Plant tissue

• What are the main types of plant tissues mentioned?

  Epidermal tissues, palisade mesophyll, spongy mesophyll, xylem, phloem, and meristem tissue
• How are the structures of plant tissues related to their functions?


  The structures are specifically adapted to perform their respective functions
• What is the function of the waxy cuticle on a leaf?


  • Protective layer on top of the leaf
  • Prevents water from evaporating
• What is the role of the upper epidermis in a leaf?


  • Thin and transparent
  • Allows light to enter the palisade mesophyll layer underneath
• What is the function of palisade mesophyll cells?


  • Column-shaped cells
  • Tightly packed with chloroplasts
  • Absorb more light to maximize photosynthesis
• What is the role of spongy mesophyll in a leaf?


  • Contains internal air spaces
  • Increases surface area to volume ratio for gas diffusion
• What do guard cells do?


  • Absorb and lose water
  • Open and close the stomata for gas exchange
• What is the function of stomata in a leaf?


  • Site of gas exchange
  • Opens during the day and closes at night
  • Evaporation of water occurs here
• Where are stomata typically found in plants?


  In much greater concentration on the underside of the leaf
• What is the role of vascular bundles in a leaf?


  • Contains xylem and phloem
  • Transports substances to and from the leaf
• What is the function of xylem in plants?


  • Transports water into the leaf
  • Used in photosynthesis and transpiration
• What does phloem transport in plants?


  • Transports sucrose and amino acids around the plant
• What adaptations does a leaf have for photosynthesis?


  • Large surface area for gas diffusion
  • Thin structure for quick diffusion
  • Chlorophyll for light absorption
  • Network of veins for transport
  • Stomata for gas exchange
  • Thin epidermis for light penetration
  • Waxy cuticle for protection
  • Palisade layer maximizes light absorption
  • Air spaces in spongy layer for gas diffusion
• How does the structure of a leaf maximize diffusion of carbon dioxide?


  The structure allows air to circulate within it, maximizing diffusion to chloroplasts
• What are the main plant organs involved in transport?

  • Roots
  • Stem
  • Leaves
• What are the functions of xylem and phloem?


  • Xylem: transports water and minerals from roots to leaves
  • Phloem: transports food materials from leaves to other parts of the plant
• What is the composition of xylem vessels?


  Xylem vessels are composed of hollow tubes strengthened by lignin
• How do phloem vessels differ from xylem vessels?


  Phloem vessels are made of living cells, while xylem vessels are made of dead cells
• What is the role of root hair cells?


  • Adapted for efficient uptake of water by osmosis
  • Absorb mineral ions by active transport
  • Increase surface area for absorption
• How does water enter root hair cells?


  Water enters by osmosis due to higher water potential in soil water
• What is the pathway of water into a root?

  • Root hair cell
  • Root cortex cells
  • Xylem
  • Leaf mesophyll cells
• Where is xylem located in relation to phloem in plant cross-sections?


  Xylem is always on the inside, and phloem is always on the outside
• What is transpiration?


  • Loss of water vapor from plant leaves
  • Occurs by evaporation at mesophyll cell surfaces
  • Followed by diffusion through stomata
• How is xylem adapted for its function?


  • Lignin strengthens cell walls
  • Cells die to form hollow tubes
  • Allows continuous water transport
• In which direction does water move in xylem?


  Water moves only in one direction, from roots to leaves
• What factors affect the rate of transpiration?


  • Air movement
  • Humidity
  • Temperature
  • Light intensity

  
• How can transpiration rates be investigated?


  • Cut a shoot underwater
  • Set up airtight apparatus
  • Dry leaves
  • Record air bubble movement
  • Change one environmental factor at a time
• What is the role of guard cells in transpiration?


  • Control the opening and closing of stomata
  • Regulate gas exchange and water loss
• How do guard cells respond to water availability?


  • Become turgid when water is high, opening stomata
  • Become flaccid when water is low, closing stomata
• Where are stomata predominantly located?


  • On the underside of the leaf
  • Cooler and shaded areas to reduce transpiration
• What is translocation in plants?


  • Transport of soluble products of photosynthesis (sugars and amino acids)
  • Occurs in phloem tubes
• How do phloem cells facilitate transport?


  • Made of living, elongated cells
  • Joined end to end with sieve plates for easy flow
• How does translocation change with the seasons?


  • In winter: transport from storage organs to other parts
  • In spring: storage organs are sources for growing areas
  • In summer: leaves become sources, roots become sinks
• What are the key differences between xylem and phloem tissue?


  • Xylem: transports water and minerals, made of dead cells
  • Phloem: transports food, made of living cells