Digestive System IB Biology Review What are the components

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IB Biology Review

• Digestive System

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What are the components of the human digestive
system?

• Mouth
• Salivary glands
• Esophagus
• Stomach
• Small intestine
• Liver
• Gall bladder
• Pancreas
• Large intestine

3
Identify the components of the human digestive
system.

• Mouth
• Salivary glands
• Esophagus
• Stomach
• Small intestine
• Liver
• Gall bladder
• Pancreas
• Large intestine

4
Be able to draw this schematic.
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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

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Digestive Enzymes

• Fill in the table
• Work left to right

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Small Intestine and Villi
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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

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1. Draw a diagram of the human digestive system.
(7 marks)

• Must include
• Mouth
• Esophagus
• Stomach
• Small intestine
• Liver
• Gall bladder
• Pancreas
• Large intestine

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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

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3. Draw a diagram of a villi in vertical section.
(4 marks)

• Must show
• Lacteal
• Capillary network
• Epithelial cells
• Microvilli

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

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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

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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

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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