The Cell Theory was proposed by: MCQ with Answer and Explanation

Explanation:
Lymphatic vessels collect interstitial fluid (lymph) and return it to the venous circulation (subclavian veins). This maintains fluid balance. Along the way, lymph nodes filter pathogens. The heart pumps blood, kidneys filter blood, lungs exchange gases. The lymphatic system is unidirectional.

Explanation:
Albert Sabin developed the attenuated oral polio vaccine (OPV), which is easier to administer and provides intestinal immunity. Salk developed the inactivated vaccine (IPV).

Explanation:
The cerebellum, located at the back of the brain below the cerebrum, coordinates voluntary movements, maintains posture, balance, and muscle tone. Damage leads to unsteady gait and tremors. The cerebrum controls thinking, memory, and voluntary actions. Thalamus relays sensory impulses, hypothalamus regulates body temperature, hunger, and endocrine functions. Cerebellum is often called the 'little brain'.