2.3.1 Plant Tissues

• What is epidermal tissue?

  The outermost layer of plants.
• What is palisade mesophyll tissue?

  The tissue where photosynthesis occurs.
• What is spongy mesophyll tissue?

  The tissue where gas exchange happens.
• What is the xylem?

  Plant tissue that transports water and nutrients from the roots to the rest of the plant.
• What is the phloem?

  Plant tissue responsible for transporting sugars and other nutrients from the leaves to other parts of the plant.
• What is meristem tissue?

  The tissue responsible for growth and development.
• What are some examples of plant organs?

  Roots, stems, leaves, and flowers.
• What are plant organs made up of?

  Tissues.
• What are the epidermal tissues covered in and why?

  A waxy cuticle which helps to reduce water loss and protect the plant.
• Why is the upper epidermis transparent?

  So that light can pass through it to the palisade layer.
• What does the palisade layer contain lots of?

  Chloroplasts.
• Why are chloroplasts located in the palisade layer?

  It is near the top therefore they will get the most light.
• What do the air spaces in the spongy mesophyll increase?

  The rate of diffusion of gases.
• What is the lower epidermis full of and why?

  The lower epidermis is full of stomata, which are small openings that allow for gas exchange and transpiration in plants.
• What are stomata controlled by?

  Guard cells.
• The four levels of plant organisation are..?

  cells ➔ tissues ➔ organs ➔ organ systems
• A leaf is an example of what?

  An organ.
• What do the roots, stem and leaves make up together?

  An organ system.
• What is a guard cell an example of?

  A cell.
• What is the palisade mesophyll layer an example of?

  A tissue.
• Which part of the leaf is indicated on the diagram?

  The waxy cuticle.

  
• Which structure is highlighted on the diagram?

  The palisade mesophyll layer.

  
• Which structure is highlighted on the diagram?

  The spongy mesophyll layer.

  
• Which structure is highlighted on the diagram?

  The lower epidermis.

  
• What name is given to the cells highlighted on the diagram?

  Guard cells.

  
• What name is given to the openings indicated on the diagram?

  Stomata.

  
• Which structures help to minimise water loss?

  Guard cells and the waxy cuticle.
• What happens if there is plenty of water in the leaf?

  If there is plenty of water in the leaf, guard cells become turgid, which opens the stomata. This allows carbon dioxide to enter the leaf, but also allows water to escape. 
• At night time, when photosynthesis can't take place, are the stomata normally open or closed? 

  Closed.