Cell Biology

• Explain how water and mineral ions are transported through plants. Include in your answer the roles of the xylem and phloem, and how the process of transpiration helps in the movement of water.

  • Water and mineral ions are transported through plants by the xylem
  • Transpiration is the loss of water vapour through stomata
  • Transpiration creates a water potential gradient
  • Water is pulled through the plant via the capillary section
  • Phloem transports sugars(mainly sucrose) in a process called translocation
  • Transpiration helps in the uptake of minerals through root hair cells
• Explain the process of mitosis and how it ensures that daughter cells have the same number of chromosomes as the parent cell.

  • Mitosis is a type of cell division and the 4 stages are the prophase, metaphase, anaphase and telophase
  • At prophase the chromosomes condense and become visible and the nuclear membrane breaks down
  • metaphase the chromosomes align at the equator
  • anaphase the nuclear membranes reform around each set of chromosomes
  • cell divides in 2 ensuring same amount of chromosomes
  • result is 2 daughter cells with same number as parent
• Describe the function of the mitochondria in eukaryotic cells

  • Mitochondria are membrane-bound organelles found in the cytoplasm of eukaryotic cells
  • They have an inner membrane that is folded into structures called cristae and an outer membrane
  • the inner membrane contains enzymes needed for aerobic respiration
  • mitochondria are the site of aerobic respiration where glucose is broken down to produce energy
  • energy is used by cells for energy in processes such as muscle contraction and active transport
  • the mitochondria are often referred to as the "powerhouses" of cell as they provide energy