1 / 15

9.1 Transport in the Xylem of Plants

9.1 Transport in the Xylem of Plants. Plant Leaves. Absorb radiant energy Optimize the rate of photosynthesis Cross Section of a leaf. Transpiration . The passive movement and evaporation of water from the stems and leaves of a plant Made of two types of cells Tracheid cells

Anita
Télécharger la présentation

9.1 Transport in the Xylem of Plants

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 9.1 Transport in the Xylem of Plants

  2. Plant Leaves • Absorb radiant energy • Optimize the rate of photosynthesis • Cross Section of a leaf

  3. Transpiration • The passive movement and evaporation of water from the stems and leaves of a plant • Made of two types of cells • Tracheid cells • Vessel elements • Pits in the sides of the cells allow water to flow between the cells of the xylem

  4. Cohesive & Adhesive Properties • Cohesive properties: (hydrogen bonding) hold water molecules together as they travel up the xylem • Evaporation creates a “pull” causing them to move up xylem • Water is also entering the plant causing a “push” of water • Adhesive properties: water is attracted to the sides of they xylem cells • Water molecules adhere to sides of vessels and resist gravitation pull downward

  5. Stomata and Guard Cells • opening and closing of stomata controlled by guard cells 1. stomata open and close due to changes in turgor pressure 2. gain and loss of water in the guard cells is largely due to the transport of potassium ions 3. A hormone abscicis acid causes potassium ions to rapidly diffuse across guard cells, causing them to close (due to lack of available water) 4. other factors like carbon dioxide levels and circadian rhythms affect opening and closing

  6. Stomata & Guard cells

  7. Abiotic Factors and Transpiration Rates

  8. Root System and Water Uptake Water and mineral uptake • Occurs in the roots which have adapted in several ways: • roots are covered in tiny hairs that increase the surface area for greater water absorption 2. Branching allows roots to cover more area and increase uptake 3. Cortex cell walls are permeable for osmosis

  9. Uptake of Mineral Ions 1. Diffusionof mineral ions a. Requires concentration gradient (not common because ions are usually in low conc. In the soil) 2. Mutualistic relationships with fungal hyphae a. Fungi have long multinucleated cells called hyphae b. Form dense networks called mycelium that grow around roots c. Plant root provides fungi with nitrates in exchange for needed minerals 3. Mass flow of water in the soil carrying ions

  10. Active Transport of Minerals Mineral ions are taken into the plant by active transport • a. root hairs secrete hydrogen ions into soil particles, exchanging them for mineral ions (calcium, magnesium, iron etc.) • b. ATP is hydrolyzed in order to provide the energy for this process

  11. Adaptions of Xerophytes • Xerophytes live in arid (dry) environments • They have developed adaptations to help with transpiration • Reduced leaves sometimes spines • Rolled leaves: block the wind from reaching stomata • Deep roots for more surface area • Thickened waxy cuticle • Reduced number of stomata • Hairs to help trap water • Water storage organ • Low growth • CAM and C4 plants: fix CO2 at very low concentrations, stomata open less frequently

More Related