Gas exchange in plants

• What are flowering plants called?

  Angiosperms
• What are the two main groups of angiosperms?

  Dicotyledons and monocotyledons
• What is the main organ for gas exchange in plants?

  The leaf
• What is the function of the cuticle in plants?

  Reduces water loss
• What is the role of the upper and lower epidermis in leaves?

  Protection and light penetration
• What is the function of palisade mesophyll?

  Maximizes light absorption
• What is the role of spongy mesophyll in leaves?

  Gas exchange for respiration and photosynthesis
• What does xylem transport?

  Water and ions
• What does phloem transport?

  Carbon compounds
• What is the function of bundle sheath cells?

  Support and protection to vascular tissue
• What are stomatal pores used for?

  Gas exchange with the environment
• How do guard cells function in relation to stomata?

  Control opening and closing of stomata
• What happens to stomata during the day?

  They open for photosynthesis
• What occurs at night regarding stomata?

  Only respiration takes place
• What is a consequence of open stomata during the day?

  Increased water loss due to evaporation
• What are stomata?

  Gaps between guard cells
• What is the structure of guard cells?

  Different from other epidermal cells
• What do guard cells contain?

  Chloroplasts
• What is unique about the cell wall of guard cells?

  Thicker inner wall than outer wall
• What is one mechanism of stomatal opening?

  Photosynthesis in guard cells produces ATP
• What happens to potassium ions during stomatal opening?

  They are actively transported into guard cells
• What is the effect of increased K+ and malate ions in guard cells?

  Lower water potential in guard cells
• What causes water to move into guard cells?

  Osmosis due to lower water potential
• How do guard cells expand?

  Absorb water in thinner cell wall areas
• What happens when guard cells expand?

  A pore opens between the cells
• How are stomata arranged in dicots?

  Randomly, reflecting vascular bundles
• How are stomata arranged in monocots?

  In parallel lines, reflecting vascular bundles
• What are the differences in stomatal opening mechanisms between dicots and monocots?

  • Stomata in dicots open randomly
  • Stomata in monocots open in parallel lines
  • Guard cell wall thickening differs
• What do plants need to generate energy constantly?

  Plants need to respire all the time
• What do chloroplasts in plant cells do?

  Chloroplasts are capable of photosynthesis
• How is carbon dioxide managed in plants?

  Most diffuses into leaves and out into air
• What happens to the oxygen produced by photosynthesis?

  Most diffuses out of the plant
• When do plants respire?

  Plants respire only at night
• Where does gas exchange primarily take place in plants?

  Gas exchange takes place at the leaves
• What is the gas exchange pattern during the day and night?

  • Day: CO₂ in, O₂ out (photosynthesis)
  • Night: O₂ in, CO₂ out (respiration)
• What is the relationship between the rates of photosynthesis and respiration?

  Photosynthesis rate is faster than respiration
• What is the net gas exchange during the day?

  Net exchange is oxygen
• What happens at night regarding gas exchange?

  No oxygen is produced, excess CO₂ accumulates
• What are the main structures involved in gas exchange in leaves?

  • Cuticle
  • Upper epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Lower epidermis
  • Stomata
  • Guard cells
• How do gases diffuse through the stomata?

  Gases diffuse down a concentration gradient