Ch 28: Plant Structure and Growth Flashcards
List the 4 major organs that make up the plant body
roots, stem, leaves, reproductive organ (flower)
List the 3 major tissues types found in plants and describe their location and function in the plant body
dermal - line of defense
vascular - xylem phloem
ground - parenchyma sclerenchyma collenchyma
Contrast the structure of xylem and phloem: what cell types are found in each, are the cells dead or alive at functional maturity, etc.
Xylem - tracheids and vessel elements; dead and lignified at maturity
phloem - sieve tube elements and companion cells; alive at maturity
Distinguish between parenchyma, sclerenchyma, and collenchyma
Parenchyma - Alive; photosynthetic cells in mesophyll
Collenchyma - Alive; flexible support structure
Sclerenchyma - Dead; lignified; rigid support structure
Describe the functions of the root and shoot systems
Root system - roots; anchor plant, absorb water and minerals, store carbs
Shoot system - everything above ground
Contrast taproots and fibrous roots
Taproots - massive root; dicots
Fibrous - a lot of small roots; monocots
Explain the function of root hairs
root hairs increase the amount of water and nutrients the plant can absorb from the soil.
Explain what mycorrhizae are and why they are beneficial
mycorrhizal fungi are made up of a root-like structure and posses a network of mycelium external to the tree roots that extends into the soil. This mycelium absorbs nutrients and translocates them back to the host plant. As a result, there is an increase in the absorption surface area of the roots.
Describe the functions of stems
support structure for leaves and elevate reproductive structures
orients shoot to maximize photosynthesis
long distance transport of water/nutrients
Identify the following structures: node, internode, petiole, blade, stomata
node - an area on a stem where buds are located
internode - a part between two nodes
petiole - a stalk that attaches a leaf to the plant stem
blade - most frequently the flat, photosynthetic part
stomata - specialized pores or openings present in the epidermis of plant cells, which play a crucial role in gaseous exchange during the process of photosynthesis
Describe the structure and function of leaves
photosynthesis
gas exchange
dissipate heat
transpire water
Explain why leaves have stomata and describe in detail how stomata are opened and closed
stomata control gas exchange and the transpiration of water, opened and closed via guard cells
Describe conditions that would cause stomata to be opened / increase transpiration
Increased Sunlight
Higher temperature
Low humidity / dry air
Higher wind
Higher soil water
Lower CO2 Levels
Describe conditions that cause stomata to be closed / decrease transpiration
Decreased sunlight
Lower temperature
High humidity
Low wind
Low soil water
Higher CO2 Levels
Define meristem
undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants
- Distinguish between apical and lateral meristems
Apical Meristems are responsible for growth in length; lengthens the shoots and roots (apical and axillary buds)
Lateral Meristems allow for growth in thickness; increases diameter of stems and roots (Vascular Cambium and Cork Cambium)
Define primary and secondary growth and identify which meristems are involved in each type of growth
Primary growth lengthens the shoots and roots, and occurs at apical meristems
Secondary growth increases the thickness, diameter of stems and roots and occurs at lateral meristems
Describe the zone of cell division, elongation, and maturation
The zone of cell division is closest to the root tip; it is made up of the actively dividing cells of the root meristem. The zone of elongation is where the newly formed cells increase in length, thereby lengthening the root. Beginning at the first root hair is the zone of cell maturation where the root cells begin to differentiate into special cell types.
Identify the cell types produced by the vascular cambium and cork cambium
Vascular cambium: adds layers of vascular tissue: produces secondary xylem & secondary phloem
Cork cambium: replaces the epidermis by periderm: renews and maintains a protective outer layer of cork
- During secondary growth the epidermis is replaced by cork which is formed from the cork cambium
- Outermost layers of cork split and peel off to accommodate new growth
- Bark = all of the tissue outside of the vascular cambium (=>includes the secondary phloem)
Explain how and why tree rings form
Tree rings form in the trunk of a treefrom new cells generated in the cambium, themeristem(growing point) that lies just beneath the tree’s bark. The annual growth rings evident in cross sections of most tree trunks in temperate regions result from the yearly activity of vascular cambium. Tree rings provide a record of yearly growth and give indications on environmental (climate) conditions
- Wide growth rings indicate higher growth rates and suggest favorable conditions
- Narrow growth rings indicate slower growth rates and suggest unfavorable conditions
List the layers of cells that one would encounter when moving from the outside to the inside of a tree
They are the outer bark, inner bark (phloem), the cambium cell layer, sapwood, and heartwood.
NOTES
- Cells of the xylem are always dead when functionally mature.
- Parenchymacells are responsible for most of the metabolic functions of a plant.
- Collenchyma cells help support young parts of the plant shoot.
- Sclerenchyma cells also function as supporting elements in the plant but are much more rigid than collenchyma cells.
- Xylem cells conduct water and dissolved minerals upward from roots into the shoots.
- Phloem cells transports sugars, the products of photosynthesis.
- Secondary xylem and phloem are produced in a root by the vascular cambium.
- Lignin is the primary substance providing strength to the structural supports in woody plants.
- The term stoma (or stomata) can refer to the stomatal pore or to the entire stomatal complex consisting of a pore flanked by two guard cells, the specialized epidermal cells that regulate the opening and closing of the pore. Guard cells are highly specialized and do not play a role in defense, reproduction, or anchoring a plant.
- Sieve-tube elements are phloem transport cells with sieve plates in the end walls between cells.
- Removal or shading of an apical bud, or shoot tip, will result in growth from an axillary bud.
