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Nutrition in Plants and Animals - Digestion in Grass-Eating Animals

Grade 7CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Ruminants: Herbivorous animals like cows, buffaloes, and deer that quickly swallow grass and store it in a part of the stomach called the Rumen.

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Cud: In the Rumen, food is partially digested and is called cud. Later, the cud returns to the mouth in small lumps for the animal to chew it again.

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Rumination: The process of chewing the cud is known as rumination, and these animals are called ruminants.

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Cellulose Digestion: Grass is rich in cellulose, a complex carbohydrate with the general formula (C6H10O5)n(C_6H_{10}O_5)_n. It can only be digested by specific bacteria present in the digestive system of ruminants.

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Caecum: Ruminants have a large sac-like structure called the caecum located between the small intestine and the large intestine where cellulose is digested by the action of certain bacteria which are not present in humans.

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Stomach Structure: The stomach of a ruminant is divided into four chambers: Rumen, Reticulum, Omasum, and Abomasum (the true stomach).

📐Formulae

Cellulose+nH2O→Cellulase/Bacterian(C6H12O6) (Simple Sugars)\text{Cellulose} + nH_2O \xrightarrow{\text{Cellulase/Bacteria}} n(C_6H_{12}O_6) \text{ (Simple Sugars)}

(C6H10O5)n (Cellulose Formula)(C_6H_{10}O_5)_n \text{ (Cellulose Formula)}

💡Examples

Problem 1:

Why can't humans digest grass like cows do?

Solution:

Humans cannot digest grass because it is rich in cellulose (C6H10O5)n(C_6H_{10}O_5)_n.

Explanation:

The digestion of cellulose requires the enzyme cellulase and specific symbiotic bacteria. These bacteria are present in the rumen or caecum of ruminants but are absent in the human digestive system. Therefore, the complex structure of (C6H10O5)n(C_6H_{10}O_5)_n remains undigested in humans.

Problem 2:

Describe the flow of food in the ruminant digestive system.

Solution:

Mouth →\rightarrow Rumen (storage/partial digestion) →\rightarrow Mouth (chewing cud) →\rightarrow Reticulum/Omasum →\rightarrow Abomasum (digestion).

Explanation:

The food is first swallowed and sent to the Rumen where it becomes 'cud'. It is then brought back to the mouth for rumination. Finally, it passes through the other chambers for complete chemical digestion by gastric juices in the Abomasum.