Plants Lesson 5 Flashcards
(58 cards)
All vascular plants make what?
Primary tissue
Lateral Meristems
2 parts: Vascular cambium & cork cambium. Secondary growth. Only in conifers & woody
eudicots, all conifers are woody. Make wood & bark. Monoicots are not woody.
Secondary growth produces what?
Wood and bark.
Why does some plants feel woody when they aren’t?
Because the just have login in their cells.
Vascular Cambium
They form in-between the vascular bundles that were in the primary growth. They make tissues inside of it, which is secondary xylem, and it also makes tissues outside of it which is secondary phloem. This splits the og bundles apart. When this happens, the primary xylem becomes non-functional. This increases circumference. It’s a single layer of cells. Comes from cortex cells.
Cork Cambium
Makes new covering. Once wood is made, the plants no longer have an epidermis, it’s replaced by bark. Adds secondary dermal covering.
What’s made more secondary xylem and phloem?
Xylem. The phloem eventually stays the same thickness. The xylem pushes itself outward to make more of it, it’s how the plant gets bigger.
Rays
Allows transport of materials across then stem instead of up and down the stem. Made by vascular cambium.
Fusiform initials make what (in VC)?
Tracheids and vessel elements (xylem). Sieve elements (phloem).
Ray initials make what (in VC)?
Rays (in both xylem & phloem).
What is wood?
Secondary xylem (heartwood). From the login that’s in the walls of the tracheiods and walls of the vessel elements. Everything before the VC.
What is bark?
Everything after the VC
Why is the middle darker?
Because it’s very old and stops working.
Growth Rays
In the beginning of the summer it causes big/wide tracheas and vessel elements and they get narrower and narrower than stop. Each one = one year of growth.
Lignin
Deposited in cell walls. Fills spaces and binds cellulose, hemicellulose & pectin. Gives strength to wood & bark. Can occur in cell walls of non-woody plants (palm trees, bamboo, wheat straw, …).
Where is the sugar removed?
Phloem
Cork cambium (aka phellogen)?
New lateral meristem. Arises from cylinder of cortex cells outside the vascular cambium & secondary phloem.
Produces the “periderm”: 3 layers:
– Phelloderm to inside (some woody species) a thin layer of living parenchymal cells
– Cork cambium itself
– Cork to outside, Suberized (wax), dead cells, and Protects woody plant (there is no more epidermis)
Cork
Is filled with wax
Periderm
Cork cambium and cork
Sap
Water and minerals that goes from the soil upward through the xylem.
1st Law of Thermodynamics
Cannot create or destroy energy. Can only change
from one form to another (e.g., electricity to light)
2nd Law of Thermodynamics
Energy spontaneously tends to flow only from being concentrated in one place to becoming spread out, or for a combined system and surroundings, entropy never decreases. It’s how water moves up the plant.
Overall messages for the 2nd law?
The movement of fluid in plants follows the 2nd
Law of Thermodynamics. The most equitable distribution of energy corresponds to maximum entropy.
Some examples
* Osmosis
* Diffusion
* Fluid movement because of differences in
hydrostatic pressure
Where does water flow to?
From being concentrated to less concentrated.
