Sugar Transport in Plants: Phloem Learning Objectives Differentiate between sugar sources and sugar sinks in plant tissues Explain the pressure flow model for sugar translocation in phloem tissue Describe the roles of proton pumps, co-transporters, and facilitated diffusion in the pressure flow model Recognize how different sugar concentrations at sources and different types of sinks affect the transport pathway used for loading or unloading sugars Compare and contrast the mechanisms of fluid transport in xylem and phloem The information below was adapted from OpenStax Biology In growing plants, photosynthates sugars produced by photosynthesis are produced in leaves by photosynthesis, and are then transported to sites of active growth where sugars are needed to support new tissue growth. Many plants lose leaves and stop photosynthesizing over the winter.
Water and Sugar Transport in Plants What are the key differences between plant vs. What are the key concepts of water and sugar transport in plants? What is the gradient that water moves along? Does water moves passively or actively?
And what is the force driving water transport? What is sugar transported? How is water involved in sugar transport? Cohesion, adhesion, root pressure vs.
Cohesion-tension theory Water moves from high to low water potential along water potential gradient differences in solute concentration and physical pressure passive.
Active transport from source to phloem.
Water from xylem osmosis bc low solute potential in phloem near source and causes pressure potential high near source.
Water and sugar moves to low pressure potential near sink. Water goes back to xylem.
How to reduce water loss through open stomata? CAM — open stomata at night to store co2, use co2 at day. Low solute potential in cell hypertonic surrounding?
Turgor pressure is really high!!! A plant cell with solute potential The spontaneous net flow of water will be: Calculate water potential inside the cell as a sum of solute potential and internal turgor pressure.
Calculate the water potential of the NaCl solution as a sum of solute potential and pressure potential. Which water potential is greater? If plant cell solute potential is Calculate the water potential of solution.
At equilibrium, the water potential of solution and the cell must be equal. How does atmospheric humidity affect water potential?
This is why we have so much rain in Vancouver. Clouds rise up, temperatures colder high up, rain! B The lowest humidity during the DAY time. You need there to be sunlight for transpiration to occur At the other points, even though humidity is lower, those are not during sunlight hours so no photosynthesis occurs, the number of stomata open at night is small, and not that much water loss.To understand transport in plants, let’s start with a little stem anatomy.
In our example, the straws that transport water and minerals up from the roots to the leaves are called xylem In plants the movement of nutrients through the phloem is driven by where the sugar is most needed for the growth of the plant.
|Learning Objectives||The Pathway of Water Soil water enters the root through its epidermis.|
some sugar transport require ATP to move sugar against concentration gradient e.g. into vacuole, pump protons so that sugar can diffuse into companion cell pressure potential drives water flow through phloem (caused by water moving into the phloem). Study 32 -- Water and sugar transport in plants flashcards from Olivia C.
on StudyBlue. It is the potential energy that water has in a particular situation compared to the potential energy of pure water at atmospheric pressure at the same temperature.
Although root pressure plays a role in the transport of water in the xylem in some plants and in some seasons, it does not account for most water transport. Few plants develop root pressures greater than 30 lb/in 2 ( kPa), and some develop no root pressure at all. Sugar Transport Sugars, which are formed by the plant during photosynthesis, are an essential component of plant nutrition.
Like water, sugar (usually in the form of sucrose, though glucose is the original photosynthetic product) is carried throughout the parts of the plant by the vascular system.