Advertisements
Advertisements
प्रश्न
Why does self-pollination not lead to seed formation in self-incompatible species?
Advertisements
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, resulting in the formation of an embryo; hence, seeds do not form in incompatible species.
APPEARS IN
संबंधित प्रश्न
Lever mechanism of pollination is observed in
- Salvia
- Jasmine
- Bougainvillea
- Butea
Describe the characteristic features of wind pollinated flowers.
A flower of tomato plant following the process of sexual reproduction produces 200 viable seeds.
Answer the following questions giving reasons :
(a) What would have been the minimum number of ovules present in pre-pollinated pistil ?
(b) How many microscope mother cells would minimally be required to produce requisite number of pollen grains ?
(c) How many pollen grains must have minimally pollinated the carple ?
(d) How many male gametes would have used to produce these 200 viable seeds ?
(e) How many megaspore mother cells were required in this process ?
Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.
Differentiate between the following:
Self pollination and cross pollination.
State the name of the chief pollinating agent against the corresponding plant by choosing from those given in brackets.
Dahlia_______ .
Fill in the blanks with suitable words.
Different timings for the maturation of gynoecium and androecium is called ________.
Name of the parts of the ovary which give rise to:
Fruit wall ______
Differentiate between geitonogamy and xenogamy (allogamy).
Answer the following question.
Write the difference in the characteristics of the progeny produced as a result of the two processes.
Put a tick mark (✓) against the correct alternative in the following statements
Pollen is produced in the
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.
Describe pollination. How many types of pollinations are found?
Write different modes of pollination in detail with suitable examples.
Differentiate Between Cross Pollination and Self Pollination:
What are the adaptations which are required in cross-pollinated
Very short answer type question:
What is hydrophily?
For which of the following attractants and rewards are required?
Cleistogamous flowers are ______.
Even in absence of pollinating agents seed-setting is assured in ______.
During Hybridization process anther of the bisexual flower is removed before it dehisces is called ______.
In the dioecious aquatic plant shown, identify the characteristics of the male flowers that reach the female flowers for pollination:
| Size of the flower | Colour of flower | The characteristic feature of pollen grain | |
| A | small | brightly coloured | Lightweight and non-sticky |
| B | large | colourless | large and sticky |
| C | small | white | small, covered with mucilage |
| D | large | colourless | non-sticky |
In which one of the following pollination is autogamous?
Autogamy can occur in a chasmogamous flower if ______.
What is ornithophily?
Give any four floral adaptations for chiropterophily.
Name the following:
Aquatic plants which are anemophilous.
Complete the following table:
| Sr. | Type of pollination | Agent | Kind of flower | Examples |
| (i) | ______ | Wind | ______ | Maize |
| (ii) | Chiropterophily | ______ | Dull colour, with strong fragrance, abundant nectar | Adansonia |
| (iii) | Entamophily | Insects | ______ | Rose/Jasmine |
| (iv) | Ornithophily | ______ | Brightly coloured, large and showy. They secrete profuse, dilute n ectar | ______ |
When and why does a plant breeder employ the emasculation technique?
