Plant Tissue

• Plant organisation includes the stem, root and leaves which form an organ system that transports substances into, around and out of a plant.
• Plant tissues, such as xylem and phloem, are responsible for transport in plants.
• Transpiration is a process where water is lost from leaves by evaporation through the stomata.
• Environmental factors, such as temperature and humidity, can affect water uptake by plants.
• The structure of a leaf is related to its functions in photosynthesis.
• The palisade mesophyll is a plant tissue containing closely packed cells in the upper layer of a leaf, adapted to absorb light efficiently.
• The spongy mesophyll is the plant tissue in a leaf which has loosely packed cells and air spaces between them to allow gas exchange.
• Gas exchange in plants occurs through the spongy mesophyll, where gases diffuse into the cells and out of them.
• Gases diffuse into the spongy mesophyll cells during photosynthesis, and out of them when the plant is not photosynthesising.
• Closing the stomata helps to control water loss.
• Stomata are small pores on the leaves of plants that allow gas exchange.