Bryophytes (General) Questions in English

(N/A) $(i)$ In bryophytes,instead of true roots,special hair-like structures are present for fixation to the substratum and absorption of water and minerals; these are called rhizoids.
$(ii)$ In liverworts,small cup-shaped structures called gemma cups develop on the thallus. They contain gemmae,which are green,multicellular,asexual buds that detach from the parent body and germinate to form new individuals.

(A) Prof. Shivram Kashyap is widely recognized as the father of Indian Bryology. He made significant contributions to the study of liverworts and mosses in India,particularly in the Himalayas.

(B) The botanist Rothmaler is known for his contribution to the classification of the plant kingdom,specifically regarding Bryophytes.
He divided the group Bryophyta into $3$ distinct classes: Hepaticopsida (Liverworts),Anthocerotopsida (Hornworts),and Bryopsida (Mosses).

(N/A) Bryophytes are known as the amphibians of the plant kingdom because they can live in soil but are dependent on water for sexual reproduction.
$1$. These plants typically grow in moist,shaded,and damp areas.
$2$. The male gametes,known as antherozoids,are flagellated and motile.
$3$. They require an external film of water to swim from the male sex organ (antheridium) to the female sex organ (archegonium) to achieve fertilization.
$4$. Since they require both land for survival and water for the completion of their life cycle,they are termed amphibians of the plant kingdom.

(N/A) $\rightarrow$ In the life cycle of bryophytes,the gametophytic stage is haploid and multicellular at the adult stage.
$\rightarrow$ It possesses male reproductive organs called $antheridia$ and female reproductive organs called $archegonia$,which produce haploid $antherozoids$ and female gametes,respectively.
$\rightarrow$ In mosses,liverworts,and hornworts,the gametophyte is the main dominant phase and is the most prominent stage in their life cycles. The gametophyte of mosses arises from haploid spores. The initial stage of a moss is the $protonema$.
$\rightarrow$ The $protonema$ develops into the main plant body (thallus) of the bryophyte. It is thalloid or prostrate/erect and is attached to the substratum by unicellular or multicellular $rhizoids$. They may possess root-like,stem-like,or leaf-like structures.

(A) $(i)$ Oogamy
$(ii)$ Gametophyte
Explanation:
$1$. Oogamy is a type of sexual reproduction where the female gamete is large,non-motile,and food-rich,while the male gamete is small and motile.
$2$. In the life cycle of bryophytes,the dominant phase is the gametophyte,which produces sex organs known as antheridia (male) and archegonia (female).

(A) In lower plants such as bryophytes,the plant body is not differentiated into true roots,stems,and leaves.
Instead,they possess root-like structures called $Rhizoids$ that help in the absorption of water and minerals from the substrate.
Unlike higher plants (gymnosperms and angiosperms),these lower plants lack a complex vascular tissue system.

(A) In Bryophytes,the male reproductive organ is the $Antheridium$ (plural: $Antheridia$) and the female reproductive organ is the $Archegonium$ (plural: $Archegonia$).
These organs are produced on the haploid gametophyte body.
The $Antheridia$ produce biflagellate motile male gametes called $antherozoids$.
The $Archegonium$ is flask-shaped and produces a single egg cell.
Water is essential for the transfer of $antherozoids$ to the $archegonium$ for fertilization.

(A) $Sphagnum$ is a bryophyte,commonly known as bog moss or peat moss.
It is highly hygroscopic and possesses a remarkable water-holding capacity.
Due to this property,it is used as a packing material for the transportation of living materials such as flowers,live plants,tubers,bulbs,and seedlings,as it keeps them moist.
Additionally,it is used in seed-beds and moss-sticks.

(A) The plant kingdom group Bryophyta is primarily divided into three classes:
$1$. Hepaticopsida (Liverworts)
$2$. Anthocerotopsida (Hornworts)
$3$. Bryopsida (Mosses)
Therefore,bryophytes include liverworts,hornworts,and mosses. Among the given options,liverworts and mosses are the correct components of the bryophyte group.

(D) The plant body of $Bryophytes$ is thalloid or leafy and attached to the substratum by unicellular or multicellular $rhizoids$. They lack true roots,stems,and leaves. Instead,they possess root-like,stem-like,and leaf-like structures. In contrast,$Pteridophytes$,$Gymnosperms$,and $Angiosperms$ possess well-differentiated plant bodies with true roots,stems,and leaves.

(D) $Sphagnum$ and other mosses are the primary constituents of peat. Due to this property,$Sphagnum$ is commonly known as peat moss.

(A) Bryophytes are known as the amphibians of the plant kingdom because they can live in soil but are dependent on water for sexual reproduction.
Specifically,the male gametes (antherozoids) require a film of water to swim to the female sex organ (archegonium) for fertilization to occur.
Option $A$ is the correct reason for this classification.
Options $B$ is a characteristic of bryophytes but not the reason they are called amphibians.
Option $C$ is incorrect because bryophytes lack vascular tissues like tracheids.

(D) In the moss $Funaria$,the capsule contains a specialized structure called the peristome.
This peristome consists of $32$ peristomial teeth.
These teeth are arranged in two concentric rings,with $16$ teeth in each ring.

(B) Haploid spores represent the first cell of the gametophytic generation in mosses.
Upon germination,these spores develop into a filamentous,green,branched structure known as the protonema.
The cells of the protonema contain chloroplasts and are responsible for the vegetative growth of the moss gametophyte.

(B) Although bryophytes are land plants,water is essential for their fertilization.
Water provides a medium for the transport of male gametes (antherozoids) to the female reproductive organ (archegonia).
Because they require both land for growth and water for reproduction,bryophytes are known as the amphibians of the plant kingdom.

(B) $Sphagnum$ is a bryophyte,commonly called bog moss or peat moss.
It is hygroscopic and possesses a remarkable water-holding capacity.
Hence,it is used as a packing material in the transportation of flowers,live plants,tubers,bulbs,seedlings,etc.
It is also used in seedbeds and in moss-sticks.

(B) In mosses,the haploid gametophyte is the dominant,long-lived,green,and independent phase of the life cycle. The diploid sporophyte is short-lived and remains attached to the gametophyte for its nutrition and support.

(C) Statement $I$ is true because liverworts are bryophytes that typically inhabit moist,shady areas,including stream banks,marshy ground,damp soil,tree bark,and deep forests.
Statement $II$ is true because leafy liverworts possess small,leaf-like appendages arranged in two rows on their stem-like axes,which distinguishes them from the thalloid forms.

(A) In the moss $Funaria$,the dispersal of spores is facilitated by the hygroscopic movements of the peristomial teeth (the lengthening and shortening of these teeth due to moisture changes).
These peristomial teeth act as a regulatory mechanism,where the inner peristome functions like a sieve,allowing only a few spores to escape at a time,ensuring efficient dispersal.

(B) $SR$ Kashyap is known as the father of Indian Bryology due to his extensive research and significant contributions to the study of bryophytes in India.

(A) Liverworts reproduce asexually by the formation of specialised structures called gemmae or through the fragmentation of thalli.
Gemmae are asexual buds,which originate from small receptacles called gemma cups.

(D) In mosses (like $Funaria$),the sporophyte is more elaborate than that in liverworts. It is differentiated into three distinct parts: $Foot$,$Seta$,and $Capsule$.

(D) The vegetative plant body of Marchantia is a dorsiventral,lobed thallus that is closely attached to the substrate.
The sporophyte of bryophytes is known as a sporogonium. In Marchantia,the sporogonium is differentiated into three parts: foot,seta,and capsule.
Asexual reproduction in Marchantia takes place by the formation of gemmae,which are green,multicellular,asexual buds that develop in small receptacles called gemma cups,located on the thalli.
Since all three statements ($I, II,$ and $III$) are correct,the correct option is $D$.

(C) The presence of biflagellated antherozoids (male gametes) and the absolute necessity of water for the process of fertilization are strong indicators that bryophytes have evolved from aquatic ancestors.

(B) Mosses belong to the group Bryophyta. In these plants,fertilization is dependent on water because the male gametes (antherozoids) are flagellated and require a water medium to swim to the female gametes (egg) for fusion. Therefore,mosses are restricted to moist and shady habitats.

(D) Bryophytes resemble algae in several aspects:
$(i)$ Both have a thalloid plant body.
$(ii)$ Both lack true roots,stems,and leaves.
$(iii)$ Both lack complex vascular tissues ($xylem$ and $phloem$).
$(iv)$ Both exhibit an autotrophic mode of nutrition.
$(v)$ Both store food material as starch.

(D) In bryophytes,the main plant body is a haploid gametophyte. The diploid sporophyte is short-lived and remains attached to the photosynthetic gametophyte for nutrition. Therefore,the sporophyte is not independent or autotrophic.

(D) The protonema is the juvenile stage in the life cycle of mosses.
It develops directly from the germination of a haploid spore.
It is characterized as a creeping,green,slender,branched,and frequently filamentous structure.

(C) In mosses,the sporophyte is differentiated into foot,seta,and capsule.
Only the capsule contains the spore sac where meiosis occurs to produce haploid spores.
These spores germinate to form the protonema,which eventually develops into the leafy gametophyte.
Therefore,the statement that 'Seta and capsule bear spores' is incorrect because the seta does not produce spores; only the capsule does.

(A) In the given figure,$A$ represents $Funaria$,which is a type of moss belonging to the class Bryopsida under Bryophytes.
$B$ represents $Sphagnum$,which is also a type of moss (peat moss) belonging to the class Bryopsida under Bryophytes.
Both $Funaria$ and $Sphagnum$ are classified as mosses within the Bryophytes group.
Therefore,the correct identification is $A$-Funaria-Moss and $B$-Sphagnum-Moss.

(A) In bryophytes like $Funaria$,the zygote develops into a sporophyte within the archegonium.
As the sporophyte grows,the venter of the archegonium also enlarges to accommodate it.
This enlarged,haploid,protective covering derived from the venter of the archegonium is known as the calyptra.
It serves to protect the developing young capsule from desiccation and mechanical injury.

(D) In bryophytes,water is essential for the following processes:
$(i)$ Dehiscence of antheridia: Water absorption causes the antheridia to burst.
$(ii)$ Liberation of antherozoids: The motile male gametes (antherozoids) are released into the water.
$(iii)$ Transfer of sperms from antheridia to archegonia: Water acts as a medium for the swimming of antherozoids.
$(iv)$ Opening of archegonial neck: The neck canal cells and ventral canal cell degenerate to form a mucilaginous mass,which absorbs water and swells,causing the neck to open.
$(v)$ The movement of antherozoids into the archegonial neck: Antherozoids are attracted chemotactically to the archegonium through the water.
Thus,all the given statements $(I, II, III, IV, V)$ are correct. Because of this dependence on water for fertilization,bryophytes are known as the 'amphibians of the plant kingdom'.

(D) All the statements provided are correct regarding the leafy stage of mosses.
$I.$ The leafy stage develops directly from the secondary protonema as a lateral bud.
$II.$ The plant body consists of an upright,slender axis that bears leaves arranged in a spiral pattern.
$III.$ The plant is anchored to the substrate (soil) by multicellular,branched rhizoids.
$IV.$ The leafy stage represents the mature gametophyte and is responsible for bearing the sex organs (antheridia and archegonia).

(B) In mosses,the sporophyte is dependent on the gametophyte. The sporophyte consists of the foot,seta,and capsule,which are diploid $(2n)$. The calyptra is a remnant of the archegonium (part of the gametophyte) and is therefore haploid $(n)$. Spores are produced via meiosis and are also haploid $(n)$. Thus,calyptra and spores represent haploid/gametophytic tissue.

(C) Some bryophytes have important medicinal and industrial uses.
Statement $I$ is true: The tea prepared from the moss $Polytrichum$ $commune$ is traditionally used to dissolve kidney and gall bladder stones.
Statement $II$ is true: $Sphagnum$,a genus of moss,forms peat. Peat is used as fuel and is a source of various chemical products including alcohol,ammonium sulphate,peat tar,paraffin,nitrates,brown dye,and tanning materials.
Therefore,both statements are correct.

(D) All the statements are correct.
Sexual reproduction in liverworts occurs by the fusion of gametes produced in specialized sex organs. The male antheridia and female archegonia are produced either on the same thallus or on different thalli.
After fertilization,the zygote develops into a sporophyte,which is differentiated into three parts: foot,seta,and capsule.
Inside the capsule,diploid spore mother cells undergo meiosis to produce haploid spores.
These spores germinate to form free-living gametophytes.

(C) The statements describe the characteristics of $Sphagnum$,a genus of mosses commonly known as 'peat moss' or 'bog moss'.
$1.$ $Sphagnum$ has a high water-holding capacity,often absorbing up to $200$ times its own weight in water. This property makes it useful in horticulture for keeping plant cuttings moist during transport.
$2.$ $Sphagnum$ grows in acidic bogs or marshes. As the plant grows,the older parts die and accumulate,forming peat. Due to the presence of phenolic compounds,these dead parts do not decay easily,exhibiting germicidal properties.
Therefore,the correct option is $C$.

(B) The given figure represents the moss $Sphagnum$ (a type of bryophyte).
In $Sphagnum$,the gametophyte is the dominant phase.
The figure shows different types of branches on the gametophyte.
$A$ represents the antheridial branch,which bears the male sex organs (antheridia).
$B$ represents the archegonial branch,which bears the female sex organs (archegonia).
Therefore,the correct identification is $A$-Antheridial branch and $B$-Archegonial branch.

(D) Mosses and lichens are pioneer species in ecological succession.
They colonise barren rocks and secrete acids to decompose the rock,which helps in soil formation.
They also form dense mats on the soil surface,which prevents soil erosion by binding the soil particles together.
Therefore,they play a significant role in both ecological succession and soil conservation.

(D) All the statements are correct.
The life cycle of bryophytes consists of two distinct phases:
$(i)$ The gametophytic phase.
$(ii)$ The sporophytic phase.
The haploid gametophyte is dominant,long-lived,green,and independent,whereas the diploid sporophyte is short-lived and dependent upon the gametophyte for nutrition.
Some cells of the sporophyte undergo meiosis to produce haploid spores.
These spores germinate to produce the gametophyte.

(B) In bryophytes,the main plant body is a free-living gametophyte,which is haploid $(n)$. The sporophyte is dependent on the gametophyte. Therefore,the statement that the main plant body is diploid is incorrect.

(A) Peat is a dark,fibrous material formed by the partial decomposition of organic matter,primarily mosses,in wetlands or bogs.
$Sphagnum$,a genus of mosses commonly known as peat moss,is the primary source of peat.
Over time,$Sphagnum$ accumulates and compresses in waterlogged,acidic conditions,forming peat,which is used as fuel and in horticulture.

(D) Liverworts reproduce asexually by the formation of specialized structures called gemmae and also through the fragmentation of the thallus.

(B) Sphagnum is a genus of mosses,commonly known as peat moss. It has a remarkable capacity to hold water,which makes it highly effective for keeping cut plants moist during transportation and propagation. Gardeners use it as a packing material for trans-shipment of living plant materials.

(C) In mosses,the life cycle consists of two stages in the gametophyte: the protonema stage and the leafy stage. The protonema develops directly from a spore. The leafy stage develops from the secondary protonema as a lateral bud. The sex organs (antheridia and archegonia) are produced at the apex of the leafy shoots in the leafy stage.

(B) In a haplo-diplontic life cycle,both multicellular haploid and diploid phases exist.
Bryophytes exhibit a haplo-diplontic life cycle where the gametophyte (haploid) is the dominant,photosynthetic,independent phase,and the sporophyte (diploid) is short-lived and dependent on the gametophyte.
Most algae exhibit a haplontic life cycle,while Angiosperms and Gymnosperms exhibit a diplontic life cycle.

(D) In $Bryophytes$,the main plant body is a gametophyte,which is independent.
The sporophyte is not free-living but is attached to the photosynthetic gametophyte and derives nourishment from it,making it parasitic or dependent.
Therefore,an independent sporophyte is not a characteristic of $Bryophytes$.

(A) Bryophytes are non-vascular plants that possess root-like,stem-like,and leaf-like structures. These structures are not homologous to the true roots,stems,and leaves of vascular plants (Pteridophytes,Gymnosperms,and Angiosperms) because they lack complex vascular tissues like xylem and phloem. However,they perform similar functions of support and photosynthesis,making them analogous to the organs of vascular plants.

(B) The plant kingdom is divided into various groups. Embryophytes include bryophytes,pteridophytes,gymnosperms,and angiosperms.
Among these,bryophytes are non-vascular plants.
$Riccia$ is a liverwort that is thalloid and lacks true leaves.
$Porella$ is a leafy liverwort (a type of bryophyte) that possesses leaf-like structures.
$Selaginella$ is a pteridophyte,which is a vascular plant.
$Macrocystis$ is a brown alga,which is not an embryophyte.
Therefore,the correct answer is $Porella$.