05 01 2014 Nutrition in all organisms involves four main steps Acquisition of nutrients Digestion if required Distribution of nutrients throughout the body Synthesis of molecules for the organism s body Digestion does not usually occur in plants When the water potential inside the cell is lower than the water potential outside the cell water moves in osmosis Increase of pressure will result in an increase in water potential Adding solute will lower water potential Translocation requires energy Acquisition of minerals 1 Active transport into root hairs 2 Diffusion to endodermis 3 Active transport into cell or extracellular cyclinder 4 Diffusion into xylem Casparian Strip leak proofs the vascular cylinder Water moves from areas of high water potential to low water potential Acquisition of water When minerals move through the cells they create a lower water potential because less water is flowing through the plant This brings about a need for water flow Transport of water and minerals Water and dissolved minerals move from roots to stems and leaves by a process known as bulk flow where water and minerals move together How does water move up a plant Cohesion Water molecules stick together to resist being pulled apart Tension Water is pulled up the xylem like a chain The process of transpiration evaporation of water from leaves provides the driving force for water to move up the plant The rate of transpiration is controlled by the opening and closing of guard cells Stomata open when the guard cells swell with water and close when they shrink from water loss When potassium concentration is high water moves in When potassium concentration is low water moves out Important triggers for stomata 1 Light Open 2 Lack of CO2 Open 3 Water loss Close Root pressure causes plant guttation Transport of Sugars Sucrose moves from a source to a sink A Phloem flow is directed by sugar production and use B Any structure that makes sugar or takes sugar out of storage will be a source of phloem flow C Any structure that uses up sugar or puts sugar into storage will be a sink towards which phloem will flow D Fruits roots flowers and new leaves are all sinks Pressure Flow Theory Sugar enters companion cells via secondary active transport Sucrose diffuses into sieve tube elements Water enters sieve tubes by osmosis from xylem cells Fruit is a sucrose sink Sucrose is actively transported out of sieve tube elements into the cells of fruit lowering sugar level in that end of the system Water leaves these sieve tubes due to osmosis and follows the sugar into the fruit Bulk flow driven by hydrostatic pressure gradient The closest relative to the animals are protists in the clade known as opisthokonts Tissues are specialized cells with a common structure and function that are grouped together Organs are centers of bodily function which are usually made up of different tissues Organ systems are groups of two or more organs that function together to perform a common task Asymmetry a body plan that lacks symmetry Radial symmetry round body plan Animals have a top and bottom but no back front or left right Diplobplastic Bilateral symmetry body plan with a left side and a right side Triploblastic Top dorsal bottom ventral front head anterior and back tail posterior surface can be determined Animals that are diploblastic have endoderm and ectoderm whereas animals that are triploblastic have endoderm mesoderm and ectoderm in the embryo A coelom is found in the mesoderm which means only animals with bilateral symmetry can possess it Acoelomates No coelom Pseudocoelomates Where a cavity is present but is not derived from the mesoderm Coelomates Where the cavity is derived from mesoderm The embryo of the protostomes go through spiral determinate cleavage They lose their totipotency and become fixed The embryo of the deutrostomes go through radial indeterminate cleavage These cells retain their totipotency and have the ability to develop into any kind of cell stem cells Child birth is the best example of positive feedback Chemoautotrophs require CO2 and they oxidize inorganic compounds The smaller the population size the greater the chance of genetic drift Allopatric speciation is interrupted by geographic barriers SOME protists can be multicellular but most are unicellular And they are eukaryotic Skeletal muscle is NOT connective tissue Skeletal muscle is voluntary Blood is a connective tissue 05 01 2014 05 01 2014
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