Question
Write a short note on Double fertilisation.
✓
Answer
→ After entering one of the synergids, the pollen tube releases the two male gametes into the cytoplasm of the synergid.
→ One of the male gametes moves towards the egg cell and fuses with its nucleus thus completing the syngamy. This results in the formation of a diploid cell, the zygote.
→ The other male gamete moves towards the two polar nuclei located in the central cell and fuses with them to produce a triploid Primary Endosperm Nucleus (PEN).
→ As this involves the fusion of three haploid nuclei it is termed triple fusion.
→ Since two types of fusions, syngamy and triple fusion take place in an embryo sac the phenomenon is termed double fertilisation, an event unique to flowering plants.
→ The central cell, after triple fusion, becomes the Primary Endosperm Cell (PEC) and develops into the endosperm while the zygote develops into an embryo.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Describe three manners in which fertilisation of human ovum by a sperm can be prevented.
How have human activities caused desertification? Explain.
A woman has certain queries as listed below, before starting with contraceptive pills. Answer them.
What do contraceptive pills contain and how do they act as contraceptives?
What do contraceptive pills contain and how do they act as contraceptives?
Explain the origin of simple organic compounds on the primitive earth.
- Why are transgenic animals so called?
- Explain the role of transgenic animals in (i) Vaccine safety and (ii) Biological products with the help of an example each.
Many plant and animal species are on the verge of their extinction because of loss of forest land by indiscriminate use by the humans. As a biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct?
Write a short note on Biopiracy highlighting the exploitation of developing countries by the developed countries.
Give three reasons as to why the prokaryotes are not given any figures for their diversity by the ecologists.
Answer the following questions:
How does a farmer use the dormancy of seeds to his advantage?
How does a farmer use the dormancy of seeds to his advantage?
Construct an ideal pyramid of energy when 10,00000 J of sunlight is available. Label all its levels.