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Chapter 14: Development and Morphogenesis (Environmental Complexity…

- - - - Detrimental
        
        When a root grows against a stone
        
        When a branch rubs against another branch
      - Beneficial
        
        After a tendril touches an object, it grows around the object and uses it as support
        
        When a fly touches the sensitive trigger hairs on a Venus' flytrap, the trap closes, catching and holding the insect during digestion
      - Each plant responds in a distinct way to touch
    - - Apples are adapted to cold weather
        
        Vernalization: Causes plants to switch to a state in which they can sense and respond to a stimulus that induces flower formation
        
        Cold temps are required for normal flowering of biennial and many perennial plants
        
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        Low temps are required to induce sleep dormancy in temperate trees and shrubs
        
        Cool temps are required to break dormancy of many seeds
    - - Can cause weight stress
      - Force it exerts on an organ does change as the weight supported by the organ changes
      - Ex) The pedicel of an apple flower supports almost no weight, but the same pedicel must later support the weight of a fully grown fruit
    - - Sometimes grow more rapidly due to favorable environments
      - Production of new leaves if water stress continues
      - Roots grow in all directions pertaining to water
    - - Direction (the gradient of light)
        
        Allows a plant to grow or to orient its leaves towards a region of light
        
        Increases the light available for photosynthesis
      - Duration (length of day)
        
        Provides information about the time of year
        
        Infallible indicator of season
    - - Larger animals can cause damage to plants
      - Physical damage
        
        Changes the plant's leaf and/or stem color
        
        Causes the plant to wilt and/or droop
        
        Damaged leaves or stems
      - Bacteria, fungi, and insects attack plants chemically with toxins and digestive
      - Chemical damage
        
        Bacteria or enzymes attack plants with digestive enzymes
        
        Can alter the plant's cell membranes
        
        Produces fragments of cellulose and hemicellulose
- - - - Is a stereotyped nongrowth response that is not oriented with regard to the stimulus
      - Sepals and petals spread open when the sun rises in diurnal species (active during daylight)
      - Sepals and petals spread open when the sun rises in nocturnal species (active at night).
      - Photosynastic - opening and closing always happen in the same manner, even if light is given artificially from the west, north, or south, above, or below
      - Sleep movements causes the blade elevated in the day, lowered at night
    - - The induction to form flowers
      - The induction of dormant seeds to germinate
      - Causes a change in the "quality" of the plant; changes in metabolism of the tissue or even the entire plant
      - The induction of buds to become dormant
      - Includes formation of extra bark where branches rub against an object
    - - Ex) Growth toward a bright light is a phototropic response
        
        Growth at an angle - plagiotropism
        
        Is a growth response oriented with regard to the stimulus
        
        Positive - growth toward a stimulus
        
        Negative - growth away from a stimulus
        
        Positive chemotropism - growing along the style to the ovary by following a gradient of chemicals
        
        Gravitropic - growing down in response to gravity
        
        Differential growth - one side of the tendril must grow more than the other
        
        Growth on the contact side slowing
        
        Growth on the opposite side accelerating
        
        Or both
    - - Mosses, ferns, cycads, and maidenhair tree
      - Is a response in which a cell swims toward (positive taxis) or away from (negative taxis) a stimulus
- - - - Signal Amplification Cascades
        
        Chemical Messengers
        
        Hormones
        
        Gibberellins
        
        Abscisic Acid
        
        Cytokinins
        
        Ethylene
        
        Auxins
        
        Other Hormones
        
        Jasmonic Acid
        
        Salicylic Acid
        
        Brassinosteroids
        
        Perception and Transduction
        
        Statoliths
        
        Presentation Time - is the length of time the stimulus must be present for the perceptive cells to react and complete transduction
        
        Statocytes
        
        Threshold - refers to the level of stimulus that must be present during the presentation time to cause perception and transduction #
        
        2 alternatives
        
        All-or-Nothing Response
        
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        Dosage-Dependent Responses
        
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