Chapter 34 Flashcards
Why the plant body is dynamic
Indeterminate growth
Indeterminate growth
plant growth in which the main stem continues to elongate indefinitely without being limited by a terminal inflorescence or other reproductive structure.
Functions of plant
Gains inorganic resources like sunlight, CO2, H20 \
Use photosynthesis to make organic molecules
Root system functions
Anchor plant to soil
Take up ions and water from soil
Conduct water and ions to shoot system
Obtain energy from sugar in the shoots
Store molecules produced by shoots
Where does a majority of photosynthesis occur in plants
Leaves due to a large surface area available for absorbing photons
Bulbs
Onion bulb store nutrients
Floral mimics
Modified to have different colors and attract pollinators
Succulent leaves
Succulent leaves store water
Traps
Modified leaf that traps insects for food
Tendrils
Allow vines to climb
Three tissue systems found in plants
Dermal tissue system
Ground tissue system
Vascular tissue system
What are features plant cells have not found in animals
- Surrounded by cellulose-rich primary cell wall and a rigid secondary cell wall
- Plant cells are interconnected by plasmodesmata
Dermal Tissue System
Consists of dermal tissue (skin tissue) also called epidermis (outermost layer of cells of any multicellular organism)
- Epidermal cells secrete cuticle
- Stomata
- Trichomes
Cuticle
Hydrophobic, waxy layer that covers shoots, protecting leaves and reducing water loss
Stomata
Part of dermal tissue system
regulate exchange of gases
– Open when plenty of water, allows CO2 to enter
– Close when H2O scarce, preventing excess water losss
Surrounded by two specialized guard cells, change shape to open or close the pore
Trichomes
Part of Dermal Tissue system
Hair-like appendages
- Keep plant cool and protect against damaging sunlight
- Minimize water loss
- Regulate gas exchange in shoots
- Provide barbs or toxins to protect from herbivores
Ground tissue system and types
Most photosynthesis and carbohydrate storage take place in ground tissue
Cells in ground tissue are responsible for most of the synthesis and storage of specialized products required for defense
Three cell types:
Parenchyma
Collenchyma
Sclerenchyma
Parenchyma
Type of cell in the ground tissue system
- Most abundant and versatile plant cells
- Primary site of photosynthesis in leaves
3.Mainly store starch in roots
These cells are totipotent
Alive at maturity and have functioning nuclei
Totipotent
Continue to divide and develop into a mature cell
Helps in repair of wounds and reproduction
New plants can grow from cuttings
Collenchyma
Type of totipotent cell in the ground tissue system
Have primary cell walls that continue to expand and provide flexible support to growing regions of shoots
Support growth: Found in elongating stems and leaf petioles, just underneath the epidermis
Sclerenchyma
Type of cell in the ground tissue system
- Produce two cell walls (1 thin and 1 thick cell wall that consists of rigid lignin and cellulose)
- Dead at maturity and contain no cytoplasm
- Fibers and sclereids are two ways they are organized
Xylem
Part of vascular tissue system
Conducts water and dissolved nutrients in one direction from the root system to the shoot system
Composed of tracheids and vessel elements
Phloem
Part of vascular tissue system
Plant vascular tissue used to transport sugar in both directions throughout plant
Made up of two types of specialized cells called sieve-tube elements and companion cells
Tracheids
Major component of xylem tissue and responsible for movement of water
Long, tapered and have pits
Meristems
region of cells capable of division and growth in plants
Allows plants to grow throughout their lives
Apical meristems
Group of undifferentiated plant cells
Found at the tip of each root and shoot; responsible for primary growth
Root cap
Actively pushed through the soil
- Group of cells that protects apical meristem
- Senses gravity to determine growth direction
- secretes lubricant
Zone of cellular elongation
In the middle of the zone of cellular division and maturation
contains cells that do not divide and instead elongate rapidly, about 10 times faster than meristem cells
Most responsible for the growth of roots through the soil
Zone of cellular maturation
Differentiate into tissues; absorb water and nutrients through root hairs
Lateral roots grow here
Secondary growth
Increases width of roots and shoots,
results from cell divisions in the vascular and cork cambia.
Major function is increasing amount of conducting tissue available and providing increased structural support
Produces wood and occurs in species that have cambium in addition to apical meristems
Occurs in some but not all plants
Cambium
a thin cell layer between the xylem and phloem of most vascular plants from which new cells (as of wood and bark) develop.
What is a function common to both roots and shoots
Harvesting resources from the environment
Phenotypic plasticity in roots and shoots
Ability to modify form depending on environmental conditions
Simple leaf
Leaf consisting of single blade
Composed of two structures called the blade and stalk of petiole
Compound leaves
Leaf consisting of two or more blades and have them divided into a series of leaflets
Double compound leaves
Have leaflets that are divided
Needlelike leaves
Adapt to very cold or hot climates
Vascular Tissue System
Tissues that transport water, nutrients, and sugars
Moves products of photosynthesis that are made and stored in ground tissue
Consist of two complex tissues: xylem and phloem
Vessel elements
An elongated, water-conducting cell in xylem that are short and wide and has pits and perforations
Dead at maturity and contain no cytoplasm
What does bark do for the tree
Replaces epidermis as protective covering
Primary growth
Increase in the length of stems and roots due to the activity of apical meristems
Major function is to increase a plant’s ability to absorb light and acquire carbon dioxide, water and nutrients
Primary meristems
Three types of partially differentiated cells produced by apical meristems
function in helping the plant increase in length or vertical growth
Protoderm
functions like the skin of the plant and forms the outer layer, protecting the plant from the environment.
root hairs
Outgrowths that increase surface area of the dermal tissue
absorb nutrients and water which are sent through the tip of the plant’s root.
Zone of cellular division
Group of apical meristematic cells just behind the root cap where cells are actively dividing
Procambium
Primary meristem tissue that gives rise to the vascular tissue
Primary Tissue
Ground tissue system
Xylem and Phloem
Three distinct populations of cells that exist behind the root cap
Zone of cellular division
Zone of cellular elongation
Zone of cellular maturation
Vascular bundles
Cluster of xylem and phloem strands that run the length of the stem
This is how the primary shoot system is organized
Two types of cambia in plants that undergo secondary growth
Vascular cambium
Secondary cambium
Cork cambium
Type of cylindrical meristem that produces cork with lenticels (main tissue associated with tree bark)
Secondary xylem (wood)
produced as a result of secondary growth from vascular cambium
Much more complex tissue than primary xylem and consists of a number of different cell types
Secondary phloem
produced as a result of secondary growth from vascular cambium
Type of phloem that forms from the vascular cambium during the secondary growth
