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Life Processes in Animals - Do all animals digest food the same way as humans do?

Grade 7CBSE

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

🔑Concepts

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Nutrition is a complex process involving five steps: Ingestion, Digestion, Absorption, Assimilation, and Egestion.

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Unlike humans, ruminants (grass-eating animals like cows) have a specialized stomach with four chambers: Rumen, Reticulum, Omasum, and Abomasum.

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Ruminants can digest cellulose, a complex carbohydrate found in grass, because of the presence of certain bacteria in their RumenRumen that are absent in humans.

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In Amoeba, digestion is intracellular. It captures food using temporary finger-like projections called PseudopodiaPseudopodia and digests it inside a Food VacuoleFood\ Vacuole.

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In the human stomach, the inner lining secretes mucous, hydrochloric acid (HClHCl), and digestive juices (pepsin) to break down proteins.

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The small intestine is the site of complete digestion of carbohydrates, proteins, and fats, where VilliVilli increase the surface area for absorption.

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The liver secretes BileBile juice, which is stored in the gall bladder and plays a crucial role in the digestion of fats.

📐Formulae

Starch→Salivary AmylaseSugars (Maltose)\text{Starch} \xrightarrow{\text{Salivary Amylase}} \text{Sugars (Maltose)}

Proteins→Pepsin/TrypsinAmino Acids\text{Proteins} \xrightarrow{\text{Pepsin/Trypsin}} \text{Amino Acids}

Fats→Bile/LipaseFatty Acids+Glycerol\text{Fats} \xrightarrow{\text{Bile/Lipase}} \text{Fatty Acids} + \text{Glycerol}

Complex Carbohydrates→EnzymesGlucose\text{Complex Carbohydrates} \xrightarrow{\text{Enzymes}} \text{Glucose}

💡Examples

Problem 1:

Why can humans not digest cellulose while cows can?

Solution:

Humans lack the specific bacteria required to break down cellulose. Cows have a large sac-like structure called the RumenRumen between the esophagus and the small intestine, containing symbiotic bacteria that digest cellulose.

Explanation:

Cellulose is a complex carbohydrate. The digestion of cellulose requires the enzyme cellulase, which is produced by bacteria in the ruminant's digestive system.

Problem 2:

Describe the process of feeding in Amoeba.

Solution:

Amoeba senses food, pushes out PseudopodiaPseudopodia around the food particle, and engulfs it. The food becomes trapped in a Food VacuoleFood\ Vacuole where digestive juices are secreted to break it down into simpler substances.

Explanation:

Since Amoeba is a single-celled organism, it does not have a complex digestive system like humans. It uses PhagocytosisPhagocytosis for ingestion.

Problem 3:

How does the surface area of the small intestine affect absorption?

Solution:

The inner walls of the small intestine have thousands of finger-like outgrowths called VilliVilli. These VilliVilli increase the surface area significantly.

Explanation:

Increased surface area ∝\propto Rate of absorption. This allows for the rapid transfer of digested nutrients into the blood vessels.