Mix Examples-Sexual Reproduction in Flowering Plants Questions in English

(C) In plants bearing bisexual flowers,the male and female reproductive organs are present in the same flower.
This proximity facilitates self-pollination,which is known as $Autogamy$.
While other forms of pollination like $Geitonogamy$ and $Xenogamy$ can occur,$Autogamy$ is the most common phenomenon observed in such plants due to the structural arrangement of the floral parts.

(C) The correct sequence of events in the fertilization process of flowering plants is as follows:
$1$. $(III)$ Dehiscence of anther: Pollen grains are released from the anther.
$2$. $(VII)$ Deposition of compatible pollen on the stigma: Pollen grains land on the receptive stigma.
$3$. $(IV)$ Germination of pollen grain: Pollen grains germinate to form a pollen tube.
$4$. $(II)$ Formation of pollen tube: The pollen tube grows through the style towards the ovary.
$5$. $(VI)$ Entry of male gametes into the synergid: The pollen tube enters the ovule through the synergid.
$6$. $(I)$ Movement of male gametes towards the egg cell and central cell: Male gametes are released and move towards their targets.
$7$. $(V)$ Fusion of nuclei: Syngamy (fusion with egg) and Triple fusion (fusion with central cell) occur.
Therefore,the correct sequence is $III, VII, IV, II, VI, I, V$.

(A) In angiosperms,after fertilization,the ovary develops into the fruit and the ovule develops into the seed simultaneously.
$(i)$ Ovule $\rightarrow$ Seed: This is a post-fertilization change.
$(ii)$ Ovary $\rightarrow$ Fruit: This is also a post-fertilization change occurring alongside seed formation.
$(iii)$ $MMC$ (Megaspore Mother Cell) $\rightarrow$ Megaspore: This occurs before fertilization (megasporogenesis).
$(iv)$ $PMC$ (Pollen Mother Cell) $\rightarrow$ Pollen grain: This occurs before fertilization (microsporogenesis).
Therefore,processes $(i)$ and $(ii)$ occur simultaneously.

(B) The correct matching is as follows:
$(a)$ Stamen is the male reproductive organ, also known as the microsporophyll. Hence, $(a-ii)$.
$(b)$ Pistil is the female reproductive organ, also known as the megasporophyll. Hence, $(b-iv)$.
$(c)$ Anther is the part of the stamen that contains the pollen sacs, which are the microsporangia. Hence, $(c-i)$.
$(d)$ Ovule is the structure within the ovary that develops into a seed, which is the megasporangium. Hence, $(d-iii)$.
Therefore, the correct sequence is $(a-ii, b-iv, c-i, d-iii)$.

(D) The correct matching is as follows:
$(a)$ Sporopollenin is the most resistant organic material known,which forms the outer layer of pollen grain called the Exine $(a-2)$.
$(b)$ The inner wall of the pollen grain is called the Intine,which is thin and made up of cellulose and pectin $(b-3)$.
$(c)$ The vegetative cell is bigger,has abundant food reserve,and a large irregularly shaped nucleus $(c-4)$.
$(d)$ The generative cell is small and floats in the cytoplasm of the vegetative cell. It is spindle-shaped with dense cytoplasm and a nucleus $(d-1)$.
Therefore,the correct sequence is $a-2, b-3, c-4, d-1$.

(A) The correct matches are as follows:
$(a)$ Maize: It is pollinated by wind,known as Anemophily $(2)$.
$(b)$ Hydrilla: It is a submerged aquatic plant pollinated by water,known as Hydrophily $(3)$.
$(c)$ Water Lily: Although it is an aquatic plant,its flowers emerge above the water level and are pollinated by insects or wind,known as Entomophily and Anemophily $(4)$.
$(d)$ Yucca: It has a specific symbiotic relationship with the moth Pronuba for pollination,known as Entomophily $(1)$.
Therefore,the correct sequence is $a-2, b-3, c-4, d-1$.

(D) In angiosperms,post-fertilization changes occur as follows:
$1$. The Zygote $(a)$ develops into the Embryo $(2)$.
$2$. The Primary Endosperm Nucleus $(PEN)$ $(b)$ develops into the Endosperm $(1)$,which provides nutrition to the developing embryo.
$3$. The Ovule $(c)$ matures into the Seed $(4)$ after fertilization.
$4$. The Ovary $(d)$ matures into the Fruit $(3)$ after fertilization.
Therefore,the correct matching is $a-2, b-1, c-4, d-3$.

$(A)$ The correct matching is as follows:
$(a)$ $PEN$ (Primary Endosperm Nucleus) develops into the white kernel of coconut, which is cellular endosperm $(a-3)$.
$(b)$ $PEC$ (Primary Endosperm Cell) gives rise to coconut water, which is free-nuclear endosperm $(b-2)$.
$(c)$ Cotyledon in monocots is known as Scutellum $(c-4)$.
$(d)$ Dicot embryo development passes through a heart-shaped stage $(d-1)$.
Therefore, the correct sequence is $a-3, b-2, c-4, d-1$.

(C) $1$. Seeds are indeed the final product of sexual reproduction in angiosperms.
$2$. Calyx and corolla are accessory whorls,not reproductive organs.
$3$. Androecium (stamen) and gynoecium (pistil) are the reproductive whorls,not accessory whorls. Therefore,statement $C$ is incorrect.
$4$. $A$ typical angiosperm anther is dithecous,meaning it has two lobes,and each lobe contains two microsporangia,totaling four microsporangia.

(A) $1$. The viability of pollen grains is highly dependent on the prevailing temperature and humidity of the environment.
$2$. In some cereals like wheat and rice,pollen grains lose viability within $30$ minutes of their release,whereas in some members of Rosaceae,Leguminosae,and Solanaceae,they maintain viability for months.
$3$. Pollen grains can be stored for years in liquid nitrogen at $-196^{\circ}C$ (cryopreservation).
$4$. The exine of the pollen grain is made of sporopollenin,which is one of the most resistant organic materials known,not cellulose.
Therefore,option $A$ and $C$ are both factually correct statements. However,in standard textbook contexts,the dependence on environmental factors is a fundamental property. Given the options,$A$ is a correct statement.

(B) $1$. Statement $A$ is true: For autogamy (self-pollination) to occur,the anther and stigma must be in close proximity.
$2$. Statement $B$ is false: The plants $Viola$,$Oxalis$,and $Commelina$ produce two types of flowers: chasmogamous and cleistogamous. Cleistogamous flowers do not open at all,ensuring self-pollination. The option incorrectly lists $Zostera$ instead of $Oxalis$ or $Commelina$ and generalizes the entire plant as cleistogamous.
$3$. Statement $C$ is true: Dioecious plants (e.g.,papaya) have separate male and female plants,so geitonogamy (transfer of pollen from anther to stigma of another flower on the same plant) cannot occur.
$4$. Statement $D$ is true: Geitonogamy involves pollen transfer between flowers of the same plant,meaning the genetic makeup of the pollen and the ovule is identical,similar to autogamy.

(B) $1$. Orchids and watermelons have many ovules in their ovaries,which is a correct statement.
$2$. In $Papaver$ (poppy),the gynoecium is multicarpellary and syncarpous (fused carpels),not apocarpous. Therefore,the statement that carpels are free is incorrect.
$3$. The ovule is indeed attached to the placenta by a stalk called the funicle,which is a correct statement.
$4$. The nucellus is the central mass of tissue in an ovule,which is protected by one or two protective envelopes called integuments,making this statement correct.

(D) The correct answer is $D$. The relationship between the moth and the $Yucca$ plant is an example of obligate mutualism. The moth deposits its eggs in the locule of the ovary of the $Yucca$ flower,and in return,the flower gets pollinated by the moth. The larvae of the moth come out of the eggs as the seeds start developing. Neither the moth nor the $Yucca$ plant can complete their life cycles without each other. Therefore,the statement that they can complete their life cycles without each other is incorrect.

(A) Based on the structure of the mature embryo sac and the process of pollen tube entry into the ovule:
$1$. '$P$' represents the Pollen tube,which carries male gametes to the embryo sac.
$2$. '$Q$' represents the Antipodal cells,which are located at the chalazal end.
$3$. '$R$' represents the Polar nuclei,located in the central cell.
$4$. '$S$' represents the Egg cell,which is part of the egg apparatus.
$5$. '$T$' represents the Synergids,which guide the pollen tube into the embryo sac.
Therefore,the correct sequence is Pollen tube,Antipodal cells,Polar nuclei,Egg cell,Synergid.

(D) Post-fertilization events are the changes that occur in the flower after the process of fertilization is completed.
These include the transformation of the ovule into a seed,the ovary into a fruit,and the zygote into an embryo.
However,the transformation of a megaspore into an embryo sac is a pre-fertilization event,as it occurs during the development of the female gametophyte before fertilization takes place.
Therefore,the correct answer is $D$.

(A) The length of the pollen tube depends on the distance it must travel through the style to reach the ovule. In $Zea mays$ (Maize), the style is extremely long (the silk of the corn), and the pollen tube must grow through this entire length to reach the ovary. Therefore, maize has the longest pollen tube among the given options.

(D) $Polysiphonous$ pollen grains are those from which more than one pollen tube emerges during germination.
In the plant families $Malvaceae$ and $Cucurbitaceae$,$polysiphonous$ pollen grains are commonly observed.
Therefore,the correct option is $D$.

(C) Water hyacinth $(Eichhornia \text{ } crassipes)$ was introduced in India primarily because of its beautiful flowers and leaf shape, not because of its pollutant-indicator property. It is an invasive aquatic weed that grows rapidly in water bodies, causing an imbalance in the ecosystem dynamics by depleting dissolved oxygen, which leads to the death of fishes and other aquatic organisms. Therefore, statement $C$ is false.

(D) In $Angiosperms$,the male and female gametophytes are highly reduced and are dependent on the sporophyte for their nutrition and development. They do not have an independent free-living existence. In contrast,in $Bryophytes$,$Pteridophytes$,and $Algae$,the gametophytic phase is often free-living and independent.

(C) Non-viable seeds are often produced as a result of $Hybridisation$ in plants. When two genetically distinct varieties are crossed, the resulting $F_1$ generation may sometimes produce seeds that lack a functional embryo or possess endosperm abnormalities, rendering them non-viable. In contrast, $Apomixis$ produces viable seeds without fertilization, $Parthenocarpy$ typically results in seedless fruits, and $Somatic$ $\text{embryogenesis}$ is a technique used for clonal propagation where embryos are derived from somatic cells.

(C) In angiosperms,the flower bears the male and female sex organs.
The male sex organ is the stamen,also known as the androecium. It consists of an anther lobe and a filament. The anther produces pollen grains.
The female sex organ is the carpel,also known as the pistil or gynoecium. It consists of three parts: the style,stigma,and ovary.

(A) Double fertilisation is a characteristic feature of angiosperms,discovered by $SG$ Nawaschin in $1898$.
In double fertilisation,one male gamete fuses with the egg cell (ovum) to form a diploid zygote $(2n)$.
The second male gamete fuses with the diploid secondary nucleus (central cell) to form the triploid primary endosperm nucleus $(3n)$,which develops into the triploid endosperm.
The endosperm provides nutrition to the developing embryo.
Therefore,statements $I$ and $II$ are correct.

(B) In angiosperms,the megaspore mother cell $(MMC)$ is diploid $(2n)$.
It undergoes meiosis to produce four megaspores,which are haploid $(n)$ in nature.
Therefore,the statement 'Megaspore - Diploid' is incorrect.
Endosperm is formed by triple fusion and is triploid $(3n)$.
Pollen grains are haploid $(n)$ gametophytes.
Synergids are part of the embryo sac and are haploid $(n)$.

(D) Double fertilisation was discovered by $SG$ Nawaschin $(1898)$ and Guignard in $Lilium$ and $Fritillaria$. Double fertilisation is a characteristic feature restricted to angiosperms.
When the pollen tube enters the ovule,it releases two male gametes into the embryo sac.
$(i)$ Generative Fertilisation: Fusion of one male gamete with the egg cell to form a diploid zygote $(2n)$.
$(ii)$ Vegetative Fertilisation (Triple Fusion): Fusion of the second male gamete with the diploid secondary nucleus (formed by two polar nuclei) to form the primary endosperm nucleus $(PEN)$,which develops into the triploid endosperm $(3n)$.
Statement $D$ is incorrect because double fertilisation encompasses both syngamy (fusion with egg) and triple fusion (fusion with polar nuclei),not just the fusion of a male gamete with the egg.

(D) In angiosperms,after the process of double fertilisation,the egg cell develops into a zygote and the central cell develops into the primary endosperm cell. The synergids and antipodal cells do not participate in the formation of the embryo or endosperm and consequently degenerate after fertilisation.

(D) Flowering plants (Angiosperms) are considered the most successful group of plants due to several evolutionary advantages:
$1$. They possess a highly developed vascular system (xylem and phloem) for efficient transport of water and nutrients.
$2$. They exhibit a wide variety of pollination mechanisms,including biotic (insects,birds,bats) and abiotic (wind,water) agents,which ensures successful reproduction.
$3$. The seeds are protected within fruits,and the embryo is well-protected,allowing it to survive during periods of unfavourable environmental conditions.

(C) Cleistogamy is a phenomenon where bisexual flowers do not open at all.
In these flowers,the anthers and stigma lie close to each other.
When anthers dehisce in the flower buds,pollen grains come in contact with the stigma to effect pollination.
Thus,cleistogamous flowers are invariably autogamous as there is no chance of cross-pollination.
$Commelina$ $benghalensis$ is a classic example of a plant that produces both chasmogamous and cleistogamous flowers.

(B) monocarpic plant is one that flowers and produces fruit only once in its lifetime,after which it dies.
Among the given options,$Corypha$ $umbraculifera$ (Talipot palm) is a well-known example of a monocarpic tree.
While $Borassus$ $flabellifer$ is polycarpic,$Corypha$ $umbraculifera$ flowers only once after a long vegetative period (often $30-80$ years) and then dies.

(B) Pollinia are coherent masses of pollen grains found in certain plant families.
These structures are characteristic features of the families $Orchidaceae$ and $Asclepiadaceae$.
In these families,the pollen grains are transferred as a single unit during pollination.

(A) $Strobilanthus$ $kunthiana$ is commonly known as $Neelakuranji$ in the local language.
It is found in the hilly regions of Kerala,Karnataka,and Tamil Nadu.
This plant exhibits a unique flowering pattern,blooming once every $12$ years.
The last mass flowering event occurred in $2006$,which resulted in a massive quantity of blue flowers,covering the hills in a blue carpet and attracting many tourists.

(C) Animals that give birth to young ones are called viviparous.
In viviparous animals,the development of the embryo takes place inside the female body,and the mother gives birth to fully developed young ones.
Oviparous animals are those that lay eggs.
Ovoviviparous animals are those where eggs develop inside the mother's body,but the embryo derives nutrition from the egg yolk rather than directly from the mother,and they eventually hatch or are delivered as young ones.

(B) Prof. $P. Maheshwari$ was a renowned Indian botanist who made significant contributions to plant embryology.
He extensively studied the embryological aspects of angiosperms and emphasized the importance of embryological characters in the classification of plants (taxonomy).
His work helped in establishing embryology as a vital tool for understanding evolutionary relationships among plant groups.

(B) Sexual reproduction involves the fusion of male and female gametes,which are formed through meiosis.
During meiosis,processes like crossing over and independent assortment occur,leading to genetic recombination.
This results in offspring that are genetically distinct from their parents and from each other.
Therefore,the primary outcome of sexual reproduction is the creation of new genetic combinations that lead to variation within a population.

(C) Sexual reproduction is characterized by genetic recombination and the fusion of gametes from two different parents.
Due to genetic recombination and independent assortment during meiosis,the progeny exhibit significant variations compared to their parents.
In sexual reproduction,the genetic material is contributed by two parents of the same species,leading to a unique combination of traits in the offspring.
In contrast,asexual reproduction involves only one individual,resulting in offspring that are genetically identical to the parent (clones).

(D) The condition where male and female reproductive organs are present on separate individual plants is known as dioecious.
In fungi and some lower plants,this condition is referred to as heterothallic.
Since the plants bear only one type of reproductive organ (either male or female),they are also described as unisexual.
Therefore,all these terms are used to describe the condition where sexes are separate.

(D) All statements are correct.
$Strobilanthes kunthiana$,commonly known as $NeelaKuranji$,is a plant species found in the hilly regions of Kerala,Tamil Nadu,and Karnataka.
It exhibits a unique flowering cycle,blooming once every $12$ years.
The last recorded mass flowering occurred in $Sept-Oct, 2006$,and the subsequent cycle occurred in $Sept-Oct, 2018$.
During this period,the flowers cover the hills in a blue hue,attracting a large number of tourists.

(D) The condition where both male and female reproductive organs are present on the same plant is referred to as 'bisexual' or 'monoecious'.
In botanical terminology,the term 'monoecious' is specifically used to describe plants where both male and female flowers are borne on the same individual.
The term 'bisexual' is also used to describe flowers that contain both stamens and carpels,or plants that possess such flowers.
Therefore,both terms are applicable to this condition.

$(A)$ Bamboo is a monocarpic plant, meaning it reproduces only once in its lifetime.
It typically flowers after a period of $50-100\; \text{years}$ of growth.
After the flowering and fruiting process, the plant dies.

$(A)$ The zygote is a diploid cell formed by the fusion of two haploid gametes (male and female) during fertilization.
It serves as the vital link between two generations because it carries the genetic material from the parents to the offspring.
Since the zygote develops into the new organism, which will eventually produce gametes for the next generation, it is considered the product of the current generation and the producer of the next.
Therefore, $Statement\; 2$ correctly explains why the zygote acts as a link between generations as stated in $Statement\; 1$.

(C) $Statement\; 1$ is True because a zygote is formed by the fusion of two gametes,resulting in a single-celled structure.
$Statement\; 2$ is False because the fusion of two haploid cells $(n + n)$ results in the formation of a single diploid cell $(2n)$,not two diploid cells.

(A) The correct matching is as follows:
$(A)$ Clone: $A$ clone is a group of genetically identical individuals,often referred to as a $Ramet$ $(5)$.
$(B)$ Plant apomixis: This is a form of asexual reproduction that mimics sexual reproduction,such as $Agamospermy$ $(1)$.
$(C)$ Grafting: This technique involves joining two plants,where the upper part is called the $Scion$ $(2)$.
$(D)$ Tissue culture: This process involves the growth of cells or tissues in a sterile medium,often resulting in an undifferentiated mass called $Callus$ $(3)$.
$(E)$ Inflorescence: This refers to the arrangement of flowers on the floral axis,which is a $Flower$ $(4)$ bearing structure.
Therefore,the correct sequence is $A-5, B-1, C-2, D-3, E-4$.

(B) The given diagram illustrates the process of sexual reproduction.
First,the fusion of male and female gametes occurs (syngamy).
Second,the formation of a zygote takes place,where the two nuclei fuse into a single diploid $(2n)$ nucleus.
Third,the zygote develops into a new individual (cell $2n$),representing the completion of the fertilization process.

(C) In angiospermic plants:
$1$. The $Zygote$ is formed by the fusion of a male gamete $(n)$ and an ovum $(n)$,resulting in a diploid structure $(2n)$.
$2$. The $Endosperm$ is formed by the process of triple fusion involving two polar nuclei $(n+n)$ and one male gamete $(n)$,resulting in a triploid structure $(3n)$.
$3$. The $Ovum$ (egg cell) is a haploid gamete produced after meiosis,represented as $(n)$.

(D) Post-fertilisation events occur after the fusion of gametes (syngamy) to form a zygote.
$1$. Embryogenesis: The process of development of an embryo from the zygote.
$2$. $PEN$ (Primary Endosperm Nucleus) formation: In angiosperms,the fusion of the male gamete with the two polar nuclei (triple fusion) results in the formation of the $PEN$.
Both embryogenesis and $PEN$ formation are characteristic post-fertilisation events.

(B) $Strobilanthus \; kunthiana$ (Neelakuranji) is a monocarpic plant that flowers once every $12 \; \text{years}$.
It is famous for transforming the hilly regions of Kerala, Karnataka, and Tamil Nadu into vast blue stretches during its mass flowering event.
The last recorded mass flowering occurred between September and October $2006$.
Therefore, statement $B$ is the correct description of this phenomenon.

(B) Self-fertilization occurs in plants where both male and female reproductive organs are present in the same flower, known as bisexual flowers.
In the case of the pea plant $(Pisum sativum)$, the flowers are bisexual and exhibit a phenomenon called cleistogamy (bud pollination), where the flower remains closed, ensuring that pollen grains from the anther fall directly onto the stigma of the same flower, leading to self-fertilization.

(C) The life cycle of an organism,particularly a plant like rice,typically consists of three main phases:
$1$. Juvenile phase: The period of growth from germination to the development of the capacity to reproduce.
$2$. Reproductive phase: The period during which the plant produces flowers,fruits,and seeds.
$3$. Senescence: The final stage of the life cycle characterized by aging,leading to the death of the organism.
Therefore,the correct sequence is Juvenile phase $\rightarrow$ Reproductive phase $\rightarrow$ Senescence.

(D) The flowering and fruiting patterns in plants are classified based on their life cycle duration:
$1$. Annuals: These plants complete their life cycle (flowering and fruiting) within a single season or year (e.g.,Rice,Wheat,Marigold,Maize,Pea).
$2$. Perennials: These plants live for many years and flower/fruit repeatedly over several seasons (e.g.,Mango,Apple).
In the given options,$A$,$B$,and $C$ consist of annual plants. Option $D$ consists of perennial plants. Therefore,$D$ is the odd one out.

(D) In $Algae$, $Bryophytes$, and $Pteridophytes$, water acts as the medium for the transfer of male gametes.
In $Gymnosperms$ and $Angiosperms$, male gametes are transferred through a pollen tube, which is a specialized structure, not water.
Therefore, $Gymnosperms$ and $Angiosperms$ form the odd pair.

(A) The incorrect statement is that the zygote is a thick-walled diploid sexual spore. In many organisms,especially algae like $Ulothrix$ and $Spirogyra$,the zygote develops a thick wall to survive unfavourable conditions,but in general biological terminology,the zygote is often thin-walled during its initial formation. However,specifically in the context of $Chara$,the nucule (female sex organ) is indeed protected by five spirally twisted tube cells and capped by five coronary cells. $Ulothrix$ exhibits external fertilisation. Sweet potato flowers are bisexual. Therefore,the statement regarding the zygote being a thick-walled spore is considered incorrect in the context of general definitions where it is described as a single-celled diploid structure.