3.3 Digestive System

IB Biology IB Biology ReviewReview

Digestive SystemDigestive System

What are the components What are the components of the human digestive of the human digestive

system?system? MouthSalivary glandsEsophagusStomachSmall intestineLiverGall bladderPancreasLarge intestine

Identify the components of Identify the components of the human digestive the human digestive

system. system. MouthSalivary glandsEsophagusStomachSmall intestineLiverGall bladderPancreasLarge intestine

Be able to draw this Be able to draw this schematic.schematic.

BileBile

Where is bile made?Liver

What is the role of bile in digestion?Acts on fats and lipidsBreaks 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 EnzymesDigestive Enzymes

Fill in the table Work left to right

Small Intestine and VilliSmall Intestine and Villi

What is the benefit of villi What is the benefit of villi and microvilli in the small and microvilli in the small

intestine?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 efficientCan absorb more nutrients, proteins, minerals

1. Draw a diagram of the 1. Draw a diagram of the human digestive system. human digestive system.

(7 marks)(7 marks)

Must includeMouthEsophagusStomachSmall intestineLiverGall bladderPancreasLarge intestine

2. State where bile is 2. State where bile is synthesized and explain its role synthesized and explain its role in digestion.in digestion. (3 marks)(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 3. Draw a diagram of a villi in vertical section. in vertical section. (4 marks)(4 marks)

Must show Lacteal Capillary network Epithelial cells Microvilli

4. State the source, substrate, 4. State the source, substrate, products and optimum pH products and optimum pH conditions for one amylase, one conditions for one amylase, one

protease and one lipase.protease and one lipase. (8 (8 marks)marks)

5. Describe the role of enzymes in the 5. Describe the role of enzymes in the process of digestion of proteins, process of digestion of proteins,

carbohydrates, and lipids in humans.carbohydrates, and lipids in humans. (6 marks)(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, 6. State the sources, substrate, product, and optimum pH conditions product, and optimum pH conditions

for the enzyme amylase.for the enzyme amylase. (4 marks)(4 marks)

Sourcessalivary glands;pancreas;

Substratestarch / glycogen (do not accept carbohydrate)

Productmaltose / disaccharide;

Optimum pH7-8 / neutral – slightly alkaline;

7. Which organ secrets 7. Which organ secrets enzymes that are active at a enzymes that are active at a low pH? low pH? (1 mark)(1 mark)

A. MouthB. PancreasC. StomachD. Liver

Correct answer: C

8. Describe the role of enzymes in 8. Describe the role of enzymes in digestion with reference to two digestion with reference to two named examples.named examples. (5 marks)(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;