Pteridophytes (General) Questions in English

(B) In Pteridophyta and gymnosperms,companion cells are absent. Instead,specialized parenchyma cells known as $Albuminous$ $cells$ (or $Strasburger$ $cells$) are present.
These cells are physiologically associated with sieve cells and perform functions similar to companion cells,such as the transport of nutrients and metabolic support.
Therefore,the correct option is $B$.

(B) Xylem vessels are characteristic features of angiosperms. They are generally absent in pteridophytes and gymnosperms (with a few exceptions like $Ephedra$,$Gnetum$,$Selaginella$,and $Pteridium$).
Companion cells are specialized parenchyma cells associated with sieve tubes in the phloem of angiosperms. They are absent in pteridophytes and gymnosperms,which instead possess albuminous cells.

(B) Trabeculae are formed by the modification of the endodermis. In the stem of $Selaginella$,the endodermis cells become elongated radially and develop Casparian strips,forming structures known as trabeculae. These trabeculae bridge the gap between the stele and the cortex,providing support to the stele.

(C) The term $Protostele$ was coined by $Jeffrey$.
It is the simplest and most primitive type of stele,characterized by a solid central core of xylem surrounded by phloem.
$Actinostele$ is a specific type of $Protostele$ where the central xylem core is star-shaped in cross-section.
Therefore,$Actinostele$ is a modification of $Protostele$.

(A) Amphicribal or hadrocentric vascular bundles are a type of closed vascular bundle where the xylem is located in the center and is completely surrounded by phloem.
These are characteristic of certain Pteridophytes, such as $Selaginella$ and other ferns.
In contrast, $Dracaena$, $Cucurbita$, and $Zea mays$ are angiosperms that typically possess collateral or bicollateral vascular bundles.

(A) In $mesarch$ xylem,the $protoxylem$ is surrounded by $metaxylem$ on all sides. This type of xylem arrangement is a characteristic feature of $ferns$ (pteridophytes) and is typically found in their stems.

(C) $protostele$ is the simplest type of stele,characterized by a solid central core of xylem surrounded by a layer of phloem.
It is considered the most primitive type of stele.
$Protosteles$ are typically found in the stems of primitive vascular plants,specifically in many members of the $Pteridophyta$ group (such as $Lycopodium$ and $Selaginella$).
Therefore,the correct option is $C$.

(A) An ectophloic siphonostele is a type of stele where the phloem is restricted to the outer side of the xylem,surrounding it completely.
This arrangement is characteristic of certain pteridophytes.
Examples include $Osmunda$ and $Equisetum$.

(B) The apical cell in lower vascular plants (like Pteridophytes) is typically tetrahedral or pyramidal in shape.
Although it is four-sided (having one base and three lateral faces),when viewed in a $T.S.$ (Transverse Section),it appears as a triangle with three sides.
Therefore,it is commonly referred to as a three-sided apical cell.

(A) When a sporangium develops from a single initial cell,it is known as the $Leptosporangiate$ type.
In this type,the sporangial wall is typically single-layered.
Conversely,when a sporangium develops from a group of cells,it is called $Eusporangiate$.

(A) $Azolla$ is an aquatic pteridophyte that forms a symbiotic relationship with the cyanobacterium $Anabaena$ $azollae$.
This cyanobacterium resides in the leaf cavities of $Azolla$ and is capable of fixing atmospheric nitrogen.
Therefore,$Azolla$ is widely used as a biofertilizer in rice fields to enhance nitrogen availability.

(C) The plant body of $Pteridophytes$ is differentiated into true roots, stems, and leaves.
$Thallophyta$ (like algae) have a thallus-like body without differentiation.
$Bryophytes$ have root-like, stem-like, and leaf-like structures but lack true vascular tissues and true roots, stems, or leaves.
$Lichens$ are symbiotic associations between algae and fungi and do not possess true roots, stems, or leaves.

(A) In the plant kingdom,the life cycle involves an alternation of generations between a haploid gametophyte and a diploid sporophyte.
In $Bryophytes$ (like $Funaria$ and $Anthoceros$),the gametophyte is the dominant,independent,and photosynthetic phase.
In $Pteridophytes$ (like $Nephrolepis$),the sporophyte is the dominant phase,and the gametophyte is a small,inconspicuous,and often short-lived structure,which can be considered secondary or reduced compared to the sporophyte.
Therefore,the gametophytic phase is secondary in $Nephrolepis$.

(B) Pteridophytes are classified based on the type of spores they produce.
Most pteridophytes produce only one type of spore,known as homosporous (e.g.,Psilotum,Equisetum,Dryopteris).
Some pteridophytes,such as Selaginella and Salvinia,produce two kinds of spores,macro (large) and micro (small) spores,and are known as heterosporous.
Among the given options,Equisetum is a homosporous pteridophyte,while Selaginella and Marsilea are heterosporous.

(D) In pteridophytes,the male sex organ is called the antheridium and the female sex organ is called the archegonium. Both of these organs are responsible for sexual reproduction by producing male and female gametes,respectively. Therefore,both $(B)$ and $(C)$ are correct.

(D) The plant kingdom is classified based on the presence or absence of vascular tissues ($xylem$ and $phloem$).
$1$. Thallophytes (Algae) lack vascular tissues.
$2$. Bryophytes are non-vascular plants.
$3$. Pteridophytes are the first group of plants to evolve well-developed vascular tissues ($xylem$ and $phloem$) for the conduction of water and nutrients.
$4$. Gymnosperms and Angiosperms also possess vascular tissues,but Pteridophytes were the first to evolve them.
Therefore,the correct option is $D$.

(D) $Rhynia$ is a well-known fossil pteridophyte belonging to the class $Psilophytopsida$. It is considered one of the earliest vascular plants found in the fossil record,dating back to the $Devonian$ period. Unlike $Dryopteris$,$Equisetum$,and $Selaginella$,which are extant (living) genera,$Rhynia$ is extinct.

(C) In plants,specifically in gymnosperms and pteridophytes,the leaves that bear sporangia (structures producing spores) are known as sporophylls.
Microspores are produced in microsporophylls,and megaspores are produced in megasporophylls.
Therefore,the general term for leaves that produce spores is sporophylls.

(C) Prophylls are the first leaves produced on a shoot or a branch. In many plants,especially in certain gymnosperms and some pteridophytes,these are typically small,scale-like,and brown in color. They serve as protective structures for the developing shoot apex or the bud.

(D) In $Pteridophytes$,the main plant body is a $sporophyte$ $(2n)$,which is differentiated into true root,stem,and leaves.
The $gametophyte$ stage is small,inconspicuous,multicellular,free-living,and usually photosynthetic,but in some cases,it can be subterranean and short-lived.
In $Angiosperms$ and $Gymnosperms$,the gametophyte is highly reduced and dependent on the sporophyte.
In $Bryophytes$,the gametophyte is the dominant,independent,and photosynthetic phase.
Therefore,the description of a reduced,haploid,short-lived,and subterranean gametophyte is characteristic of $Pteridophytes$.

(D) haplo-diplontic life cycle is characterized by the alternation between a multicellular haploid gametophyte and a multicellular diploid sporophyte.
This type of life cycle is observed in Bryophytes and Pteridophytes.
Among the given options,Pteridophytes exhibit a haplo-diplontic life cycle,where both phases are multicellular and often free-living,though the sporophyte is the dominant phase.

(C) Pteridophytes are vascular plants that reproduce via spores and do not produce seeds or flowers. Like Bryophytes and seed-bearing plants (Gymnosperms and Angiosperms),Pteridophytes form embryos during their life cycle. Therefore,they are classified as Embryophytes. They are the first group of plants to possess a well-developed vascular system ($Xylem$ and $Phloem$).

(D) In Pteridophytes,the main plant body is a sporophyte,which is diploid $(2n)$.
This sporophyte is independent,long-lived,and photosynthetic.
It is differentiated into true roots,stems,and leaves.
Therefore,being 'parasitic' is not a characteristic of the main plant body of Pteridophytes,as they are autotrophic.

(D) In Pteridophytes,the sporophylls (leaves bearing sporangia) can produce spores.
Based on the type of spores produced,Pteridophytes are classified into two categories:
$1$. Homosporous: Plants that produce only one type of spore (e.g.,$Dryopteris$).
$2$. Heterosporous: Plants that produce two different types of spores,macrospores and microspores (e.g.,$Selaginella$,$Salvinia$).
Therefore,Pteridophytes can be either homosporous or heterosporous.

(C) $1$. In Pteridophytes (like ferns),the main plant body is a sporophyte,which is differentiated into true root,stem,and leaves.
$2$. This sporophytic phase is long-lived and dominant in the life cycle.
$3$. The gametophytic phase,known as the prothallus,is small,inconspicuous,and multicellular,often heart-shaped and photosynthetic.
$4$. Therefore,statement $A$ is true because the sporophyte is the dominant phase.
$5$. Statement $R$ is false because the sporophyte is not a thallus; the gametophyte (prothallus) is the thalloid structure.

(C) $Nephrolepis$ (fern) is a pteridophyte,which is a type of cryptogam (non-flowering plant). Therefore,statement $A$ is true.
Bryophytes are non-vascular plants like mosses and liverworts. Since $Nephrolepis$ is a pteridophyte (vascular cryptogam),statement $R$ is false.
Thus,$A$ is true and $R$ is false.

(A) $S$ is true: $Pteridophytes$ are spore-producing vascular plants where spores are formed within specialized structures called sporangia.
$R$ is true: These sporangia are typically borne on leaf-like appendages known as sporophylls.
Since the production of spores in sporangia $(S)$ is a direct consequence of the sporangia being located on sporophylls $(R)$,$R$ provides the correct explanation for $S$.

(C) : $Equisetum$ is a pteridophyte. Like other pteridophytes,it produces sex organs known as antheridia (male) and archegonia (female). Thus,statement $A$ is true.
$R$: In pteridophytes,the dominant phase is the sporophyte,which is diploid. The gametophyte (prothallus) is small,inconspicuous,and usually short-lived. It is not long-lived. Therefore,statement $R$ is false.

(C) $Selaginella$ is a pteridophyte that produces two types of spores,microspores and megaspores,hence it is heterosporous.
This is a significant evolutionary step towards the seed habit.
However,the strobili (cones) in $Selaginella$ are typically bisexual,containing both microsporophylls and megasporophylls.
Therefore,the assertion $A$ is true,but the reason $R$ is false.

(B) $1$. $Equisetum$ is a Pteridophyte and possesses vascular tissues (xylem and phloem). Thus,option $A$ is incorrect.
$2$. $Selaginella$ is a well-known heterosporous Pteridophyte,producing two types of spores: microspores and megaspores. Thus,option $B$ is correct.
$3$. $Ferns$ typically reproduce vegetatively through rhizomes or adventitious buds,not gemmae (which are characteristic of liverworts like $Marchantia$). Thus,option $C$ is incorrect.
$4$. $Rhynia$ is a fossil Pteridophyte,not a bryophyte. Thus,option $D$ is incorrect.

(D) The correct pair is $Equisetum$ - Asexual reproduction by heterospory.
$Equisetum$ (horsetail) is a pteridophyte that produces two types of spores (microspores and megaspores),a condition known as heterospory.
$Strychnos$ is an angiosperm,not a spore-producing plant.
Bread mold $(Rhizopus)$ reproduces asexually by sporangiospores,not conidia.
$Anthoceros$ (a bryophyte) reproduces vegetatively by tubers or death and decay of older parts,not by gemmae (gemmae are characteristic of $Marchantia$).

(A) In $Pteridophytes$,plants that produce only one type of spore are called $Homosporous$ plants. Examples include $Psilotum$ and $Equisetum$. In contrast,plants that produce two types of spores (microspores and megaspores) are called $Heterosporous$ plants,such as $Selaginella$ and $Salvinia$.

(A) The prothallus of $Dryopteris$ (a fern) is a heart-shaped,photosynthetic,independent gametophyte.
In ferns,the sex organs,which are the antheridia (male) and archegonia (female),are typically found on the ventral or lower surface of the prothallus.
This position protects the delicate sex organs from desiccation and facilitates the movement of flagellated sperms towards the egg in the presence of water.
Therefore,both antheridia and archegonia are located on the lower surface of the prothallus.

(B) In pteridophytes,the main plant body is a sporophyte $(2n)$.
These sporophytes bear sporangia in which spore mother cells $(2n)$ are present.
Reduction division (meiosis) occurs in these spore mother cells to produce haploid $(n)$ spores.
Therefore,the correct answer is spore mother cell.

(A) In $Pteridophytes$,the main plant body is a sporophyte,which is differentiated into true root,stem,and leaves.
The gametophyte,known as the $prothallus$,is small,inconspicuous,multicellular,and usually free-living.
It is photosynthetic and requires cool,damp,and shady places to grow.
The gametophyte bears the male and female reproductive organs called $antheridia$ and $archegonia$,respectively.

(D) In $Pteridophytes$, the sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls.
In some $Pteridophytes$ like $Selaginella$, these sporophylls may form distinct compact structures called strobili or cones.
These sporophylls are often green and photosynthetic in nature, contributing to the plant's energy production.
Therefore, photosynthetic sporophylls are a characteristic feature found in $Pteridophytes$.

(D) Pteridophytes are classified into $4$ main classes:
$1$. $Psilopsida$ (e.g.,$Psilotum$)
$2$. $Lycopsida$ (e.g.,$Selaginella$,$Lycopodium$)
$3$. $Sphenopsida$ (e.g.,$Equisetum$)
$4$. $Pteropsida$ (e.g.,$Dryopteris$,$Pteris$,$Adiantum$)
$Bryopsida$ is a class of $Bryophytes$,not $Pteridophytes$. Therefore,the correct option is $D$.

(A) The evolution of the seed habit is a critical evolutionary trend in plants.
In $Selaginella$ and $Salvinia$,the female gametophyte is not completely independent; instead,it is retained on the parent sporophyte for a variable period.
The development of the zygote into a young embryo takes place within the female gametophyte,which is held on the parent sporophyte.
This retention and development of the embryo within the female gametophyte,which is attached to the parent plant,is a precursor to the seed habit found in higher plants (gymnosperms and angiosperms).

(A) Ovules are specialized structures that develop into seeds after fertilization.
In the plant kingdom,$Pteridophytes$ (ferns and their allies) are vascular cryptogams that reproduce via spores and do not produce seeds or ovules.
$Gymnosperms$ and $Angiosperms$ are seed-bearing plants (Spermatophytes) and both possess ovules.
Therefore,ovules are absent in $Pteridophytes$.

(B) In the life cycle of pteridophytes,the main plant body is a sporophyte,which is differentiated into true root,stem,and leaves. This sporophyte is the dominant,independent,and photosynthetic phase of the plant. The gametophyte phase is small,inconspicuous,and usually short-lived. Therefore,the correct option is $B$.

(A) The aquatic fern $Azolla$ belongs to the family $Salviniaceae$. It is a heterosporous pteridophyte. In these aquatic ferns,the sporangia are enclosed within a specialized,hardened,nut-like structure known as a sporocarp. $Selaginella$ is a heterosporous pteridophyte but is not primarily aquatic. $Pteridium$ and $Equisetum$ are terrestrial plants. Therefore,the correct answer is $Azolla$.

(B) In many ferns,the young leaves (circinate vernation) and rhizomes are covered with brown,dry,scaly,hair-like structures known as ramenta. These structures provide protection against desiccation and mechanical injury.

(A) The genus $Selaginella$ belongs to the class $Lycopsida$ of the division $Pteridophyta$.
$Selaginella$ is characterized by the presence of heterospory,meaning it produces two types of spores: microspores and megaspores.
Additionally,the leaves of $Selaginella$ are small (microphylls) and possess a small,scale-like outgrowth at the base on the adaxial surface known as a $ligule$.
Therefore,the presence of heterospory and ligulate leaves is a diagnostic feature of $Selaginella$.

(C) Pteridophytes exhibit diversity in the size of their leaves.
$1$. Microphyllous leaves are small,as seen in $Selaginella$.
$2$. Macrophyllous leaves are large,as seen in ferns.
Therefore,pteridophytes can be either microphyllous or macrophyllous.

(A) In many pteridophytes,the sporophylls (spore-bearing leaves) may form distinct compact structures called strobili or cones (e.g.,in Selaginella or Equisetum). These structures are specialized for the production and protection of spores.

(A) Cambium is a lateral meristem responsible for secondary growth in plants.
Secondary growth is a characteristic feature of most dicotyledonous angiosperms and gymnosperms.
Pteridophytes lack secondary growth because they do not possess vascular cambium.
Therefore,cambium is absent in Pteridophytes.

(A) In the classification of Pteridophytes,the class $Lycopsida$ is characterized by the presence of small leaves known as microphylls. Examples include $Selaginella$ and $Lycopodium$. In contrast,$Pteropsida$ typically possesses large leaves known as megaphylls. Therefore,the correct classification for plants with microphylls is $Lycopsida$.

(C) In $Pteridophytes$,the main plant body is a sporophyte,which is differentiated into true roots,stems,and leaves.
These leaves bear sporangia that are subtended by leaf-like appendages called sporophylls.
Inside the sporangia,spore mother cells undergo meiosis to produce spores.
Therefore,the spore-producing part is the sporangium of the sporophyte.

(B) In $Dryopteris$ (fern),the primary root is short-lived and is replaced by adventitious roots that arise from the rhizome. These adventitious roots are the permanent roots of the plant. Therefore,the correct option is $B$.

(B) In pteridophytes,the main plant body is a sporophyte.
When the spores are released from the sporangia,they germinate in suitable conditions.
This germination process gives rise to a small,multicellular,free-living,mostly photosynthetic,thalloid gametophyte,which is known as the prothallus.
Therefore,the germination of spores in pteridophytes leads to the formation of the prothallus.