Class 12 Biology - Chapter Sexual Reproduction in Flowering Plants NCERT Solutions | What is self-incompatibility? Why does s
What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?
Self-incompatibility is a genetic mechanism in angiosperms that prevents self-pollination. It develops 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 takes place.
More Questions From Class 12 Biology - Chapter Sexual Reproduction in Flowering Plants
- Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.
- Q:- Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.
- Q:- What is apomixis and what is its importance?
- Q:- Differentiate between:
(a) Hypocotyl and epicotyl
(b) Coleoptile and coleorrhiza
(c) Integument and testa
(d) Perisperm and pericarp - Q:- Why is apple called a false fruit? Which part(s) of the flower forms the fruit?
- Q:- Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
- Q:- Explain the role of tapetum in the formation pollen-grain wall.
Popular Questions of Class 12 Biology
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- Q:-
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________. - Q:- What do you think is the significance of reproductive health in a society?
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Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine. - Q:- Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
- Q:- What are the various public health measures, which you would suggest as safeguard against infectious diseases?
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