2.3-plant tissues,organs and systems

• What does epidermal tissue cover in a plant?

  The entire plant
• How does the waxy cuticle of epidermal tissue help the plant?

  It reduces water loss from the leaf surface
• What is a key feature of spongy mesophyll tissue?

  It has lots of air spaces
• Why are air spaces important in spongy mesophyll tissue?

  They allow gases to diffuse in and out
• What is a characteristic of palisade mesophyll tissue?

  It contains lots of chloroplasts
• How does the presence of chloroplasts in palisade mesophyll tissue benefit the plant?

  It allows photosynthesis to progress rapidly
• What is the structure of xylem tissue?

  Made up of dead cells forming a hollow tube
• How does the structure of xylem facilitate its function?

  It allows movement of water and minerals
• What role does lignin play in xylem tissue?

  It strengthens and waterproofs the vessel
• What are bordered pits in xylem tissue used for?

  Transporting minerals to specific places
• What type of cells make up phloem tissue?

  Elongated living cells
• What are sieve plates in phloem tissue used for?

  Connecting cells for cell sap movement
• Why do sieve tube cells have few organelles?

  To allow efficient transport of substances
• What tissues are found in the leaf organ?

  • Epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Xylem
  • Phloem
  • Guard cells
• How is meristem tissue adapted for its function?

  It consists of stem cells for growth
• What is the function of guard cells?

  Control opening and closing of stomata
• How do stomata contribute to plant function?

  They control gaseous exchange and water loss
• Why are there more stomata on the base of the leaf?

  To minimize water loss in cooler areas
• How do guard cells regulate stomata?

  They control their opening and closing
• What is translocation in plants?

  Movement of dissolved sugars from leaves
• How are root hair cells adapted for their function?

  They have a large surface area for absorption
• Why do root hair cells contain many mitochondria?

  To release energy for active transport
• What is transpiration in plants?

  Evaporation of water vapour from the plant
• How does transpiration occur?

  Water evaporates from the leaf via stomata
• What happens to water molecules during transpiration?

  They cohere, pulling more water up the xylem
• What creates a continuous transpiration stream?

  More water taken up from the soil
• How does humidity affect transpiration rate?

  Increasing humidity decreases transpiration rate
• Why does high humidity reduce transpiration?

  It lowers the water vapour concentration gradient
• How does temperature affect the rate of transpiration?

  Increasing temperature increases transpiration rate
• Why does higher temperature increase transpiration?

  It raises evaporation and diffusion rates
• How does wind speed affect transpiration rate?

  Increasing wind speed increases transpiration rate
• Why does increased air movement raise transpiration rate?

  It lowers water vapour concentration outside the leaf
• How does light intensity affect transpiration rate?

  Increasing light intensity increases transpiration rate
• Why does higher light intensity increase transpiration?

  It opens more stomata for evaporation