Answer to Question 1
A recent study of 4,000 Australian twins has provided evidence that strongly supports the view that genetic factors contribute to ADHD. The concordance rate for MZ twins was 80 percent; whereas the rate for DZ was 40 percent. These concordance rates are close to what one would expect for a purely genetic disorder. Genetic factors explain 90 percent of the variance of ADHD symptoms. At this point, however, a specific gene (or genes) responsible has not been isolated.
Answer to Question 2
Few children or adolescents identify themselves as having an emotional or behavioral problem. Instead, some adult, often a parent or teacher, decides that the child has a problem. Sometimes, a child is unable to recognize or admit to his or her difficulties. Other times, however, the problem is as much the adult's as the child's. For example, a stressed parent may have trouble coping with normal misbehavior. This can make it challenging to figure out where the problem lies.
Genetic control of root hair development.
Role of calcium, tropomyosin, and troponin in cross-bridge cycling.
Some organisms used as models in genetic research
Sociodramatic play is exhibited here.
Cell surface recognition factors
Evidence for the covalent intermediate in the mechanism of lysozyme