Chapter 36 - Chapter 36 Resource Acquisition and Transport...

Info icon This preview shows pages 1–3. Sign up to view the full content.

Chapter 36: Resource Acquisition and Transport in Vascular Plants 1 Adaptations for acquiring resources were key steps in evolution of vascular plants 2 Different mechanisms transport substances over short or long distances 3 Transpiration drives the transport of water and minerals from roots to shoots via the xylem 4 Rate of transpiration is regulated by stomata 5 Sugars transported from sources to sinks via phloem 6 Symplast: highly dynamic 1 Adaptations for acquiring resources were key steps in evolution of vascular plants Evolution of land plants Natural selection: taller plants with flat appendages, multicellular branching roots & efficient transport Adaptations compromises between enhancing photosynthesis & minimizing water loss Shoot Architecture & Light Capture Positive correlation between water availability & leaf size Phyllotaxy: arrangement of leaves on stem specific to each species Most angiosperms: alternate phyllotaxy with leaves arranged in spiral Angle between leaves: 137.5 Golden Angle: minimizes shading of lower leaves Leaf area index (LAI): measure of canopy structure LAI= total leaf area / total ground area Fish-eye photography: LAI ~area occupied by canopy/area of visible sky dimensionless number Selective logging result Intact topical forest
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Deep shade: Lower leaves & branches respire more than photosynthesize undergo programmed cell death (self-prune) Leaf orientation affects light absorption: Low-light conditions horizontal leaves capture more sunlight Sunny conditions vertical leaves less damaged by sun & light can reach lower leaves Root Architecture and Acquisition of Water and Minerals Root growth can adjust to local conditions: Ex: branch more in pocket of high nitrate NO3− than low nitrate Roots less competitive with roots from same plant than with roots from different plants produce more proteins for more efficient uptake of nitrate across plasma membrane Mycorrhizae: mutualistic associations of roots & hyphae of soil fungi Mycorrhizal fungi increase surface area for absorbing water & minerals(specially phosphate) 2 Different mechanisms transport substances over short or long distances 2 major compartments in plants: Apoplast (external to PM): cell walls, extracellular spaces & interior of vessel elements & tracheids Symplast: cytosol of plant cells & plasmodesmata 3 transport routes for water & solutes: Apoplastic route: through cell walls & extracellular spaces Symplastic route: through cytosol Transmembrane route: across cell walls Short-Distance Transport of Solutes Across Plasma Membranes
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern