the digestive system is considered incomplete when it has only one opening that communicates with the external environment through which food is captured and undigested remains are eliminated. This type of digestive system occurs in cnidarians and flatworms.

Food provides organisms with the necessary energy for the realization of their cellular and metabolic processes. They are also sources of raw material for the development and maintenance of the organism. Digestion is a physiological process through which food is reduced to small absorbable particles and available for metabolic use. Considering the process of digestion and the structure of organisms' digestive system, it is CORRECT to state that

The correct alternative is the one that states that the digestive system is considered incomplete when it has only one opening that communicates with the external environment through which food is captured and undigested remains are eliminated. This type of digestive system occurs in cnidarians and flatworms. In cnidarians, such as jellyfish and corals, the gastrovascular cavity is responsible for digestion and nutrient distribution. In flatworms, such as planarians, the mouth is the only opening of the digestive system, and undigested waste is eliminated through the same opening.

After passing through the stomach, the food goes to the small intestine where essential nutrients for the bird's body are absorbed. Which of these nutrients below are not absorbed in the small intestine?

glucose present in cellulose can be obtained through the action of cellulase secreted by microorganisms present in some herbivorous animals.

Cellulose is a polysaccharide, derived from the joining of thousands of glucose molecules in beta configuration, is insoluble in water, presents a linear structure, and can reach molecular masses of the order of 400,000 u. It exists practically throughout the Plantae kingdom, being the main component of the cell wall, considered the basic skeleton of plant cells. It is an essential food source for various herbivorous animals. Paradoxically, these animals are not able to digest cellulose molecules just like humans. In the context discussed, it can be stated that

In animals, digestion is a fundamental process for obtaining energy and nutrition. There are two basic types of digestion, intracellular and extracellular. Knowing this, what is the main difference between intracellular digestion and extracellular digestion?

filter food particles in the surrounding water.

Mussels are among the marine invertebrates directly affected by the presence of microplastic particles in the waters, since, to feed, they filter food particles in the surrounding water.

Question bank: Animals: Digestive System

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