Pteridophytes (General) Questions in English

(B) In ferns,approximately $32$ multiflagellate,spirally coiled sperms are produced in the antheridium.
These sperms swim towards the open archegonia due to the presence of malic acid in the archegonial neck,which acts as a chemical stimulus.
This movement of sperms in response to a chemical gradient is known as chemotaxis.

(B) Indusium is a thin,membranous outgrowth of the leaf surface that covers and protects the developing sori (clusters of sporangia) in ferns. It is a characteristic feature of many pteridophytes,specifically ferns.

(B) In ferns,the main plant body is a sporophyte,which produces spores through meiosis.
These spores germinate to form a small,multicellular,photosynthetic,free-living,thalloid gametophyte known as the prothallus.
The prothallus bears sex organs called antheridia (male) and archegonia (female),which produce gametes (sperm and eggs,respectively).
Therefore,the prothallus is responsible for the production of gametes.

(A) The characteristic feature of fern leaves is circinate vernation,in which the young leaves are coiled like a watch spring in the bud stage.

(A) $Dryopteris$ is a genus of ferns. The antherozoids (male gametes) produced by the prothallus of $Dryopteris$ are characteristically large,spirally coiled,and multiflagellate structures. They possess a prominent vesicle and a nucleus,which helps them in swimming through the water film to reach the archegonia.

(A) Pteridophytes that produce two kinds of spores,macro (large) and micro (small) spores,are known as heterosporous.
Examples of heterosporous pteridophytes include $Selaginella$ and $Salvinia$.
Most pteridophytes are homosporous,meaning they produce only one type of spore.

(C) Ramenta are thin,brown,scale-like or hair-like outgrowths that cover the stems,petioles,and young leaves of many ferns (pteridophytes).
Among the given options,$Marchantia$ is a bryophyte (liverwort),$Laminaria$ is an alga (brown algae),$Sequoia$ is a gymnosperm,and $Equisetum$ is a pteridophyte (horsetail). While ramenta are most typically associated with true ferns (Filicopsida),$Equisetum$ is the only pteridophyte listed here,and it is the most appropriate choice in the context of plant morphology studies involving these groups.

(C) The heart-shaped prothallus is the independent,photosynthetic gametophytic stage in the life cycle of ferns (Pteridophytes).
It bears both male reproductive organs (antheridia) and female reproductive organs (archegonia) on the same thallus.
Therefore,it is a monoecious gametophyte.

(B) Pteridophytes are called vascular cryptogams because,among cryptogams,vascular tissues are present only in pteridophytes.
All the vegetative parts of pteridophytes possess vascular tissues,i.e.,$xylem$ and $phloem$.

(C) Pteridophytes are the first group of plants to possess vascular tissues ($xylem$ and $phloem$).
They are spore-forming,non-seed-bearing,and non-flowering vascular plants.
Thallophytes (like algae) do not have vascular tissues.
Bryophytes are also non-vascular plants.
Spermatophytes are seed-bearing vascular plants,which include gymnosperms and angiosperms,and they evolved after pteridophytes.

(B) In the life cycle of plants,the dominant phase refers to the generation that is independent,photosynthetic,and long-lived. In bryophytes (like Marchantia,Mosses,and Liverworts),the gametophytic generation is dominant. In Pteridophytes,such as Ferns,the sporophytic generation is the dominant phase,which is differentiated into true roots $(2n)$,stems,and leaves.

(D) The class $Pteropsida$ under the division $Pteridophyta$ includes ferns. Common examples of plants belonging to this class are $Dryopteris$,$Pteris$,and $Adiantum$. Therefore,$Pteris$ and $Adiantum$ are the correct representatives of this class.

(C) Maidenhair fern is the common name given to the fern $Adiantum$ $capillus-veneris$.
It is known as maidenhair fern or Venus hair fern because of its delicate,long,dark-colored leaf stalks that resemble human hair and its feathery foliage that gently wafts in the breeze.
$Adiantum$ is a genus of about $250$ species of ferns in the family $Pteridaceae$.

(C) In ferns,the sporangium consists of a stalk and a capsule. The capsule is filled with sporocytes,which undergo meiosis to produce haploid spores.
The one-layered wall of the capsule is thin and features a specialized strip of cells known as the annulus.
The cells of the annulus have thickenings on their inner and radial walls,but in certain regions,the cells are thin-walled. These regions are called the stomium.
Both the annulus and the stomium work together to facilitate the dispersal of spores.

(B) Pteridophytes are known as vascular cryptogams.
They possess well-developed vascular tissues (xylem and phloem) for the conduction of water and nutrients.
They reproduce by producing spores and do not form seeds,which distinguishes them from gymnosperms and angiosperms.

(B) $Pteridophytes$ are considered the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$).
All the vegetative parts of $Pteridophytes$ possess vascular tissues,which are organized into definite groups.

(A) In $Equisetum$,the anterior part of the antherozoid (sperm) is spirally coiled and has numerous flagella,whereas the posterior part is somewhat expanded.
In contrast,the sperms of $Lycopodium$,$Riccia$,and $Anthoceros$ are biflagellated (possess two flagella).

(B) The provided figure represents the pteridophyte $Equisetum$.
In this plant:
$A$ points to the $Strobilus$ (or cone), which is a structure bearing sporangia.
$B$ points to the $Node$, the region on the stem from where branches or leaves arise.
$C$ points to the $Branch$ (or lateral branch), which arises from the node.
Therefore, the correct identification is $A-Strobilus, B-Node, C-Branch$.

(D) Ferns exhibit a life cycle characterized by the alternation of generations,where the dominant,independent sporophyte generation is morphologically very distinct from the small,inconspicuous,and independent gametophyte generation. This is known as a heteromorphic life cycle.

(A) In Selaginella,the male gametophyte development begins within the microspore while it is still inside the microsporangium.
The mature $13$-celled male gametophyte consists of:
$1$ prothallial cell (which is the first cell formed).
$4$ jacket cells (which form the outer layer of the antheridium).
$8$ androgonial cells (which eventually produce the spermatozoids).
Thus,the total number of cells is $1 + 4 + 8 = 13$ cells.
This corresponds to $1$ prothallial cell and $12$ antheridial cells ($4$ jacket $+ 8$ androgonial cells).

(A) Heterosporous pteridophytes,such as $Selaginella$ and $Marsilea$,produce two types of spores: microspores and megaspores.
Microspores germinate to form the male gametophyte,while megaspores germinate to form the female gametophyte.
Since the male and female gametophytes develop from separate spores,the gametophyte is always dioecious.

(C) In some pteridophytes, sporophylls aggregate to form distinct compact structures called cones or strobili $(A)$.
Examples of such pteridophytes include $Selaginella$ $(B)$ and $Equisetum$ $(C)$.
Therefore, $A$ is strobilus, $B$ is $Selaginella$, and $C$ is $Equisetum$.

(D) Statement $I$ is correct: In ferns (pteridophytes),water is essential for the transfer of antherozoids to the mouth of the archegonium.
Statement $II$ is correct: The male gametophyte (prothallus) produces antheridia (male sex organs) which release antherozoids,and the female gametophyte produces archegonia (female sex organs) which contain the egg cell.
Statement $III$ is correct: Fertilization involves the fusion of the antherozoid with the egg cell to form a zygote. The zygote undergoes mitotic divisions to form an embryo,which eventually develops into a mature sporophyte plant.

(D) Antherozoids are the flagellated or ciliated male gametes produced in the antheridia of bryophytes,pteridophytes,and some gymnosperms. They are motile and swim through a film of water to reach the female gamete (egg) for fertilization. Therefore,they represent motile male gametes.

(A) In $Pteridophytes$,the spores germinate to produce a small,multicellular,free-living,mostly photosynthetic thalloid gametophyte called $Prothallus$.

(B) In $Selaginella$,the zygote undergoes division to form an embryo. This embryo subsequently develops into the $sporophyte$ generation,which is the dominant phase in the life cycle of pteridophytes.

(D) In pteridophytes,the megaspore germinates to form the female gametophyte. Unlike seed plants,the female gametophyte in pteridophytes is retained on the parent sporophyte for variable periods,but it develops from the megaspore.

(C) In pteridophytes,the zygote develops into a young embryo within the female gametophyte. This retention and development of the embryo within the female gametophyte is an evolutionary step that eventually led to the development of the seed habit in higher plants (spermatophytes).

(C) Pteridophytes are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$) but they do not produce seeds.
Among the given options,Ferns belong to the group Pteridophytes.
Mosses and Liverworts are Bryophytes,which lack vascular tissues.
Volvox is an Alga.

(D) In the plant kingdom,the main plant body is differentiated into true root,stem,and leaves starting from the group $Pteridophytes$.
$1$. Green algae and Blue-green algae (Cyanobacteria) have a thalloid body structure.
$2$. Bryophytes have a plant body that is thallus-like or leaf-like but lacks true roots,stems,or leaves.
$3$. Pteridophytes are the first group of land plants to possess true roots,stems,and leaves along with a well-developed vascular system.

(B) Pteridophytes are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$). While bryophytes are the first land plants, they lack true vascular tissues. Pteridophytes represent the evolutionary transition where complex transport systems first appeared in land plants.

(D) In pteridophytes,the male gametes (antherozoids) are released from the antheridium and travel through water to reach the archegonium. The fusion of the male gamete with the egg cell occurs inside the archegonium,resulting in the formation of a zygote.

(B) The prothallus of a fern is a heart-shaped,photosynthetic,independent gametophyte. It is monoecious (bisexual),meaning it bears both male and female sex organs. It is protandrous,meaning the antheridia (male sex organs) mature before the archegonia (female sex organs). It is anchored to the substrate by unicellular rhizoids.

(C) In $Pteridophytes$, the main plant body is a $sporophyte$ $(2n)$, which is differentiated into true root, stem, and leaves.
These plants possess specialized structures called $sporangia$ that produce spores.
Inside the $sporangia$, the spore mother cells undergo $meiosis$ (reduction division) to produce haploid $(n)$ spores.
Therefore, reduction division occurs during the formation of spores.

(B) $Selaginella$ exhibits several evolutionary advancements that bridge the gap between Pteridophytes and Seed plants.
$(a)$ Heterospory (production of two types of spores) is a significant evolutionary step towards the seed habit.
$(b)$ Endosporic development of the gametophyte means the gametophyte develops within the spore wall,which is an advanced trait.
$(c)$ The gametophyte is highly reduced compared to primitive Pteridophytes.
$(d)$ The formation of strobili (cones) is an advanced feature for spore protection and dispersal.
$(e)$ Unisexual gametophytes are an evolutionary advancement.
$(f)$ Fertilization with the help of water is a primitive trait,not an advanced one,as it keeps the plant dependent on external water sources for reproduction.
Therefore,all features except $(f)$ are considered evolutionary advancements.

(C) In a typical fern (Pteridophyte),the main plant body is the sporophyte $(2n)$.
Let us analyze the ploidy of each structure:
$a.$ Indusium cell: Part of the sporophyte $(2n)$.
$b.$ Stomium cell: Part of the sporangium wall,sporophytic $(2n)$.
$c.$ $NCC$: Neck Canal Cell,part of the female gametophyte $(n)$.
$d.$ Rhizome cell: Part of the sporophytic stem $(2n)$.
$e.$ Sporophyll cell: Leaf bearing sporangia,sporophytic $(2n)$.
$f.$ Prothallus cell: The gametophyte stage $(n)$.
$g.$ $SMC$: Spore Mother Cell,undergoes meiosis,sporophytic $(2n)$.
$h.$ Spore: Product of meiosis,gametophytic $(n)$.
$i.$ Antherozoid mother cell: Part of the gametophyte $(n)$.
The diploid structures are $a, b, d, e,$ and $g$. Total count = $5$.

(B) The organism shown in the figure is Equisetum,which is commonly known as horsetail.
It belongs to the class Sphenopsida of the division Pteridophyta.
Structure $A$ represents a strobilus or cone,which is bisexual in Equisetum,not exclusively a male cone.
Therefore,the statement 'It is a member of Sphenopsida' is the correct statement.

(D) The Assertion is incorrect because spike moss $(Selaginella)$ belongs to the group Pteridophyta,which are seedless vascular plants. While $Selaginella$ exhibits the 'seed habit' (heterospory and retention of the megaspore),it does not produce true seeds.
The Reason is also incorrect because,although $Selaginella$ shows precursors to seed habit,it does not fulfill all conditions required for the formation of a true seed (such as the development of an integumented megasporangium or ovule that matures into a seed).
Therefore,both the Assertion and the Reason are incorrect.

(A) In pteridophytes like $Selaginella$ and $Salvinia$,which are heterosporous,the female gametophytes are retained on the parent sporophytes for variable periods.
The development of the zygotes into young embryos takes place within the female gametophytes retained on the parent sporophytes.
This event is a precursor to the seed habit,considered an important step in evolution.
Therefore,both the Assertion and the Reason are correct,and the Reason provides the correct explanation for the Assertion.

(A) The leaves of $Selaginella$ are microphyllous. Each leaf is traversed by a single unbranched midrib. $A$ ligule arises from the base of each leaf (ligulate) as an adaxial outgrowth. It is a delicate,scale-like structure,often green,with an entire or serrate margin and an acute apex.

(B) Apogamy was first reported by $Farlow$ $(1874)$.
It is defined as the development of a sporophyte directly from the gametophyte without the intervention of sex organs and gametes.

(B) The $Cooksonia$ is considered the oldest known vascular plant.
It belongs to the group $Rhyniophyta$,which is an extinct group of early vascular plants.
These plants appeared during the $Silurian$ period and were prevalent in the $Devonian$ period.
$Cooksonia$ was a small plant,approximately $6.5 \ cm$ tall,with dichotomously branched leafless stems and terminal sporangia.
Since $Rhyniophytes$ are entirely extinct,they represent the earliest vascular plants that have no living descendants.

(B) Plants that produce two different kinds of spores,namely microspores and megaspores,are known as heterosporous plants.
$Selaginella$ and $Salvinia$ are classic examples of pteridophytes that exhibit heterospory.
This phenomenon is considered a precursor to the seed habit in higher plants.

(A) The classification of Pteridophytes into four classes is as follows:
$1$. Psilopsida: Includes primitive forms like $Psilotum$.
$2$. Lycopsida: Includes plants like $Selaginella$ and $Lycopodium$.
$3$. Sphenopsida: Includes $Equisetum$ (horsetails).
$4$. Pteropsida: Includes ferns like $Dryopteris$,$Pteris$,and $Adiantum$.
Therefore,the correct matching is $(P-I), (Q-II), (R-III), (S-IV)$.

(C) Horsetails (Equisetum) and ferns are classified under the group $Pteridophytes$.
$Pteridophytes$ are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$).
They are commonly used for medicinal purposes and as soil-binders,and are frequently grown as ornamentals.

(D) Pteridophytes are useful in various ways:
$1$. As soil binders: They help in preventing soil erosion by binding the soil particles together.
$2$. Medicinal purposes: Many pteridophytes are used in traditional medicine for treating various ailments.
$3$. Ornamental purposes: Pteridophytes,especially ferns,are widely grown as ornamental plants due to their aesthetic appeal.
Therefore,the correct option is $D$.

(B) The plant kingdom is classified based on the presence or absence of vascular tissues and seeds.
$1$. Bryophytes are non-vascular, seedless plants.
$2$. Pteridophytes are the first terrestrial plants to possess vascular tissues ($Xylem$ and $Phloem$) but they do not produce seeds; they reproduce via spores.
$3$. Gymnosperms and Angiosperms are seed-bearing plants (Spermatophytes).
Therefore, Pteridophytes are the correct answer.

(D) The correct answer is $D$.
$Pteridophytes$ are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$).
They are found in cool,damp,and shady places.
They are $NOT$ known as the 'amphibians of the plant kingdom'; this term is reserved for $Bryophytes$ because they require water for fertilization despite being terrestrial.
$Pteridophytes$ do not thrive well in sandy soil; they prefer moist,shady habitats.

(A) In the plant kingdom, $Pteridophytes$ are the first terrestrial plants to possess vascular tissues ($xylem$ and $phloem$).
Their main plant body is a $sporophyte$, which is well-differentiated into true roots, stems, and leaves.
In contrast, $Bryophytes$ have a thallus-like body that is not differentiated into true roots, stems, or leaves.
Therefore, the correct answer is $Pteridophytes - Sporophyte$.

(A) Based on the $NCERT$ textbook diagrams of Pteridophytes:
$(a)$ represents Selaginella,which shows a creeping habit with small leaves.
$(b)$ represents Equisetum,characterized by its jointed stem and strobilus.
$(c)$ represents a Fern (Dryopteris),showing typical fronds.
$(d)$ represents Salvinia,an aquatic pteridophyte.
Therefore,the correct sequence is $A$: Selaginella,$B$: Equisetum,$C$: Fern,$D$: Salvinia.