SB6e- Plant adaptions

• The structure of a leaf is adapted for photosynthesis and gas exchange
• What are the leaf adaptions?

  • Has a waxy cuticle (which is transparent to prevent water loss)
  • The upper epidermis is transparent to let light through for photosynthetic cells
  • mesophyll cells are packed with chloroplasts for maximum photosynthesis
  • spongy mesophyll has air gaps between cells so gas can diffuse through
  • xylem cells bring water for photosynthesis
  • phloem removes the sugars made in photosynthesis
  • has a stomata in the lower epidermis which allows co2 from air into the leaf and allow O2 from photosynthesis to leave the lead
  • guard cells open and close the stomata
• Explain why the stomata is usually open in the day time and closed at night

  Leaves keep the stomata open in the day time to allow carbon dioxide into the leaf for photosynthesis. At night, the stomata are usually closed because photosynthesis does not occur unless light is available. Closing the stomata reduces water loss.
• Where can water be lost?

  Water can be lost on the top and lower epidermis, but is mostly lost on the stoma.
• How are plants adapted to live in hot, dry conditions?

  • small leaves
  • thick waxy cuticle to reduce water loss
  • shallow but wide roots
  • thick stem
• How are plants adapted for tropical conditions?

  • large leaves to take in a lot of light
  • leaves with a drip tips so water runs off them
• How are plants adapted to with waterlogged soil?

  • spongy tissue in their roots to store oxygen
  • Fine surface roots that take in oxygen at the water surface
• What is the order of the leaf tissues from top to bottom?

  Upper epidermis, Palisade mesophyll, Spongy mesophyll, Lower epidermis