Water uptake by the roots

• why must terrestrial plants conserve water?

  as they risk dehydration
• how is water taken in through the roots?

  water is taken in from the soil through the roots and transported to the leaves, where it maintains turgidity, and is a reactant in photosynthesis
• by what process is water lost through the stomata?

  transpiration
• what must the loss of water through transpiration be offset by?

  by constant replacement from the soil
• what is the region of greatest water uptake in plants?

  the root hair zone, where the surface area of the root is enormously increased by the presence of root hairs and water uptake is enhanced by their thin cell walls
• what does soil water contain?

  a very dilute solution of mineral salts and has a high water potential
• what do the vacuole and cytoplasm of the root hair cells contain?

  they contain a concentrated solution of solutes and have a lower, more negative, water potential
• how does water pass into the root hair cells?

  by osmosis, down a water potential gradient
• how much water lost by a plant is by evaporation through the leaf epidermis?

  about 5%
• what prevents more water evaporating from leaves?

  the cuticle
• what is this an image of?

  a diagram of the absorption of water by root hair cell