The energy driving evaporation from the leaves comes from the heat generated by the Sun. Thus, the energy required for pulling water up against the force of gravity comes not from the metabolic activity of the tree but directly from the Sun. Water is heavy, so there is a limit to the height to which this mechanism can draw it. This is currently calculated to be slightly over 400 feet. The tallest known redwood tree measures 379 feet, within about 30 feet of the theoretical limit.
The molecules of chlorophyll contained in the chloroplasts absorb energy in the form of light from the sun. Some plants need more sunlight than others, but all need at least a little.
Water is absorbed from the soil into the cells of roots
Yes, isn’t biology full of complexity and subtlety? As you say, what tall trees accomplish does not fit the model of sucking on a tube; neither can it be explained by root pressure generated by osmosis, or by capillary action in and of itself. The transpiration-cohesion theory, in which capillarity plays an important role that I did not address, was developed to meet this challenge. It has a history dating back to the late 19th century, and substantial experimental support; it is widely accepted though not without occasional substantive uncertainty. You might enjoy browsing through the Wikipedia article on xylem, which also addresses the role of capillarity in a nice way (). As for cavitation, all the evidence I know of argues that it destroys rather than facilitates the upward transport of water. Finally, you might enjoy the article “Limits to Tree Height” in Nature 428, 851-854 (22 April 2004).
Where does photosynthesis occur in plant? | Biology - Quora
Instead of taking in oxygen and breathing out carbon dioxide like animals do, plants take in carbon dioxide from the atmosphere. Plants absorb water from the ground up through their roots.
Biology Plant cells and photosynthesis Flashcards | Quizlet
Although the cuticle provides important protection from excessive water loss, leaves cannot be impervious because they must also allow carbon dioxide in (to be used in photosynthesis), and oxygen out. These gases move into and out of the leaf through openings on the underside called stomata (Figure 3b). After carbon dioxide enters the leaf through stomata it moves into the mesophyll cells where photosynthesis occurs and glucose is constructed.
Photosynthesis and plant cells - Mindmap in GCSE Biology
So, water travels through cellular tubes within the wood, but what makes this water actually rise within a tree, sometimes for hundreds of feet? We know that in animals like ourselves, blood is circulated around the body by a mechanical pump, the heart. A tree has no pump of any kind. What, then, makes the water move?
18-1-2013 · Photosynthesis and plant cells
Water from the soil is carried within the conducting tubes of the xylem all the way into this dense network. The veins are in close proximity to the cells that contain chlorophyll and conduct photosynthesis. Along the way, side pathways are available to deliver water to all of the tree’s other living cells.
Like all other cells in a plant, ..
Several processes contribute, but here is the most important. Look at this photograph of the underside of a needle of a western hemlock, one of the dominant trees of the Pacific Northwest. We are working here at the edge of what a camera lens can resolve, but, still, the image is revealing. You can