum.
Therefore,the choanocytes line the spongocoel.

(B) $Spirulina$ is a cyanobacterium (blue-green algae) and belongs to the kingdom Monera,not the phylum Porifera.
$Sycon$,$Euspongia$,and $Spongilla$ are all members of the phylum Porifera,commonly known as sponges.

(D) Cnidocytes,also known as stinging cells,are specialized cells found exclusively in the phylum $Cnidaria$. They are used for prey capture,defense,and anchorage. They are not present in sponges (phylum $Porifera$).
Archaeocytes are totipotent cells in sponges involved in regeneration and food storage.
Trophocytes are nurse cells in sponges that provide nutrients to developing oocytes.
Myocytes are contractile cells found around the osculum in sponges that regulate water flow.

(A) The $Canal$ $system$ is a unique and peculiar characteristic of sponges (Phylum $Porifera$). It is a complex network of interconnected chambers, canals, and openings that facilitate water circulation for feeding, respiration, and excretion.
Also:
- $Water$ $vascular$ $system$ is a characteristic feature of $Echinoderms$.
- $Central$ $gastrovascular$ $cavity$ is a characteristic feature of $Cnidarians$.
- $Bioluminescence$ is a characteristic feature of $Ctenophora$.

(B) Choanocytes,also known as collar cells,are the characteristic cells of the phylum $Porifera$ (sponges).
In sponges,the internal lining of the canal system and the $spongocoel$ is formed by these choanocytes.
Among the given options:
$A$. $Physalia$ belongs to the phylum $Cnidaria$ (Coelenterata).
$B$. $Sycon$ belongs to the phylum $Porifera$ (sponges),thus it possesses choanocytes.
$C$. $Pleurobrachia$ belongs to the phylum $Ctenophora$.
$D$. $Echinus$ (sea urchin) belongs to the phylum $Echinodermata$.
Therefore,the correct option is $B$.

(A) In $Porifera$,the skeleton is formed by two types of structures:
$1$. $Spicules$: These are secreted by $Scleroblast$ cells. In calcareous sponges,these are called $calcoblasts$,and in siliceous sponges,they are called $silicoblasts$.
$2$. $Spongin$ $fibres$: These are secreted by $Spongioblast$ cells present in the $mesohyal$ layer of the sponge body.
Therefore,the skeleton of $Poriferans$ is composed of $spongin$ $fibres$ and $spicules$.

(D) Sponges are also known as $Porifera$,which means pore-bearing animals.
Sponges have a perforated body with numerous small openings called $Ostia$.
Water enters the body of sponges through these $Ostia$.
$A$ larger opening through which water flows out of the sponge is called the $Osculum$.
Therefore,$Porifera$ have numerous mouth-like pores called $Ostia$ for the entry of water and a single large pore for the exit of water called the $Osculum$.

(D) Sponges are hermaphrodites,meaning male and female gametes are produced by the same individual.
Most sponges are marine and asymmetrical animals.
Both sexual and asexual reproduction occur in them.
Sponges exhibit intracellular digestion,where food is digested within food vacuoles inside the cells.
There is no extracellular digestion in sponges.

(D) Poriferans are sessile organisms and remain attached to a substratum. They do not exhibit locomotion. In sponges,the canal system performs the functions of food gathering,gas exchange during respiration,and the removal of waste products. Therefore,the canal system does not help in locomotion.

(A) The canal system in sponges is a unique feature of the phylum $Porifera$. It is formed by the complex folding of the body wall,which includes the outer ectoderm (pinacoderm) and the inner endoderm (choanoderm). This system facilitates water circulation,which is essential for nutrition,respiration,and excretion.

(B) Sponges (Phylum $Porifera$) possess a remarkable ability for regeneration. If a sponge is fragmented due to mechanical injury or decay,each fragment has the potential to develop into a complete,new sponge. Even individual cells from a crushed sponge can reaggregate and reorganize to form a functional sponge. This high regenerative power is a characteristic feature observed across the phylum.

(N/A) $\rightarrow$ Sponges reproduce asexually by fragmentation and sexually by the formation of gametes.
$\rightarrow$ Fertilisation is internal,and development is indirect,involving a larval stage that is morphologically distinct from the adult.
$\rightarrow$ Development is mostly indirect,with larval stages known as parenchymula (e.g.,Leucosolenia) or amphiblastula (e.g.,Sycon).
$\rightarrow$ Examples: Sycon (Scypha),Spongilla (freshwater sponge),Euspongia (bath sponge).

(B) $\rightarrow$ Location: Collar cells,also known as choanocytes,are found lining the spongocoel and the canals of the body wall in sponges (Phylum Porifera).
$\rightarrow$ Function: These cells possess a flagellum that beats to create a water current,which brings in food particles and oxygen. The collar structure helps in trapping food particles from the water current,which are then ingested by the cell.

(A) $\rightarrow$ Location: In sponges,the canals and the spongocoel are lined by specialized flagellated cells called choanocytes (collar cells).
$\rightarrow$ Function: The beating of flagella on choanocytes maintains a constant flow of water from the ostia to the osculum through the spongocoel,which is essential for food capture,respiration,and excretion.

(C) Collar cells,also known as $choanocytes$,are specialized flagellated cells that line the internal cavity (spongocoel) and canals of sponges.
These cells are a characteristic feature of the phylum $Porifera$.
They help in water circulation,capturing food particles,and respiration.
Therefore,the correct option is $C$.

(A) In the phylum Porifera (sponges),water enters the body through minute pores called $Ostia$ in the body wall into a central cavity called the $Spongocoel$.
From the $Spongocoel$,the water exits the body through a large opening called the $Osculum$.
Therefore,the correct pathway of water flow is $Ostia \rightarrow Spongocoel \rightarrow Osculum$.

(A) In the phylum $Porifera$ (sponges),digestion is strictly intracellular. This means that food particles are engulfed by choanocytes and digestion takes place within the cells. In contrast,phyla like $Cnidaria$,$Ctenophora$,and $Platyhelminthes$ exhibit both extracellular and intracellular digestion.

(B) Based on the provided image:
$P$ represents $Sycon$,which is a tubular sponge.
$Q$ represents $Euspongia$,which is commonly known as the bath sponge.
$R$ represents $Spongilla$,which is a freshwater sponge.
Therefore,the correct sequence is $P = Sycon$,$Q = Euspongia$,$R = Spongilla$.

(D) The water canal system (or water transport system) is a characteristic feature of the phylum $Porifera$.
Water enters through minute pores called $ostia$ into a central cavity called $spongocoel$ and goes out through the $osculum$.
This pathway of water transport is helpful in:
$1$. Food gathering: Food particles are filtered from the water.
$2$. Respiratory gas exchange: Oxygen is taken in and carbon dioxide is released.
$3$. Removal of waste products: Metabolic wastes are flushed out of the body.
Therefore,all these functions are performed by the water canal system.

(C) The level of organization in the animal kingdom progresses from cellular to tissue,organ,and organ system levels.
$1$. In the phylum $Porifera$ (sponges),the cells are arranged as loose cell aggregates,exhibiting a cellular level of organization. They do not possess tissues.
$2$. In the phylum $Cnidaria$ (Coelenterata),the arrangement of cells is more complex,and they exhibit a tissue level of organization.
$3$. In the phylum $Platyhelminthes$ (flatworms),the organization reaches the organ level.
Therefore,tissues are not found in $Porifera$.

(A) In the animal kingdom,the level of organization refers to the complexity of the body structure.
$1$. Cellular level of organization: This is the simplest level where cells are arranged as loose cell aggregates,but they do not form tissues. This is characteristic of the phylum $Porifera$ (sponges).
$2$. Tissue level of organization: Cells performing the same function are arranged into tissues,as seen in $Coelenterata$ and $Ctenophora$.
$3$. Organ level of organization: Tissues are grouped together to form organs,specialized for particular functions,as seen in $Platyhelminthes$.
$4$. Organ system level of organization: Organs are associated to form functional systems,as seen in higher phyla starting from $Aschelminthes$ to $Chordata$.
Therefore,the cellular grade of organization is found in sponges.

(A) $Spongilla$ is a well-known genus of freshwater sponges belonging to the phylum $Porifera$.
Most members of the phylum $Porifera$ are marine,but $Spongilla$ is an exception as it is found exclusively in freshwater habitats.
$Porifera$ are diploblastic,not triploblastic.
They have a single large opening called the $osculum$ for the exit of water,while water enters through numerous minute pores called $ostia$.
They possess characteristic flagellated collar cells known as $choanocytes$ that line the spongocoel and canals.

(B) Sponges (Phylum $Porifera$) possess a characteristic internal skeleton that provides structural support to their body.
This skeleton is composed of either calcareous or siliceous spicules,or proteinaceous spongin fibres,or a combination of both.
Therefore,the assertion that the body of sponges is supported by a skeleton is true.
The reason correctly explains that this support is provided by spicules and spongin fibres.
Thus,both $(A)$ and $(R)$ are true,and $(R)$ is the correct explanation of $(A)$.

(B) The diagram provided shows a sponge with a massive,rounded body shape,which is characteristic of the genus $Euspongia$ (commonly known as the bath sponge).
$Sycon$ typically has a tubular,branched body structure.
$Spongilla$ is a freshwater sponge that often exhibits a branching or encrusting growth form.
$Scypha$ is a synonym for $Sycon$.
Therefore,the correct identification for the given diagram is $Euspongia$.

(D) In sponges (Phylum Porifera),water enters the body through minute pores called $Ostia$ present on the body wall.
From the $Ostia$,water enters a central cavity known as the $Spongocoel$.
Finally,the water leaves the body through a large opening called the $Osculum$.
Therefore,the correct path of water flow is $Ostia \rightarrow Spongocoel \rightarrow Osculum$.

(D) The phylum $Porifera$ includes organisms commonly known as sponges.
These are primitive multicellular animals with a cellular level of body organization,not a tissue level.
They possess numerous pores on their body called $ostia$ for water entry and a central cavity called $spongocoel$.
Therefore,the statement that sponges have a tissue level of body organization is incorrect.

(B) Collar cells,also known as $choanocytes$,are specialized flagellated cells that line the $spongocoel$ and the canals of sponges ($Phylum$ $Porifera$).
These cells help in creating water currents and capturing food particles.
$Sycon$ is a member of $Phylum$ $Porifera$,whereas $Jelly$ $fish$ belongs to $Phylum$ $Cnidaria$,$Taenia$ to $Phylum$ $Platyhelminthes$,and $Pila$ to $Phylum$ $Mollusca$.
Therefore,the correct answer is $Sycon$.

(A) The water transport system,also known as the water canal system,is a unique and defining characteristic of the phylum $Porifera$ (sponges).
In this system,water enters through minute pores called $ostia$ in the body wall into a central cavity called $spongocoel$,and from there,it goes out through the $osculum$.
$Sycon$ is a member of the phylum $Porifera$.
$Physalia$ belongs to the phylum $Cnidaria$.
$Ctenoplana$ belongs to the phylum $Ctenophora$.
$Taenia$ belongs to the phylum $Platyhelminthes$.

(A) Based on the standard diagrams provided in the $NCERT$ Biology textbook for Class $11$ (Chapter $4$: Animal Kingdom,Figure $4.3$):
$1$. Image $(a)$ represents $Sycon$,which is a marine sponge with a branched,tubular body structure.
$2$. Image $(b)$ represents $Spongilla$,which is a freshwater sponge typically having a massive,encrusting,or globular body form.
$3$. Image $(c)$ represents $Euspongia$,commonly known as the bath sponge,which has a complex,branching,or irregular body structure.
Therefore,the correct identification is $(a) \rightarrow$ Sycon,$(b) \rightarrow$ Spongilla,$(c) \rightarrow$ Euspongia.