Thousands of human genes determine the physical and biological characteristics of each individual. Defects in one or more genes can cause an inherited disorder or disease. Environmental factors that a fetus is exposed to during development also can produce physical or biological abnormalities. called Choose...mutationsteratogenscongenital defects genetic diseases . Drugs prescribed during pregnancy or other chemicals that cause abnormal fetal development are called Choose...mutationsteratogens congenital defects genetic diseases . Hereditary disorders are always caused by defective Choose...mutations teratogens congenital defects chromosomes that are passed on from one or both parents. Genes consist of a chemical substance called deoxyribonucleic acid (DNA). Most genes direct the synthesis of Choose...proteins cellsDNAfats and carbohydrates in cells. Some hereditary disorders can be prevented in progeny if couples planning to have a child undergo Choose...chemotherapyprenatal testing and genetic counseling gene therapy magnetic resonance imaging . A noninvasive technique used to examine the fetus for physical abnormalities is Choose...amniocentesis chorionic villus analysis ultrasound scanning gene therapy . Most inherited disorders cannot be treated effectively or cured. However, some inherited disorders such as Choose...hemophiliaDown's syndrome congenital defects phenylketonuria can be managed by supplying the affected person with the missing protein. Genetic tests can be used to determine if a person carries a defective gene that may be passed on to progeny. Genetic tests also can be used to test fetal cells to determine if a defective gene has been inherited. Genetic engineering has altered the genes in some plants and animals and consequently in our Choose...people drugsfoods atmosphere. Modifying genes in plants and animals that are released into the environment is considered to be Choose...economically useless potentially harmful vital to health an important biological weapon by many people. Some day it may be possible to cure certain inherited diseases by using Choose...genetically modified foods amniocentesis gene therapy genetic counseling .