Which valve below prevents blood from flowing back into the right ventricle?

Correct Answer: C

Rationale: The pulmonary semilunar valve (C) prevents backflow from the pulmonary artery into the right ventricle. Tricuspid (A) guards atrium-to-ventricle, bicuspid (B) is left-sided, and aortic (D) is systemic.

Correct Answer: B

Rationale: The left ventricle pumps blood through the aortic semilunar valve (B) into the aorta during systole. Mitral (A) is inflow, pulmonary (C) is right-sided, tricuspid (D) is right AV.

Correct Answer: C

Rationale: The myocardium (C) is the muscular layer responsible for contraction. Endocardium (A) is inner, epicardium (B) is outer, pericardium (D) is the sac.

Correct Answer: C

Rationale: Blood temperature is ~100.4°F (A) and pH is 7.35-7.45 (B), but it’s red due to erythrocytes/hemoglobin, not leukocytes (C). Volume is ~5L (D).

Correct Answer: A

Rationale: Eosinophils (A) combat parasites and immune complexes. Monocytes (B) phagocytize broadly, lymphocytes (C) are immune, basophils (D) promote inflammation.