Tissues and organs in plants

• The specialised cells in multicellular plants are organised into tissues and organs
• Plant organs include: the leaf, root and stem
• Plant tissues include meristem, palisade mesophyll, spongy mesophyll
• The meristem tissue at the growing tips of roots and shoots is made up of rapidly dividing plant cells that grown and differentiate into all other cell types needed
• Plant organs include the leaf, root, and stem. Here are their functions:

  • Root: absorbs water and mineral ions
  • Leaf: carries out photosynthesis
  • Stem: supports leaf and flowers
• Epidermal tissues (upper and lower) cover the surfaces and protect them
• These cells often secrete a waxy substance that waterproofs the surface of the leaf
• The upperepidermis is transparent to allow light to pass through for photosynthesis
• The lower epidermis contains the stomata made up of two guard cells which can open and close to allow CO2 in and O2 out
• Palisade mesophyll tissue contains lots of chloroplasts, which carry out photosynthesis
• Spongy mesophyll tissue contains big air spaces and a large surface area to make the diffusion of gases easier
• Guard cells fill with/lose water to open or close the stomata, which enables gas exchange
• Xylem and phloem are the transport tissues in plants. They are found in vascular bundles in the roots, stems and leaves