Phylum - Ctenophora Questions in English

(D) $Ctenophora$ is a small phylum of marine animals,which are commonly known as comb jellies or sea walnuts.
These animals possess eight external rows of ciliated comb plates,which help in locomotion.
The name $Ctenophora$ is derived from two Greek words: $ctenos$ = comb and $phora$ = bearing.

(B) phylum is considered a 'minor phylum' if it contains a very limited number of species or genera compared to major phyla like $Arthropoda$ or $Chordata$.
$Ctenophora$ is classified as a minor phylum because it comprises only a small number of known genera and species (approximately $100-150$ species).
Therefore,the correct reason is that it includes only a few genera.

(B) minor phylum is defined as a phylum that contains a relatively small number of species compared to major phyla like $Arthropoda$ or $Mollusca$. $Ctenophora$ (comb jellies) is considered a minor phylum because it comprises only about $100-150$ described species,which is a very low diversity compared to other animal phyla.

(D) The phylum $Ctenophora$,commonly known as sea walnuts or comb jellies,exhibits several unique characteristics:
$1$. They possess eight external rows of ciliated comb plates,which help in locomotion.
$2$. Unlike the phylum $Cnidaria$,they lack cnidoblasts (stinging cells).
$3$. They possess specialized cells called $lasso$ $cells$ or $colloblasts$ on their tentacles,which are used for capturing prey.
Since all these statements are correct,the correct option is $D$.

(D) : In $Ctenophora$,asexual reproduction is absent. They are monoecious and fertilization is generally external.
In $Cnidaria$,asexual reproduction (budding) is found in the polyps and sexual reproduction is found in the medusa form.
Both asexual and sexual reproduction occur in $Porifera$ (sponges). Asexual reproduction occurs by budding and gemmules.
In $Protozoa$,asexual reproduction takes place by binary fission,budding,etc.,and sexual reproduction takes place by syngamy and conjugation.

(C) : $Ctenophora$ is a small phylum of exclusively marine,invertebrate animals. $Ctenoplana$ and $Beroe$ are examples of $Ctenophora$. They exhibit biradial symmetry,which is a combination of radial and bilateral symmetries. They lack the specialized stinging cells known as cnidoblasts or nematocysts,which are characteristic of the phylum $Cnidaria$ (coelenterates). Although one species,$Haeckelia$ $rubra$,can incorporate stinging cells from its jellyfish prey for defense,it is not a general characteristic of the phylum.

(B) The phylum that exhibits bioluminescence is $Ctenophora$.
$Ctenophora$ are exclusively marine,radially symmetrical,and diploblastic organisms.
They possess tissue-level organization.
They are hermaphrodite (sexes are not separate).
They are acoelomate.
Therefore,among the given options,'Diploblastic' is the correct characteristic for $Ctenophora$.

(A) Ctenophores (comb jellies) are exclusively marine animals.
They exhibit radial symmetry.
They are diploblastic,meaning they have two germ layers: ectoderm and endoderm.
They possess a tissue level of body organization.
Therefore,$X$ is radial symmetrical and $Y$ is diploblastic.

(B) Bioluminescence,the property of a living organism to emit light,is a well-known characteristic of the phylum $Ctenophora$.
These organisms are commonly known as sea walnuts or comb jellies.
The light emission is typically a result of chemical reactions within the organism's body.

(C) $Ctenoplana$ belongs to the phylum $Ctenophora$.
Members of the phylum $Ctenophora$ are exclusively marine and are known as comb jellies or sea walnuts.
These organisms are hermaphrodite,meaning they possess both male and female reproductive organs.
Reproduction in $Ctenophora$ takes place only by sexual means.
They do not exhibit asexual reproduction like budding or fission.

(A) The question asks for organisms that exhibit bilateral symmetry and the absence of true tissues (often referred to as 'absence of cells' in some contexts,though biologically it implies the lack of tissue-level organization or specific cellular differentiation). However,in the context of the $Animal$ $Kingdom$,$Ctenophora$ (like $Ctenoplana$ and $Beroe$) are known for their radial symmetry. The question likely refers to the absence of true tissue-level organization. $Ctenoplana$ and $Beroe$ belong to the phylum $Ctenophora$. Note: If the question implies 'absence of true tissues',it is a characteristic of $Porifera$. Given the options,$Ctenoplana$ and $Beroe$ are the standard examples for $Ctenophora$.

(N/A) $Ctenophora$,commonly known as sea walnuts or comb jellies,are exclusively marine organisms.
They are diploblastic,radially symmetrical,and have tissue-level organization.
The body bears $8$ external rows of ciliated comb plates,which help in locomotion.
Digestion is both extracellular and intracellular.
Bioluminescence (the property of a living organism to emit light) is well-marked in $Ctenophora$.
Sexes are not separate (hermaphrodite).
Reproduction takes place only by sexual means.
Fertilization is external with indirect development.
Examples include $Pleurobrachia$ and $Ctenoplana$.

(N/A) $\rightarrow$ Bioluminescence,the property of a living organism to emit light,is well-marked in ctenophores.
$\rightarrow$ Ctenophores,commonly known as sea walnuts or comb jellies,are exclusively marine,radially symmetrical,diploblastic organisms with tissue level of organisation.
$\rightarrow$ The body bears eight external rows of ciliated comb plates,which help in locomotion.
$\rightarrow$ Digestion is both extracellular and intracellular.
$\rightarrow$ Sexes are not separate (hermaphrodite).
$\rightarrow$ Reproduction takes place only by sexual means.
$\rightarrow$ Fertilisation is external with indirect development.
$\rightarrow$ Examples: Pleurobrachia and Ctenoplana.

(N/A) $\rightarrow$ Bioluminescence,the property of a living organism to emit light,is a well-marked characteristic of the phylum $Ctenophora$.
$\rightarrow$ $Ctenophores$,commonly known as sea walnuts or comb jellies,are exclusively marine,radially symmetrical,and diploblastic organisms with a tissue level of body organisation.
$\rightarrow$ The body bears eight external rows of ciliated comb plates,which help in locomotion.
$\rightarrow$ Digestion is both extracellular and intracellular.
$\rightarrow$ Sexes are not separate (hermaphrodite).
$\rightarrow$ Reproduction takes place only by sexual means.
$\rightarrow$ Fertilisation is external with indirect development.
$\rightarrow$ Examples: $Pleurobrachia$ and $Ctenoplana$.

(D) $Pleurobrachia$ belongs to phylum-$Ctenophora$.
$Ctenophora$ are diploblastic,with tissue level of organisation and presence of comb plates.
Comb plates are a characteristic feature of phylum-$Ctenophora$.
$Pleurobrachia$ are not triploblastic; therefore,the statement that they are triploblastic is incorrect.

(D) $Pleurobrachia$ (Sea gooseberry) belongs to the phylum $Ctenophora$.
$Ctenophores$ bear eight external rows of ciliated comb plates.
These comb plates possess cilia that are fused together to form the plates.
The primary function of these ciliated comb plates is to assist in locomotion.

(B) $Ctenoplana$ belongs to the phylum $Ctenophora$.
$Ctenophores$ are multicellular animals that exhibit radial symmetry and possess a tissue level of organization.

(A) Bioluminescence is the property of production and emission of light by a living organism.
This property is well-marked in phylum $Ctenophora$.
Most ctenophores emit light by special light-producing cells called $photocytes$.

(C) Biradial symmetry and the absence of cnidoblasts are the defining characteristics of the phylum $Ctenophora$.
$Ctenoplana$ and $Pleurobrachia$ are members of the phylum $Ctenophora$,commonly known as comb jellies.
Unlike the phylum $Cnidaria$,members of $Ctenophora$ lack cnidoblasts (stinging cells) and instead possess colloblasts for prey capture.

(C) $Ctenophora$ possess a unique sense organ known as the $statocyst$ located at the aboral end,which is the end opposite to the mouth. This is a diagnostic and characteristic feature of the phylum $Ctenophora$.

(N/A) $\rightarrow$ Bioluminescence is the property of a living organism to emit light. It is a well-known characteristic of the phylum $Ctenophora$ (comb jellies),where the organism produces and emits light through chemical reactions within its body.

(N/A) The animals that exhibit the phenomenon of bioluminescence are $Pleurobrachia$ and $Ctenoplana$. These animals belong to the phylum $Ctenophora$.

(C) Bioluminescence (the property of a living organism to emit light) is a well-marked characteristic of the phylum $Ctenophora$. These organisms are commonly known as sea walnuts or comb jellies. They possess eight external rows of ciliated comb plates which help in locomotion.

(B) The organism shown in the image is $Pleurobrachia$,which belongs to the phylum $Ctenophora$.
It is characterized by the presence of $8$ external rows of ciliated comb plates,which help in locomotion.
$Pleurobrachia$ is commonly known as the sea gooseberry.
$Ctenoplana$ is another member of this phylum but has a different body shape.
Jellyfish belong to the phylum $Cnidaria$,and sea fans $(Gorgonia)$ also belong to the phylum $Cnidaria$.

(D) The phylum $Ctenophora$ is commonly known as sea walnuts or comb jellies.
These organisms are exclusively marine,radially symmetrical,and diploblastic.
They possess eight external rows of ciliated comb plates,which help in locomotion.

(B) The phylum $Ctenophora$,commonly known as sea walnuts or comb jellies,possesses eight external rows of ciliated comb plates on the body. These comb plates are specialized structures that help in locomotion by beating in a coordinated manner. Therefore,the primary function of the comb plates is locomotion.

(D) The phylum $Ctenophora$ is commonly known as sea walnuts or comb jellies.
These organisms possess $8$ external rows of ciliated comb plates on their body.
These comb plates are composed of cilia that beat to facilitate locomotion in the water.
Therefore,the correct number of rows is $8$.

(C) In the phylum $Ctenophora$,digestion is both extracellular and intracellular.
Extracellular digestion occurs in the gastrovascular cavity,while intracellular digestion occurs within the cells lining the cavity.

(B) Bioluminescence is the property of a living organism to emit light.
This phenomenon is a well-known characteristic of the phylum $Ctenophora$.
Among the given options,$Pleurobrachia$ belongs to the phylum $Ctenophora$ (also known as sea walnuts or comb jellies).
$Sycon$ belongs to $Porifera$,$Hydra$ belongs to $Cnidaria$,and $Taenia$ belongs to $Platyhelminthes$.
Therefore,the correct option is $B$.

(D) The correct answer is $D$.
Phylum $Ctenophora$ exhibits the following characteristics:
$1$. They are exclusively marine,radially symmetrical,and diploblastic organisms.
$2$. Their body bears eight external rows of ciliated comb plates,which help in locomotion.
$3$. Digestion in these organisms is both extracellular and intracellular.
$4$. Reproduction takes place only by sexual means.