Out breeding Devices Questions in English

(C) In bisexual flowers,when the male and female reproductive organs mature at different times,it prevents self-pollination. This phenomenon is known as $Dichogamy$.
$Apogamy$ refers to the development of an embryo without fertilization.
$Polygamy$ refers to the presence of both unisexual and bisexual flowers on the same plant.
$Herkogamy$ is a mechanical barrier that prevents self-pollination.

(C) is the correct answer.
Heterostyly is a condition in which flowers of the same species exhibit different lengths of styles and stamens.
This mechanism promotes cross-pollination by preventing self-pollination.
In $Primula$ (Primrose),there are two types of flowers:
$1$. Pin-eyed: Flowers with a long style and short stamens.
$2$. Thrum-eyed: Flowers with a short style and long stamens.
This dimorphism ensures that pollen from one type of flower is effectively transferred to the stigma of the other type.

(C) Heterostyly is a mechanism in some flowering plants where the flowers exhibit different lengths of styles and stamens.
This adaptation promotes cross-pollination by ensuring that pollen from one flower type is deposited on the stigma of another flower type with a corresponding style length.
Therefore,the condition where styles are of different lengths relative to stamens is known as Heterostyly.

(B) When stamens (anthers) mature earlier than the stigma of the same flower,this condition is known as $Protandry$.
Flowers exhibiting this condition are called protandrous.
This mechanism promotes cross-pollination by preventing self-pollination.
Examples include $Coriander$,$Jasmine$,and $Sunflower$.

(B) . In $Dichogamy$,the maturation periods of male and female reproductive organs (anther and stigma) are different. This temporal separation prevents self-pollination and makes cross-pollination compulsory. $Cleistogamy$ and $Homogamy$ generally promote self-pollination.

(B) Continuous self-pollination leads to inbreeding depression.
Inbreeding depression is the reduction in biological fitness in a given population as a result of inbreeding,which is the mating of related individuals.
This process increases homozygosity,which often leads to the expression of harmful recessive alleles,resulting in weaker offspring.

(B) $Dichogamy$ is a mechanism that promotes cross-pollination by ensuring that the anther and the stigma of the same flower mature at different times. This prevents self-pollination. It is of two types: $Protandry$ (anthers mature first) and $Protogyny$ (stigma matures first). An example is the sunflower.

(D) Self-pollination is prevented by several mechanisms in plants to promote cross-pollination:
$1$. $Self-sterility$ (or self-incompatibility): $A$ genetic mechanism where pollen grains fail to germinate on the stigma of the same flower.
$2$. $Herkogamy$: $A$ physical or mechanical barrier between the anther and the stigma of the same flower, preventing self-pollination.
$3$. $Dichogamy$: $A$ condition where the anthers and stigma of the same flower mature at different times (protandry or protogyny).
Therefore, all these mechanisms prevent self-pollination.

(D) Autogamy (self-pollination) leads to inbreeding depression over successive generations.
Inbreeding depression refers to the reduced biological fitness in a given population as a result of inbreeding.
This results in the production of seeds that are fewer in number,have lower germination rates,and produce less healthy or less vigorous plants compared to those produced by cross-pollination (allogamy).

(B) In bisexual flowers,to prevent self-pollination and promote cross-pollination,plants have evolved various outbreeding devices.
One such mechanism is dichogamy,where the stamens and carpels mature at different times.
When the gynoecium (female reproductive part) matures earlier than the androecium (male reproductive part),the condition is known as Protogyny.
Conversely,when the androecium matures earlier than the gynoecium,it is called Protandry.

(C) Allogamy or cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower.
$1$. Homogamy refers to the maturation of anthers and stigma at the same time,which promotes self-pollination.
$2$. Cleistogamy refers to flowers that never open,ensuring self-pollination.
$3$. Dicliny (or unisexuality) refers to the presence of only one type of reproductive organ (either staminate or pistillate) in a flower. This condition makes self-pollination impossible,thereby strictly favouring allogamy.
Therefore,the correct option is $C$.

(A) Dichogamy is a mechanism used by plants to prevent self-pollination and promote cross-pollination.
In this process,the male reproductive part (anther) and the female reproductive part (stigma) of the same flower mature at different times.
This can occur in two ways:
$1$. Protandry: Anthers mature before the stigma.
$2$. Protogyny: Stigma matures before the anthers.
Therefore,the correct option is $A$.

(C) Herkogamy is a mechanical device that prevents self-pollination and favors cross-pollination,even in homogamous flowers where the anthers and stigma mature at the same time. It involves physical barriers between the anthers and the stigma.

(B) Herkogamy is a mechanical or physical barrier that prevents self-pollination in bisexual flowers.
In this mechanism,the spatial arrangement of the anthers and the stigma is such that the pollen grains from the anthers cannot easily reach the stigma of the same flower.
This physical separation or barrier ensures cross-pollination by preventing self-pollination.
Therefore,the correct option is $B$.

(B) Protandry is a type of dichogamy in which the anthers (male reproductive organs) of a flower mature before the stigma (female reproductive organ) of the same flower. This mechanism prevents self-pollination and promotes cross-pollination. Therefore,the correct option is $B$.

(B) In flowering plants,$Autogamy$ refers to the transfer of pollen grains from the anther to the stigma of the same flower.
$Geitonogamy$ refers to the transfer of pollen grains from the anther to the stigma of another flower of the same plant.
$Dioecy$ (the condition of being dioecious) is a mechanism where male and female flowers are borne on separate plants.
Because the male and female flowers are on different plants,the plant cannot perform $Autogamy$ (as it requires the same flower) or $Geitonogamy$ (as it requires the same plant).
Therefore,dioecy prevents both $Autogamy$ and $Geitonogamy$.

(A) The term $Herkogamy$ refers to a mechanical barrier that prevents self-pollination in bisexual flowers. This is a common adaptation in many plants to promote cross-pollination. $Cleistogamy$ refers to flowers that never open,$Heterostyly$ refers to different lengths of styles and stamens,and $Dichogamy$ refers to the maturation of male and female reproductive parts at different times. Based on standard botanical diagrams associated with this question,the mechanical separation of anthers and stigma is identified as $Herkogamy$.

(A) In dioecious plants,male and female flowers are present on different plants.
Since the male and female reproductive structures are physically separated on distinct individuals,self-pollination cannot occur.
Autogamy (transfer of pollen grains from the anther to the stigma of the same flower) is prevented because the plant is unisexual.
Geitonogamy (transfer of pollen grains from the anther of one flower to the stigma of another flower on the same plant) is also prevented because there is only one sex per plant.
Therefore,dioecious plants prevent both autogamy and geitonogamy.

(A) : Autogamy and geitonogamy are two forms of self-pollination.
In autogamy,pollen grains are transferred from the anther to the stigma of the same flower.
In geitonogamy,pollen grains are transferred from the anther of one flower to the stigma of another flower on the same plant.
Papaya is a dioecious plant,meaning male and female flowers are borne on separate plants.
Because the male and female reproductive structures are on different individuals,both autogamy and geitonogamy are prevented.

(C) : Unisexuality or dicliny is a condition in which two types of unisexual flowers are present,$i.e.$,staminate (male flower) and pistillate (female flower).
In a monoecious plant,unisexual flowers prevent autogamy (self-pollination within the same flower) because the male and female reproductive parts are in different flowers.
However,geitonogamy (transfer of pollen from the anther of one flower to the stigma of another flower on the same plant) can still occur in monoecious plants.
Therefore,unisexuality prevents autogamy but does not prevent geitonogamy.

(B) Continued self-pollination in plants leads to the accumulation of recessive deleterious alleles in the homozygous state.
This process reduces the genetic diversity within a population.
The reduction in fitness, vigor, and reproductive capacity due to this increased homozygosity is known as $Inbreeding \text{ } depression$.
Therefore, the correct option is $B$.

(A) Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower. Geitonogamy is the transfer of pollen grains from the anther of one flower to the stigma of another flower on the same plant. Both of these processes can be prevented in dioecious plants. In dioecious plants,male and female flowers are borne on separate plants. Therefore,neither self-pollination (autogamy) nor pollination between flowers of the same plant (geitonogamy) can occur. Among the given options,$Papaya$ is a dioecious plant,while $Cucumber$,$Maize$,and $Castor$ are monoecious plants.

(A) Cleistogamy is a phenomenon where flowers do not open at all. In such 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. $Commelina$ is a classic example of a plant that produces both chasmogamous (open) and cleistogamous (closed) flowers.

(C) Outbreeding devices are mechanisms that promote cross-pollination.
Monoecious plants,such as $Castor$ and $Maize$,possess both male and female flowers on the same plant.
In these plants,the presence of unisexual flowers prevents autogamy (transfer of pollen from the anther to the stigma of the same flower) because the flower is either staminate or pistillate.
However,geitonogamy (transfer of pollen from the anther of one flower to the stigma of another flower on the same plant) can still occur because both types of flowers are present on the same individual.
Therefore,$Castor$ and $Maize$ are the correct examples.

(D) Unisexuality is an outbreeding device in flowering plants.
If a plant is dioecious (e.g.,papaya),it prevents both autogamy (self-pollination within the same flower) and geitonogamy (pollination between two flowers on the same plant).
Since the flowers are unisexual and located on different plants,the pollen cannot reach the stigma of the same flower or another flower on the same plant.
Therefore,it prevents both autogamy and geitonogamy.

(A) Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower.
Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Dioecious plants,such as papaya,bear male and female flowers on different plants.
Because the male and female flowers are on separate plants,neither autogamy (same flower) nor geitonogamy (same plant) can occur.
In contrast,monoecious plants like cucumber,castor,and maize bear both male and female flowers on the same plant,which allows for geitonogamy.

(B) In a dioecious plant,male and female flowers are present on different plants.
$1$. Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower. Since the plant is dioecious,this is impossible.
$2$. Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower of the same plant. Since the plant is dioecious,the male and female flowers are on different individuals,making this impossible as well.
Therefore,dioecy prevents both autogamy and geitonogamy.

(A) In a bisexual flower,if the androecium (male reproductive part) and gynoecium (female reproductive part) mature at different times,this condition is known as dichogamy. This mechanism prevents self-pollination and promotes cross-pollination. Dichogamy can be further classified into protandry (anthers mature first) and protogyny (stigma matures first).

(B) Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower. Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Dioecious plants, such as $Papaya$, are plants where male and female flowers are borne on separate individuals.
Because the male and female flowers are on different plants, both autogamy (self-pollination within the same flower) and geitonogamy (pollination between flowers of the same plant) are prevented.
In contrast, $Wheat$, $Maize$, and $Castor$ are monoecious or bisexual plants where autogamy or geitonogamy can occur.

(N/A) Self-pollination involves the transfer of pollen from the stamen to the pistil of the same flower. Two strategies that have evolved to prevent self-pollination in flowers are as follows:
$1$. Self-incompatibility: In certain plants,the stigma has the capability to prevent the germination of pollen grains from the same flower or other flowers of the same plant,thereby preventing the growth of the pollen tube. This is a genetic mechanism to prevent self-pollination.
$2$. Dichogamy: In some plants,the gynoecium and androecium mature at different times. If the gynoecium matures before the androecium,it is called protogyny. If the androecium matures before the gynoecium,it is called protandry. This temporal separation prevents the pollen from coming in contact with the receptive stigma of the same flower.

(N/A) Self-incompatibility is a genetic mechanism in angiosperms that prevents self-pollination.
It develops genetic incompatibility between individuals of the same species or between individuals of different species.
The plants which exhibit this phenomenon have the ability to prevent the germination of pollen grains and thus,prevent the growth of the pollen tube on the stigma of the flower.
This prevents the fusion of the gametes along with the development of the embryo.
As a result,no seed formation takes place.

(N/A) Outbreeding devices are mechanisms developed by flowering plants to discourage self-pollination and encourage cross-pollination.
Importance: Continued self-pollination leads to inbreeding depression,which reduces the genetic diversity and fitness of the plant population. Outbreeding devices prevent this by promoting cross-pollination,thereby increasing genetic variation.
Key mechanisms include:
$(i)$ Dichogamy: In some species,pollen release and stigma receptivity are not synchronized. Either the pollen is released before the stigma becomes receptive,or the stigma becomes receptive before the pollen is released (e.g.,$Palms$).
$(ii)$ Herkogamy: The arrangement of anther and stigma at different positions so that the pollen cannot come in contact with the stigma of the same flower (e.g.,$Primula$).
$(iii)$ Self-incompatibility: $A$ genetic mechanism that prevents self-pollen from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.

(N/A) Outbreeding devices are mechanisms developed by flowering plants to discourage self-pollination and encourage cross-pollination.
$1$. Prevention of Inbreeding Depression: Continuous self-pollination leads to inbreeding depression,which reduces the genetic diversity and vigor of the offspring over generations.
$2$. Genetic Variation: Cross-pollination introduces new combinations of genes,leading to increased genetic variation,which enhances the adaptability and survival of the species in changing environments.
$3$. Increased Vigor: Offspring produced through cross-pollination often exhibit 'hybrid vigor' or heterosis,resulting in healthier,more robust,and more fertile plants compared to those produced by self-pollination.
$4$. Evolutionary Advantage: By promoting cross-pollination,outbreeding devices ensure that the population remains genetically healthy and capable of evolving,thereby maintaining high fertility levels within the species.

(N/A) $1.$ Chasmogamous flowers are flowers that open and expose their anthers and stigmas to the environment,allowing for cross-pollination. Examples include $Viola$,$Oxalis$,and $Commelina$.
$2.$ Cleistogamous flowers are flowers that do not open at all. In these flowers,the anthers and stigmas lie close to each other,ensuring self-pollination (autogamy) even in the absence of pollinators. Examples include $Viola$,$Oxalis$,and $Commelina$.

(N/A) Self-incompatibility is a genetic mechanism in flowering plants that prevents self-pollination. It functions by inhibiting pollen germination or the growth of the pollen tube within the pistil,thereby preventing the fertilization of ovules by pollen from the same flower or another flower on the same plant.

(B) Self-incompatibility is a genetic mechanism that prevents self-pollen (from the same flower or other flowers of the same plant) from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
Since self-pollination is obstructed by this mechanism,these plants must rely on cross-pollination to achieve fertilization.
Therefore,the type of pollination in self-incompatible plants is cross-pollination.

(N/A) To prevent self-pollination (autogamy) in bisexual chasmogamous flowers,plants have evolved several outbreeding devices:
$(A)$ Dichogamy: In this mechanism,the maturation of the anther and the stigma occurs at different times. This can be protandry (anthers mature first) or protogyny (stigma matures first),which prevents the pollen from reaching a receptive stigma of the same flower.
$(B)$ Herkogamy: This is a mechanical or spatial arrangement where the male and female reproductive organs are placed in such a way that the pollen from the same flower cannot come into contact with the stigma. This physical barrier ensures cross-pollination,as seen in plants like $Hibiscus$ and $Gloriosa$.
$(C)$ Self-incompatibility (Self-sterility): This is a genetic mechanism where the pollen grains of a flower are unable to germinate on the stigma of the same flower or fail to grow pollen tubes in the style,thereby preventing fertilization,as seen in $Abutilon$.

(N/A) Yes,self-incompatibility imposes a significant restriction on autogamy.
Reasons: Self-incompatibility is a genetic mechanism that prevents self-pollen (from the same flower or other flowers of the same plant) from fertilizing the ovules by inhibiting pollen germination or pollen tube growth on the stigma.
Method of Pollination: In such plants,pollination must occur through cross-pollination (allogamy). Since self-pollination is genetically blocked,the plant relies on external agents such as wind,water,or biotic agents (insects,birds,etc.) to transfer pollen grains from the anther of one flower to the stigma of another flower of the same species.

(D) Flowering plants have evolved several 'outbreeding devices' to discourage self-pollination and encourage cross-pollination.
Self-pollination leads to inbreeding depression over successive generations,which reduces the genetic diversity and fitness of the plant population.
Common outbreeding devices include:
$1$. Dichogamy: Pollen release and stigma receptivity are not synchronized.
$2$. Herkogamy: Anther and stigma are placed at different positions so that pollen cannot come in contact with the stigma of the same flower.
$3$. Self-incompatibility: $A$ genetic mechanism that prevents self-pollen from fertilizing the ovules.
$4$. Production of unisexual flowers.
Therefore,the correct answer is $D$.

(B) Continuous self-pollination leads to the accumulation of recessive alleles and reduces genetic variation within a population. This process increases homozygosity, which often results in the expression of harmful recessive traits. This phenomenon is known as $Inbreeding \text{ } depression$.

(D) Inbreeding refers to the fertilization of a flower by pollen from the same plant or the same flower. To promote cross-pollination and increase genetic diversity,plants have evolved several 'outbreeding devices'.
$1$. Self-incompatibility is a genetic mechanism that prevents self-pollen (from the same plant or flower) from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
$2$. Bisexual flowers and self-pollination actually promote inbreeding.
$3$. Development of male and female flowers on the same plant (monoecious) prevents autogamy but not geitonogamy.
Therefore,self-incompatibility is the most effective genetic mechanism to prevent inbreeding.

(C) Plants develop various outbreeding devices to discourage self-pollination and promote cross-pollination.
Self-pollination leads to inbreeding depression over successive generations,which reduces the genetic diversity and fitness of the plant population.
By promoting cross-pollination,plants ensure genetic variation,which is essential for adaptation and evolution.

(A) Self-pollination is the transfer of pollen grains from the anther to the stigma of the same flower. To promote cross-pollination,plants have evolved several 'outbreeding devices'.
$1$. Self-incompatibility is a genetic mechanism that prevents self-pollen (from the same plant or flower) from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
$2$. Anther and stigma placed close to each other,production of bisexual flowers,and self-compatibility actually promote self-pollination rather than preventing it.
Therefore,the correct option is $A$.

(B) Cross-pollination (xenogamy) is promoted by several outbreeding devices in flowering plants to avoid self-pollination and promote genetic diversity:
$(i)$ Non-synchronization of pollen release and stigma receptivity: The pollen is released before the stigma becomes receptive or vice-versa.
$(ii)$ Anther and stigma are placed at different positions (herkogamy): This prevents the pollen from coming in contact with the stigma of the same flower.
$(iv)$ Production of dioecious plants: In species like papaya,male and female flowers are present on different plants,making self-pollination impossible.
$(v)$ Self-incompatibility: This is a genetic mechanism that prevents self-pollen from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
Therefore,the correct devices are $(i), (ii), (iv),$ and $(v)$.

(C) Self-incompatibility is a genetic mechanism in flowering plants that prevents self-fertilization.
It acts as an outbreeding device by inhibiting pollen germination on the stigma or the growth of the pollen tube in the style of the same flower or other flowers of the same plant.
This ensures cross-pollination and promotes genetic diversity.

(C) Maize is a monoecious plant,meaning it bears both male (staminate) and female (pistillate) flowers on the same individual plant.
Because both types of flowers are present on the same plant,the plant cannot prevent geitonogamy (pollination between two flowers on the same plant).
However,maize has mechanisms to promote cross-pollination (allogamy) and reduce autogamy (self-pollination within the same flower).
Therefore,geitonogamy is not prevented in maize.

(A) In dioecious plants,male and female flowers are present on different individuals.
Since the male and female reproductive organs are on separate plants,the pollen grains cannot reach the stigma of the same plant.
Therefore,both autogamy (transfer of pollen from anther to stigma of the same flower) and geitonogamy (transfer of pollen from anther to stigma of another flower on the same plant) are prevented.
Examples include papaya and date palm.

(C) In plants,when male and female flowers are present on the same individual,it is called monoecious (e.g.,maize,castor).
When male and female flowers are produced on separate individuals (different plants),the condition is known as dioecious (e.g.,papaya,date palm).
This mechanism acts as an outbreeding device to prevent self-pollination and promote cross-pollination.

(B) Autogamy is the transfer of pollen grains from the anther to the stigma of the same flower.
Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower of the same plant.
Both autogamy and geitonogamy are prevented in dioecious plants, where male and female flowers are present on different plants.
Papaya $(Carica \, papaya)$ is a dioecious plant, meaning it has separate male and female plants.
Therefore, it prevents both autogamy and geitonogamy.
Hibiscus is bisexual, while Castor and Maize are monoecious (having both male and female flowers on the same plant), which allows geitonogamy.

(D) Autogamy is a type of self-pollination where pollen grains are transferred from the anther to the stigma of the same flower.
In $Papaya$ $(Carica papaya)$, the plant is dioecious, meaning male and female flowers are borne on separate plants, making autogamy impossible.
In $Castor$ $(Ricinus communis)$ and $Maize$ $(Zea mays)$, the plants are monoecious, meaning male and female flowers are present on the same plant. While they can perform geitonogamy, they have evolved mechanisms to prevent autogamy (self-pollination within the same flower).
Therefore, in all the given examples, autogamy is prevented by various reproductive strategies.