B2- Organisation

• What is the basic building block of all living organisms?

  Cells
• What is the process by which cells become specialised?

  Differentiation
• When does differentiation occur in multicellular organisms?


  During the development of a multicellular organism
• What is a tissue?


  A group of cells with a similar structure and function
• Can a tissue include more than one type of cell?


  Yes
• What are examples of tissues and their functions?

  • Muscular tissue: contracts to move attached structures
  • Glandular tissue: makes and secretes chemicals like enzymes and hormones
  • Epithelial tissue: covers parts of the body, e.g., the inside of the gut
• What is an organ system?


  A group of organs working together to perform a particular function
• What are enzymes?


  Biological catalysts that speed up chemical reactions in living organisms
• What are the two types of metabolic reactions?

  • Anabolic (synthesis): converts small molecules to large molecules (e.g., protein synthesis, photosynthesis)
  • Catabolic (breaking down): breaks down large molecules to small molecules (e.g., digestion, respiration)
• What are enzymes made up of?


  Proteins
• How does temperature affect enzyme activity?


  As temperature increases, enzyme activity increases until it reaches an optimum temperature, then decreases rapidly
• What happens to enzyme activity as temperature increases?


  Enzyme and substrate gain more energy, leading to more successful collisions
• How can pH affect enzyme activity?


  Different enzymes work at different pH values, and extreme pH changes can destroy the enzyme's active site
• What is an example of an enzyme that is specific for its substrate?


  Protease, which can break down only proteins
• Lock and key model

  
• What should you be able to describe by the end of this video?

  You should be able to describe a tissue, an organ, and an organ system.
• What is a tissue?


  A tissue is a group of cells with a similar structure and function.
• What is an organ?


  An organ is a group of tissues working together for a specific function.
• Can you give an example of an organ?


  The stomach is a good example of an organ.
• What is an organ system?


  An organ system is a group of organs that work together to form organisms.
• What is an example of an organ system mentioned in the video?


  The digestive system is an example of an organ system.
• What are the three main nutrients found in food?

  • Carbohydrates (e.g., starch)
  • Proteins
  • Lipids (fats)
• Why must large food molecules be digested?


  They must be digested because they are too large to be absorbed into the bloodstream.
• What role do enzymes play in digestion?


  Enzymes break down large food molecules into smaller molecules.
• What happens to food in the mouth?

  Food is chewed and enzymes in saliva begin to digest starch.
• What is the function of hydrochloric acid in the stomach?


  Hydrochloric acid helps enzymes to digest proteins.
• How does the stomach aid in digestion?


  The stomach churns food to turn it into a fluid, increasing the surface area for enzymes.
• What chemicals are released into the small intestine from the liver and pancreas?


  The pancreas releases enzymes, and the liver releases bile.
• What is the role of bile in digestion?


  Bile speeds up the digestion of lipids and neutralizes stomach acid.
• How are small food molecules absorbed in the small intestine?


  They are absorbed either by diffusion or by active transport.
• What happens in the large intestine?


  Water is absorbed into the bloodstream.
• What is done with the products of digestion in the body?


  They are used to build new carbohydrates, lipids, and proteins.
• What is one use of glucose produced from digestion?


  Some glucose is used in respiration.
• Where can you find questions on the digestive system for revision?


  • In the revision book
  • By clicking on the provided link
• What should you be able to identify regarding the digestive system?


  You should be able to identify the main organs and their functions.