✧ chp 1 - transport in plants

• porins are proteins that form huge pores in the outer membrane of plastids, mitochondria and some bacteria. They allow molecules upto the size of small proteins to pass through it.
• water potential is the relative tendency of of 1 mole of water compared to water potential of pure water.
• water potential of pure water is 1.
• osmosis is movement of water molecules from a higher concentration to a lower concentration through a semipermeable membrane.
• diffusion is movement of solvent/solute molecules from an area of low concentration to an area of high concentration.
• apoplast is the movement of molecules without crossing any membranes.

  symplast is the movement of molecules by crossing few membranes.
• guttation is the loss of water in the form of water droplets and it is a fast process.

  transpiration is the loss of water in the form of water vapour and it is a slow process.
• ascent of sap

  cohesion - mutual attraction between the water molecules.

  adhesion - attraction of water molecules to the surface of trachids.
• source is the part of the plant where food is is prepared or collected from. eg - leaves or stems.
• sink is the part of a plant where food is stored or needed. eg - flower buds.
• transpiration can occur at night. eg - bryophyllum.
• during opening of stomata, pH increases due to efflux of H+

  during closing, pH decreases.
• ABA or abscisic acid helps in driving out K+ ions during closing of stomata under water stress conditions.
• pea seeds are proteinaceous seeds and have more imbibing capacity than starchy wheat seeds.

  so, proteins have more imbibing capacity than carbohydrates.