cells and control

• Mitosis


  A type of cell division which produces two identical diploid daughter cells
• Specialised cells


  Formed when stem cells differentiate
• Nervous system

  • Enables humans to react to their surroundings and to coordinate their behaviour
  • Comprises millions of neurones
  • Uses electrical impulses to communicate very quickly
• Understanding how to approach exam questions helps to boost exam performance
• Question types will include multiple choice, structured, mathematical and practical questions
• Mitosis


  A specific type of cell division that results in two identical diploid daughter cells
• Metaphase


  The third stage of mitosis, during which the chromosomes align in the center of the cell
• Anaphase


  The fourth stage of mitosis, during which the sister chromatids separate and move towards opposite ends of the cell
• Telophase


  The fifth stage of mitosis, during which the chromosomes reach the opposite ends of the cell and begin to decondense
• Prophase


  The first stage of mitosis, during which the chromosomes condense and become visible
• Cytokinesis


  The process of dividing the cytoplasm and organelles to create two separate daughter cells
• 1. Read the question carefully

  - Look for keywords such as "analyze," "compare," or "contrast" to understand what the question is asking for. - Make sure you understand what is being asked before you start writing your answer.
• 2. Identify the key concepts


  - Break down the question into its component parts. - Identify the key concepts or terms that you need to address in your answer.
• Mitosis

  1. Interphase

  2. Prophase

  3. Metaphase

  4. Anaphase

  5. Telophase

  6. Cytokinesis
• Interphase


  Cell replicates DNA and makes more organelles like mitochondria and ribosomes
• Prophase


  Nucleus breaks down, spindle fibers appear
• Metaphase


  Spindle fibers pull chromosomes to the middle of the cell
• Anaphase


  Spindle fibers pull chromatids to each end of the cell
• Telophase


  Nucleus reforms
• Cytokinesis


  Cytoplasm splits creating two daughter cells
• Mitosis always produces identical cells
• Mistakes in DNA copying during mitosis


  Can cause uncontrolled cell division and tumors
• Plant cell growth


  • Cells elongate and divide at the roots
• Animal cell growth


  • Cells typically just divide
• Percentile charts


  Used to measure growth compared to other organisms
• Stem cells


  Unspecialized cells that can differentiate into specialized cells
• Types of stem cells

  • Embryonic
  • Adult
  • Plant
• Embryonic stem cells


  Can turn into any type of specialized cell
• Adult stem cells

  Can only turn into certain types of specialized cells
• Plant stem cells


  Can turn into any type of specialized cell
• Stem cells could continue to divide and create a tumor or be rejected by the immune system
• Nervous system


  Sends and receives information
• Parts of the nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system (all other neurons)
• Types of nerve cells

  • Sensory neurons
  • Motor neurons
  • Relay neurons
• Myelin sheath


  Insulates neurons and speeds up impulses
• Nerve impulse


  1. Stimulus

  2. Receptor

  3. Sensory neuron

  4. Relay neuron

  5. Motor neuron

  6. Effector (muscle or gland)

  7. Response
• Synapse


  Small gap between neurons where neurotransmitters are released
• Reflex arc


  Unconscious process that allows the body to quickly react to dangerous situations