Bio topic 6

• What does IAA control in plants?

  Cell elongation in shoots and roots
• What is the definition of a stimulus?

  A detectable change in the environment
• What are receptors in organisms?

  Cells that detect changes in the environment
• What is the term for plant responses to their surroundings?

  Tropism
• What are the two types of tropisms in plants?

  • Positive tropism: grows towards stimulus
  • Negative tropism: grows away from stimulus
• What are the two stimuli that affect tropisms?

  Light and gravity
• What is phototropism?

  Plant response to light
• How does IAA affect shoots and roots differently?

  It elongates shoots and inhibits roots
• What happens to IAA in the presence of light?

  It diffuses to the shady side of the plant
• What is gravitropism?

  Plant response to gravity
• What is a reflex?

  A rapid automatic response to danger
• What are the three types of neurons in a reflex arc?

  Sensory, relay, and motor neurons
• What are taxes and kinesis in organisms?

  • Taxes: Movement towards or away from a stimulus
  • Kinesis: Change in speed and direction of movement
• What is positive taxis?

  Movement towards a favorable stimulus
• How do earthworms respond to light?

  They move away from light
• What happens to an organism's kinesis response in harmful stimuli?

  It increases the rate of changing direction
• What do receptors do?

  Detect changes in the environment
• What are pacinian corpuscles?

  Pressure receptors in the skin
• What type of channels do pacinian corpuscles have?

  Stretch-mediated sodium channels
• What do rod cells detect?

  Light in black and white
• What is the function of cone cells?

  Detect color in bright light
• What is the significance of the fovea?

  High concentration of cone cells for clarity
• What is myogenic muscle?

  Muscle that contracts without nervous input
• What is the role of the sinoatrial node?

  Sets the pace of the heart's contractions
• What is the function of the AV node?

  Relays electrical impulses to ventricles
• How does the heart contract?

  From the apex upwards to pump blood
• How does the nervous system influence heart rate?

  It controls the speed of depolarization waves
• What part of the brain controls heart rate?

  Medulla oblongata
• What is the autonomic nervous system?

  Controls involuntary bodily functions
• What are the two parts of the autonomic nervous system?

  Sympathetic and parasympathetic
• What does the sympathetic nervous system do?

  Increases heart rate during stress
• What does the parasympathetic nervous system do?

  Decreases heart rate during rest
• How does the heart's contraction process benefit blood flow?

  Ensures efficient blood ejection from ventricles
• What happens after the cardiac muscle repolarizes?

  The muscle relaxes and the cycle repeats
• What initiates the cardiac cycle?

  Release of depolarization from the SA node
• Why is the delay in ventricular contraction advantageous?

  Allows atria to fully empty into ventricles
• What is the role of the bundle of His?

  Conducts impulses to the ventricles
• What do Purkinje fibers do?

  Spread electrical impulses throughout ventricles
• What is the function of the cardiac cycle?

  Regulates heart contractions and blood flow
• How does the heart ensure efficient blood flow?

  By contracting from the apex upwards