B4 - organising plants

• What are the epidermal tissues?

  They cover the surfaces and protect the plants - often waxy
• what is the palisade mesophyll?

  contains lots of chloroplasts for photosynthesis
• what is the spongy mesophyll?

  contains some chloroplasts for photosynthesis but also has big air spaces for easy diffusion of gas
• what is the xylem?

  transports water and mineral ions rom the soil around the plant to the stem and the leaves
• what is the phloem?


  transports food around the plant - the movement of dissolved sugars from the leaves to the rest of the plant is called translocation
• what are the plant organs?

  leaves, stems and roots
• what is the job of the leaf?

  to carry out photosynthesis
• what is the job of the stem?

  supports leaves and flowers
• what is the job of the roots?

  take up minerals from the soil
• Water in lost all over the plant
• wafter in the leaves evaporates through the stomata which cover the bottoms of the leaves. Guard cells open and close the stomata to reduce the evaporation of water from the leaves. This loos of water vapour is known as transpiration
• What are the factors affecting transpiration?

  Temperature, humidity, the amount of air movements and light intensity
• Anything that increases the rate of photosynthesis affects the rate of transpiration
• to reduce water loss plants have certain adaptions. these include a waxy, waterproof layer to prevent the water from being evaporated.
• stomata are mostly found on the underside of the leaf to protect them from direct light energy from the sun
• if too much water is lost the plant mat wilt or the stomata will close and stop photosynthesis