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IB Biology Digestive System

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SABINA HSU The Digestive System Assignment 1. Draw and label the entire digestive tract, labeling the required components. 2. Complete the data-based questions on page 205 of your supplemental text. 1. B: HCl acid 2. A: abdomen, small intestine 4. D: I, ii, and iii 5. A: enzymes of digestion work slightly faster 7b) Salivary glands secrete fluid into the mouth ? wall of stomach secrete fluid into the mouth ? pancreas, liver or gull bladder secretes fluid into the small intestine 9) a: (i) 3.7% (ii) 96.3% b: (i) transgene that was not recovered from this person has been digested in the small intestine (broken down into subunits) c: amount of DNA digesting enzymes speed that food moves inside the gut d: an indigestible marker was used in the experiment in order to find out the rate of digestion. Another reason could be in order to ensure that DNA reached the small intestine e: - transgenes for the most part are clearly digested in the gut - in one person in the experiment, not as much was digested - but for the most part, seems to cause no harm 3. Explain why enzymes are necessary to the digestive process. - Enzymes are globular proteins that increase the rate of a reaction by lowering the activation energy. ...read more.


- The function of the stomach is best described as a good processing unit and a storage cistern. - Chemical: Various chemicals in the stomach like the digestive enzymes pepsin, rennin, and lipase interact to break down the food. In addition, hydrochloric acid creates suitable environment for the enzymes and assists in the digestion. Water mucus also provide a protective lining for the muscular walls of the stomach so it will not be digested by the acid or enzymes. - Mechanical: The mechanical action of the muscles in the stomach constrict and relax in a continuous motion blending, whipping, and stirring the stomach?s contents in the chyme, a pulpy substance that can be handled by the small intestine. 6. What is the significance of HCl in the stomach (Hint: there are 2 roles!) HCl is a vital component in digestive health as it is produced by the stomach to aid in the digestion of food. When the stomach produces too much HCl, the condition is known as Hyperchlorhydria. On the other hand, when the stomach does not produce enough HCl, the condition is known as hypochlorhydra. - HCl allows for the digestion an absorption of the trace minerals zinc, iron, copper, and magnesium, calcium, selenium, and vitamins B12 and B3. ...read more.


Smoothness- The wall of the small intestine is smooth, while that of the large intestine is sacculated forming haustra Mucous Membrane- The mucous membrane of the small intestine has permanent folds, known as the plicae circulars. These are absent in the large intestine, where occasional incomplete folds may be present. Villi- The mucous membrane of small intestine presents numerous microscopic projections called villi. These help to increase the surface area of the intestine. However, they are absent in the large intestine. Lymphoid Tissue- The mucous membrane of small intestine presents aggregations of lymphoid tissue, called Peyer’s patches. These are absent in the large intestine. 10. What, specifically, exits the anus after processing by the digestive tract? What is it composed of? Food enters the mouth, passes through a long tube, exists as feces through the anus. - During the process of absorption, nutrients that come from the food (including carbohydrates, proteins, fats, vitamins, and minerals) pass through channels in the intestinal wall and into the bloodstream. The blood works to distribute these nutrients to the rest of the body. The waste parts of food that the body can't use are passed out of the body as feces. - Feces are ¾ water and ¼ non digestible solids such as bacteria, fiber and others. Bacteria produce sulfur-rich organic compounds such as indole, skatole, and mercaptans, and the in organic gas hydrogen sulfide. ...read more.

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