Biology digestion




Biology digestion


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Biology digestion



5.1.1Explain why digestion of large food molecules is essential.

  • Digestion is neccesary because it breaks large food molecules into smaller molecules that can be absorbed into the villi of the small intestine and eventually travel through the blood. Simple molecules can then dissolve in blood and go into circulation to reach every part of the body.

5.1.2 Explain the need for enzymes in digestion.

  • Enzymes are needed for digestion because they increase the rate at which food molecules are broken down into their simplest form. Without enzymes, the reactions needed for digestion would take a really really long time.

5.1.3 State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase.

  • One amylase: source is salivary glands in the mouth; substrate is starch; product is maltose; and optimum pH is about 7 (balanced). One protease (a.k.a. pepsin): source is glands in stomach wall; substrate is proteins; product is polypeptides; optimum pH is 2 (acidic). One lipase: source is the pancreas; substrate is lipids; product is glycerol and fatty acids; optimum pH is basic(higher than 7).

5.1.4 Draw a diagram of the digestive system.

  • Drawing will be inserted at a later date.

5.1.5 Outline the functions of the stomach, small intestine, and large intestine.

  • The stomach is where the protein digestion process begins. Pepsin breaks the proteins down into small polypeptides. The small intestine is the site where most of the breaking down of food occurs, and also where absorbtion of nutrients occurs. This is where fats being to be broken down. Starch, glycogen, and smaller polysaccharides are hydolyzed into disaccharides such as maltose. Maltose in the split into two simpler molecules of maltase. The lining of the small instestine is made of small villi, little finger-like membrane folds that absorb small molecules, putting them in the circulatory system(sugars & peptides) or the lymphatic system(fats). In the large intestine, or colon, water is reabsorbed and the wastes of the digestive tract, feces, are taken up. They become more solid by the removal of water, and then go out of the rectum.

5.1.6 Distinguish between absorption and assimilation.

  • Absorption is the passage of digested substances through the wall of the intestine into the blood capillaries in bodies. Assimilation is a process by which food becomes incorporated with the body without being broken down.

5.1.7 Explain how the structure of the villus is related to its role in absorption of the end products of digestion.

  • A villi is a folded finger-like structure. They increase the surface area for absorption. They contain a network of blood capillaries and a lymph vessels so that the absorbed materials can circulate throughout the body. They are located in the small intestine.


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Biology digestion


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Biology digestion