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#seed development

6 public questions tagged with this topic.

plant Development - 1

Nucellus is primarily a:

Nucellus constitutes central parenchymatous tissue of ovule derived from megasporangium forming massive bulk surrounding and protecting megaspore mother cell and later embryo sac. It serves primarily as nutritive tissue providing carbohydrates, amino acids, lipids, and hormonal cues to developing female gametophyte through apoplastic and symplastic transport pathways. Depending on crassinucellate or tenuinucellate configuration degree of tissue development may be substantial. After fertilization nucellus generally degenerates, but may occasionally persist as perisperm storage tissue in beet, pepper, black pepper, continuing important maternal nutritive contribution supporting embryo growth and seed filling.

Ref: Mohammad et al., Seed Sci; Reiser & Fischer: nucellus is nutritive tissue surrounding and feeding embryo sac.

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plant Development - 1

Endosperm is:

Endosperm is triploid or generally polyploid nutritive tissue arising from fusion of second sperm cell with homodiploid central cell containing two or more polar nuclei depending on species and embryo sac type. After fertilization primary endosperm nucleus undergoes rapid mitoses either free nuclear forming syncytium then cellularizing, entirely cellular, or helobial patterns generating tissue rich in starch, storage proteins, lipids, and hormones sustaining embryo development. Polyploid nature permits vigorous metabolic activity and genomic imprinting regulates resource allocation between maternal and paternal genomes, analogous to mammalian placenta providing nutrition and regulatory signals within seed environment.

Ref: Li & Berger, Curr Opin Plant Biol 2012: angiosperm endosperm is polyploid nutritive tissue from central cell fertilization.

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Plant Classification

Seed coat develops from

Ovule integuments maternal diploid sporophytic tissue origin undergo post-fertilization differentiation and sclerification: outer integument often forms testa outer seed coat providing mechanical protection impermeability dormancy, inner integument tegmen membranous thin often crushed. Both derived sporophyte, nucellus mostly consumed or persisting as perisperm in Caryophyllales beet family example, ovule overall refers to pre-fertilization structure including nucellus female gametophyte, endosperm triploid product after fertilization nutritive. Thus seed coat lineage directly traces to integument, explaining maternal inheritance of coat color texture patterns such as mottled beans studied by Mendel and imposing physical dormancy via phenolics cutin suberin layers.

Ref: NCERT Class 12 Biology, Chapter 2: Integument forms seed coat testa development origin

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Phytohormone ALL PYQS

Seed maturation involves accumulation of storage reserves and:

Correct option is C, LEA protein expression. In Phytohormone ALL problems like this, the accurate statement is LEA protein expression; the others are common mix-ups. Not these: A) Increase moisture; B) Decrease ABA; D) GA dominance. Tissue transport questions usually turn on xylem vs phloem, living vs dead cells, or source vs sink.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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