A stroke occurs when blood flow to a part of the brain stops. A stroke is sometimes called a brain attack.. If blood flow is cut off for longer than a few seconds, the brain cannot get nutrients and oxygen. Brain cells can die, causing lasting damage.
A cell is said to be homozygous for a particular gene when identical alleles of the gene are present on both homologous chromosomes. The cell or organism in question is called a homozygote. True breeding organisms are always homozygous for the traits that are to be held constant.
If a homozygous organism has two identical dominant alleles, it is said to be homozygous dominant, while an organism with two identical recessive alleles is said to be homozygous recessive. If this was not what you're asking, please clarify your question on the discussion page so someone can improve this answer.