What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?
Solution and Explanation
Self-incompatibility is a genetic mechanism in angiosperms that prevents self-pollination. It develop 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 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 take place.
Top Questions on sexual reproduction in flowering plants
Flowering plants with hermaphrodite flowers have developed many reproductive strategies to ensure cross-pollination. Study the given outbreeding devices adopted by certain flowering plants and answer the questions that follow.
Note : All plants belong to the same species. No pollen tube growth/inhibition of pollen germination on stigma. Pollen germination on stigma.- [(a)] Name and define the outbreeding device described in the above table.
- [(b)] Explain what would have been the disadvantage to the plant in the absence of the given strategy.
- CBSE CLASS XII - 2025
- Biology
- sexual reproduction in flowering plants
- Student to attempt either option (A) or (B): (A) What is meant by ‘right’ and ‘wrong’ type of pollen when pollen lands on the stigma? A two-celled right type pollen has landed on the stigma. Explain the events taking place till fertilization in angiosperms. Why is pollen pistil interaction said to be dynamic?
OR
(B)- Give the schematic representation of oogenesis in human females indicating chromosome number at each step.
- In which part of the female reproductive system do the following events take place?
- I. Formation of corpus luteum
- II. Maturation of tertiary follicle
- III. Fertilisation
- IV. Implantation
- CBSE CLASS XII - 2025
- Biology
- sexual reproduction in flowering plants
The following question is based on pollination. Study the figures carefully and answer the questions that follow.
- Give the scientific terms for the processes taking place in Figures A and B respectively.
- Mention two conditions necessary for the process occurring in Figure B.
-
- [(i)] State one advantage and one disadvantage of the process occurring in Figure B.
OR - [(ii)] Name one plant where, in some flowers only, the process in Figure B takes place and give the reason responsible for it.
- [(i)] State one advantage and one disadvantage of the process occurring in Figure B.
- CBSE CLASS XII - 2025
- Biology
- sexual reproduction in flowering plants
- Choose the option that correctly describes the gynoecium of Michelia:
- CBSE CLASS XII - 2025
- Biology
- sexual reproduction in flowering plants
- Given below are the events that are observed in an artificial hybridisation programme. Arrange them in the correct sequential order and select the correct option.
- Re-bagging
- Selection of parents
- Bagging
- Dusting the pollens on stigma
- Emasculation
- Collection of pollens from male parent
- CBSE CLASS XII - 2025
- Biology
- sexual reproduction in flowering plants
Questions Asked in CBSE CLASS XII exam
- Pulkit and Ravinder were partners in a firm sharing profits and losses in the ratio of 3 : 2. Sikander was admitted as a new partner for \( \frac{1}{5} \)th share in the profits of the firm. Pulkit, Ravinder and Sikander decided to share future profits in the ratio of 2 : 2 : 1. Sikander brought Rs 5,00,000 as his capital and Rs 10,00,000 as his share of premium for goodwill. The amount of premium for goodwill that will be credited to the old partners' capital accounts will be :
- CBSE CLASS XII - 2025
- Partnership Accounts
- What is the term used for the milk produced during the initial days of lactation?
- CBSE CLASS XII - 2025
- human health and disease
- Find: \[ I = \int (\sqrt{\tan x} + \sqrt{\cot x}) dx. \]
- CBSE CLASS XII - 2025
- Integration by Parts
Rupal, Shanu and Trisha were partners in a firm sharing profits and losses in the ratio of 4:3:1. Their Balance Sheet as at 31st March, 2024 was as follows:
(i) Trisha's share of profit was entirely taken by Shanu.
(ii) Fixed assets were found to be undervalued by Rs 2,40,000.
(iii) Stock was revalued at Rs 2,00,000.
(iv) Goodwill of the firm was valued at Rs 8,00,000 on Trisha's retirement.
(v) The total capital of the new firm was fixed at Rs 16,00,000 which was adjusted according to the new profit sharing ratio of the partners. For this necessary cash was paid off or brought in by the partners as the case may be.
Prepare Revaluation Account and Partners' Capital Accounts.- CBSE CLASS XII - 2025
- Partnership Accounts
- A coil of 60 turns and area \( 1.5 \times 10^{-3} \, \text{m}^2 \) carrying a current of 2 A lies in a vertical plane. It experiences a torque of 0.12 Nm when placed in a uniform horizontal magnetic field. The torque acting on the coil changes to 0.05 Nm after the coil is rotated about its diameter by 90°. Find the magnitude of the magnetic field.
- CBSE CLASS XII - 2025
- Magnetism and matter
Concepts Used:
Pollination and Double Fertilization
Pollination is defined as the pre-fertilization event or process, where pollen grains from another are transferred to the stigma of a flower.
Double fertilization is a complex process that involves the fusion of one female gametophyte with two male gametes.
Types of Pollination:
All plants having flowers completely rely on the pollination method for reproduction. There are 2 types of pollination –
- Self Pollination
- Cross-Pollination
The end products of double fertilization are:
- Diploid Zygote
- Primary Endosperm Nucleus