Sexual reproduction requires a cycle that alternates between haploid (n) and diploid (2n) cells. Meiosis is required for sexual reproduction. The offspring from sexual reproduction are not identical to either parent. By contrast, asexual reproduction does not alternate between haploid and diploid. Asexual reproduction is nothing more than mitosis and the offspring are exactly like the parent (genetically speaking and not counting mutations) because they are clones.

Bacteria, blue-green algae, most protozoa, yeast, and flatworms all reproduce Asexually Horizontal above-ground stems like found in strawberries Underground stems = rhizomes, bulbs, tubers Irises and day lilies spread rapidly by the growth of their rhizomes

World’s Largest Fungus

In animals, meiosis generates the haploid gametes — sperm and eggs. These single cells fuse to form the zygote which will develop into another diploid animal. In most plants meiosis and fertilization divide the life of the organism into two distinct phases or "generations".

The gametophyte generation begins with a spore produced by meiosis. The spore is haploid, and all the cells derived from it (by mitosis) are also haploid. The gametophyte produces gametes — by mitosis. Sexual reproduction produces the diploid sporophyte generation.

The sporophyte generation begins as a zygote. Its cells contain the diploid number of chromosomes. Specific sporophyte cells undergo meiosis, forming spores, and starting a new gametophyte generation.

Mitosis can occur in haploid cells as well as diploid cells. A haploid set of chromosomes— a single set of genes, is sufficient to control cell function in these organisms (but not in most animals).

Flower Anatomy and Physiology

Pollen is a fine, powdery substance consisting of microscopic grains containing the male gametophyte of certain plants that reproduce sexually. Pollination occurs in seed-bearing plants, as opposed to the more primitive spore-producing plants, such as ferns and mosses. Angiosperms produce flowers containing a male organ called the stamen and a female organ called the pistil. Double Fertilization Flash

Fertilization One

Fertilization Two