Plant tissues: Organisation: Biology: GCSE (9:1)

• Epidermal tissue


  Tissue that covers and protects the plant

  
• Waxy cuticle


  A layer on the surface of the leaf which protects the plant and reduces water loss, thicker on the upper surface

  
• Palisade mesophyll


  Photosynthetic tissue below the epidermis in a leaf, palisade cells contain high concentrations of chlorophyll and high quantities of chloroplasts for photosynthesis

  
• Spongy mesophyll

  Layer of tissue found beneath the palisade mesophyll that is packed loosely for efficient gas exchange of carbon dioxide and oxygen

  
• Xylem


  Non-living vascular tissue that carries water and dissolved minerals from the roots of a plant to its leaves, the xylem is hollow and nearby cells are lignified or dead so water can move continuously

  
• Lignin


  A chemical that provides support to xylem cells and prevents the unwanted movement of water into nearby cells

  
• Phloem


  Living and elongated vascular tissue that carries sugar and organic substances throughout a plant, the phloem has sieve plates that act as pores to allow molecules to diffuse between cells

  
• Meristem


  Undifferentiated plant tissue from which new cells are formed, found in the shoots and roots

  
• Shoots

  The aerial portion of a plant body consisting of stems, leaves and flowers

  
• Roots


  Underground plant organs that absorb water and minerals

  
• Stomata


  Small openings on the underside of a leaf through which oxygen, carbon dioxide and water can move

  
• Guard cells


  Pairs of cells that surround the stomata and control their opening and closing to optimise gas exchange and reduce water loss

  
• Root hair cell

  Cells that absorb water and mineral ions from the soil, via diffusion, osmosis or active transport using structures with a large surface area

  
• Transpiration


  The process of the movement of water through a plant and the loss of water from a plant through its leaves

  
• Factors affecting transpiration

  Changing temperature, humidity, air movement and light intensity
• Effect of factors affecting transpiration

  Light, wind and heat will increase the rate of transpiration, humidity will decrease the rate of transpiration
• Rate of transpiration

  The rate of water loss from a plant
• Potometer


  A device used for measuring the rate of water uptake of a plant due to photosynthesis and transpiration, a bubble of water will move along the potometer to indicate the rate of transpiration

  
• Translocation

  The transportation of sugars and amino acids around the plant via phloem tissue, sugars are prone to translocation as they are made in the leaves and needs to be transported around the plant