Gymnosperms (General) Questions in English

(A) In the female $Cycas$ plant,the apical meristem remains unaffected by the reproductive structures.
Consequently,the main axis continues to grow indefinitely,resulting in a monopodial growth pattern.
In contrast,the male $Cycas$ plant exhibits sympodial growth because the apical meristem is consumed in the formation of the male cone.

(A) The $Cycas$ microsporophyll is a leaf-like structure that bears microsporangia on its abaxial surface.
The distal,sterile,and expanded portion of the microsporophyll is referred to as the $Apophysis$.
This structure helps in protecting the developing sporangia.

(B) The $Megasporophylls$ are the female reproductive structures in gymnosperms.
In $Cycas$,the female plant bears $Megasporophylls$ which are arranged spirally in an acropetal order.
Therefore,$Megasporophylls$ are found in the female $Cycas$ plant.

(B) The leaflets of $Cycas$ are sessile (lacking a petiole),straight,and linear-lanceolate in shape. They are arranged in a pinnately compound manner on the rachis.

(A) The plant body of $Cycas$ is a sporophyte and it is dioecious in nature.
Dioecious means that the male and female reproductive structures (cones) are borne on separate individual plants.
Therefore,$Cycas$ is considered a unisexual plant because each individual plant produces only one type of sex organ (either male cones or female megasporophylls).

(C) living fossil is an organism that has remained unchanged over a long period of geological time and whose close relatives have become extinct.
$Cycas$ is considered a living fossil because it exhibits primitive characteristics and has a very restricted geographical distribution,making it a relic of the past.

(D) The characteristic features mentioned are:
$1$. Top-shaped multiciliate male gametes (antherozoids).
$2$. Mature seeds containing an embryo with two cotyledons.
These features are characteristic of the group $Cycads$ (e.g.,$Cycas$).
$Cycas$ is a gymnosperm that produces large,top-shaped,multiciliate male gametes and seeds that contain an embryo with two cotyledons.

(C) $Cycas$ is a genus of plants belonging to the family $Cycadaceae$.
It is widely distributed across the tropical and subtropical regions of the world.
In the context of its natural distribution,$Cycas$ species are commonly found in $South$ $East$ $Asia$,including countries like India,China,and Japan.
Therefore,option $C$ is the correct answer.

(D) The spermatozoids (male gametes) of $Cycas$ are the largest in the entire plant kingdom.
They are top-shaped and possess $4-5$ spiral coils of cilia at their anterior end.
Due to the presence of numerous cilia,they are described as multiciliated.

(C) $Cycas$ belongs to the group Gymnosperms.
Gymnosperms are characterized by naked ovules,circinate vernation (in young leaves),and the presence of girdling leaf traces.
Vessels are a characteristic feature of Angiosperms,whereas the xylem in Gymnosperms typically consists of tracheids.
Therefore,the presence of vessels is not a characteristic feature of $Cycas$.

(D) Cycas is known for having the largest structures in the plant kingdom among the given options:
$1$. It has the largest ovule,measuring approximately $6 \ cm$ in length and $4 \ cm$ in diameter.
$2$. It possesses the largest sperm (male gamete),which is about $300 \ \mu m$ in size.
$3$. It also has the largest egg (female gamete),which is about $0.5 \ mm$ in diameter.
Therefore,the correct answer is $(d)$ All of these.

(B) $Cycas$ is dioecious,meaning that the male and female reproductive structures are borne on separate individual plants. In $Cycas$,the male plant produces microsporophylls (forming a male cone),while the female plant produces megasporophylls (which are not organized into a compact cone).

(D) The correct answer is $D$. $Cycas$ $revoluta$ is commonly known as the $Sago$ $Palm$. It is a gymnosperm belonging to the family $Cycadaceae$. The stem of this plant is rich in starch,which is extracted and used to produce a type of sago,hence the name $Sago$ $Palm$.

(B) The wood of $Cycas$ is described as manoxylic and polyxylic.
Manoxylic wood is characterized by being loose,soft,and having a large amount of parenchyma with less vascular tissue.
It contains broad medullary rays and a wide pith and cortex,making it commercially useless.
Polyxylic refers to the presence of multiple rings of xylem formed by successive cambia.

(A) $Cycas$ is a gymnosperm that belongs to the order $Cycadales$.
One of the characteristic anatomical features of the stem and leaves of $Cycas$ is the presence of numerous mucilage canals or mucilage ducts.
These ducts are specialized structures that secrete mucilage,which helps in water retention and protection.
Therefore,the correct option is $A$.

(A) In $Cycas$,pollination is anemophilous,which means it occurs through the wind.
The pollen grains of $Cycas$ are light in weight and are easily dispersed by wind currents to reach the female ovules.

(A) In $Cycas$,the megasporophyll is differentiated into a proximal stalk-like rachis and a distal leaf-like lamina.
The ovules are borne in pairs on the lateral margins of the rachis part of the megasporophyll.
Therefore,the correct attachment is lateral.

(D) $Cycas$ is a gymnosperm. Both gymnosperms and angiosperms are seed-bearing plants (spermatophytes) that produce ovules.
$1$. Circinate vernation is a characteristic feature of pteridophytes and some gymnosperms like $Cycas$,but not angiosperms.
$2$. Vessels are typically absent in gymnosperms (except Gnetales) and present in angiosperms.
$3$. Motile sperms are present in $Cycas$ but absent in angiosperms.
$4$. Both groups produce ovules,which develop into seeds after fertilization. Therefore,the presence of ovules is a common feature.

(C) In $Cycas$,the pollen grains are shed at the three-celled stage.
These three cells consist of one $prothallial$ cell,one $generative$ cell,and one $tube$ cell.

(B) In $Cycas$ (a gymnosperm),the endosperm is a haploid $(n)$ tissue that represents the female gametophyte.
Unlike angiosperms,where the endosperm is formed after fertilization (triploid,$3n$),the endosperm in gymnosperms is formed before fertilization and is independent of the fertilization process.

(D) The male gametes of $Cycas$ are the largest in nature (approximately $300 \ \mu m$).
They are broad and naked at the posterior end.
The anterior half is spirally coiled and bears thousands of small cilia,which help in motility.

(D) The coralloid roots of $Cycas$ are specialized,negatively geotropic roots that branch dichotomously. These roots contain a symbiotic association with nitrogen-fixing cyanobacteria,specifically $Anabaena$ $cycadae$ and $Nostoc$. This association is an example of symbiosis,where the alga helps in $N_2$ fixation for the plant,and in return,the plant provides shelter and nutrients to the alga.

(A) $Cycas$ produces specialized roots called coralloid roots.
These roots are apogeotropic (grow upwards) and dichotomously branched.
They contain a symbiotic association with nitrogen-fixing cyanobacteria such as $Anabaena$ and $Nostoc$.
Therefore,the primary function of coralloid roots is the fixation and absorption of nitrogen for the plant.

(B) The sago obtained from the stem of $Cycas$ is a type of starch.
It is recommended for patients with stomach disorders because it is easily digestible and contains a lower percentage of starch (approximately $31\%$) compared to other sources,making it gentle on the digestive system.

(A) The correct answer is $A$. $Cycas$ belongs to the group $Gymnospermae$. $A$ characteristic feature of gymnosperms is the absence of vessels in the xylem (except in the order $Gnetales$). Therefore,the statement that $Cycas$ xylem has vessels is incorrect. $Cycas$ exhibits circinate vernation in its leaves,lacks a true female flower (forming megasporophylls instead),and its coralloid roots contain symbiotic blue-green algae like $Anabaena$ and $Nostoc$.

(C) Vegetative reproduction in $Cycas$ occurs by bulbils.
Bulbils are adventitious buds that develop on the stem in the axil of scale leaves.
These bulbils detach from the parent plant and germinate to form new $Cycas$ plants.

(B) $Cycas$ exhibits two types of leaves: brown scale leaves and green foliage leaves. The foliage leaves are large,pinnately compound,and are arranged in a crown at the apex of the stem.

(D) The leaflet of $Cycas$ is diploxylic,which means it contains two types of xylem: centripetal xylem (exarch) and centrifugal xylem (endarch). This arrangement is a characteristic feature of the vascular bundles in the leaflets of $Cycas$.

(B) In $Cycas$,the microsporophylls are scale-like structures that bear numerous microsporangia on their abaxial (lower) surface.
These microsporangia are often arranged in groups called sori.
The terminal portion of the microsporophyll is typically sterile and pointed,while the abaxial surface is fertile.

(B) The microsporophyll of $Cycas$ is equivalent to the $stamen$ of an $angiosperm$. It is a hard,leafy,triangular structure that bears a large number ($700$ to $1160$) of microsporangia (pollen sacs) on its lower $(abaxial)$ surface.

(D) The trunk of $Cycas$ is typically thick and columnar. It is covered by persistent leaf bases of old foliage leaves and scale leaves,which are arranged in alternate whorls. Therefore,both leaf bases and scale leaves contribute to the covering of the trunk.

(C) In young condition,young leaves of $Cycas$ show circinate ptyxis,similar to fern leaves,and are covered by ramenta.

(B) The vascular bundles in the $Cycas$ rachis are arranged in an inverted omega $(\Omega)$ shaped manner.
These bundles vary in their structure: they are $endarch$ at the base, $pseudomesarch$ in the centre, and $exarch$ at the apex of the rachis.

(B) The correct answer is $B$.
In $Cycas$ leaflets,lateral veins are absent.
To facilitate the lateral translocation of water and nutrients,specialized tissue known as transfusion tissue is present in the leaflets.

(A) In $Cycas$,the male gametophyte is highly reduced and consists of only a few cells.
Specifically,the male gametophyte of $Cycas$ consists of one prothallial cell,one tube cell,and one generative cell.
Therefore,the number of prothallial cells is $1$.

(A) The ovule of $Cycas$ is orthotropous (straight) and unitegmic (possessing a single integument).
It is the largest ovule in the plant kingdom,measuring approximately $6-7 \text{ cm}$ in diameter.
Being a gymnosperm,the ovule is naked,meaning it is not enclosed within an ovary.

(D) In the genus $Cycas$,the number of archegonia developing on a single female gametophyte varies by species.
Specifically,$2-8$ archegonia develop in $C. revoluta$,$3-6$ in $C. rumphii$,and $3-8$ in $C. circinalis$.
Given the options provided,$3-6$ is the most appropriate range representing the typical development of archegonia in $Cycas$ species.

(B) The germination of $Cycas$ seed is $Hypogeal$.
In $Hypogeal$ germination,the cotyledons remain inside the seed coat within the soil or just at the soil surface,while the epicotyl elongates to push the plumule above the ground.

(D) The archegonium of $Cycas$ consists of a neck composed of two cells,but it lacks neck canal cells. Therefore,the number of neck canal cells is $0$.

(B) $Cycas$ is a gymnosperm. Although the seeds of $Cycas$ possess $2$ cotyledons,it is not classified under angiosperms because it produces naked seeds (seeds not enclosed within an ovary).

(C) The $Cycas$ plant belongs to the group Gymnosperms. It has a stout,unbranched stem and a crown of large,pinnately compound leaves. Due to this specific morphology,it bears a strong resemblance to a palm tree,specifically the $Date \ palm$ $(Phoenix \ dactylifera)$.

(C) The vascular bundles in the stem of $Cycas$ are conjoint,collateral,and open.
Conjoint means xylem and phloem are present in the same bundle.
Collateral means phloem is located towards the outer side and xylem towards the inner side.
Open means a cambium strip is present between the xylem and phloem,which allows for secondary growth.

(B) $Cycas$ is a gymnosperm that typically grows in environments where water conservation is necessary.
Its leaves are thick,leathery,and possess a sunken stomata,a thick cuticle,and a hypodermis,which are all classic adaptations to reduce transpiration.
These structural features are known as xerophytic characters,which allow the plant to survive in dry or arid conditions.

(C) In $Cycas$,the megasporophylls are loosely arranged to form a female cone.
Each megasporophyll bears $1-6$ pairs of ovules that are laterally attached to the upper part of the rachis.

(D) $Cycas$ is a dioecious plant,meaning the male and female reproductive structures are borne on separate individual plants. The male plant produces male strobili (cones),while the female plant produces megasporophylls that bear ovules. Therefore,option $(d)$ is correct.

(B) $Cycas$ is a gymnosperm.
Gymnosperms are characterized by the presence of tracheids and the absence of vessels in their xylem (except in the order Gnetales).
Therefore,the secondary wood of $Cycas$ lacks vessels.

(C) $C. \ circinalis$ produces the largest male cones among the $Cycas$ species,which can reach a length of approximately $45 \ cm$.

(A) $Cycas$ is a gymnosperm that exhibits a specific growth pattern.
In $Cycas$,the main stem is generally unbranched and shows monopodial growth.
However,the growth pattern can be influenced by the reproductive structures.
In male plants,the growth is monopodial because the male cone is terminal,but the stem continues to grow from a lateral bud.
In female plants,the megasporophylls are produced in a crown-like arrangement,and the growth is also essentially monopodial as the apical meristem remains active.
Therefore,both male and female $Cycas$ plants exhibit monopodial growth.

(B) Negatively geotropic roots,also known as pneumatophores or respiratory roots,are specialized roots that grow vertically upwards against gravity to obtain oxygen in waterlogged or swampy habitats.
These are characteristic features of certain mangrove plants like $Rhizophora$ and $Avicennia$.
Among the given options,$Cycas$ (a gymnosperm) produces specialized coralloid roots which are apogeotropic (negatively geotropic) and contain symbiotic cyanobacteria ($Anabaena$ or $Nostoc$) for nitrogen fixation.
Therefore,$Cycas$ is the correct answer.

(A) living fossil is an extant taxon that closely resembles related species known only from the fossil record. $Cycas$ is considered a living fossil primarily because it retains primitive characteristics,such as the presence of motile,ciliated sperms,which are a feature typically associated with ancestral pteridophytes rather than modern seed plants. This evolutionary link to ancient plant groups makes it a living representative of a bygone era.