BIO 252 MIDTERM EXAM – LATEST 2026 QUESTIONS AND
ANSWERS WITH RATIONALES/GRADED A+/2026 UPDATE/100%
CORRECT /INSTANT DOWNLOAD
1. Which layer of the heart wall is responsible for the contractile force of the heart?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Answer: B
Rationale: The myocardium is the thick, middle layer composed of cardiac muscle tissue
responsible for contraction. The epicardium (A) is the outer layer (visceral pericardium). The
endocardium (C) lines the chambers. The pericardium (D) is the sac surrounding the heart.
2. The chamber of the heart that receives deoxygenated blood from the superior and inferior
vena cava is the:
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
Answer: A
Rationale: The right atrium receives deoxygenated blood from the systemic circulation via the
superior vena cava (upper body), inferior vena cava (lower body), and coronary sinus (heart).
The right ventricle (B) pumps blood to the lungs. The left atrium (C) receives oxygenated blood
from the lungs. The left ventricle (D) pumps blood to the body.
3. The tricuspid valve is located between which two structures?
A. Left atrium and left ventricle
B. Right atrium and right ventricle
, C. Right ventricle and pulmonary trunk
D. Left ventricle and aorta
Answer: B
Rationale: The tricuspid valve (right atrioventricular valve) is between the right atrium and right
ventricle. The bicuspid/mitral valve (A) is on the left. The pulmonary semilunar valve (C) is
between the right ventricle and pulmonary trunk. The aortic semilunar valve (D) is between the
left ventricle and aorta.
4. Which of the following correctly lists the order of blood flow through the heart starting from
the vena cava?
A. Right ventricle, right atrium, left ventricle, left atrium, aorta
B. Right atrium, right ventricle, left atrium, left ventricle, aorta
C. Left atrium, left ventricle, right atrium, right ventricle, aorta
D. Right atrium, left atrium, right ventricle, left ventricle, aorta
Answer: B
Rationale: Blood flows: vena cava → right atrium → right ventricle → pulmonary artery → lungs
→ pulmonary veins → left atrium → left ventricle → aorta. Option B is correct.
5. The pulmonary veins carry:
A. Deoxygenated blood to the lungs
B. Deoxygenated blood to the heart
C. Oxygenated blood to the left atrium
D. Oxygenated blood to the lungs
Answer: C
Rationale: Pulmonary veins are unique because they carry oxygenated blood from the lungs to
the left atrium. Pulmonary arteries carry deoxygenated blood to the lungs (A, D). Deoxygenated
blood returns to the heart via the vena cava (B).
6. The first heart sound (S1, "lub") is caused by:
A. Closure of the semilunar valves
B. Closure of the atrioventricular (AV) valves
ANSWERS WITH RATIONALES/GRADED A+/2026 UPDATE/100%
CORRECT /INSTANT DOWNLOAD
1. Which layer of the heart wall is responsible for the contractile force of the heart?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
Answer: B
Rationale: The myocardium is the thick, middle layer composed of cardiac muscle tissue
responsible for contraction. The epicardium (A) is the outer layer (visceral pericardium). The
endocardium (C) lines the chambers. The pericardium (D) is the sac surrounding the heart.
2. The chamber of the heart that receives deoxygenated blood from the superior and inferior
vena cava is the:
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle
Answer: A
Rationale: The right atrium receives deoxygenated blood from the systemic circulation via the
superior vena cava (upper body), inferior vena cava (lower body), and coronary sinus (heart).
The right ventricle (B) pumps blood to the lungs. The left atrium (C) receives oxygenated blood
from the lungs. The left ventricle (D) pumps blood to the body.
3. The tricuspid valve is located between which two structures?
A. Left atrium and left ventricle
B. Right atrium and right ventricle
, C. Right ventricle and pulmonary trunk
D. Left ventricle and aorta
Answer: B
Rationale: The tricuspid valve (right atrioventricular valve) is between the right atrium and right
ventricle. The bicuspid/mitral valve (A) is on the left. The pulmonary semilunar valve (C) is
between the right ventricle and pulmonary trunk. The aortic semilunar valve (D) is between the
left ventricle and aorta.
4. Which of the following correctly lists the order of blood flow through the heart starting from
the vena cava?
A. Right ventricle, right atrium, left ventricle, left atrium, aorta
B. Right atrium, right ventricle, left atrium, left ventricle, aorta
C. Left atrium, left ventricle, right atrium, right ventricle, aorta
D. Right atrium, left atrium, right ventricle, left ventricle, aorta
Answer: B
Rationale: Blood flows: vena cava → right atrium → right ventricle → pulmonary artery → lungs
→ pulmonary veins → left atrium → left ventricle → aorta. Option B is correct.
5. The pulmonary veins carry:
A. Deoxygenated blood to the lungs
B. Deoxygenated blood to the heart
C. Oxygenated blood to the left atrium
D. Oxygenated blood to the lungs
Answer: C
Rationale: Pulmonary veins are unique because they carry oxygenated blood from the lungs to
the left atrium. Pulmonary arteries carry deoxygenated blood to the lungs (A, D). Deoxygenated
blood returns to the heart via the vena cava (B).
6. The first heart sound (S1, "lub") is caused by:
A. Closure of the semilunar valves
B. Closure of the atrioventricular (AV) valves
