Plant tissues

• Placed at the top of the leaf, the epidermal tissue is a single cell thick and protects the leaf. It has a waterproof waxy surface to prevent water loss.
• What are palisade cells? Describe them.

  They are of a shape that allows them to be closely packed together. They also have lots of chloroplasts which maximises the amount of light energy for photosynthesis.
• The spongy mesophyll is the middle layer of cells, how are they adapted for their use?

  They are loosely packed with a large surface area and lots of air gaps so gas exchange can happen more easily especially through the leaf and to the stomata.
• At the centre of the leaf there is Xylem and phloem tissue (the transport tissues).
• What does xylem tissue transport?

  water and minerals
• What does phloem tissues transport?

  sugar
• Give two adaptations of xylem tissue for transporting water and mineral ions.

  Xylem tissue is made of hollow tubes with no cell contents so the water can be transported freely.

  Walls are strengthened by lignin so the tubes are less likely to collapse
• Name the two elements that are at the bottom of the leaf.

  Guard cells and stoma
• What are guard cells?


  They open and close the stomata
• Gas diffuses through the stoma, which are basically pores which close during the night
• What is meristem tissue and where is it found?

  It is made of undifferentiated cells the divide repeatedly to make other cells, allowing the plant to grow. They are found in the growing tips of the roots and shoots.
• Explain why palisade mesophyll is the tissue that carries out most photosynthesis.

  It contains the most chlorophyll to maximise the photosynthesis. It is also at the top of the leaf so therefore is able to capture the most light energy. Because of its shape, many cells can be packed into small spaces.