Sexual Reproduction in Flowering Plants Questions in English

(N/A) Pollination is the process of transfer of pollen grains from the anther to the stigma of a flower. It is an external process that occurs with the help of agents like wind,water,birds,or insects.
Fertilization,on the other hand,is the biological process involving the fusion of the male gamete with the female gamete. It occurs internally within the ovule and leads to the formation of a diploid zygote.

(C) The anther is the part of the stamen (the male reproductive organ of a flower) that produces and contains pollen grains. Pollen grains are the male gametophytes that carry the male gametes necessary for fertilization.

(N/A) The longitudinal section of a flower consists of the following main parts:
$1$. Sepal: The outermost green,leaf-like structures that protect the flower in the bud stage.
$2$. Petal: The brightly colored parts that attract insects for pollination.
$3$. Stamen: The male reproductive part of the flower,consisting of an anther and a filament.
$4$. Carpel (Pistil): The female reproductive part of the flower,consisting of the stigma,style,and ovary.

(B) In a flowering plant, the reproductive parts are located within the flower.
- The male reproductive part is the $stamen$, which consists of an $anther$ and a $filament$. The $anther$ produces pollen grains, which contain the male gametes.
- The female reproductive part is the $pistil$ (or $carpel$), which consists of the $stigma$, $style$, and $ovary$. The $ovary$ contains ovules, which produce the female gametes (egg cells).
- Therefore, the $anther$ produces male gametes and the $ovary$ produces female gametes.

(C) The process of sexual reproduction in a flower follows a specific biological order:
$1$. $Pollination$: The transfer of pollen grains from the anther to the stigma of a flower.
$2$. $Fertilisation$: The fusion of the male gamete with the female gamete (egg) to form a zygote.
$3$. $Embryo$: The zygote develops into an embryo within the seed.
$4$. $Seedling$: Upon germination, the seed develops into a new plant or seedling.
Therefore, the correct sequence is $Pollination \rightarrow Fertilisation \rightarrow Embryo \rightarrow Seedling$.

(B) In flowering plants, the reproductive process follows a specific sequence:
$1$. Gametes: The process begins with the formation of male and female gametes (pollen grains and egg cells).
$2$. Zygote: Fertilization occurs when the male and female gametes fuse to form a single-celled $zygote$.
$3$. Embryo: The $zygote$ undergoes repeated cell divisions to develop into an $embryo$ within the seed.
$4$. Seedling: Upon germination, the $embryo$ grows into a young plant known as a $seedling$.
Therefore, the correct sequence is: $gametes \rightarrow zygote \rightarrow embryo \rightarrow seedling$.

(C) The pollen tube is a tubular structure produced by the male gametophyte (pollen grain) after it lands on the stigma of a flower.
Its primary function is to transport the male gametes from the pollen grain to the ovule located within the ovary.
Therefore,the growth of the pollen tube must continue until it reaches the ovule.
Consequently,the total length of the pollen tube is determined by the distance it must travel from the point of germination (the upper surface of the stigma) to the target (the ovule).

(D) Statement $(i)$ is false because flowers can be unisexual (staminate or pistillate) or bisexual.
Statement $(ii)$ is true because flowers are the reproductive structures in angiosperms.
Statement $(iii)$ is false because flowers are only produced by angiosperms (flowering plants),not by all plant groups like algae,bryophytes,or pteridophytes.
Statement $(iv)$ is true because after fertilisation,the ovary develops into a fruit and the ovules develop into seeds.
Therefore,statements $(ii)$ and $(iv)$ are correct.

(A) Unisexual flowers are those that contain either only stamens (male reproductive part) or only pistils (female reproductive part),but not both.
Statement $(i)$ is false because unisexual flowers do not possess both stamen and pistil.
Statement $(ii)$ is true as they contain either stamen or pistil.
Statement $(iii)$ is true because unisexual flowers often require cross-pollination to transfer pollen from the male flower to the female flower.
Statement $(iv)$ is true because fruits are formed from the ovary of the pistil. Flowers possessing only stamens (staminate flowers) lack an ovary and therefore cannot produce fruits.
Thus,statements $(ii), (iii),$ and $(iv)$ are correct.

(B) Sexual reproduction in flowering plants involves the fusion of male and female gametes,making statement $(i)$ true.
Fertilisation,which is the fusion of these gametes,is a compulsory event in sexual reproduction,making statement $(ii)$ true.
The product of the fusion of male and female gametes is a zygote,making statement $(iii)$ true.
Offspring produced through sexual reproduction are genetically different from their parents due to meiosis and recombination,meaning they are not clones. Clones are produced through asexual reproduction. Thus,statement $(iv)$ is false.
Therefore,statements $(i), (ii),$ and $(iii)$ are correct.

(C) The provided figure shows the internal structure of a germinating seed.
$A$ represents the plumule,which is the part of the embryo that develops into the shoot system.
$B$ represents the cotyledon,which is the seed leaf that provides nourishment to the developing embryo.
$C$ represents the radicle,which is the part of the embryo that develops into the root system.
Therefore,the parts $A, B$,and $C$ are sequentially plumule,cotyledon,and radicle.

(B) The process of removing stamens from a bisexual flower is known as emasculation.
If a flower produces fruit after the removal of its own stamens,it indicates that cross-pollination has occurred.
Cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower of the same or a different plant.
Since the pistil (stigma,style,and ovary) remains intact,it is capable of receiving pollen grains from an external source (another flower).
Once the pollen grains land on the stigma,they germinate to form a pollen tube,which travels down the style to reach the ovary,resulting in fertilization and subsequent fruit formation.

(N/A) In a tobacco plant,the male gamete is a haploid cell $(n)$ containing $24$ chromosomes.
Since the female gamete is also a haploid cell $(n)$,it will also contain $24$ chromosomes.
The zygote is formed by the fusion of the male and female gametes,making it a diploid cell $(2n)$.
Therefore,the number of chromosomes in the zygote is $24 + 24 = 48$.

(N/A) Fertilisation is the process of fusion of male and female gametes. In flowering plants,the male gametes are contained within the pollen grains. Pollination is the transfer of pollen grains from the anther to the stigma of a flower. If pollination does not occur,the male gametes cannot reach the female gametes present in the ovary. Therefore,without the presence of male gametes,fertilisation cannot take place.

(B) After fertilization,the male gamete fuses with the female gamete (egg cell) to form a zygote. This process occurs within the ovule. The ovule is located inside the ovary of the flower. Therefore,the zygote is located inside the ovule.

(A) The exchange of genetic material,also known as genetic recombination,occurs during sexual reproduction.
In sexual reproduction,two parents contribute gametes (sperm and egg) which fuse during fertilization.
This process involves meiosis,where crossing over occurs between homologous chromosomes,leading to new combinations of genes.
This variation is a hallmark of sexual reproduction,whereas asexual reproduction (including vegetative reproduction and budding) typically produces clones with identical genetic material.

(N/A) Pollination is the process of transfer of pollen grains from the anther to the stigma of a flower.
Fertilisation is the process of fusion of the male gamete with the female gamete (egg) to form a zygote.
The site of fertilisation in a flower is the ovule.
The product of fertilisation is the zygote.

(N/A) The four whorls of a flower are:
$1$. Calyx (Sepals)
$2$. Corolla (Petals)
$3$. Androecium (Stamens)
$4$. Gynoecium (Pistil/Carpel)
Gamete-producing organs:
- Male gamete-producing organ: The stamen (specifically the anther,which produces pollen grains containing male gametes).
- Female gamete-producing organ: The pistil (specifically the ovary,which contains ovules that produce the egg cell/female gamete).

(N/A) Organisms that possess both male and female sex organs in the same individual are called bisexual or hermaphrodite organisms.
Example: $Hydra$,Earthworm,Mustard,or Hibiscus.

(N/A) Pollen grains are the male reproductive units in flowering plants that contain the male gametes. They are typically produced in the anther.
Ovules are the female reproductive structures in flowering plants that contain the female gamete (egg cell). They are located within the ovary and develop into seeds after fertilization.

(N/A)

Pollination	Fertilization
$(i)$ It is the transfer of pollen grains from the anther to the stigma of a flower.	$(i)$ It is the fusion of the male gamete with the female gamete (egg).
$(ii)$ It is achieved by agents like wind,water,or animals.	$(ii)$ It is achieved by the growth of the pollen tube so that the male gamete reaches the female germ cells.
$(iii)$ It leads to fertilization.	$(iii)$ It leads to the formation of seeds.
$(iv)$ It is an external process.	$(iv)$ It is an internal process.

(N/A)

Plumule	Radicle
$(i)$ The part of the growing embryo which later forms the shoot of the young plant.	$(i)$ The part of the growing embryo which later forms the root of the young plant.
$(ii)$ It is positively phototrophic and negatively geotrophic.	$(ii)$ It is positively geotrophic and negatively phototrophic.

(N/A) $(i)$ The ovum (egg cell) fuses with the male gamete to form a zygote.
$(ii)$ The ovary ripens and develops into the fruit.
$(iii)$ The ovule develops into the seed.
$(iv)$ The sepals and petals usually wither,shrivel,and fall off.

(N/A)

Self-pollination	Cross-pollination
$(i)$ It is the transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant.	$(i)$ It is the transfer of pollen grains from the anther of one flower to the stigma of another flower on a different plant of the same species.
$(ii)$ It does not require external agents like insects, wind, or water.	$(ii)$ It requires external agents like insects, wind, or water for pollination.
$(iii)$ It results in less genetic variation in the offspring.	$(iii)$ It results in greater genetic variation in the offspring.

(N/A) $(i)$ The stigma is the sticky terminal part of the carpel that serves as a landing platform for pollen grains.
$(ii)$ The ovary is the swollen basal part of the carpel that contains ovules. It protects the female germ cells and develops into a fruit after fertilization.
$(b)$ After fertilization,the zygote divides several times to form an embryo within the ovule. The ovule develops a tough seed coat and is gradually converted into a seed.

(N/A) The labels are as follows:
$A -$ Pollen grain
$B -$ Pollen tube
$C -$ Ovary
$D -$ Female germ cell (Egg cell)
$(b)$ Pollination is the process of transfer of pollen grains from the anther to the stigma of a flower.
Significance: It is essential for fertilization,as it brings the male gametes to the female reproductive part.
$(c)$ Fertilization in flowers occurs when a pollen grain lands on a suitable stigma and germinates to form a pollen tube. This tube grows through the style,carrying the male germ cell,and reaches the ovary. The male germ cell then fuses with the female germ cell present in the ovule to form a zygote.
$(i)$ Seed develops from the ovule.
$(ii)$ Fruit develops from the ovary.

(N/A) Two reasons for variations in sexual reproduction are:
$(i)$ Involvement of two different individuals (parents) with different genetic makeups.
$(ii)$ Creation of new combinations of gene variants due to the process of meiosis and recombination during gamete formation.
$(b)$ $(i)$ '$A$' represents the Pollen grain.
$(ii)$ '$A$' reaches part '$B$' (stigma) through the process of pollination,which is facilitated by various agents like wind,water,insects,or animals.
$(iii)$ '$C$' is the Pollen tube. Its importance lies in providing a pathway for the male gametes to travel from the stigma to the ovule for fertilisation.
$(iv)$ '$D$' represents the Ovule. After fertilisation,the ovule develops into a seed.

(N/A) $(i)$ Testis: The $Anther$ produces pollen grains, similar to how the testis produces sperm.
$(ii)$ Ovary: The $Ovary$ in a flower contains ovules, similar to how the ovary in animals produces eggs.
$(iii)$ Eggs: The $Ovule$ (or the egg cell within the embryo sac) serves the same function as the egg in animals.
$(iv)$ Sperms: The $Male \text{ } gametes$ contained within the pollen grains serve the same function as sperms in animals.

(N/A) Double fertilization: It occurs when one male gamete fuses with the egg cell to form a $zygote$ and the other male gamete fuses with two polar nuclei to form the primary endosperm nucleus (triple fusion).
Since these two processes occur simultaneously in the embryo sac,it is known as double fertilization.
After fertilization:
$(i)$ The ovary develops into the fruit.
(ii) The ovules develop into the seeds.

(B) Sexual reproduction in flowering plants involves the following characteristics:
$(i)$ It requires two types of gametes (male and female gametes),which is true.
$(ii)$ Fertilization (fusion of gametes) is a compulsory event in sexual reproduction,which is true.
$(iii)$ The fusion of gametes always results in the formation of a zygote,which is true.
$(iv)$ Offspring formed through sexual reproduction are not clones because they show genetic variation due to the fusion of gametes from two different parents. Therefore,this statement is false.
Thus,statements $(i), (ii),$ and $(iii)$ are correct.

(C) The figure shows the structure of a germinating seed (specifically a dicot seed embryo).
$A$ points to the plumule,which is the part of the embryo that develops into the shoot system.
$B$ points to the cotyledon,which stores food for the developing embryo.
$C$ points to the radicle,which is the part of the embryo that develops into the root system.
Therefore,the parts $A$,$B$,and $C$ are sequentially plumule,cotyledon,and radicle.

(C) The pollen tube is a tubular structure that develops from the pollen grain after it lands on the stigma of a flower.
Its primary function is to transport the male gametes from the pollen grain to the ovule located within the ovary.
Therefore,the length of the pollen tube must be sufficient to cover the distance from the point of germination (the upper surface of the stigma) to the target (the ovule).
Thus,the length of the pollen tube depends on the distance between the pollen grain on the upper surface of the stigma and the ovule.

(D) Statement $(i)$ is false because flowers can be unisexual (staminate or pistillate) or bisexual.
Statement $(ii)$ is true because flowers contain the reproductive parts (stamens and carpels) of angiosperms.
Statement $(iii)$ is false because flowers are only produced by angiosperms (flowering plants),not by algae,bryophytes,pteridophytes,or gymnosperms.
Statement $(iv)$ is true because after fertilization,the ovary develops into a fruit and the ovules develop into seeds.
Therefore,statements $(ii)$ and $(iv)$ are correct.

(A) Unisexual flowers are those that contain either only stamens (male reproductive part) or only pistils (female reproductive part),but not both. Therefore,statement $(ii)$ is true and statement $(i)$ is false.
Because they lack one of the reproductive organs,they typically require cross-pollination to achieve fertilization,making statement $(iii)$ true.
Since fruits develop from the ovary (part of the pistil) after fertilization,flowers that possess only stamens (staminate flowers) lack an ovary and therefore cannot produce fruits. Thus,statement $(iv)$ is true.
Combining these,statements $(ii), (iii),$ and $(iv)$ are correct.

(D) In flowering plants, the reproductive process follows a specific sequence:
$1$. Gametes: The process begins with the formation of male and female gametes.
$2$. Zygote: Fertilization occurs when the male and female gametes fuse to form a diploid zygote.
$3$. Embryo: The zygote undergoes repeated cell divisions to develop into an embryo within the seed.
$4$. Seedling: Upon germination, the embryo grows into a young plant known as a seedling.
Therefore, the correct sequence is $gametes \rightarrow zygote \rightarrow embryo \rightarrow seedling$.

(D) The growth of the pollen tube towards the ovule is a classic example of $Chemotropism$.
This occurs because the ovule releases specific chemical substances that act as a signal for the pollen tube.
The pollen tube senses these chemicals and grows in the direction of the higher concentration of these substances,which leads it directly to the ovule for fertilization.

(D) In angiosperms (flowering plants),the flower is the specialized reproductive structure.
It contains the male reproductive parts (stamen) and the female reproductive parts (pistil/carpel).
These organs are responsible for sexual reproduction,leading to the formation of seeds and fruits.

(B) In the majority of flowering plants,the flowers are bisexual (also known as hermaphrodite).
This means that both the male reproductive part (stamen) and the female reproductive part (pistil/carpel) are present within the same flower.
This arrangement facilitates self-pollination and ensures reproductive success in many species.

(C) In a flower,the female reproductive part is the carpel or pistil.
The carpel consists of three parts: the stigma,the style,and the ovary.
The ovary contains the ovules,and inside each ovule,the female germ cell (egg cell) is present.
Therefore,the female germ cells are located in the ovary.