Plant Vascular Adaptations (Eudicot)
Primary site of photosynthesis. Produces Erich organic molecules and releasing O2 gas. (see leaf page)
stem Leaf
Hold leaves; connections for transport of materials between roots and leaves; bear buds (embryonic shoots.)
Stem region between successive nodes
Where leaves attach to stems Lateral bud Where leaf meets stem; if it becomes active, it develops into a new branch (extension of shoot system.) Root system: anchors the plant in place; provides nutrition. Extreme branching of plant roots and their high surface area-to-volume ratio allow them to absorb water and mineral nutrients from the soil.
Root System: water and minerals enter through this. Lies in the soil where light does not hit it. No photosynthesis.
Leaf Structure
Blade
Thin, flat structure attached to the stem. During the day, the blade is perpendicular to the rays of the sun. this maximizes the amount of light available for photosynthesis. Some leaves track the sun; moving constantly so they always face it.
Petiole
A stalk where the stem is attached to the blade. Helps the leaf face the sun and stuff.
Water Food
Regulates the opening of the stomata according to the humidity.
Sunlight causes the stomates to open and close.
Guard cells are sensitive to light, which causes proton pumps to be active, allowing Na and P ions to be pumped. So... it becomes highly osmotic inside. Cellulose is wrapped around the cells; when they fill up with water, they buckle apart.
Plant Cells
Plant cells contain chloroplasts, vacuoles, and cell walls.
Cell walls
Plant cell walls form as the final step in cell division. Cell plate middle lamella primary wall secondary wall More complex:
2 daughter cells are separated by a cell plate. The daughter cells deposit a glue-like substance which constitutes the middle lamella. The daughter cells secrete cellulose and other polysaccharides to form a primary wall. This continues until the cell expands to its final size. Once cell expansion stops, a plant cell may deposit one of more additional cellulosic layers to form a secondary cell wall (internal to the primary.) cell walls contains cellulose, other polysaccharides, and proteins, some of which are enzymes. Chemical reactions in the wall play important roles in cell expansion and in defense against invading organisms. Cell walls may thicken or be sculpted as cells differentiate into specialized cell types. permeable to water, small molecules, and mineral ions, except where the secondary wall is waterproofed. Primary wall has thin regions where strands of plasmodesmate pass through the primary wall, allowing direct communication between plant cells. Sometimes the plasmodesma can enlarge a lot, which allows viruses to pass through. secondary cell walls have pits, which are interruptions in the wall that allow water and other materials to pass from cell to cell.
Plant Tissues
Have the ability to regenerate from a single plant cell.
Parenchyma
cells are alive when they perform their functions most numerous; thin walls consisting only of primary wall and middle lamella; enlarged vacuoles. Photosynthesis. Nonphotosynthetic parenchyma cells store substances such as starch or lipids. Many retain the capacity to divide, hence giving rise to new cells (because of the thin cell walls)
Collenchyma
cells provide flexible support while alive Supporting cells; irregularly thick primary walls at corners; elongated; no secondary walls; support to leaf petioles, nonwoody stems, and growing flexible organs; tissue (allowing stems to sway in wind;) alive at maturity
Sclerenchyma
cells provide rigid support Thickened secondary wall for support; functions when dead; 2 types: elongated fibers (provide rigid support in wood and stem and leaf veins) and shaped sclereids (packed together densely; stone cells give fruits gritty texture;) dead at maturity (wont divide anymore.) Cells that die: tonoplasts bursts. The cytoplasm is pushed to the side of the cell and the cell degenerates.
Xylem and Phloem
Xylem: transports water from roots to stems and leaves. Contains
tracheary elements that undergo cell death before they assume their function. Two types: tracheids and vessel elements. Tracheids are found in gymnosperms. When the nucleus and cytoplasm disintegrate upon death, water can move easily from one to another by pits. Vessel elements also die before they can transport water. They secrete lignin which aids in the death of their cell walls. The result is a hollow tube that water can flow through. The water goes up the tube (allowed by H bonding, cohesion, and adhesion) and then through the plant.
Phloem: translocates carbs and other nutrients
Living cells. Sieve tube elements form sieve tubes which transport carbs and others from their sources to tissues that consume or store them. Photosynthesis products move from leaves to root tissues in mature leaves, for example. Sieve plates are formed when plasmodesmata enlarge to form pores. As the holes expand, the tonoplast disappears, which unclogs the pores. Sieve tubes are filled with sap (water, dissolved elements, and other solutes) which moves from cell to cell along the tube. Companion cells are linked with its sieve tube element. They retain all their organelles and are the "life-support systems."
Xylem: water: transpiration Phloem: food: translocation Angiosperms have both.
Plant Growth
Meristems: regions of cell division by initial cell division
Apical meristems: produce the primary plant body, which is the entire body of many plants. location: tips of roots and stems; buds
Lateral meristems: produce the secondary plant body (wood and bark.) Derived from the vascular cambium and the cork cambium.
Shoot apical meristems: supply the cells that extend stems and branches, allowing more leaves to form and photosynthesize. Protoderm
Root apical meristems: supply the cells that extend roots, enabling the plant to "forage" for water and minerals. procambium vascular
Vascular cambium: dividing cells that form new xylem toward the inside (the secondary xylem) and new phloem toward the outside (secondary phloem)
Cork cambium: produces new protective cells that keep the tree from exposing to damage when the outer layers of the stem crack and fall off
ground meristem ground
Dermal tissue system
apical meristems primary meristems tissue systems
How do plants circulate their fluids?
A: by diffusion and osmosis! Osmosis: the movement of water through a membrane with the laws of diffusion. Energy is not directly required. Solute potential: measure of the effect of dissolved solutes on the osmotic behavior of the solution. solute concentration, the more negative the solute potential, and the tendency of water to move into it from another solution of lower solute concentration. As more water enters a plant cell, the Turgor pressure (pressure potential) becomes greater and greater. Plants can adapt to be able to take water from the soil with cellulose that allows it to stick together.