Cells and control

• Mass


  Measured in kg
• Length


  Measured in cm
• Head circumference


  Measured in cm
• Monitoring growth of babies


  1. Measure mass

  2. Measure length

  3. Measure head circumference
• Percentile growth charts


  • Used to monitor growth of babies in all three measurements
• Stem cells


  Undifferentiated cells capable of cell division
• Meristem


  A type of tissue found in plants, consisting of undifferentiated cells capable of cell division
• Cells in the meristem


  Can develop into all other tissues and organs in plants
• Embryonic Stem cells


  Cells derived from the early stages of an embryo which are capable of differentiating into any type of body cell
• Embryonic stem cells are used for differentiating into any type of body cell in the embryo
• Adult stem cells

  undifferentiated cells found through the boy after development.
• Adult stem cells

  Multiply by cell division to replenish dying cells and regenerate damaged tissue
• Receptors


  • Detect different stimuli
  • Biological transducers that convert energy into electrical impulses
• Nervous system


  Carries electrical impulses

  Carry information around the body
• Parts of the nervous system

  • Receptors
  • Sensory neurons
  • CNS
  • motor neurons
  • effectors
• CNS


  Brain and spinal cord, receives, processes and organizes stimuli from sensory neurons to motor neurons
• Impulses are sent from the CNS to effectors
• Impulses are electrical
• Reflex arc

  1. Danger is detected by receptors
  2. impulse sent from receptors down to sensory neurons to CNS
  3. Impulse is sent along relay neuron into CNS, motor neuron and effector
  4. Effectors produce a quick response to prevent damage - involuntary movement
• Synapses

  1. Electrical impulse travels along first neuron to the end.
  2. This causes the release of chemicals called neurotransmitters
  3. Neurotransmitters diffuse across the gap and bind receptors to second neuron

  4. Sets off an electrical impulse
• Neuron structure

  • long axon to carry impulse over long distances
  • Axon is a fatty sheath to help impulse travel quickly
  • Branched at both ends to easily pass signals between them
• Photosynthesis equation

  carbon+water =glucose + oxygen

  dioxide
• Limiting factors for photosynthesis

  • CO2 concentration
  • Temperature
  • light