A: The inability of pollen to germinate on the stigma of the same flower is called selfincompatibility or self-sterility.
Ex: Abutilon
Q: Which is the triploid tissue in a fertilized ovule? How is the triploid condition
achieved?
A: Endosperm.
Triploid condition is achieved by fertilization of second male gamete with two polar
nuclei of central cell to form a primary endosperm nucleus. The primary endosperm nucleus (PEN) divides and forms endosperm in fertilized ovule (seed).
Q: What is the function of two male gametes produced by each pollen grain in
angiosperms.
A: The first male gamete fuses with the female egg cell to form a zygote (fertilization
or syngamy).
The second male gamete fuses with the diploid secondary nucleus (triple fusion) to
form PEN (Primary endosperm nucleus) which gives rise to endosperm.
Q: Name the parts of an angiosperm flower in which development of male and female
gametophyte take place.
A: Male gametophyte - pollen grain.
Female gametophyte (embryosac) - nucellus of the ovule.
Q: Mention two strategies evolved to prevent self-pollination in flowers.
A: Dichogamy
Herkogamy
Q: Why do you think the zygote is dormant for some time in a fertilized ovule?
A: Zygote is dependent for its nourishment on the endosperm to form an embryo.
Hence it is dormant for some time until some endosperm is formed.
Q: What is meant by scutellum? In which type of seeds it is present?
A: The cotyledon of a monocot embryo is called scutellum. It is present in monocot
seeds Ex: Grasses.
Q: Define with examples endospermic and non-endospermic seeds.
A: Endospermic seeds - castor and coconut
Non endospermic seeds - groundnut, beans and peas.
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