Biomes are pretty easy- just where things live. <span>A forest biome= Evergreen trees, squirrels, chipmunks, ferns, sparrows, hawks, etc. </span> <span>A desert biome= Snakes, cactus, etc. </span> <span>A tundra biome= lemmings, voles, caribou, low shrubs, sedges, reindeer mosses, liverworts, and grasses </span> <span>There's three common ones. You could also do a rainforest, a taiga, a grassland, a savanna... Experiment on Google... </span> <span>Here are some good biome sites: </span> http://www.ucmp.berkeley.edu/exhibits/bi... http://www.blueplanetbiomes.org/world_bi... http://www.enchantedlearning.com/biomes/<span> </span>
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
Down syndrome is usually caused by an error in cell division called nondisjunction which results in an embryo with three copies of chromosome 21 instead of the usual two
Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separates
With development in embryo the extra chromosome is replicated in every cell of the body;this type of Down syndrome which accounts for 95% of cases is called trisomy 21
Maternal age is the only factor that has been linked to an increased chance of having a baby with Down syndrome resulting from nondisjunction;here environmental agents such as drugs, chemicals, and radiation act as mutagens which induce mutation in the fetus
