Q4. Assertion: humans have a complete double circulation. Reason: oxygenated and deoxygenated blood are pumped out of the two ventricles without mixing. Are both true, and does the reason explain the assertion?
Both are true. Two linked pulmonary and systemic circuits account for double circulation, while separation of the ventricular outflows explains complete separation (NCERT pages 197 and 204).
Q5. What is the tunica intima made of?
Squamous endothelium, the inner lining of arteries and veins (NCERT page 201).
Q6. Which circulation starts from the left ventricle, and where does it end?
The systemic circulation; it ends when the vena cava empties into the right atrium (NCERT page 201).