B4 - Using food and controlling growth

• Mitosis is used for growth and repair as they create identical copies of cells
• There are 2 phases of mitosis,

  • Interphase - Cells grow and new cell structures are formed then duplicated
  • Mitosis - Cells then split/halve so there are double the amount of cells
• Meiosis is used to create sex cells, e.g, gametes, egg cells and sperm cells
• In Meiosis, chromosomes halve from diploid (2n) to haploid (1n)
• Mitosis creates identical genetic copies of the cells whereas meisosis generate random genetic variation in the cells
• Meiosis


  A type of cell division that results in four non-identical daughter cells, each with half the number of chromosomes as the parent cell (haploid or 1n).
• Mitosis


  A type of cell division that results in two identical daughter cells, each with the same number of chromosomes as the parent cell (diploid or 2n).
• Aerobic respiration 


  Glucose + Oxygen --> Carbon Dioxide + Water
• Aerobic/Cellular respiration is exothermic
• Anaerobic respiration equation in animals


  Glucose --> Lactic Acid
• Anaerobic respiration in plants in microorganisms


  Glucose --> Ethanol + Carbon Dioxide
• Aerobic respiration takes place in the mitochondria
• Anaerobic respiration takes place in the cytoplasm
• Magnification = Image Size/Actual Size
• Light Microscopes uses a beam of light and focuses using a lense. The maximum resolution is 0.25 microns (or 250nm) and it's depth of field is shallow
• Electron microscopes use a beam of electrons and focuses using powerful magnets. It's maximum resolution is 0.25nm and the depth of field is greater than a light microscope (2D + 3D)
• The electron microscope has a higher resolving power because the wavelength of an electron is much smaller than that of visible light.
• Meristem cells are dividing cells that allow plants to regrow organs such as the xylem or phloem
• Embryonic stem cells are unspecialised cells that can differentiate into any type of cell/organelle
• Adult stem cells are cells that can differenciate into fewer types of cells, organelles
• Stem cell therapy could be used in medicine to help treat damage and diseases such as pneomonia. The benefits are that it treates blood and spinal cord disorders as well as brain damage and diabetes. The risks are that it can cause infections, tumours, organ damage and immune rejection
• Graft-host-disease only happenes when stem cells from another patient are rejected by the immune system via white blood cells