However, when feelings of intense fear and distress are overwhelming and prevent us from doing everyday things, an anxiety disorder may be the cause. Anxiety disorders are the most common mental health concern in the United States. An estimated 40 million adults in the U.S., or 18%, have an anxiety disorder. Approximately 8% of children and teenagers experience the negative impact of an anxiety disorder at school and at home.
Sexual Reproduction: Sexual reproduction promotes genetic variation by producing different gene combinations. Meiosis is the process by which sex cells or gametes are created. Genetic variation occurs as alleles in gametes are separated and randomly united upon fertilization. The genetic recombination of genes also occurs during crossing over or the swapping of gene segments in homologous chromosomes during meiosis.
Crossing over in meiosis results in genetic recombination, which is responsible for the genetic diversity of a population. Genetic recombination and natural selection are the driving forces behind evolution. It causes most of the differences between parents and their offspring and differences between siblings.