Which organ is the first major site of chemical digestion in a frog?

• A. Mouth
• B. Small intestine
• C. Liver
• D. Stomach

Answer: (D)

Verified step by step guidance

1. Understand the process of digestion in frogs: Digestion in frogs involves both mechanical and chemical processes. Mechanical digestion begins in the mouth, but chemical digestion involves the breakdown of food molecules using enzymes and acids.
2. Review the role of the mouth: In frogs, the mouth is primarily responsible for mechanical digestion (chewing and breaking down food into smaller pieces) and some enzymatic activity in saliva, but it is not the primary site of chemical digestion.
3. Examine the role of the stomach: The stomach is the first major site of chemical digestion in frogs. It secretes gastric juices, including hydrochloric acid and digestive enzymes like pepsin, which break down proteins into smaller peptides.
4. Consider the role of the small intestine: The small intestine is where most nutrient absorption occurs and where further chemical digestion takes place with the help of enzymes from the pancreas and bile from the liver. However, it is not the first site of chemical digestion.
5. Clarify the role of the liver: The liver produces bile, which aids in the digestion of fats, but it does not directly perform chemical digestion. Therefore, the stomach is the correct answer as the first major site of chemical digestion in frogs.