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प्रश्न
Why does self-pollination not lead to seed formation in self-incompatible species?
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उत्तर
Self-incompatibility is a gene-physiological event. A single gene, known as the S-gene, regulates incompatibility reactions and contains many alleles. Pollen grains with the S-allele, which is shared by either of the two alleles in pistil cells, won’t work on that pistil. However, any pollen grain that does not share S-alleles with the pistil will function on that plant’s pistil. Self-pollens are unable to fertilize the egg, preventing the formation of an embryo; hence, seeds do not form in self-incompatible species.
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संबंधित प्रश्न
As a senior biology student you have been asked to demonstrate to the students of secondary level in your school, the procedure(s) that shall ensure cross-pollination in a hermaphrodite flower. List the different steps that you would suggest and provide reasons for each one of them.
Make a list of any three outbreeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.
Fill in the blank:
Male sex cells in plants are called _________.
Find the odd-one out, giving reason:
Ovary, style, pollen grain, stigma
Select and write the most appropriate answer from the given alternatives for the following subquestion:
A versatile anther is an adaptation for _______ type of pollination.
Name of the parts of the ovary which give rise to:
Fruit wall ______
When maturation time of reproductive parts in a flower is different.
Describe the advantages and disadvantages of cross-pollination to the plant.
Answer the following question.
Write the difference in the characteristics of the progeny produced as a result of the two processes.
Coelacanth was caught in South Africa. State the significance of the discovery of Coelacanth in the evolutionary history of vertebrates.
Put a tick mark (✓) against the correct alternative in the following statements
Vegetative propagation is not observed in:
What is a flower? Draw a typical flower and label its different parts.
What are the adaptations which are required in self-pollinated plants?
At which stage pollen grains are shed from the anther in Angiosperms?
Mention various adaptations for wind pollination.
What are the different adaptations shown by bird-pollinated flowers?
For which of the following attractants and rewards are required?
Wind pollination is common in ______.
From among the situations given below, choose the one that prevents both autogamy and geitonogamy.
Cleistogamous flowers are ______.
Even in absence of pollinating agents seed-setting is assured in ______.
Male and female flowers are present on different plants (dioecious) to ensure xenogamy, in ______.
From among the situations given below, choose the one that prevents both autogamy and geitonogamy.
Match the Column I with Column II.
| Column I | Column II |
| A. Pea | (i) Xenogamy |
| B. Jawar | (ii) Epihydrophily |
| C. Maize | (iii) Anemophily |
| D. Vallis | (iv) Bisexual |
| E. Cannabis | (v) Geitonogamy |
Pollination in water lilies is carried out by ______.
Which of the following floral adapation are adapted by hydrophilous flowers?
What is hypohydrophily?
