Digestive System - SS2 Biology Past Questions and Answers - page 2

Flatworms

 Earthworms

Cockroaches

Bird

Earthworms

Flatworms have a blind sac digestive system, where the mouth serves as both an intake and an excretory organ. They rely on extracellular digestion, secreting enzymes into the surrounding environment to break down food. Nutrients are absorbed through the body wall.

Earthworms have a complete digestive system with a mouth and anus. They have a specialized structure called the typhlosole to increase the surface area for absorption. Cockroaches, on the other hand, have a chewing mechanism to break down food and a crop and gizzard for digestion.

Birds have a complex digestive system, including a proventriculus and gizzard. They have a muscular stomach that mechanically breaks down food, and a gizzard with small stones to aid in grinding. Birds also have a specialized organ called the cloaca, which functions in excretion and reproduction.

Cockroaches have malpighian tubules, which are responsible for excreting waste products and regulating water balance. These tubules actively transport nitrogenous waste and other metabolic byproducts from the hemolymph into the gut, where they are eliminated along with feces.

Both humans and birds have complete digestive systems with specialized organs for digestion. However, humans have a longer small intestine for efficient nutrient absorption, while birds have a shorter intestine adapted for rapid digestion of a primarily carnivorous or omnivorous diet. Additionally, birds have a specialized beak and crop for food intake and storage, whereas humans have teeth and a salivary gland to initiate the breakdown of food.