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26.1 Nutrition and transport in plants
  • Certain inorganic nutrients (e.g., NO3-, K+, Ca2+) are essential to plants; others that are specific to a type of plant are termed beneficial.
  • Soil is built up over time by the weathering of rock and the action of organisms.
  • Soil particles, humus, and living organisms are components of soil that provide oxygen, water, and minerals to plants.
  • Soil erosion is a serious threat to agriculture, worldwide.
  1. What are the characteristics that make a nutrient essential to plants?
    Answer
  2. ________________ nutrients are specific to particular plants and are required for the growth of those particular plants.
    Answer
  3. What is the process that creates soil from rock?
    Answer
  4. What things make up the mixture we call soil?
    Answer
 Essential Study Partner Summaries of major points
  1. Early views
  2. Essential inorganic nutrients
  3. Determination of essential elements
  4. Soil formation
  5. The nutritional function of soil
Art Review
26.2 Uptake of water and minerals
  • The tissues of a root are organized so that water and minerals entering between cells or at the root hairs will eventually enter xylem.
  • Mineral ions cross plasma membranes by a chemiosmotic mechanism.
  • Plants have various adaptations that assist them in acquiring nutrients; e.g., symbiotic relationships are of special interest.
  1. What process allows water to cross the membranes of root cells and does it require energy?
    Answer
  2. By what process do root cells get minerals across the membranes and does it require energy?
    Answer
  3. Epiphytes have reduced or no roots and have no connection to the soil, living as they do on the branches of trees. How do they gain water and nutrients?
    Answer
 Essential Study Partner Summaries of major points
  1. Mineral and water uptake
  2. Adaptations of roots for mineral uptake
Art Review Art Quizzes Animations Lab exercises
26.3 Transport mechanisms in plants
  • The vascular system in plants is an adaptation to living on land.
  • The vascular tissue, xylem, transports water and minerals; the vascular tissue, phloem, transports organic nutrients.
  • Because water molecules are cohesive and adhere to xylem walls, the water column in xylem is continuous.
  • Transpiration (evaporation) creates a tension that pulls water and minerals from the roots to the leaves in xylem.
  • Stomata must be open for transpiration to occur.
  • Active transport of sucrose into phloem creates a positive pressure that causes organic nutrients to flow in phloem from a source (where sucrose enters) to a sink (where sucrose exits).
  1. Explain the cohesion-tension model of xylem transport.
    Answer
  2. Differentiate between stomata and guard cells.
    Answer
  3. Explain the pressure-flow model of nutrient transport.
    Answer
 Essential Study Partner Summaries of major points
  1. Transport tissues
  2. Water potential
  3. Water transport
  4. Cohesion-tension model of xylem transport
  5. Open and closing of stomata
  6. Organic nutrient transport
  7. Pressure-flow model of phloem transport
Art Review Art Quizzes Animations Animation Quizzes Lab exercises





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