Ch 5Digestion and Absorption — Class 11 Zoology, concept-first.

We all eat food — skip breakfast and the difference is unmistakable by noon. The food we eat supplies energy and the organic material the body needs for growth and for replacing worn or damaged tissue…

Digestion is really a sequence of five linked events: ingestion (taking food in), digestion proper (breaking macromolecules down into micromolecules), absorption (moving those micromolecules into the…

The alimentary canal is a single, continuous, muscular tube that begins at the mouth and ends at the anus, and each stretch of it is shaped for a specific task.

Whatever part of the gut you look at, from the oesophagus down to the rectum, the wall is built from the same four concentric layers, and this shared plan is what lets the canal move, protect and regu…

Digestion depends on exocrine glands that manufacture and release the enzymes and other secretions the canal needs.

Digestion turns solid food into monomers small enough to absorb, using both mechanical breakdown and enzyme-driven chemical breakdown at each stop along the canal.

Absorption is the step where the small molecules produced by digestion actually cross the intestinal lining into the blood and lymph, and the villi lining the small intestine — each built around a cen…

Whatever the small intestine fails to digest or absorb — mostly indigestible fibre, called roughage — passes on into the large intestine.

The nutrients in food fall into two broad groups by the quantity the body needs: macronutrients — carbohydrates, proteins and lipids — required in relatively large amounts, and micronutrients — vitami…

The three macronutrient classes do not all supply the same amount of usable energy per gram, and the body typically draws around half of its daily energy from carbohydrates, a little over a third from…

Because the gut is constantly exposed to what we eat and drink, it is vulnerable to infection, poor diet and mechanical strain, and this produces a wide range of disorders.

This closing section works through the chapter's Evaluation questions — a run of multiple-choice questions on the alimentary canal, digestive enzymes, sphincters and hormonal control, several matching…

Sample papers and previous-year board questions for this subject.