Roots Flashcards
What are the functions of roots?
- Anchorage of the plant in a substrate
- Absorbs water and minerals from the soil
- Production of hormones for growth and development
It develops from an embryonic cell known as the “radicle” and grows to be the largest root in the system
Tap root
Similarly sized roots and arose because the radicle dies during or immediately after germination
Fibrous root
Does not arise from pre-existing roots and increases the absorptive and transfer capacity of the root system
Adventitious root
Type of adventitious root that arises from the main trunk stem
Brace root
Type of adventitious root that arises from lateral branches of the main stem
Prop root
The root tips are protected by ___?
Root caps
Give the 3 parts of the root cap
- Slime or mucigel
- Columella and peripheral cells
- Quiescent center
What is the function of the slime or mucigel?
Lubricates the passage of the root through the soil
What is the function of the quiescent center?
It is a mitotically inactive region which acts as a reserve of health cells and is resistant to toxic substance.s
What are the parts of the internal structure of young dicot root?
- Dermal region
- Cortex
- Stele or vascular cylinder
Explain dermal region
It is simply the epidermis with root hairs
Explain cortex
Outer collenchyma, middle parenchyma, inner endodermis
Explain stele
Consists of pericycle, vascular cambium, primary xylem and primary phloem
It controls the passage of minerals across the vascular tissues
Endodermis
What consists the endodermis?
Thick-walled cells with casparian strips and thin-walled cells known as the “passage cells”
What is casparian strip?
Bands of lignin and suberin across the radial walls causing the cell wall to be come waterproof
What is the type of stele present in a dicot root?
Protostele
What is the type of stele present in a monocot root?
Siphonostele
Type of diffusion wherein the water and mineral diffuse only through the walls in intercellular spaces
Apoplastic
Type of diffusion wherein the material has passed through a plasma membrane and enters the protoplasm
Symplastic
What are the parts of the internal structure of a monocot root?
- Dermal
- Cortex
- Stele or vascular cylinder - siphonostele
Where does the lateral root originate?
Pericycle
What are the parts of the internal structure of an OLD dicot root?
- Region of secondary vascular tissues: secondary phloem, secondary xylem and vascular cambium
- Region of periderm layers: phellem, phellogen, phelloderm
It is the zone of cell division
Apical meristem
Region where growth in length occurs
Root tip
Rapidly dividing cell and is protected by a thick layer of cell
Zone of cell division or meristem
What are the three primary meristem?
- Protoderm - epidermis
- Ground meristem - stores food and uptake of minerals
- Procambium - gives rise to stele
Region where cells expands greatly there cells can be seen. It is also where cells begin to differentiate to visible patterns
Zone of elongation
True or false: There is no cell maturation in the zone of elongation
True
Zone where root hairs grow, no distinct boundary exist between elongation and maturation, transfer minerals from the epidermis to the vascular bundle
Zone of maturation
Structure of zone of maturation: Function only for several days, after which they die and degenerate, increases absorption of water and minerals
Root hairs
Structure of zone of maturation: Outermost layer
Epidermis
Structure of zone of maturation: Innermost layer of cortical cell differentiated as a cylinder and is a tangential wall
Endodermis
Structure of zone of maturation: Transfer minerals from the epidermis to the vascular tissue
Cortex
Structure of zone of maturation: Irregular region, between the vascular tissue and endodermis and where lateral roots arise
Pericycle
Food conducting tissue
Phloem
Water conducting tissue
Xylem
