responses to environment

• What are plant growth factors?

  Chemicals that influence plant growth
• What is the key hormone discussed in the video?

  Auxin
• What is indole acetic acid abbreviated as?

  IAA
• What effect does high concentrations of IAA have in shoots?

  It causes cell elongation
• What effect does high concentrations of IAA have in roots?

  It inhibits cell elongation
• Where is IAA produced in plants?

  In the tips of roots and shoots
• What is phototropism?

  Response of plants to light
• Why do plants need light?

  For photosynthesis and energy production
• What happens to IAA when light is evenly distributed?

  It diffuses downwards evenly
• What is the result of unilateral light on IAA distribution?

  IAA diffuses to the shaded side
• What causes the plant to bend towards the light?

  Cell elongation on the shaded side
• What is negative phototropism?

  Growth away from the light stimulus
• What is the role of roots in relation to light?

  To grow away from the light source
• What is gravitropism?

  Response of plants to gravity
• What happens to IAA in shoots under gravity?

  It diffuses to the lower side
• What is the effect of IAA on shoot cells in a vertical plant?

  Cells at the bottom elongate
• What would happen if a plant is laid on its side in a dark room?

  IAA diffuses to the lower side
• What is the result of IAA in roots under gravity?

  It causes roots to bend towards gravity
• What is positive gravitropism?

  Growth towards the gravity stimulus
• What are the three key stimuli that affect plant growth?

  • Light
  • Gravity
  • Water
• What are the effects of IAA in shoots and roots?

  In shoots:

  • High IAA concentration causes cell elongation

  
  

  In roots:

  • High IAA concentration inhibits cell elongation
• How does IAA affect phototropism and gravitropism?

  Phototropism:

  • IAA diffuses to shaded side, causing bending towards light

  
  

  Gravitropism:

  • IAA diffuses to lower side, causing bending towards gravity
• What is the significance of IAA in plant growth?

  • Regulates cell elongation
  • Influences plant responses to stimuli
  • Essential for proper growth direction
• Who is the presenter of the A Level Biology video?

  Miss Estrich
• What topic does this video focus on?

  Taxes and kinesis
• What is a stimulus?

  A detectable change in the environment
• What can stimuli include?

  Light, pressure, moisture
• What are the cells that detect changes called?

  Receptors
• How do organisms increase their chances of survival?

  By responding to stimuli
• What are the responses being discussed in the video?

  • Taxes
  • Kinesis
• What is a taxis response?

  Movement towards or away from a stimulus
• What is positive taxes?

  Movement towards a favorable stimulus
• What is negative taxes?

  Movement away from an unfavorable stimulus
• What type of taxes do earthworms exhibit towards light?

  Negative taxes
• Why do earthworms move away from light?

  To avoid dehydration and predators
• What type of taxes do bacteria exhibit?

  Positive chemotaxis
• Why do bacteria move towards certain chemicals?

  To avoid the immune response
• What is kinesis?

  Change in speed and direction of movement
• How does kinesis differ from taxis?

  Kinesis involves speed and direction changes
• What happens when an organism moves from beneficial to less desirable stimuli in kinesis?

  It increases the rate of changing direction