Causes. Sunburn results when the amount of exposure to the sun or other ultraviolet light source exceeds the ability of the melanin to protect the skin. Melanin is the skin's protective coloring (pigment).kin cancer usually appears in adulthood. But it is caused by sun exposure and sunburns that began as early as childhood. You can help prevent skin cancer by protecting your skin and your children's skin from the harmful rays of the sun.
The angiosperms, or flowering plants, are one of the major groups of extant seed plants and arguably the most diverse major extant plant group on the planet, with at least 260,000 living species classified in 453 families (Judd et al., 2002; APG II, 2003; Soltis et al., 2005).
Defining Characteristics. The term angiosperm derives from two Greek words: angeion, meaning vessel, and sperma, meaning seed.. The angiosperms are those plants whose seeds develop within a surrounding layer of plant tissue, called the carpel, with seeds attached around the margins.This arrangement is easily seen by slicing into a tomato, for example.owever, some current studies suggest that endosperm is not unique to angiosperms. Angiosperm flowers are generically characterized by having four whorls, or sets of organs: sepals, petals, stamens, and carpels.