Plant Structures Flashcards
What are the three main plant structures?
Root
Stem
Leaf
How can you tell that a cross section is that of a root?
It will have root hairs
It will have vascular tissue in the form of a cross
It will have a thicker endodermis
How can you tell that a cross section is that of a stem?
It will have vascular bundles
It will have pith
It has quite a thin endodermis
What is the function of the root?
Absorb water and mineral salts from soil
Anchors the plant in the soil
What are the two root systems?
Tap root system
Fibrous root system
What are the five regions of a root?
Mature region Root hair region Region of elongation Meristematic region Root cap
What is Spring wood?
Secondary xylem
Is lighter and bigger, because it forms quickly
What is autumn wood?
Secondary xylem
Is darker and smaller, because it forms slowly
What is cork?
The outer bark of the tree
How does cork form?
The parenchyma tissue becomes meristematic
What makes bark so strong?
It is reinforced with suberin
What are angiosperms?
Flowering plants
What is the most advanced group in the plant kingdom?
Angiosperms
What two groups can angiosperms be divided into?
Monocotyledons
Dicotyledons
What is the function of the root cap?
Surrounds and protects the growing point
What is the function of the meristematic region?
Continuously forms new cells
What is the function of the region of elongation?
New cells elongate in this region
What is the function of the root hair region?
The place where root hairs (unicellular epidermal outgrowths) occur
What is the function of the mature region?
Where lateral roots develop and branch
What is the function of the lateral roots?
Increase absorption surface
Anchor the plant more firmly in the soil
What three regions occur within a root?
Epidermis
Cortex
Central cylinder
Where does the epidermis of a root occur?
On the outside
What does the epidermis consist of?
Epidermal cells
Root hairs
Where can the cortex of the root be found?
In the middle section of a root
What are the components of the cortex?
Parenchyma
Endodermis
Where does the central cylinder of a root occur?
In the innermost ring
What are the components of the central cylinder?
Pericycle
Xylem
Cambium
Phloem
Where can the root be found?
In the soil
It is dark
There are micro and burrowing organisms found here
What is the root cap made of?
Thin walled parenchyma cells
How does the root cap perform its function?
Fluid nature of protoplasm lubricates passage of root apex
How does the root grow?
Elongating cells push the root tip further in the soil
What is the outer layer of a root hair like?
Sticky to adhere to soil particles
What are the functions of the cortex parenchyma?
To store food
Allow water and mineral salts to pass through
Diffuse oxygen
How does the endodermis occur?
As parenchyma cells
Border between the cortex and central cylinder
Has Casparian strips on the radial and transverse walls
What is a Casparian strip?
A thickened cork part of the cell walls in the endodermis
What is the function of the Casparian strips?
Direct water straight into the xylem
What is the pericycle?
Parenchyma cells
They give rise to secondary (lateral) roots
Where is the vascular tissue located?
Within the pericycle
How is the vascular tissue arranged?
Xylem in the form of a cross
Phloem between the ‘arms’ of the cross
What is the function of the root xylem?
Transportation of water and mineral salts from the root to the rest of the plant
Lignified walls strengthen the plant and give it structure
What is the role of cambium cells?
In a dicotyledonous plant, they occur between xylem and phloem
They cause secondary thickening
What is the function of phloem?
Transportation of manufactured organic substances throughout the plant
What are the main functions of a stem?
Bears the leaves Bears the flowers Bears fruits Transportation of essential substances Stores reserve nutrients and water
What does the external structure of a stem consist of?
Nodes
Internodes
Terminal buds
Axillary buds
What is a node?
Where the leaves and side branches develop
What is the internode?
The part of a stem between nodes
What are buds?
Meristematic tissue in the stem
What is the terminal bud?
Occurs at the tip of the stem