Which observation did researchers make in studies on separated twins? separated twins develop traits that differ according to the environments in which they are raised. separated twins tend to have the same behavioral characteristics, regardless of environment. although separated twins share behavioral traits during their early development, the environment might suppress such traits later. environmental factors play a more dominant role than genes do in shaping an individual’s behavioral traits. certain physical traits of separated twins differ due to environmental influences.

The amount of oxygen that is actually used by the body during the rest or a hand workout is determined by the heart rate, the stroke volume, and the amount of a. blood circulating in the vascular system b. oxygen removed from the vascular system c. oxygen provided to the vascular system d. blood that individual has in the body e. hemoglobin in the red blood cells

A46-year-old man with a history of hypertension and hypercholesterolemia visits the physician for a routine followup. the patient's job involves a lot of travelling, and he admits to occasionally forgetting to take his medications with him when he travels. he complains of several episodes of chest pain in the past few months. the pain is sharp in nature, mainly over his lower chest and epigastrium, and tends to come on when walking. he believes these episodes are due to indigestion and has been taking antacids. there is a family history of heart disease, and his father died of a heart attack at age 48. on physical examination, his blood pressure is 150/80 mmhg and heart rate is 86/min. his lungs are clear to auscultation. cardiac auscultation reveals normal rate and rhythm, without rubs, gallops, or murmurs. there is no pedal oedema. he is sent for an exercise stress test. five minutes into the test, he develops st depression of 3mm in leads v1-v5. the st segment depression is greater than 0.12 seconds in duration and the stress test is stopped. which of the following is the most appropriate next step in management? - coronary angiography- holter monitor- no further tests are required- repeat stress test with thallium- upper gastrointestinal endoscopy

Why do you need two different circuits of blood vessels in your body?