Digestion

• What is meant by a tissue?

  A group of cells with similar structure
• What is an organ?

  A group of tissues working together
• What is an organ system?

  A group of organs working together
• What is the main function of the digestive system?

  To break down food and absorb nutrients
• What are the three main nutrients found in food?

  Carbohydrates, proteins, and lipids
• Why must large food molecules be digested?

  They are too large to be absorbed directly
• What role do enzymes play in digestion?

  They break down large molecules into smaller ones
• What begins the digestion of starch in the mouth?

  Enzymes in saliva
• What is the function of hydrochloric acid in the stomach?

  It helps enzymes digest proteins
• What happens to food in the stomach?

  It is churned into a fluid for digestion
• What does the pancreas release into the small intestine?

  Enzymes for digestion
• What is the role of bile in digestion?

  It speeds up lipid digestion and neutralizes acid
• How are small food molecules absorbed in the small intestine?

  By diffusion or active transport
• What is absorbed in the large intestine?

  Water into the bloodstream
• What happens to the waste after digestion?

  It is released as feces from the body
• What is one use of glucose produced from digestion?

  It is used in respiration
• What are the main functions of the organs in the digestive system?

  • Mouth: Chews food and begins starch digestion
  • Stomach: Digests proteins and churns food
  • Small intestine: Digests proteins, starch, and lipids; absorbs nutrients
  • Large intestine: Absorbs water and forms feces
• How do the digestive system organs work together?

  • Mouth chews food and starts digestion
  • Stomach digests proteins and churns food
  • Pancreas and liver release enzymes and bile
  • Small intestine absorbs nutrients
  • Large intestine absorbs water and eliminates waste
• What are the adaptations of muscle cells?

  • Contain special protein fibers for contraction
  • Have many mitochondria for energy production
• What is the process of digestion in the digestive system?

  1. Large food molecules are broken down by enzymes
  2. Smaller molecules are absorbed into the bloodstream
  3. Nutrients are used to build carbohydrates, lipids, and proteins
• What is the effect of temperature on enzyme activity?

  Temperature affects the rate of enzyme reactions
• What is the role of enzymes in chemical reactions?

  They speed up chemical reactions
• What is the groove on an enzyme's surface called?

  Active site
• What is a substrate in relation to enzymes?

  It is the molecule that the enzyme reacts with
• What does the lock and key theory describe?

  How substrates fit into the active site
• What happens to enzyme activity as temperature increases?

  It increases until the optimum temperature
• What is the optimum temperature for most human enzymes?

  37 degrees Celsius
• What occurs when the temperature exceeds the optimum for enzymes?

  Enzyme activity rapidly decreases to zero
• What does it mean when an enzyme's active site is denatured?

  It no longer fits the substrate perfectly
• What is the effect of pH on enzyme activity?

  pH affects the rate of enzyme reactions
• What happens to enzyme activity when pH is too acidic or alkaline?

  Activity drops to zero due to denaturation
• What is the optimum pH for enzymes?

  It is the pH where activity is maximum
• What type of enzyme works best at an acidic pH?

  Protease enzyme in the stomach
• What type of enzyme works best at an alkaline pH?

  Lipase enzyme from the pancreas
• What are the effects of temperature and pH on enzyme activity?

  • Temperature increases enzyme activity until optimum
  • Optimum temperature for human enzymes is 37°C
  • High temperatures denature enzymes, stopping activity
  • pH affects enzyme activity; each enzyme has an optimum pH
  • Extreme pH levels denature enzymes, stopping activity
• Where can students find more questions on enzyme activity?

  In the vision workbook linked above