Gymnosperms (General) Questions in English

(B) Gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed,both before and after fertilization. The seeds that develop post-fertilization are not covered,i.e.,they are naked. Therefore,the correct option is $B$.

(B) Coralloid roots are specialized roots found in the genus $Cycas$ (a gymnosperm). These roots show a symbiotic association with nitrogen-fixing cyanobacteria,such as $Anabaena$ or $Nostoc$. These bacteria reside in the cortical cells of the coralloid roots and help in the fixation of atmospheric nitrogen,which is beneficial for the plant.

(A) In gymnosperms,the cones or strobili that bear microsporophylls (which contain microsporangia) are called male strobili or male cones. These structures produce microspores,which develop into male gametophytes.

(A) $Pinus$ is a gymnosperm that exhibits the following characteristics:
- It produces endospermic seeds (seeds containing food storage tissue).
- It has perispermic seeds (remnants of nucellus persist in the seed).
- It is polycotyledonous (having more than two cotyledons).
- It possesses winged seeds for wind dispersal.
- $Pinus$ is also famous for the phenomenon of 'sulphur shower',which occurs when massive amounts of yellow pollen grains are released into the air,creating a cloud-like appearance.

(D) Gymnosperms are the dominant vegetation in colder regions because they are well-adapted to harsh,cold climates. Their needle-like leaves,thick cuticles,and sunken stomata help reduce water loss,and their seeds are naked (not enclosed in fruits),which allows them to survive in environments where conditions for seed development within a fruit might be unfavorable.

(B) The seed of a gymnosperm consists of three distinct generations:
$(a)$ Parental sporophyte: Represented by the seed coat,which is diploid $(2n)$.
$(b)$ Female gametophyte: Represented by the endosperm (nutritive tissue),which is haploid $(n)$.
$(c)$ New plant: Represented by the embryo,which is the next sporophytic generation and is diploid $(2n)$.

(A) In $Cycas$ (a gymnosperm),the endosperm is formed before fertilization from the female gametophyte,making it haploid $(n)$.
$Cycas$ roots exhibit a specialized structure called coralloid roots,which contain cyanobacteria (also known as oxyphotobacteria like $Anabaena$ or $Nostoc$) that help in nitrogen fixation.
Both statements are scientifically accurate.

(D) In gymnosperms,the term 'lax' is not standard terminology; however,the question refers to the strobilus (cone).
Gymnosperms are generally heterosporous,producing microspores and megaspores.
In many gymnosperms (like $Pinus$),male and female strobili are produced on the same plant (monoecious),but they are distinct structures.
In $Cycas$,male and female cones are produced on different plants (dioecious).
Since microspores and megaspores are produced in separate microsporangiate and megasporangiate strobili,the assertion that they are produced in the 'same lax' is incorrect.
Therefore,both the Assertion and the Reason are incorrect.

(B) Gymnosperms lack vessels in their xylem tissue. Vessels are also absent in most pteridophytes. Their tracheary elements comprise only tracheids. Flowering plants (angiosperms) possess both vessels and tracheids,but vessels are the characteristic feature of angiosperms.

(B) Connecting links are organisms that exhibit characteristics of two different taxonomic groups. $Cycas$ and $Ginkgo$ are primitive gymnosperms that possess certain features of pteridophytes,such as flagellated motile sperms and circinate vernation in young leaves. Therefore,they are considered connecting links between pteridophytes and gymnosperms.

(A) The anti-cancer drug known as $Taxol$ is obtained from the bark of the $Taxus$ tree (commonly known as the Yew tree).
$Taxus$ is a genus of gymnosperms.
$Taxol$ is widely used in chemotherapy for the treatment of various cancers,particularly breast cancer and ovarian cancer.

(D) In $Cycas$, the coralloid roots are specialized root structures that grow upwards and branch dichotomously. These roots contain cyanobacteria (such as $Anabaena$ or $Nostoc$) in their cortical cells. The cyanobacteria fix atmospheric nitrogen for the plant, while the plant provides shelter and nutrients to the cyanobacteria. This mutually beneficial interaction is known as $Mutualism$ (or symbiosis).

(C) The tallest gymnosperm is the giant redwood tree,known as $Sequoia$ $sempervirens$.
Among angiosperms,some species of $Eucalyptus$ are considered the tallest flowering plants.
Therefore,the correct pair is $Sequoia$ for gymnosperms and $Eucalyptus$ for angiosperms.

(B) $Gymnosperms$ are plants that are well-adapted to survive in harsh environmental conditions.
Many $Gymnosperms$ (like $Pinus$ and $Cycas$) possess features such as needle-like leaves,thick cuticles,and sunken stomata to reduce water loss.
These adaptations are characteristic of $Xerophytes$,which are plants adapted to survive in dry or arid environments.

(A) In the group $Gymnosperms$,the stem characteristics vary among different genera.
$1$. $Cycas$ typically possesses an unbranched,columnar stem that is often covered with persistent leaf bases.
$2$. $Pinus$ and $Cedrus$ possess branched stems.
Therefore,the correct pairing is: Branched stem $(Pinus, Cedrus)$ and Unbranched stem $(Cycas)$.

(D) Conifers are gymnosperms that are well-adapted to survive in harsh,cold,or dry environments.
Their leaves exhibit several xerophytic adaptations:
$1$. Needle-like shape: This reduces the surface area,which minimizes water loss through transpiration.
$2$. Thick cuticle: $A$ waxy,thick layer on the leaf surface prevents excessive water loss and protects against environmental stress.
$3$. Sunken stomata: Stomata are located in pits (sunken) to reduce the rate of transpiration by creating a humid microenvironment around the pore.
Therefore,all these features are present in conifers.

(C) In Gymnosperms,fertilization is simple (single fertilization) as they lack the double fertilization process characteristic of Angiosperms.
The endosperm in Gymnosperms is formed before fertilization from the female gametophyte,making it haploid $(n)$.
Therefore,the correct combination is Single fertilization and Haploid endosperm.

(C) Mycorrhiza is a symbiotic association between a fungus and the roots of higher plants.
In the case of $Pinus$ (pine trees),the seeds are obligately dependent on mycorrhizal fungi for germination.
The fungal hyphae provide the necessary nutrients and water,which the seeds cannot absorb efficiently on their own from the soil.
Therefore,without the presence of mycorrhiza,$Pinus$ seeds fail to germinate.

(D) Assertion $A$ is true because in gymnosperms,pollination is anemophilous (wind-pollinated),and pollen grains are released from the microsporangium to be carried by air currents.
Reason $R$ is false because,in gymnosperms,a pollen tube is indeed formed. The pollen grains reach the opening of the ovules,where they germinate to form a pollen tube that grows towards the archegonia to discharge the male gametes.

(B) The term $Gymnosperms$ is derived from the Greek words $gymnos$ (meaning naked) and $sperma$ (meaning seed).
In $Gymnosperms$,the ovules are not enclosed by any ovary wall and remain exposed,both before and after fertilization.
Consequently,the seeds that develop post-fertilization are not covered,which is why they are referred to as 'naked seeds'.
In contrast,$Angiosperms$ have seeds enclosed within fruits.

(C) dioecious plant is one where male and female reproductive organs are present on separate individuals.
$1$. $Marchantia$ is a bryophyte (liverwort),not a gymnosperm.
$2$. $Pinus$ is a monoecious gymnosperm,meaning both male and female cones are present on the same plant.
$3$. $Cycas$ is a dioecious gymnosperm,where male and female cones are produced on separate plants.
$4$. $Selaginella$ is a pteridophyte,not a gymnosperm.
Therefore,the correct answer is $Cycas$.

(A) The plant shown in the image is $Ginkgo$ $biloba$,which is a gymnosperm.
Gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed,both before and after fertilization.
Since they are gymnosperms,they are heterosporous,meaning they produce two kinds of spores: microspores and megaspores.
They do not produce fruits,as fruits are characteristic of angiosperms.
They are neither mosses (bryophytes) nor ferns (pteridophytes).
Therefore,the correct statement is that it is heterosporous.

(B) The presence of vessels is a characteristic feature of angiosperms,but they are generally absent in gymnosperms. However,$Ephedra$ is an exceptional gymnosperm that possesses vessels in its xylem. Companion cells are specialized cells associated with sieve tubes in the phloem of angiosperms. Since $Ephedra$ is a gymnosperm,it lacks companion cells (it has albuminous cells instead). Therefore,an organ showing vessels but lacking companion cells belongs to $Ephedra$.

(D) The correct answer is $D$. In Gymnosperms,the ovules are naked,meaning they are not enclosed by any ovary wall or fruit wall. This is the defining characteristic of the group Gymnospermae (Gymnos = naked,sperma = seed).
Option $A$ is true: $Pinus$ roots show a symbiotic association with fungi known as ectomycorrhiza.
Option $B$ is true: $Cycas$ roots show a specialized association with nitrogen-fixing cyanobacteria $(BGA)$ like $Nostoc$ and $Anabaena$ in their coralloid roots.
Option $C$ is true: Conifers possess needle-like leaves with a thick cuticle and sunken stomata to reduce water loss,which is a xerophytic adaptation.

(A) In Gymnosperms,the female gametophyte is multicellular and is retained within the megasporangium,which is commonly known as the ovule.
Unlike Angiosperms,Gymnosperms do not have an ovary,and their ovules are naked (not enclosed by an ovary wall).
The female gametophyte in Gymnosperms bears two or more archegonia (female sex organs).
Therefore,the correct location for the female gametophyte is the ovule.

(D) Plants that produce seeds but lack flowers are known as $Gymnosperms$.
$Gymnosperms$ are naked-seeded plants where the ovules are not enclosed by any ovary wall and remain exposed both before and after fertilization.
$Maize$,$Pulses$,and $Peepal$ are $Angiosperms$ (flowering plants) where seeds are enclosed within fruits.
$Pinus$ is a $Gymnosperm$ that produces seeds in structures called cones or strobili,but it does not produce flowers.

(C) In gymnosperms,the male gametes are non-motile (in most advanced gymnosperms) or motile (in primitive ones like Cycas and Ginkgo).
Regardless of their motility,the pollen grain germinates to form a pollen tube.
The pollen tube grows through the tissue of the nucellus and reaches the micropyle of the ovule.
Finally,the pollen tube discharges the male gametes near the mouth of the archegonia to facilitate fertilization.

(C) In gymnosperms,the pollen grain germinates to form a pollen tube.
This pollen tube grows through the tissue of the nucellus and reaches the micropyle of the ovule.
The male gametes are carried by the pollen tube and are discharged near the mouth of the archegonia to facilitate fertilization.

(A) Gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilization.
Since fruits are formed from the ovary wall after fertilization, the absence of an ovary wall in gymnosperms means they do not produce true fruits.
Therefore, the Assertion that gymnosperms do not produce fruit is true, and the Reason that ovules are not enclosed by an ovary wall is the correct explanation for this phenomenon.

(A) In $Cycas$,specialized roots known as coralloid roots are formed.
These roots are apogeotropic (grow upwards) and dichotomously branched.
They contain a symbiotic association with nitrogen-fixing cyanobacteria,such as $Anabaena$ and $Nostoc$,which reside in the cortical region of the root.
This association helps the plant in nitrogen fixation.

(B) In $Pinus$,both male and female cones are produced on the same plant body,which means it is a monoecious plant.
$Cycas$ is dioecious,meaning male and female cones are produced on separate plants.
$Mango$ is an angiosperm and does not produce cones.
$Equisetum$ is a pteridophyte that produces strobili or cones,but it is not the standard example for monoecious cone-bearing plants in the context of gymnosperms compared to $Pinus$.

(A) The order $Gnetales$,which comprises the genera $Gnetum$,$Ephedra$,and $Welwitschia$,is considered one of the most advanced groups of gymnosperms.
Fossil evidence suggests that this group evolved and diversified significantly during the $Cretaceous$ period.

(A) Gymnosperms are plants in which the ovules are not enclosed by any ovary wall and remain exposed both before and after fertilization.
$Pinus$ is a gymnosperm.
$Wolffia$ is an angiosperm,where ovules are enclosed within an ovary.
$Funaria$ is a bryophyte,which does not produce seeds or ovules.
$Selaginella$ is a pteridophyte,which does not produce seeds or ovules.
Therefore,option $(1)$ is correct.