BIO-108: Quiz 2

• tolerance limit


  the limit to which an organism can withstand changes in its environment
• xerophytes (xeric environment)


  plants that live in water-deficient environments
• hydrophytes (hydric environment)


  plants that live in aquatic environments
• mesophytes (mesic environment)


  plants that live where water is in optimum amounts or where there is a moderate amount of water
• photosynthesis


  the utilization of sunlight as an energy source to produce food (complex organic molecules) within the plant
• autotrophs


  organisms that produce their own food through photosynthesis or chemosynthesis
• heterotrophs


  organisms that do not produce their own food and rely on others for food
• transpiration


  the process of excess water being removed from a plant through its leaves
• Two major functions of leaves:

  (1) They are the site of photosynthesis.

  (2) They remove excess water from the plant.
• What do leaves do?

  absorb the necessary gases (chiefly carbon dioxide) for the photosynthetic process and expel oxygen and water vapor
• epidermis


  a single layer of cells in thickness that is continuous over the top and bottom of a leaf and mediates exchanges (e.g., water loss, gas exchange, sunlight absorption, etc.) between a leaf and its environment
• cuticle


  a waxy layer that usually covers the epidermis and acts as a protective barrier
• guard cells


  components of the epidermis that occur in pairs that shrink and swell to open and close stomata to regulate transpiration and other solutes in a leaf
• stoma (stomata)


  a pore that separates guard cells and allows gas exchange between a leaf and the environment (CO2 in and O2 and water vapor out)
• mesophyll


  the tissue between the upper and lower epidermis that is photosynthetic in function
• chloroplasts


  the sites of food synthesizing through photosynthesis
• palisade mesophyll


  the layer closest to the upper epidermis that contains the majority of the chloroplasts and enables photosynthesis
• spongy mesophyll


  the layer closest to the lower epidermis that may contain many air spaces and loosely-arranged tissue and facilitate the exchanges of gases
• vascular (conducting) tissue


  
the tissue made up of veins that carries materials to and from the leaf
• xylem


  the type of vascular tissue that carries water throughout the plant
• phloem


  the type of vascular tissue that carries sugars and other organic molecules throughout the plant
• bundle sheath


  what holds the vascular tissues of a plant (the xylem and the phloem) together
• Characteristics of a hydrophyte:


  (1) Lives in aquatic environments

  (2) Generally contains many air chambers

  (3) Does not have a sophisticated vascular system or the need to conserve water

  (4) Has an epidermis with a thin cuticle
• Characteristics of a xerophyte:

  (1) Lives in dry environments

  (2) Usually has closed stomata when photosynthesis is not occurring

  (3) Has substantial supportive tissue to support the leaf and prevent water loss and water-storage tissue

  (4) Has a thick, waxy cuticle made of cutin, which is water-proofing
• Where are the stomata located on a hydrophyte?

  only the upper epidermis
• Where are the stomata located on a xerophyte?

  below the epidermis (recessed from the epidermis)
• Allen's Rule


  the rule that states that the extremities of animals (tails, ears, bills, etc.) are shorter on individuals in the cooler parts of their range than the warmer parts
• Bergmann's Rule


  the rule that states that members of a species possessing smaller-body size are found in the warmer parts of their range while larger members are found in the cooler parts of their range

  > appears true for homotherms (organisms that can regulate their body temperature) and poikilotherms (organisms that cannot regulate their body temperature)
• leaf diagram

  labeled:

  A) palisade mesophyll

  B) stoma

  C) upper epidermis

  D) stoma

  E) cuticle

  F) xylem

  G) phloem

  H) chloroplasts

  I) vein

  J) guard cell

  K) lower epidermis

  L) air space

  M) spongy mesophyll

  
• leaf diagram


  labeled:

  
• potamogeton


  > hydrophyte

  
• syringa


  > xerophyte

  
• basic leaf


  > xerophyte

  
• nymphaea


  > hydrophyte

  
• typha


  > hydrophyte

  
• pinus


  > xerophyte

  
• zea


  > hydrophyte

  
• ammophil


  > xerophyte

  
• myriophillum


  > hydrophyte

  
• yucca


  > xerophyte