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Biology
Sexual Reproduction in Flowering Plants
126 questions from 36 papers, each with its answer.
- 126 questions
- 36 papers
- 3.57% of Biology
Agents of Pollination
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Assertion (A): Both wind and water pollinated flowers are not very colourful and do not produce nectar.Reason (R): The flowers produce enormous amount of pollen grains in wind and water pollinated flowers.
Both statements are true facts of abiotic pollination, but Reason does not explain why they lack colour/nectar (lack of biotic pollinators is the cause).
Wind and water pollinated flowers do not need visual cues or rewards like nectar because their vectors are abiotic, making Assertion true. They produce copious pollen to compensate for random passive dispersal loss, making Reason true. However, R is not the explanation for A.
Female Gametophyte (Embryo Sac)
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Assertion (A): A typical unfertilized, angiosperm embryo sac at maturity is 8 nucleate and 7-celled.Reason (R): The egg apparatus has 2 polar nuclei.
Assertion is true; Reason is false because polar nuclei reside in the large central cell, not in the egg apparatus.
A mature angiosperm female gametophyte has 7 cells and 8 nuclei (3 antipodals, 1 central cell with 2 polar nuclei, and a 3-celled egg apparatus comprising 1 egg cell and 2 synergids). The polar nuclei are in the central cell, not the egg apparatus, so Reason is false.
Microsporangium and Tapetum
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Assertion (A): Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.Reason (R): Presence of more than one nucleus in the tapetum increases the efficiency of nourishing the developing microspore mother cells.
Assertion is true; Reason is false (tapetum nourishes developing microspores / pollen grains, and polyploidy arises due to endomitosis without cytokinesis, not MMC nourishment efficiency).
Tapetal cells feature dense cytoplasm and multinucleate or polyploid state due to endomitosis. Tapetum primarily functions to nourish developing microspores/pollen grains. Stating that multinucleation specifically evolved to nourish microspore mother cells is incorrect.
Megasporogenesis and Megagametogenesis
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How many meiotic and mitotic divisions need to occur for the development of a mature female gametophyte from the megaspore mother cell in an angiosperm plant?
1 meiosis forms 4 megaspores (1 functional survives); 3 sequential free-nuclear mitotic divisions form the 8-nucleate embryo sac.
From 1 diploid Megaspore Mother Cell (MMC): 1 meiotic division produces a linear tetrad of 4 haploid megaspores. Three degenerate, leaving 1 functional megaspore. This functional megaspore undergoes 3 consecutive mitotic nuclear divisions to form an 8-nucleate, 7-celled mature female gametophyte (monosporic development).
Seed Structure and Development
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Match List-I with List-II.
Pick the matching item from Column II for each row.
Column I
- A. Scutellum
- B. Non-albuminous seed
- C. Epiblast
- D. Perisperm
Column II
- I. Persistent nucellus
- II. Cotyledon of Monocot seed
- III. Groundnut
- IV. Rudimentary cotyledon
Correct answer: A → II, B → III, C → IV, D → I
A-II, B-III, C-IV, D-I.
Scutellum is the shield-shaped cotyledon of monocots (II). Groundnut is a non-endospermic/non-albuminous seed (III). Epiblast represents the remains of the second cotyledon in grass embryos (IV). Perisperm is the persistent remnants of nucellar tissue (e.g., black pepper) (I).
That is every question in Sexual Reproduction in Flowering Plants for this filter.
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