1.2 Organisation

• What is a cell?

  The basic building block of a living organism.
• Why is a cell considered the basic building block of life?

  Because it is the smallest unit that can carry out all life processes.
• What is an organ?

  A collection of tissues working together to perform a specific function.
• Can you give an example of an organ and its tissues?

  The stomach contains glandular, muscular, and epithelial tissues.
• What is an organ system?

  A group of organs working together to perform specific functions.
• What are some organs included in the digestive system?

  The stomach, the small intestine, the large intestine, the liver, and glands
• What is a tissue?

  A group of cells with a similar structure and function working together.
• What is an example of a type of tissue and its function?

  Muscular tissue contracts to bring about movement.
• What are the levels of biological organization from smallest to largest?

  • Cell: Basic building block of life
  • Tissue: Group of similar cells
  • Organ: Collection of tissues
  • Organ System: Group of organs
• What is the main function of the digestive system?

  To digest food and absorb the nutrients obtained from digestion.
• What do the pancreas and salivary gland produce?

  Digestive juices containing enzymes.
• What is the role of the stomach in digestion?

  It produces hydrochloric acid to kill bacteria and provide an optimal pH for protease enzymes.
• What is the role of the small intestine in the digestive system?

  It is the site where soluble food molecules are absorbed into the bloodstream.
• What does the liver produce in the digestive system?

  Bile, which emulsifies lipids and aids lipase enzyme efficiency.
• What is the role of the large intestine in digestion?

  It absorbs water from undigested food, producing faeces.
• How do enzymes function in the digestive system?

  Enzymes act as biological catalysts that speed up the breakdown of food without being used up.
• How does the shape of an enzyme affect its function?

  Enzymes have a specific active site that is complementary to their substrate.
• What is metabolism?

  The sum of all the reactions in a cell or an organism.
• What types of metabolic reactions do enzymes catalyse?

  • Building larger molecules from smaller ones (e.g., glucose to starch)
  • Changing one molecule to another (e.g., glucose to fructose)
  • Breaking down larger molecules into smaller ones (e.g., carbohydrates to glucose)
• What is the lock and key hypothesis of enzyme function?

  The enzyme's active site and the substrate are complementary, allowing them to bind and form an enzyme-substrate complex.
• How does temperature affect enzyme action?

  Increasing temperature up to a point increases enzyme action, but too high a temperature denatures the enzyme.
• What is the optimum temperature for enzyme action?

  Around 37° Celsius.
• How does pH affect enzyme function?

  The optimum pH for most enzymes is 7, and extreme pH levels can alter the active site shape, preventing enzyme function.
• Where are carbohydrases, proteases, and lipases produced in the body?

  • Carbohydrases: Amylase (salivary gland and pancreas), Maltase (small intestine)
  • Proteases: Pepsin (stomach), others (pancreas and small intestine)
  • Lipases: Pancreas and small intestine
• What is the role of carbohydrases in the digestive system?

  Carbohydrases break down carbohydrates into simple sugars (glucose)
• What is the role of proteases in the digestive system?

  Proteases break down proteins into amino acids.
• What is the role of lipases in the digestive system?

  Lipases break down lipids into fatty acids and glycerol.
• How are the products of digestion used in the body?

  They are used to build larger molecules such as carbohydrates and proteins, and glucose is used in respiration.
• Where is bile made and stored in the body?

  Bile is made by the liver and stored in the gallbladder.
• What is the role of bile in the digestive system?

  • Neutralises hydrochloric acid from the stomach
  • Emulsifies (breaks lipids into tiny droplets) lipids to increase surface area for lipase action
• What is the heart?

  An organ that pumps blood around the body.
• What is the purpose of the circulatory system?

  It carries oxygen and other useful substances to bodily tissues and removes waste substances.
• How does the double circulatory system work?

  • One pathway carries blood from the heart to the lungs for gas exchange.
  • Another pathway carries blood from the heart to the tissues.
• Where does blood pumped by the right ventricle go?

  To the lungs.
• Where does blood pumped by the left ventricle go?

  To the body tissues.
• Why is the double circulatory system important?

  It makes the circulatory system more efficient by allowing oxygenated blood to be pumped at higher pressure.
• How many chambers does the heart have and what are they called?

  4 chambers: right atrium, right ventricle, left atrium, left ventricle.
• Why is the wall of the left ventricle thicker?

  It pumps blood at a higher pressure around the whole body.
• What are the four main blood vessels associated with the heart?

  • Aorta: carries oxygenated blood from the heart to the body
  • Pulmonary vein: carries oxygenated blood from the lungs to the heart
  • Vena cava: carries deoxygenated blood from the body to the heart
  • Pulmonary artery: carries deoxygenated blood from the heart to the lungs
• What is the purpose of valves in the heart?

  To prevent the backflow of blood.