Superlatives! World’s oldest almost 10,000 Years old

Movement of water animation Leaf cross section

Plant cell types Parenchyma: relatively unspecialized with a primary cell wall Schlerenchyma: thick secondary cell wall, usually with lignin, protoplast gone at maturity Collenchyma: primary cell wall with thickened corners

Plant tissue types Xylem: water conducting tissue made of several types of cells, tracheids, vessel elements and other cells Phloem: distributes the carbs. made by photosynthesis, sieve tube elements and companion cells but other cells are present also. Epidermis: outermost layer of cells, secrete cutin that makes up the cuticle, guard cells that form stomata and root, stem and leaf “hairs”

Xylem! Tracheids are the earliest to evolve, fiber like with a lignified secondary cell wall Cells overlap with each other with a series of membrane covered pits that from a “tube” connecting the roots to stem to leaf petiole to vein for water transport. Vessel elements evolved later and found only in flowering plants, they have a larger diameter and have holes instead of pits to allow for more efficient water flow.

Tracheids

Phloem Companion cells have a nucleus, seive tubes do not. They are associated with each other via plasmodesmata and the companion cells function in phloem loading. As with xylem, phloem may contain fibers and parenchyma cells.

Meristems Apical – located at tips plant gets longer Lateral – located as cylinders of dividing cells running the length of the plant from root to stem to leaf petiole to vein – plant grows wider

Primary versus Secondary Primary – herbaceous plants – only type of growth Secondary – thickening of the roots and shoots, product of lateral meristems. One lateral meristem replaces the epidermis with a secondary dermal tissue such as bark. A second lateral meristem adds vascular tissue.

Drawings! The teacher will now diagram with you the arrangement of these tissues in roots, stems and leaves on mono and dictot plants.

Do It NOW! Through what tissue does water move in a plant?(1) What two main cell types make up this tissue in angiosperms?(2) Are these cells alive at functional maturity?(1) What mechanism moves water through a plant?(1) Through what tissue do organic materials move in a plant?(1) What two main cell types make up this tissue?(2) Are these cells alive?(1) What process moves organics (sucrose) in a plant?(2)

Movement of carbohydrates The Pressure Flow Model(Hypothesis) Remember that in the phloem tissue, there are sieve tube cells and companion cells that are living cells responsible for the movement of organic materials in the plant.

Remember that the root and shoot would have apical meristems

First Let’s review The next few slides are cross sections of moncots and dicots. Make sure you include these diagrams with your AP Lab 9

Lateral root arising from the pericycle the layer of cells interior of the endodermis

What is a legume? Plant that grows bacteria in their roots that fix nitrogen. Bumpy roots!!! Leghemoglobin is a protein that absorbs oxygen. Peanuts, soybean, clover, beans…

Mycorrhizae – fungi associated with roots Helps plants to absorb water and minerals as an extension of their root system. Fungi break down organic material in the soil and create usable forms of nitrogen – ammonia, nitrates and nitrites.

N P K Nitrogen – proteins, nucleic acids Phosphorous – nucleic acids Potassium – help controls water movement by helping the plant to open and close stomata.

Dicot Root Cross-Sections                                                                                                                                                                                            

What is this??? You will have a lab practical which is a quiz on which you will be required to identify the organs, tissues and functions of the items as viewed on the microscope – good practice for college!!!!

Why do plants have guard cells and stomata? Explain how guard cells operate in detail. Are there more stomata on the top or bottom of the dicot leaf? Explain your results. 5. If the total leaf area on a plant is 4 centimeter squared, and there are 10 stomata for each millimeter squared, how many stomata are on the entire surface of the leaf?

Movement across membranes Diffusion – Carbon dioxide, Oxygen Osmosis – Water Ions – requires transport proteins

Proton Pumps ATP is hydrolyzed to ADP. The net release of energy is used to move H+ ions across the membrane against the gradient – Proton gradient generates a negative charge inside the cell compared to the positive charge outside the cell a.k.a a membrane potential. Plants use this potential to power the absorption of K+, NO3- and others into roots.

Water Potential Review