1.Plant Roots Flashcards
2.31 State the primary/secondary functions of the root
Primary:
- Anchorage / Support of plant in the growing medium
- Water uptake from growing medium
- Mineral uptake from growing medium
Secondary:
- Storage - of water and nutrients
- Propagation - development of new plants
2.32a Describe a ‘tap root’ to include its origin
- Main root originates from the radicle (in the plant embryo)
- Grows vertically downwards
- Many smaller lateral (secondary) roots growing out from it at intervals.
- Found in plants where anchorage for a tall stem is required
- Many short lives perennials
- E.g Carrot, Oak
2.32c Describe ‘fibrous’ roots to include their origin
- Formed when the secondary roots equal or exceed the primary root in size and there is no well defined single tap root.
- Formed from thin, moderately branching roots which grow down and out to form a mass of small roots
- Less effective at stabilisation
- Grow from the base of stem
2.32d Describe ‘adventitious’ roots to include their origin
- Lateral roots coming from organs other than the main root system, such as the stem, branches and leaves
- Do not derive from the radicle
- Good for stabilisation and spreading to new territories
2.33 Describe the tissues of monocotyledon roots
- Cortex = Wide
- Cambian tissue = Within Xylem - No secondary growth
- Pericycle = Multi layered
- Pith = Well developed
- Vascular bundles = numerous (more than 6)
- Xylem = oval/rounded
- Phloem = Alternating
2.33 Describe the tissues of dicotyledon roots
- Cortex = Narrow
- Cambian tissue = Within pericycle - Allows for secondary growth
- Pericycle = Single layered
- Pith = Little or none
- Vascular bundles = 2-6
- Xylem = vessels are angular
- Phloem = Separated
2.34a Describe and state the function of the ‘root cap’
Description: The root cap: is a layer of mature cells protecting the apical meristem at the tip of the root. Root cap cells secrete a lubricating fluid to help the root tip grow through the soil
Function: The root cap protects the apical meristem from damage
2.34b Describe and state the function of the ‘apical meristem’
- Growth tissue containing actively dividing cells
- Covered by root cap - protective layer producing lubricating gel to enable movement through soil
2.34e Describe and state the functions of ‘root hairs’
- Lateral extensions single cells on the epidermal which have elongated
- Short lived
- Continually being sloughed off by the soil and regrown
- Enable the absoption of water and nutrient through their massively increased surface area
2.35a Describe how the root is adapted to perform other functions including storage / perennation
- Swell to store enough food or water to sustain the plant during unfavorable conditions
- Develop into one or more new plants the following year.
- Swollen tap root = Carrot
- Tubers - Potato
2.35b Describe how the root is adapted to perform other functions including: climbing
- Adventitious roots develop along the stem allowing it to attach to vertical surfaces
- Enables the plant to access more light for photosynthesis
- Optimally position flowers for pollination
- May also help to absorb moisture from the atmosphere
- E.g Aerial roots - Hedera helix (Ivy)
2.35b Describe how the root is adapted to perform other functions including: support
- Adventitious roots develop along the stem or at the base of the plant
- To provide support or anchorage
- E.g prop roots - Ficus elastica
Describe Rhizomes and their function
- Horizontal underground stem that is capable of producing shoot and root systems
- Store starches and proteins and enable plants to survive underground during unfavorable seasons
- Many plants use these structures for asexual reproduction
- Helps plants to spread
