The structure which prevents entry of food into wind pipe during swallowing in mammals is-

Correct Answer: C

Rationale: The epiglottis closes over the glottis during swallowing to prevent food from entering the trachea.

Correct Answer: B

Rationale: Ptyalin (salivary amylase) is secreted by salivary glands and works in a slightly acidic to neutral pH.

Correct Answer: B

Rationale: Bilirubin and biliverdin are bile pigments formed in the liver from hemoglobin breakdown.

Correct Answer: A

Rationale: Pepsin functions optimally in the highly acidic pH of the stomach (around 1.8-2).

Correct Answer: D

Rationale: Amino acids are absorbed mainly in the jejunum and ileum of the small intestine.