IB Biology Review Digestive System

What are the components of the human digestive system? Mouth Salivary glands Esophagus Stomach Small intestine Liver Gall bladder Pancreas Large intestine

Identify the components of the human digestive system. Mouth Salivary glands Esophagus Stomach Small intestine Liver Gall bladder Pancreas Large intestine

Be able to draw this schematic.

Bile Where is bile made? Liver What is the role of bile in digestion? Acts on fats and lipids Breaks down fat into smaller droplets of fat Why is this useful for the body? This creates more surface area on which enzymes can act

Digestive Enzymes Fill in the table Work left to right

Small Intestine and Villi

What is the benefit of villi and microvilli in the small intestine? Villi and microvilli increase the surface area of the small intestine Why is more surface area good? It means the small intestine can be more efficient Can absorb more nutrients, proteins, minerals

1. Draw a diagram of the human digestive system. (7 marks) Must include Mouth Esophagus Stomach Small intestine Liver Gall bladder Pancreas Large intestine

2. State where bile is synthesized and explain its role in digestion. (3 marks) Synthesized in liver cells; Acts on fats / lipids; Emulsifies / breaks down fat into smaller droplets of fat; This creates more surface area on which enzymes can act;

3. Draw a diagram of a villi in vertical section. (4 marks) Must show Lacteal Capillary network Epithelial cells Microvilli

4. State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase. (8 marks)

5. Describe the role of enzymes in the process of digestion of proteins, carbohydrates, and lipids in humans. (6 marks) protease / trypsin / pepsin digest proteins into polypeptides / dipeptides / amino acids / peptides; lipase digests lipids into glycerol / fatty acids; amylase digests polysaccharides into disaccharides / monosaccharides; enzymes must match products; speed up / catalyze reactions / increased efficiency; lower the (activation) energy required for digestive reactions to occur; occurs at body temperature; require optimum pH; enzymes are specific;

6. State the sources, substrate, product, and optimum pH conditions for the enzyme amylase. (4 marks) Sources salivary glands; pancreas; Substrate starch / glycogen (do not accept carbohydrate) Product maltose / disaccharide; Optimum pH 7-8 / neutral – slightly alkaline;

7. Which organ secrets enzymes that are active at a low pH? (1 mark) A. Mouth B.Pancreas C.Stomach D. Liver Correct answer: C

8. Describe the role of enzymes in digestion with reference to two named examples. (5 marks) large food molecules must be broken down; such as carbohydrates / proteins etc. ; by hydrolysis of bonds / to form monomers; rate of reaction at body temperature too slow; enzymes increase the rate of breakdown / act as catalysts; first enzyme example – name, substrate, and product; second enzyme example –name, substrate, product;