3.3 Digestion and Absorption

• What is the purpose of breaking down food in digestion?

  Absorption of nutrients
• One benefit of digestion is the supply of energy
• Chewing food breaks it down into smaller pieces, increasing its surface area
• Chemical digestion breaks down food molecules through enzymatic reactions
• Chemical digestion builds on the mechanical breakdown achieved earlier.

  True
• Order the key processes involved in mechanical digestion:

  1️⃣ Chewing

  2️⃣ Swallowing

  3️⃣ Stomach contractions
• Mechanical digestion increases the surface area of food for more efficient chemical digestion.

  True
• Which enzyme is responsible for breaking down fats into fatty acids and glycerol?

  Lipase
• Amylase breaks down carbohydrates into sugars.


  True
• Absorption is the process where digested nutrients enter the bloodstream
• What is the primary purpose of digestion?

  Extract essential nutrients
• Chewing increases the surface area of food for more efficient chemical digestion
• What is the source of protease in chemical digestion?

  Stomach, Pancreas
• Match the absorption mechanism with its characteristics:

  Passive Diffusion ↔️ No energy required

  Active Transport ↔️ Moves against concentration gradient
• Active transport moves molecules against their concentration gradient
• What is the process called where digested nutrients move into the bloodstream?

  Absorption
• The inner lining of the small intestine contains circular folds called plicae circulares
• Which adaptation of the small intestine increases its surface area?

  Villi
• Epithelial cells in the small intestine are specialized for absorption.


  True
• Match the absorption mechanism with its characteristics:

  Passive Diffusion ↔️ No energy needed

  Active Transport ↔️ Moves against concentration gradient
• Capillaries within the villi transport absorbed nutrients into the bloodstream
• Digestion is the process of breaking down large, complex molecules into smaller, simpler ones
• Digestion transforms macromolecules into micromolecules.


  True
• Match the benefit of digestion with its description:

  Energy supply ↔️ Nutrients converted into fuel

  Nutrient availability ↔️ Essential molecules for body

  Body growth and repair ↔️ Contributes to cell and tissue health
• Mechanical digestion prepares food for chemical digestion by increasing its surface area.


  True
• Match the enzyme with its source, substrate, and product:

  Amylase ↔️ Salivary glands, Pancreas ||| Carbohydrates ||| Sugars

  Protease ↔️ Stomach, Pancreas ||| Proteins ||| Amino acids

  Lipase ↔️ Pancreas ||| Fats ||| Fatty acids and glycerol
• Digestion provides energy to fuel the body's activities
• What is the purpose of stomach contractions in mechanical digestion?

  Mix and break down food
• Protease is secreted by the pancreas and acts on proteins
• The enzyme amylase is produced by the salivary glands and the pancreas
• What is the substrate and product of lipase?

  Fats and fatty acids
• Passive diffusion requires energy to move molecules across a membrane.

  False
• Steps involved in mechanical digestion

  1️⃣ Chewing

  2️⃣ Swallowing

  3️⃣ Stomach contractions
• Chemical digestion involves enzymatic reactions to break down food molecules.


  True
• In passive diffusion, molecules move down their concentration gradient
• What type of molecules move through passive diffusion?

  Small, uncharged molecules
• Passive diffusion requires energy to move molecules.

  False
• Structural adaptations of the small intestine in order of decreasing size

  1️⃣ Length

  2️⃣ Plicae circulares

  3️⃣ Villi

  4️⃣ Microvilli
• Microvilli are found on the surface of villi.

  True
• Capillaries within the villi provide a rapid blood supply.