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प्रश्न
Mention two strategies that evolved to prevent self-pollination in flowers.
Explain any four contrivances to prevent self-pollination in plants with an appropriate example of each type.
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उत्तर
Continued self-pollination decreases the vigour and vitality of a particular race. Thus, flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination.
- Unisexuality: Either male or female flowers are borne by plants. For instance, monoecious plants such as maize, mulberry, and papaya are dioecious.
- Dichogamy protogyny: The gynoecium matures before the androecium. For instance, this is the case with gloriosa.
- Dichogamy protandry: The androecium matures earlier than the gynoecium. For instance, consider the disc florets of sunflowers.
- Prepotency: The pollen grains of other flowers germinate rapidly on the stigmas of different flowers. Consider the example of the apple flower.
- Herkogamy: The anther and the stigma are placed at different positions or have a mechanical barrier so that anthers cannot contact or touch the stigma of the same flower. Consider the example of calotropis.
- Heterostyly: Styles of the flowers of the same species are at different heights. Consider the primrose as an example.
- Self-incompatibility (Male sterility): The pollen grains of some plants are not functional. Such plants set seeds only after cross-pollination. Examples of these plants include Tobacco and Thea.
Notes
Students can refer to the provided solutions based on their question and preferred marks.
संबंधित प्रश्न
With the help of a suitable example, explain protandry.
The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as ______.
Write two ways in which pollination may occur in plants.
Name two characteristics of flowers in which pollination occur by wind.
Differentiate between the following:
Self pollination and cross pollination.
Exine and intine are the parts of
Fill in the blanks with suitable words.
Different timings for the maturation of gynoecium and androecium is called ________.
Name of the part of the ovary which gives rise to:
Fruit ______
Name of the parts of the ovary which give rise to:
Fruit wall ______
Give one word/term for the following:
Pollination of flowers by insects.
Give one word/term for the following:
Pollination of flowers by birds.
In bisexual flowers, maturation of gynoecium before androecium is known as ______.
State four features of flowers pollinated by insects.
Answer the following question.
Express the process of pollination in Vallisneria.
Coelacanth was caught in South Africa. State the significance of the discovery of Coelacanth in the evolutionary history of vertebrates.
Describe pollination. How many types of pollinations are found?
Describe the Advantages and Disadvantages of self-pollination to the Plant.
Give an account of any two biotic agents for pollination along with their adaptations.
For which of the following attractants and rewards are required?
Wind pollination is common in ______.
Pollination by water occurs in ______.
Which of the following pair has haploid structures?
In some plants anther and stigma mature at the same time this condition is called ______.
During Hybridization process anther of the bisexual flower is removed before it dehisces is called ______.
The flower which does not open at all are called ______.
A botanist studying Viola (common pansy) noticed that one of the two flower types withered and developed no further due to some unfavorable condition, but the other flower type on the same plant survived and it resulted in an assured seed set. Which of the following will be correct?
Which one of the following may require pollinators, but is genetically similar to autogamy?
Describe any three adaptations in anemophilous flowers.
Consider the following statements depicting adaptation of flowers to carryout successful pollination.
- Stigma is long, sticky and unwettable.
- Sepals, petals or perianth (if present) have waxy coating.
- Stamens with long filament and versatile anthers.
- Tubular corolla is seen.
- Flowers are noctumal.
Which of the above statements clearly depict hydrophily?
Describe any three adaptations in hydrophilous flowers.
Mention any one example of the hydrophilous flower.
Give any four floral adaptations for chiropterophily.
What are the major abiotic factors that influence habitat?
Name the pollinating agent of a flowering plant with large and coloured flowers with sticky stigma. State one characteristic feature of the pollen grains produced in such flowers.
When and why does a plant breeder employ the emasculation technique?
Which one of the following flower is hypohydrophilous?
Bird pollinated flowers are usually ______.
