Biology
Assertion (A): One polar nucleus fuses with two sperm nuclei of a flower and develop into an endosperm during the process of fertilization.
Reason (R): The large central cell of the embryo sac contains two polar nuclei, which fuse with one male nucleus. This process is termed as 'triple fusion'.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Pollination
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Answer
A is false but R is true.
Reason — One of the two male gametes fuses with the two polar nuclei, this fusion forms the triploid endosperm nucleus. The other male gamete fuses with the egg cell to form the zygote.
The large central cell in the embryo sac contains two polar nuclei. One male gamete fuses with these two to form the endosperm, a process called triple fusion (2 polar nuclei + 1 male gamete).
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Related Questions
Assertion (A): Herkogamous flowers favour cross-pollination as these flowers have a structural barrier between the male and female reproductive parts.
Reason (R): Pansy is an example of a herkogamous flower which has a hood covering the stigma.
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Assertion (A): Entomophilous flowers are brightly coloured and often scented.
Reason (R): The pollinating agents of entomophilous flowers are insects which usually get attracted towards the bright colours or scents of the flowers.
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Assertion (A): The process of removal of anthers in young flowers is termed as 'emasculation'.
Reason (R): Emasculation is mainly performed during artificial pollination to produce the desired variety of the plants.
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Shaista is working on her school project about plant reproduction. Her teacher Mrs. Aggrawal gave her the task of investigating pollination in pea flower, a common garden plant. Shaista is curious to know how pollination in pea flower and maize flower differs from each other.
(a) Is pollination a necessary event before fertilization for reproduction in plants? Explain.
(b) What are the pollinating agents for pea and maize flowers respectively?
(c) Write scientific terms for the kind of pollination found in pea flower and maize flower on the basis of pollinating agents.
(d) Mention the technical term for the specific condition of stamens in pea flower.
(e) What are the two advantages of cross-pollination?