Essential to understanding the life cycle of a plant is the concept of alternation of generations. One of the defining traits of plants is that a single adult plant exists in two separate states, called generations, with differing purposes. The sporophyte generation contains a full set of chromosomes in each cell and produces spores.
SD cards are an extension of MMC memory cards; this means that it's possible to use MMC cards in newer SD devices. It's also possible to use regular SD cards in SDHC and SDXC devices.
Unveiled in 1997 by SanDisk and Siemens AG, it is based on Toshiba 's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as CompactFlash. MMC is about the size of a postage stamp: 24 mm Ã 32 mm Ã 1.4 mm.