Plant Physiology Reproduction Quiz

Plant Reproduction

• Plant reproduction is the production of a new generation of individuals of the same species.
• There are two methods of plant reproduction: sexual reproduction and asexual reproduction.

Sexual Reproduction

• Sexual reproduction involves the fusion of two gametes to form a zygote.
• It occurs in two distinct phases or "generations" (Alternation of generations).
• The haploid gametophyte generation begins with a spore produced by meiosis.
• The gametophyte generation produces gametes by mitosis.
• Sexual reproduction then produces the diploid sporophyte generation.

Male Gametophyte Generation

• The male gametophyte generation consists of a stamen, which comprises an anther and filament.
• Meiosis of the diploid microspore mother cells in the anther produces four haploid microspores.
• Each microspore develops into a pollen grain, consisting of a larger tube cell and a smaller generative cell/germ cell.
• The germ cell divides by mitosis to produce two sperm cells.

Female Gametophyte Generation

• The female gametophyte generation consists of a carpel/pistil, which comprises a stigma, style, and ovary.
• Meiosis of the megaspore mother cell in each ovule produces four haploid cells: a large megaspore and three small cells that disintegrate.
• The nucleus of the megaspore undergoes three successive mitotic divisions, producing eight nuclei.
• The eight nuclei are distributed and partitioned off by cell walls to form the embryo sac, which is the mature female gametophyte generation.

Pollination and Fertilization

• When a pollen grain reaches the stigma, it germinates into a pollen tube.
• The germ cell divides by mitosis, forming two sperm cells.
• The sperm cells, along with the tube nucleus, migrate down the pollen tube as it grows through the style, micropyle, and into the ovule chamber.
• One sperm cell fuses with the egg cell, forming the diploid zygote.
• The other sperm cell fuses with the polar nuclei, forming the endosperm nucleus.

Seed and Fruits Dispersal

• Seed and fruits are structurally adapted for dispersal by air currents, water currents, and animals.
• Examples of dispersal mechanisms include exploding fruits, hitchhiking fruits, and airborne seeds and fruits with wings or plumes.

Wind-Pollinated vs Insect-Pollinated Flowers

• Wind-pollinated flowers have stamen hanging outside the flower to release pollen, feathery stigma to trap pollen, and produce a large quantity of pollen.
• Insect-pollinated flowers have stamens enclosed within the flower, a small stigma, and produce less pollen.
• Wind-pollinated flowers are non-scented and lack nectaries, while insect-pollinated flowers are scented and have nectaries.

Asexual Reproduction

• Asexual reproduction requires only a single parent and does not involve haploid gametes or meiosis.
• Asexual reproduction occurs by a single organism without the production of gametes.