Biology · Sexual Reproduction in Flowering Plants · NEET
Apomixis is a form of ASEXUAL reproduction that only mimics sexual reproduction. NCERT says clearly: 'apomixis is a form of asexual reproduction that mimics sexual reproduction.' It looks sexual because a seed is formed, but no meiosis-plus-fertilisation of two gametes happens. This is a very common NEET trap, so remember: seed is made, but the process is asexual.
Apomixis = SEED without fertilisation (embryo forms without fusion of gametes). Parthenocarpy = FRUIT without fertilisation (fruit forms but there is no seed, e.g., banana). One simple rule: apomixis gives a seed, parthenocarpy gives a seedless fruit. NEET often puts both in the same question to confuse you.
Yes. Since there is no fertilisation, there is no mixing of two parents' genes and no reduction division that shuffles genes. So the embryo is genetically identical to the mother plant, i.e., a clone. This is exactly why apomixis is useful in agriculture — hybrid characters do not segregate and stay the same year after year.
NCERT gives two ways. (1) The diploid egg cell is formed WITHOUT reduction division (meiosis) and develops into the embryo without fertilisation. (2) More often, as in many Citrus and Mango varieties, some of the NUCELLAR cells around the embryo sac start dividing, push into the embryo sac, and develop into embryos — this is nucellar embryony.
Hybrid seeds are costly and their good characters segregate (break up) in the next generation, so farmers must buy new hybrid seed every year. If hybrids are made into apomicts, the hybrid characters do NOT segregate — the farmer can keep re-using the same hybrid seed year after year without buying again. That is why scientists are trying to transfer apomictic genes into hybrid varieties.
Seed formation without fertilization in flowering plants involves the process of:
In some plants, the female gamete develops into embryo without fertilization. This phenomenon is known as
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Apomixis is the making of a seed without fertilisation. A few flowering plants, such as some Asteraceae and grasses, form seeds without the fusion of male and female gametes. It is asexual reproduction that only looks like sexual reproduction.
Apomictic embryos are genetically identical to the mother plant because there is no fertilisation and no gene mixing. So yes, they can be called clones of the parent.
NCERT mentions some species of Asteraceae and grasses. Nucellar embryony (a type of apomixis) is common in many Citrus and Mango varieties.
It is a type of apomixis where some nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac, and develop into embryos. Because many embryos form in one ovule, this often leads to polyembryony, as in Citrus and Mango.
Normal seeds are products of fertilisation (fusion of male and female gametes). Apomictic seeds form WITHOUT fertilisation, so they carry only the mother's genes and are clones, while normal seeds show variation from two parents.
