Plant Cell Organisation

• What are the different levels of organization in plants?

  Cells, tissues, organs, organ systems
• What is the function of the organ system formed by leaves, stems, and roots?

  Transport of substances around the plant
• What is the structure of a leaf compared to?

  A cross-section sliced from top to bottom
• What is the primary function of leaves?

  Photosynthesis
• What do leaves require for photosynthesis?

  Carbon dioxide and water
• How is water transported to the leaves?

  By roots and xylem
• How does carbon dioxide enter the leaf?

  Through stomata from the outside air
• What are stomata?

  Little holes for gas exchange
• Where are stomata primarily located?

  On the lower epidermis of leaves
• What is the spongy mesophyll tissue's role in leaves?

  Facilitates gas diffusion through air gaps
• Where does most photosynthesis occur in the leaf?

  In the palisade mesophyll layer
• What do palisade cells contain that aids photosynthesis?

  Chloroplasts
• Why is the upper epidermis of the leaf almost transparent?

  To allow sunlight to reach chloroplasts
• How are sugars transported in the plant after photosynthesis?

  By phloem
• What is the main problem leaves face regarding water?

  Water loss
• How does the waxy cuticle help the leaf?

  It prevents water loss
• What happens to stomata when the plant has plenty of water?

  They open wider for gas exchange
• What occurs to guard cells when the plant is short of water?

  They become flaccid, closing the stomata
• Why do guard cells close at night?

  To conserve water when photosynthesis isn't occurring
• Why are most stomata located on the underside of leaves?

  To reduce water evaporation in shade
• What is meristem tissue in plants?

  Plant form of stem cells
• Where is meristem tissue found?

  At the growing tips of roots and shoots
• What can meristem tissue differentiate into?

  Different cell types for plant growth
• What are the main functions of leaves in plants?

  • Photosynthesis: converting light energy into sugars
  • Gas exchange: taking in carbon dioxide and releasing oxygen
  • Water regulation: minimizing water loss through stomata
• How do guard cells regulate stomata to balance gas exchange and water loss?

  • Guard cells swell (turgid) when water is abundant, opening stomata
  • Guard cells shrink (flaccid) when water is scarce, closing stomata
  • Sensitive to light, closing at night when photosynthesis stops
• What adaptations do leaves have to minimize water loss?

  • Waxy cuticle on the upper surface
  • Stomata primarily on the lower epidermis
  • Guard cells that regulate stomatal opening
• What is the role of xylem and phloem in plants?

  • Xylem: transports water from roots to leaves
  • Phloem: transports sugars from leaves to other parts