Angiosperm Sexual and Asexual Reproduction

Flashcards covering key vocabulary related to Angiosperm sexual reproduction, including alternation of generations, microsporogenesis, megasporogenesis, double fertilization, seed development, and various methods of asexual (clonal) reproduction.

Alternation of Generations

A life cycle in which there is both a multicellular diploid sporophyte form and a multicellular haploid gametophyte form.

Zygote

A diploid cell (2n) formed by the fusion of two haploid gametes.

Sporophyte

The diploid (2n) multicellular stage in the life cycle of a plant that produces spores by meiosis.

Gametophyte

The haploid (1n) multicellular stage in the life cycle of a plant that produces gametes by mitosis.

Sporic Meiosis

Meiosis that produces spores, which then develop into gametophytes.

Microsporangium

A structure (pollen sac) within the anther where microspores are produced, containing sporogenous tissue.

Sporogenous tissue

Diploid tissue (2n) inside the microsporangium that undergoes meiosis to produce microspores.

Microsporogenesis

The process of microspore formation within the anther, involving meiosis of sporogenous tissue.

Microspore

A haploid (1n) spore that develops into a male gametophyte (pollen grain).

Anther

The part of the stamen that contains the pollen, typically with two lobes and four pollen sacs.

Microgametophyte (Pollen)

The male gametophyte of angiosperms, containing a tube cell and a generative cell.

Generative cell

A cell within the pollen grain that divides to form two non-motile sperm.

Tube cell

A cell within the pollen grain that forms the pollen tube, facilitating sperm delivery.

Pistil

The female reproductive part of a flower, containing ovules.

Ovule

A structure within the pistil that contains the megasporangium and develops into a seed after fertilization.

Integuments

Protective outer layers of the ovule that develop into the seed coat.

Nucellus

The central part of the ovule where the megaspore mother cell forms.

Micropyle

A small opening in the integuments of the ovule, through which the pollen tube typically enters.

Megaspore mother cell (Megasporocyte)

A diploid cell (2n) in the nucellus that undergoes meiosis to produce four haploid megaspores.

Megasporogenesis

The process of megaspore formation in the ovule, involving meiosis of the megaspore mother cell.

Megaspore

A haploid (1n) spore, typically one survives, which develops into the female gametophyte (embryo sac).

Megagametophyte (Embryo Sac)

The mature female gametophyte, typically 8-nucleate and 7-celled, containing the egg cell and other cells crucial for fertilization.

Synergids

Two cells located next to the egg cell in the embryo sac, which guide the pollen tube and undergo programmed cell death.

Egg cell

The haploid female gamete (E) within the embryo sac that fuses with a sperm to form the zygote.

Antipodals

Three cells located at the opposite end of the embryo sac from the egg cell, whose function is not fully understood.

Central cell

A large cell in the embryo sac containing two polar nuclei, which fuses with a sperm to form the endosperm mother cell.

Double Fertilization

A unique process in angiosperms where one sperm fertilizes the egg to form a diploid zygote, and another sperm fertilizes the central cell to form a triploid endosperm mother cell.

Endosperm Mother Cell

A triploid cell (3n) formed by the fusion of a sperm with the two polar nuclei of the central cell, which develops into the endosperm.

Endosperm

A triploid (3n) tissue that provides nourishment for the developing embryo within the seed.

Seed Coat

The protective outer layer of a seed, developed from the integuments of the ovule.

Cotyledon

An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.

Embryo axis

The main stem of the embryo, including the radicle, hypocotyl, and epicotyl.

Asexual (Clonal) Reproduction

Reproduction that produces genetically identical offspring from a single parent without the fusion of gametes.

Rhizomes

Horizontal underground stems that can produce new shoots and roots, leading to clonal reproduction.

Stolons

Horizontal above-ground stems (runners) that can produce new plants at their nodes, enabling clonal reproduction.

Adventitious roots

Roots that develop from tissues other than the primary root, such as stems or leaves, often involved in vegetative propagation.

Tubers

Swollen underground stems, like potatoes, which store food and have 'eyes' (axillary buds) that can sprout into new plants.

Corms

Short, vertically swollen underground stems that store food and can produce new daughter corms and shoots.

Bulbs

Underground storage organs consisting of a short stem and fleshy leaves (e.g., onions), capable of producing new plants from lateral buds.

Plantlets

Small, miniature plants that form on the leaves, stems, or roots of a parent plant and can detach to grow into new independent plants.