Gymnosperms (General) Questions in English

(D) $Cycas$ belongs to the group $Gymnospermae$. In $Gymnosperms$,the ovules are not enclosed by any ovary wall and remain exposed both before and after fertilization. Therefore,they produce naked seeds. In contrast,$Angiosperms$ are characterized by seeds that are enclosed within fruits (developed from the ovary). Although $Cycas$ may exhibit two cotyledons,the presence of naked seeds classifies it as a $Gymnosperm$ rather than an $Angiosperm$.

(B) In $Cycas$,the zygote is the first cell of the sporophytic generation. Following fertilization,the zygote undergoes several rounds of free nuclear divisions without immediate cell wall formation. This process is a characteristic feature of early embryogeny in $Cycas$.

(C) The coralloid roots of $Cycas$ exhibit a specialized internal structure.
These roots are apogeotropic (grow upwards) and dichotomously branched.
In the cortex of these roots,a distinct region known as the algal zone is present.
This zone contains symbiotic cyanobacteria,such as $Anabaena$ and $Nostoc$,which help in nitrogen fixation.

(D) Transfusion tissue,also known as hydrostereom,is a specialized tissue found in the leaves of gymnosperms like $Cycas$ and $Pinus$.
It consists of tracheids and parenchyma cells that facilitate the lateral conduction of water and nutrients between the vascular bundles and the mesophyll tissue.
Therefore,both $Cycas$ and $Pinus$ contain transfusion tissue.

(A) In $Cycas$,pollination occurs when the pollen grains are at the $3$-celled stage.
These pollen grains are released from the microsporangia and are carried by wind to the ovule.
Since $Cycas$ is a gymnosperm,it lacks a stigma,style,and ovary.
Instead,the ovule secretes a sticky fluid known as the pollination drop,which captures the pollen grains at the $3$-celled stage.

(A) Coralloid roots are a specialized type of root found in the genus $Cycas$.
These roots are apogeotropic (negatively geotropic),dichotomously branched,and greenish in color.
They contain symbiotic $Cyanobacteria$ (such as $Anabaena$ or $Nostoc$) in the cortical region,which help in nitrogen fixation.

(D) The correct answer is $D$. In $Angiosperms$,the ovules are enclosed within an ovary,which later develops into a fruit. In contrast,$Gymnosperms$ possess naked ovules that are not enclosed by any ovary wall. Therefore,$Gymnosperms$ are characterized by the presence of naked ovules,whereas $Angiosperms$ are distinguished by the absence of naked ovules (as they are covered).

(A) $Sequoia \text{ } sempervirens$, commonly known as the coast redwood, is recognized as the tallest tree species in the world.
It belongs to the family $Cupressaceae$ and is a type of gymnosperm.
These trees can reach heights exceeding $115 \text{ } m$.

(D) Seeds are formed after fertilization and the subsequent development of the ovule.
In $Pinus$,two ovules or megasporangia are present on the adaxial surface of the ovuliferous scale.
The ovuliferous scale and the bract scale together constitute the megasporophyll (or female cone scale).
Therefore,the seed originates on the megasporophyll.

(D) The term 'sulphur shower' refers to the phenomenon observed in the month of May in hilly regions.
$Pinus$ plants produce a massive quantity of yellow-colored pollen grains.
These pollen grains are released into the air in such large numbers that they appear like a yellow cloud or a shower of sulphur dust,hence the name 'sulphur shower'.

(A) $Pinus$ is a gymnosperm.
In gymnosperms,the endosperm is a haploid $(n)$ tissue formed before fertilization by the process of gametogenesis and subsequent development of the female gametophyte.
Since the haploid number of chromosomes $(n)$ is given as $12$,the endosperm cells will also contain $12$ chromosomes.

(A) The plant commonly known as "Monkey's puzzle" is $Araucaria$ $imbricata$ (also known as $Araucaria$ $araucana$).
It belongs to the family $Araucariaceae$ within the division $Gymnospermae$.
The name "Monkey's puzzle" originated because the tree's sharp, spiny leaves make it very difficult for monkeys to climb, creating a "puzzle" for them.
Therefore, the correct option is $A$.

(D) The male cones of $Pinus$ are borne in a cluster on a branch of unlimited growth behind the apical bud,in the axil of a scale leaf.
$A$ cone consists of a central axis bearing $60-135$ microsporophylls arranged in a spiral manner.
Each microsporophyll bears two microsporangia on its abaxial surface,which contain microspore mother cells that produce microspores (pollen grains). Therefore,the male cone is composed of microsporophylls.

(B) In $Pinus$,the life cycle is complex and spans over two years.
$1$. The female cones are formed in the summer of year $0$.
$2$. Pollination occurs shortly after the formation of the female cones.
$3$. However,the pollen tube growth is very slow,and the development of the female gametophyte takes a long time.
$4$. Fertilization typically occurs in the late spring of the $2nd$ year,approximately $12$ to $15$ months after pollination.

(D) In $Pinus$ (a gymnosperm),the gametophytic generation is haploid $(n)$.
$1$. The endosperm in gymnosperms is formed before fertilization from the female gametophyte,so it is haploid $(n)$.
$2$. Sperm cells are male gametes,which are haploid $(n)$.
$3$. The megaspore is the first cell of the female gametophyte,which is haploid $(n)$.
Therefore,the set (Endosperm,sperm,megaspore) consists entirely of structures belonging to the gametophytic generation.

(A) In $Pinus$,the seed is winged to facilitate wind dispersal.
At maturity,a thin layer of the ovuliferous scale separates and fuses with the testa (seed coat) of the developing seed.
This structure forms the wing of the seed,which is derived from both the outer layer of the integument and the basal part of the ovuliferous scale.

(C) The mature embryo of $Pinus$ consists of the following parts:
$(i)$ Cotyledons: $Pinus$ embryos are polycotyledonous,typically having $3$ to $18$ cotyledons.
$(ii)$ Plumule: Located between the cotyledons,it gives rise to the shoot system.
$(iii)$ Radicle: Directed towards the micropyle,it gives rise to the root system.
Therefore,the mature embryo comprises a radicle,a plumule,and multiple cotyledons.

(D) In $Pinus$,the pollen grains are released from the male cones and are carried by wind to the female cones (pollination).
After pollination,the pollen tube grows very slowly through the nucellus to reach the archegonia.
This process of pollen tube growth and subsequent fertilization takes approximately $1$ year to complete after the initial pollination event.

(D) $Pinus$ is a gymnosperm. Gymnosperms do not possess true sieve tubes or companion cells. Instead,they have sieve cells. Sieve cells are elongated cells with tapering ends that lack distinct sieve plates. Therefore,the correct answer is that none of the above options are applicable because $Pinus$ does not have sieve tubes.

(B) In gymnosperms,the endosperm is formed before fertilization by the process of megasporogenesis followed by the development of the female gametophyte.
Since it represents the female gametophyte tissue,it is always haploid $(n)$.

(C) Gymnosperms are plants that produce naked seeds.
$1$. Heterospory: Gymnosperms are heterosporous,meaning they produce two types of spores: microspores and megaspores.
$2$. Seed formation: They produce seeds that are not enclosed within an ovary (naked seeds).
$3$. Fertilization process: Fertilization occurs in gymnosperms,typically involving the transfer of pollen grains to the ovule via wind (anemophily).
Therefore,all three statements $(A, B, C)$ are correct for gymnosperms.

(D) The correct answer is $D$. The edible part known as 'chilgoza' is the seed of the gymnosperm $Pinus \, gerardiana$ (also known as the chilgoza pine).
These plants are commonly found in the dry valleys of the North-West Himalayas and Kashmir. In gymnosperms,seeds are not enclosed within a fruit,so 'chilgoza' is botanically a seed,not a fruit.

(B) Bordered pits are specialized structures found in the cell walls of tracheids and vessels.
They are most characteristic and common in the xylem of $Gymnosperms$ (specifically in tracheids).
These pits allow for the efficient lateral movement of water between adjacent xylem elements.

(C) In the leaves of $Pinus$,the vascular bundles are surrounded by a specialized tissue known as transfusion tissue.
This tissue consists of tracheids with bordered pits and parenchyma cells.
Its primary function is to conduct water and dissolved nutrients between the vascular bundles and the mesophyll cells of the leaf.

(A) In gymnosperms,the xylem consists mainly of tracheids,which are the primary water-conducting elements.
Unlike angiosperms,gymnosperms typically lack vessels in their xylem and companion cells in their phloem (which are replaced by albuminous cells).
Therefore,tracheids are the characteristic conducting elements present in the vascular bundles of gymnosperms.

(C) Companion cells are specialized cells associated with sieve tube elements in angiosperms. They are absent in pteridophytes and gymnosperms,such as $Pinus$. Instead,gymnosperms contain albuminous cells which perform a similar function.

(C) Vessels are characteristic features of angiosperms.
$Chir$ $(Pinus)$ is a gymnosperm.
Gymnosperms lack vessels in their xylem,except for members of the order $Gnetales$.
Therefore,$Chir$ wood does not contain vessels.

(A) Tracheids are the primary water-conducting elements in gymnosperms.
These cells possess bordered pits on their walls,which facilitate the lateral movement of water between adjacent tracheids.
Bordered pits are characteristic features of the xylem tracheids in gymnosperms,providing an efficient mechanism for water conduction.

(A) Resin canals are specialized secretory structures found in many gymnosperms,such as $Pinus$.
They are formed by the separation of cells,which creates an intercellular space lined by epithelial cells.
Since these canals originate from the separation of cells (schizogeny) rather than the breakdown of cells (lysigeny),they are classified as schizogenous in origin.

(B) Conifers (gymnosperms) often inhabit environments where water uptake is limited by specific anatomical features. $A$ primary reason for their relatively inefficient water uptake compared to many angiosperms is that they possess poorly developed or entirely absent root hairs. Root hairs are critical for increasing the surface area for water and mineral absorption from the soil. Consequently,the absence or poor development of these structures significantly hinders the efficiency of water uptake in these plants.

(A) In the leaflets of $Cycas$,the vascular bundles are located in the midrib. Water is transported from the midrib to the lamina (leaf blade) through the veins. This movement of water from the midrib towards the margins of the leaflet is known as lateral movement.

(A) Conifers are gymnosperms adapted to cold climates. They possess specialized physiological mechanisms that allow them to maintain metabolic activities,including photosynthesis,at very low temperatures,even reaching down to $-35^o C$. This adaptation is crucial for their survival in boreal forests and alpine regions where temperatures remain freezing for extended periods.

(B) In the life cycle of $Pinus$ (a gymnosperm),pollination occurs when pollen grains are transferred to the ovule. However,the pollen tube growth is very slow. It generally takes about $13$ months from the time of pollination to the time of fertilization,during which the male gametophyte matures and fertilization eventually occurs.

(C) In gymnosperms, the endosperm is formed before fertilization by the process of megasporogenesis and subsequent development of the female gametophyte. Since it represents the female gametophyte tissue, it is always $Haploid$ $(n)$.

(B) In $Cycas$,prokaryotic autotrophic symbiotic nitrogen-fixing cyanobacteria (like $Anabaena$ or $Nostoc$) are found in the coralloid roots. These bacteria live in symbiosis with the plant,providing fixed nitrogen in exchange for carbohydrates and a protected environment.

(B) Mycorrhiza is a symbiotic association between the roots of higher plants and fungi.
For example,the root system of $Pinus$ is associated with fungal hyphae,which help in the absorption of water and minerals from the soil.

(C) In $Gymnosperms$, the endosperm is a haploid tissue formed before fertilization as a result of the development of the female gametophyte. Among the given options, $Araucaria$ is a $Gymnosperm$. In $Angiosperms$, the endosperm is formed after fertilization through the process of triple fusion. $Equisetum$ is a $Pteridophyte$, $Rhynia$ is a fossil $Pteridophyte$, and $Anthoceros$ is a $Bryophyte$, none of which produce endosperm in the same manner as $Gymnosperms$.

(C) The plant $Araucaria$ $heterophylla$ is commonly known as the Christmas tree. It is a coniferous tree belonging to the family $Araucariaceae$. It is often used as an ornamental plant and is widely recognized for its symmetrical,conical shape which resembles a traditional Christmas tree.

(C) In gymnosperms,the male reproductive structure is the microstrobilus or male cone,which consists of microsporophylls.
Each microsporophyll bears microsporangia that produce microspores.
In angiosperms,the male reproductive organ is the stamen,which consists of an anther (bearing pollen sacs/microsporangia) and a filament.
Therefore,the microsporophyll of gymnosperms is homologous to the stamen of angiosperms.

(A) Plants that possess naked seeds are known as Gymnosperms.
In Gymnosperms,the ovules are not enclosed by any ovary wall and remain exposed both before and after fertilization.
Among the given options:
$A$. $Araucaria$ is a genus of evergreen coniferous trees belonging to the family $Araucariaceae$,which is a group of Gymnosperms.
$B$. $Anthoceros$ is a genus of hornworts (Bryophytes).
$C$. $Equisetum$ is a genus of horsetails (Pteridophytes).
$D$. $Selaginella$ is a genus of spike mosses (Pteridophytes).
Therefore,$Araucaria$ is the correct answer.

(D) Gymnosperms are heterosporous plants,meaning they produce two types of spores: microspores and megaspores. These spores develop into male and female gametophytes,respectively. Therefore,the statement that sporophylls are homosporous is incorrect. Gymnosperms have naked seeds (ovules not enclosed by an ovary wall),they often bear cones (strobili),and they typically possess both foliage leaves and scale leaves.

(B) In gymnosperms,the plant body is differentiated into roots,stems,and leaves.
They produce two types of spores: microspores and megaspores.
These spores are produced within sporangia that are borne on sporophylls.
Microsporophylls are arranged to form male strobili or cones,while megasporophylls are arranged to form female strobili or cones.
Therefore,megasporophylls are located in the female cone.

(B) In $Gymnosperms$, the endosperm is formed as a result of the development of the female gametophyte, which occurs before fertilization. Therefore, the endosperm in $Gymnosperms$ is haploid $(n)$.
In contrast, in $Angiosperms$, the endosperm is formed after fertilization through the process of triple fusion, making it triploid $(3n)$.

(B) Gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed both before and after fertilization. In Gymnosperms,the leaves are well-adapted to withstand extremes of temperature,humidity,and wind. In conifers,needle-like leaves reduce the surface area. Their leaves can be simple or compound. For example,in $Cycas$,the pinnate leaves persist for a few years. Therefore,Gymnosperms exhibit both simple and compound leaf structures depending on the species.

(D) In $Gymnosperms$,the male and female cones $(strobili)$ are formed by the arrangement of sporophylls (microsporophylls or megasporophylls) spirally along an axis to form lax or compact structures. This is a characteristic feature of $Gymnosperms$ like $Pinus$.

(C) The plant $Zamia$ $pygmaea$ is known for having a subterranean tuberous stem.
It is considered one of the smallest gymnosperms.
Unlike $Cycas$ or $Sequoia$, which have distinct aerial trunks, $Zamia$ has a stem that remains mostly underground, appearing tuberous or bulb-like.

(C) The sporophytic phase in $Cycas$ (a gymnosperm) is the dominant,diploid $(2n)$,and long-lived phase of the life cycle. It is represented by the plant body,which is well-differentiated into roots,stems,and leaves. The plant body of $Cycas$ is aerial and not underground. Therefore,'underground' is not applicable to the sporophytic phase of $Cycas$.

(D) In flowering plants (Angiosperms),the ovary develops into the fruit after fertilization.
Since Gymnosperms do not possess an ovary,their ovules are exposed (naked) and are not enclosed within an ovary wall.
Consequently,they do not form true fruits after fertilization.

(A) Pollination in $Cycas$ is anemophilous,meaning it occurs through the agency of wind. $Cycas$ is a gymnosperm where the male and female cones are produced on separate plants (dioecious). The pollen grains are released from the male cones and are carried by wind currents to the ovules present on the megasporophylls of the female plant.

(A) Bennettites is an extinct genus of seed plants that lived during the Mesozoic era. They are well-known fossil plants belonging to the group Cycadeoidophyta. Araucaria,Thuja,and Pinus are extant (living) gymnosperms.