Types of pollination - class-XII
Description: types of pollination | |
Number of Questions: 60 | |
Created by: Nitesh Divan | |
Tags: reproduction in plants and animals pollination, fertilization and development of endosperm and embryo flower and fruit asexual and sexual reproduction in plants biology pollination and fertilization botany |
Name the types of pollination which ensures genetic variation?
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Parthenocarpy
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Cross pollination
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Tissue culture
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Insects
- Transfer of pollen grains from the male reproductive organ (anther) of one plant to the female reproductive organ (stigma) of another plant.
- Insects and wind are the main agents of cross-pollination.
- Thus, it creates genetic variations in the plants making it more resistant to diseases and other conditions than the parent plants.
Allogamy is very useful because it results in ...............
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Formation of male off-springs
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Weaker progeny
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Superior progeny
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formation of seeds
Allogamy is also called as cross pollination. In the case of allogamy, the pollen from a flower falls on the flower of a different plant. This causes the genetic recombinations to take place. This is not possible in any other type of pollinations. Thus it produces the superior progeny.
During breeding, the removal of anthers from a flower is called as
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Anthesis
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Pollination
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Emasculation
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Vasectomy
Emasculation involves the removal of stamens from bisexual flowers of the female parents in order to avoid self-pollination in these flowers. It is done before the anthers mature. If in a condition the female parent bears bisexual flowers, then elimination of anthers from the flower bud before the anther dehisces by means of a pair of forceps is necessary. This step is called as emasculation.
Cross-pollination is advantageous because it results in
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Formation of weaker progeny
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Formation of better progeny
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Formation of male off-spring
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Formation of female offspring
Cross-pollination is advantageous because it results in formation of better progeny. The transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and wind are agents of cross-pollination.
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Progeny shows enhanced vigor.
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Offsprings are more viable and resistant.
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There is a possibility to get new desirable characters.
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Yield of crop can be maintained.
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It helps in evolution.
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Undesirable characters of the plant can be eliminated.
In plant breeding / hybridization, removal of stamens in the early stage of bisexual flower is practiced and it is known as
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Emasculation
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Crossing
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Sterilization
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Pure-line selection
- Emasculation is the removal of anthers in a bisexual flower to prevent self-pollination.
- The female reproductive part is not involved in this process. It is a technique used by plant breeders to obtain the desired variety by crossing a plant with the desired pollen grain obtained by emasculation.
Thus the correct answer is option A.
Select the correct pair of a statement.
A. Flowers are said to be unisexual when it contains either stamens or carpels.
B. Flower are said to be bisexual when both stamens or carpels are present.
C. If the transfer of pollen occurs in the same flower, it is referred to as cross-pollination.
D. If the pollen is transferred from one flower to another it is known as self-pollination.
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A and B
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C and D
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A and C
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B and D
Cross-pollination is the transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and the wind are the main agents of cross-pollination.
Which of the following statements is true with reference to cross pollination?
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It most often results in higher yield of plants.
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It occurs only in unisexual flowers.
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It can fail to occur due to distance.
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It requires production of large number of pollen grains.
Cross pollination: The transfer of pollen from the anthers of one flower to the stigma of another flower by the action of wind, insects, etc. It requires production of large number of pollen grains. Progeny shows enhanced vigor.
Offsprings are more viable and resistant. There is a possibility to get new desirable characters. Yield of crop can be maintained. It helps in evolution.
Undesirable characters of the plant can be eliminated.
Emasculation is achieved by
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Removal of stigma
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Removal of anthers
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Removal of sepal and petals
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Removal of gynoecium
Emasculation involves the removal of anthers of a flower in order to prevent self-pollination or the undesirable pollination of neighbouring plants. After emasculation the female reproductive part of the plant should be covered to prevent unwanted fertilisation.
Thus, the correct answer is option (B), 'Removal of anthers'.
Removal of stamens in an inter-sexual flower before they dehisce is called as____________
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Protogyny
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Protandry
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Inducing male sterility
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Emasculation
- Emasculation is the removal of anthers in a bisexual flower to prevent self-pollination.
- The female reproductive part is not involved in this process. It is a technique used by plant breeders to obtain the desired variety by crossing a plant with the desired pollen grain obtained by emasculation.
Cross pollination is considered as a/an
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Natural method
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Artificial method
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Both A and B
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None of the above
Cross pollination occur when pollen grains are transferred to a flower from a different plant. The plants that undergo cross pollination often have taller stamens than their carpels. They use mechanisms to ensure that the pollen grains are spread to other plants' flowers. The process of cross pollination requires the help of abiotic or biotic agents like wind, water, insects, birds, bats, snails and other animals as pollinators.
Main condition for a plant to perform cross pollination is
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Herkogamy
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Dichogamy
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Self sterility
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All of the above
Herkogamy - common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male and female function. Herkogamy differs from other such strategies by supplying a spatial separation of the anthers and stigma.
Dichogamy - having pistils and stamens that mature at different times, thus promoting cross - pollination rather than self - pollination.
Self sterility - sterile to its own pollen or sperm.
Pollination is a characteristic of
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Angiosperms
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Pteridophytes
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Bryophytes
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None of the above
Pollination is a process in which pollen is transferred to the female reproductive organs of seed plants, thereby enabling fertilization and reproduction through growth of the pollen tube and eventual release of sperm. Both gymnosperms and angiosperms undergo pollination, although the mechanism for angiosperms is much faster and more complex. A successful angiosperm pollen grain (gametophyte) containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. Pteridophytes and bryophytes pollination does not occur.
Pollination which occurs in closed flowers is known as
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Allogamy
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Cleistogamy
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Dicliny
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Protogyny
Cleistogmay is also called as automatic self - pollination. It describes the trait of certain plants to propagate using non - opening, self - pollinating flowers.
In which crops, is the method of mass selection applied?
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Cross-pollinated
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Self-pollinated
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Both self and cross-pollinated
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Potato and sugarcane
Mass selection is a simplest , common and oldest method of crop improvement, in which large number of plants of similar phenotype are selected and their seeds are harvested and mixed together to constitute the new variety. This method is practised in both self and cross – pollinated crops and plants are selected on the basis of their phenotype of appearance. Therefore, selection is done for easily observable characteristics such as plant height, ear/type, grain colour, grain size, etc.
Cross pollination is important for producing
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New varieties of plants
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Plants with better growth
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More viable seeds
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All of the above
- Cross-pollination is important for the production of new varieties of plants. Plants are having better growth and the creation of more viable seeds.
- Cross-pollination is the process where the plants of different variety can breed with another to create a unique plant.
- The resultant plant shows the characteristics of both the parent generation and therefore it is used to create new varieties of plants.
- Cross-pollination is also performed to create more viable seeds of plants and also to generate plants having a better scope of growth.
- The correct option is D.
Which of the following is the wrong match between the plant and its character for adaptation of cross pollination?
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Zostera - Bright coloured flowers with nectar
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Bougainvillea - Petaloid bracts
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Passion Flower - Corona
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Adansonia - Copious nector
One plant produces only female white flower, if it produce pink flower in the next generation then which one of the following is possible?
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Double fertilisation
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Self pollination
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Cross pollination
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No fertilisation
If it produces a pink flower in the next generation then cross-pollination might have occurred.
When a red flowered plant was cross pollinated by white flowered one and the offspring were self pollinated to obtain a phenotypic ratio of 1:2:1, it has to be a case of -
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Incomplete dominance
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Co-dominance
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Recessive epistasis
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Pleurotropic effect of genes
Incomplete dominance or blending dominance is a type of inheritance where the hybrid is not related to either of the parents but exhibit a blending of characters of the two parents.
Transfer of pollen from one flower to stigma of another flower of same species is termed as
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Cross-pollination
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Pollination
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Self-pollination
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None of the above
- Cross-pollination is the transfer of pollen from the anthers of one flower to the stigma of another flower by the action of wind, insects, etc.
- The two plants genetic material combines and the resulting seeds from that pollination will have characteristics of both varieties and is a new variety.
- Sometimes cross-pollinating is used intentionally in the garden to create new varieties. So option A is correct.
Statement $1$ : In pea plant, transfer of pollen grains to the stigma is easy.
Statement $2$: In cross pollinating plants, pollination does not take place.
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Both statements $1$ and $2$ are correct
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Statement $1$ is correct but statement $2$ is incorrect
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Statement $1$ is incorrect but statement $2$ is correct
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Both statements $1$ and $2$ are incorrect
In pea, anthers and stigma are present close to each other therefore pollination is easy while in cross pollinating plants pollination takes place with the help of an external agency.
Heterostyly as a contrivance for cross-pollination is found in.
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Pennisetum
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Impatiens
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Primula vulgaris
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Oenothera
Heterostyly is the presence of $2-3$ types of flower with different heights of styles and stamens. In diheterostyly (dimorphic heterostyly), there are two types of flower, pin eyed (long style and short stamens) and thrum eyed(short style and long stamens), e.g., Primula vulgaris (primrose), jasmine.
The process of removing stamens of a flower during the hybridization process is called as________________
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Hybridization
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Emasculation
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Sterilisation
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Crossing
- Emasculation is the removal of stamens or anthers or killing the pollen of a flower without the female reproductive organ is known as emasculation. In bisexual flowers, emasculation is essential to prevent self-pollination. In monoecious plants, male flowers are removed or male inflorescence is removed.
- In species with large flowers e.g., (cotton, pulses) hand emasculation is accurate and it is adequate. In species with large flowers, removal of anthers is possible with the help of forceps. It is done before anther dehiscence.
- The corolla of the selected flower is opened with the help of forceps and the anthers are carefully removed with the help of forceps.
- An efficient emasculation technique should prevent self-pollination and produce a high percentage of seed set on cross-pollination.
By cross pollinating certain tobacco species, some fertile hybrids were obtained by
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Mendel
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Morgan
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Kolreuter
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Khorana.
In tobacco, due to the continuous self-pollination, homozygosity increases. It results in the occurrence of inbreeding depression, and the plants are called Inbred lines. When these inbred lines are subjected to hybridization, fertile hybrids are obtained. This is called Hybrid vigour or heterosis. This was developed by Kolreuter.
So, the correct option is ‘Kolreuter’.
Both chasmogamous and cleistogamous flowers are present in
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Helianthus
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Commelina
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Rosa
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Gossypium
Commelina produces two types of flower chasmogamous flowers which are similar to the flower of other species with exposed anthers and stigma, and cleistogamous flowers which 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-pollen landing on the stigma. Cleistogamous flowers assure seed-setting even in the absence of pollinators.
How can plants prevent self pollination?
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Plants should produce bisexual flowers
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Pistil should have increased receptivity for pollens from same plant
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Stamen and pistil mature at different times
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All of the above
Plants prevent self-pollination by following methods:-
Flowering plants have developed certain outbreeding devices to discourage self-pollination and encourage cross-pollination. One of these is not an example of such outbreeding device.
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Dicliny
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Dichogamy
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Herkogamy
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Cleistogamy
Cleistogamous flowers are intersexual. They remain closed causing self-pollination. Cleistogamy occurs late in the flowering season in some plants. e.g., Commelina, balsam, Oxalis, Viola. These plants possess both chasmogamous and cleistogamous flowers. In cleistogamous flowers, the anthers dehisce inside closed flowers. The growth of style brings the pollen grains in contact with stigma. Cleistogamy ensures self-pollination. So, the correct answer is 'Cleistogamy'.
Advantage of cleistogamy is ..................
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More vigorous offspring
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Non-dependence on pollinators
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Vivipary
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Higher genetic variability
Cleistogamy procedure do not depend on pollinators. It is because, cleistogamy is automatic self-pollination which describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas and beans, this behaviour is most widespread in the grass family.
The term used when anthers and stigmas of intersexual or perfect flowers ripen before the opening of buds is .............
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Chasmogamy
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Cleistogamy
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Immature pollination
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None of the above
Cleistogamy or automatic self-pollination describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas and beans, this behaviour is most widespread in the grass family. The principal advantage of cleistogamy is that it requires less plant resources to produce seeds than does chasogamy because development of petals, nectar and large amounts of pollen are not required. This efficiency makes cleistogamy particularly useful for seed production on unfavourable sites or adverse conditions.
In which of the following cleistogamous flowers are present?
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Balsam
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Arachis
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Commelina
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All of the above
Cleistogamy is a type of self-pollination occurs in closed flower in which transfer of pollen grain from an anther to stigma when they lie close to each other in a flower e.g., Balsam, Arachis and Commelina.
Self pollination is prevented by .............
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Dichogamy
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Self Sterility
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Hekrogamy
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All of the above
Self pollination is a form of pollination that can occur when a flower has both stamen and a carpel in which the sultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination. It is prevented by: dichogamy, self-sterility and hekrogamy. Dichogamy - having pistils and stamens that mature at different times, thus promoting cross-pollination rather than self pollination. Herkogamy - common strategy employed by angiosperms to reduce sexual interference between male (anthers) and female (stigma) function.
Self pollination is transfer of pollen from anther to the stigma of
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Same flower.
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Same or different flower of the same plant.
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Same or genetically similar flower of the same or other plant.
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Different flowers of the same plant.
Self pollination is the transfer of pollen from the anther to the stigma of the same flower. This is called Type I self pollination.
In Type II self-pollination, pollen is transferred from the anther of one flower to the stigma off another flower from the same plant.
Thus, the correct answer is option (C), 'Same or genetically similar flower of the same or other plant'.
Device for self pollination is
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Heterostyly
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Dicliny
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Unisexuality
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None of the above
- Heterostyly is the anther and stigma are present at different levels of the flower which prevents the self-pollination and fertilization.
- The decline in the presence of only one kind of reproductive whorl in a flower. The decline is thus called unisexuality.
- The plant may be unisexual means this may exhibit either male or female gametes.
So the correct answer is none of these.
The correct option is D.
Self-pollination means
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Germination of pollens within the anther.
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Transference of pollens from anthers to the stigma within the same flower.
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Transference of pollens from one flower to another on the same plant.
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Presence of male and female sex organs in the same flower.
- Self-pollination is when pollen from the same plant arrives at the stigma of a flower or at the ovule.
- Examples of self-pollinating plants include wheat, barley, oats, rice, tomatoes, potatoes, apricots, and peaches.
- Hence Self-pollination means transference of pollen from anthers to the stigma within the same flower.
- So, the correct answer is 'Transference of pollen from anthers to the stigma within the same flower'.
For self pollination, a flower should be
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Asexual
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Monosexual
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Unisexual
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Bisexual
When a flower has both the essential whorls, i.e., androecium and gynoecium (male and female reproductive units), including stamens, carpels and an ovary, it is called as bisexual or perfect flower. In bisexual flowers, the stamens are generally numerous.
Thus, the correct answer is option D.
Self-pollination means,
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Germination of pollens within the anther.
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Transference of pollens from anthers to the stigma within the same flower.
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Transference of pollens from one flower to another on the same part.
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The presence of male and female sex organs in the same flower.
Self-pollination is when pollen from the same plant arrives at the stigma of a flower or at the ovule (in gymnosperms). There are two types of self-pollination. In autogamy, pollen is transferred to the stigma of the same flower. In geitonogamy, pollen is transferred from the anther of one flower to the stigma of another flower on the same flowering plant, or from microsporangium to ovule within a single (monoecious) gymnosperm. Some plants have mechanisms that ensure autogamy, such as flowers that do not open, or stamens that move to come into contact with the stigma.
Contrivances for self pollination are
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Bisexuality
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Homogamy
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Cleistogamy
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All of the above
Flowers by nature are mostly cross pollinated. There are various adaptations for this process. In unisexual and bisexual flowers, certain devices are present for the effective self pollination and avoiding cross pollination, which are called as contrivances of self pollination. They are: bisexuality- both male and female sex organs in single flower, homogamy- inbreeding and cleistogamy- propagation using non-opening, self pollinating flowers.
The disadvantage of self-pollination is ..............
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There is no wastage of pollen grains.
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The seeds are less in number.
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Self-pollination is sure in bisexual flowers.
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Flowers need not depend on agents of pollination.
Very less number of seeds were seen in the flower which undergoes self-pollination.
During self pollination of Mirabilis,
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Flowers are closed
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Flowers are open and growing style brings the stigma in contact with anthers
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Filaments bring anthers in contact with stigma
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Style bends to bring stigma in contact with anthers
A mechanism to prevent cross pollination is
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Protogyny
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Protandry
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Heterostyly
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Cleistogamy
A mechanism to prevent cross-pollination is called cleistogamy. It is a condition in which flower does not open. In such flowers, the anthers and sigma lie close to each other. When anther dehisces in the flower buds, pollen grains come in contact with stigma to effect pollination, e.g., Arachis hypogea. It ensures seed formation even in the absences of any pollination agent. It is cheaper for the plant as there is no costly nectar or fragrance which the plant has to produce for pollination.
Assured seed set is possible even in absence of pollinators when flower is
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Xenogamous
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Chasmogamous
-
Geitonogamous
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Cleistogamous.
An advantage of cleistogamy is
-
It leads to greater genetic diversity.
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Seed dispersal is more efficient and wide spread.
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Each visit of pollinator brings hundreds of pollen grains.
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Seed set is not dependent upon pollinators.
Cleistogamy is effective in
-
Oryza sativa
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Brassica campestris
-
Allium cepa
-
Pisum sativum.
Bisexual flower which never opens is
-
Homogamous
-
Heterogamous
-
Dichogamous
-
Cleistogamous
A bisexual flower which never opens is cleistogamous. It is a condition in which flower does not open. It is an adaptation seen in plants to ensure self-pollination. In such flowers, the anthers and stigma lie close to each other. When anther dehisces in the flower buds, pollen grains come in contact with stigma to effect pollination, e.g., Arachis hypogaea.
Cleistogamous flower is found in
-
Tobacco
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Mirabilis
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Viola
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None of the above
Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. The largest genus of cleistogamous plants is Viola.
In Catharanthus ($=$ Vinca) anthers occur near the mouth of corolla tube. Self pollination is performed by.
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Growth of style
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Bending of filaments
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Shedding of pollen and falling on the low lying stigma
-
Entry of insect
The anthers and stigmas of chasmogamous or the open flowers are brought together by the growth, bending as well as by folding. In Catharanthus, the growth of style brings the stigma in contact of ripe anthers present on the mouth of corolla tube When cross-pollination fails in Sunflower, the bifid bent style stigma curls back so as to pick the pollen sticking to the surface of style. It is a fail-safe mechanism of self-pollination.
So the correct option is A.
Cleistogamous flowers are
-
Male female which never open
-
Female flowers which never open
-
Bisexual flowers which never open
-
Open bisexual flowers which perform self pollination in bud condition
In Tape Grass ($=$ Vallisneria).
-
Both male and female flowers break from the plant and float on the surface of water
-
Only the female flowers break from the plant while the male flowers are brought to the surface by long stalks
-
Only the male flowers break from the plant and rise to the surface while the female flowers are brought to the surface by long pedicels
-
Any of the two types of flowers can break
Tape grass is a submerged hydrophyte. It is a dioecious plant with the flowers borne underwater. The male flowers detach on maturity and float on the surface of the water while the female flowers grow underwater and they come up to the surface with the help of their thin long stalk.
So the correct option is C.
Lever or turn - pipe mechanism of pollination occurs in.
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Salvia
-
Antirrhinum
-
Phlox
-
Gloriosa
In Salvia, pollination is entomophilous, which means it occurs by insects. Pollination occurs by the lever or turns pipe mechanism. The petals of the Salvia are bifurcated. When the insect visits some flower and sits on the petals, then the stamens are brought down to the touch the back of insect and pollen are laden on it.
When the insect visits another flower, cross-pollination occurs.
Thus, the correct answer is A.
Continued self pollination results in
-
Self incompatibility
-
Gametes lose vigour
-
Inbreeding depression
-
Formation of unisexual flowers.
Identify the correct pair of statements.
(i) White kernel of Coconut is a free nuclear endosperm
(ii) In dioecious plants, autogamy is prevented but geitonogamy occurs
(iii) Cleistogamous flowers are always self pollinated
(iv) Castor is an endospermic seed.
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i, ii
-
iii, iv
-
ii, iv
-
ii, iii
Above ground cleistogamous flowers are formed late in the season in
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Balsam
-
Viola
-
Oxalis
-
All the above
-
No pollination agent is required
-
It assures heterozygosity
-
It allows xenogamy
-
It favours insect pollination
Both autogamy and geitonogamy cannot occur in
-
Papaya
-
Cucumber
-
Castor
-
Maize
Match the columns and choose the correct combination.
I | II | ||
---|---|---|---|
(a) | Cleistogamy | (m) | Insect pollination |
(b) | Geitonogamy | (n) | Bud pollination |
(c) | Entomophily | (o) | Pollination between flower of the same plant |
(d) | Xenogamy | (p) | Wind pollination |
(q) | Cross pollination |
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a-m, b-q, c-n, d-o
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a-n, b-o, c-m, d-q
-
a-q, b-p, c-o, d-n
-
a-o, b-m, c-q, d-n
Which one of the following is one of the characteristics of self-pollinated flowers ?
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Flowers are large and showy
-
Flowers remain closed and do not open
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Stigma and anthers mature at the same time
-
Pollen is produced in very large quantities
Self-pollinated flowers remain closed and don't open allowing maximum time for the mature stamens and pistils to exchange and receive the gametes.
Which of the following features are mostly observed in self pollinating flowers?
-
Inconspicuous flowers
-
Presence of nectaries
-
No fragrance
-
Short style
-
Versatile anthers
The inconspicuous flower is a flower that is small, not showy and difficult to see. They are observed in self-pollinating flowers.
Which of the following statement is NOT correct?
-
Pollen germination and pollen tube growth are regulated by chemical components of pollen interacting with those of the pistil.
-
Some reptiles have have also been reported as pollinators in some plant species.
-
Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style.
-
Insects that consume pollen or nectar without bringing about pollination are called pollen/nectar robbers.
Pollen grains of other species are not compactable and do not germinate on the stigma of the flower of different species.
Select the mismatched pair.
-
Storage of pollen grains - $196^o$C
-
Pollen allergy - Carrot grass
-
Chasmogamous flowers - Exposed anthers and stigmas
-
Xenogamy - Self pollination
Xenogamy or cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of a genetically different flower. Cross pollination is performed with the help of an external agency.
Even in absence of pollinating agents seed-setting is assured in.
-
Commelina
-
Zostera
-
Salvia
-
Fig
Commelina bears aerial, chasmogamous (stigma and anthers exposed to pollinating agents), insect pollinated flowers and underground cleistogamous flowers. Cleistogamous flowers are bisexual flowers which never open. In such flowers, the anther and stigma lie very close to each other. When anther dehisce in the flower buds, pollen grains come in contact with the stigma of the same flower i.e, autogamy occurs. So, these flowers produce assured seed set, even in the absence of pollinators.
How can plants prevent self pollination?
-
Stamen and pistil mature at different times.
-
Plants should develop bisexual flowers.
-
Pistil should have increased receptivity for pollens from same plant.
-
All of the above.
- There are several methods to prevent self-pollination in plants. Bisexual flowers show self-pollination.
- Chances of self-pollination increases when pistil has increased receptivity for pollen from the same plant. Self-pollination occurs in flowers where the stamen and carpel mature at the same time.
- Hence, to prevent self-pollination, stamen and pistil must mature at different times.