LESSON 11: PLANT GROWTH Flashcards
Plant growth can be affected by many things including…
-The type of seed or species of plant
-The quality of the soil
-The amount of water present
-The amount of light
In order to produce new roots…
cells in the plant’s stem must undergo both growth and differentiation
Growth
the process of increasing in size (i.e. blowing up a balloon)
increase in height comes from
apical meristems.
Apical meristems
regions of actively dividing cells found at the apices of plants (i.e. tips of their buds, stems, and roots)
All growth from the apical meristems is called
PRIMARY GROWTH.
-Primary growth always increases the height of a plant, but not its width
what arises from lateral meristems
SECONDARY GROWTH
-Lateral meristems
areas of actively dividing tissue in the stems and roots
–Secondary growth increases the girth (width) of a plant
Primary Growth
Primary growth increases the length of a plant shoot or root
-It begins as the cells of the apical meristems divide by mitosis (this increases the # of cells)
-Once cell division has occurred, each cell grows longer and begins to specialize which results in the production of different cell types
-Cell types can include: parenchyma (most abundant type of ground tissue), epidermal, or vascular cell types
what does The shoot apical meristem produce?
he tissues that form stems, leaves, and organs responsible for sexual reproduction (i.e. flowers in angiosperms)
What doesroot apical meristem produces?
produces the cells of the root cap and all other cell types in the root
What are all tissue formed from apical meristems called?
primary tissue (i.e. xylem & phloem that arise from apical meristem are called primary xylem and primary phloem
Primary growth in woody planst only occur when…
only happens in woody species after the plant’s first year.
What does secondary growth arises from?
arises from a lateral meristem
what tissues form from laterial meristem?
all tissues that are formed by it are called secondary tissues.
Lateral meristems are never…
Lateral meristems are never at the apex of the shoot or root
Exampel of lateral meristems?
Vascular cambium is an example of a lateral meristem
After the first year of growth, primary and secondary growth happen…
simultaneously
Do woody speices grow in length and width?
Woody species continue primary growth and increase in length (height) and they also increase in diameter through secondary growth from two lateral meristems (the cork cambium & the vascular cambium)
Cork cambium produces…
the cells that form the bark and vascular cambium produces secondary xylem and phloem
Photoperiodism
a plant’s response to changes in day length.
Macro
nutrients needed in large quantities
Micro
nutrients needed in small quantities
The main environmental factors that affect plant growth and development are:
-Light (i.e. seasonal changes in light,
photoperiodism)
-Water
-Temperature (i.e. specific temperature
range for cellular processes)
-Nutrient availability (i.e. soil
composition/pH, macronutrients vs.
micronutrients)
tropism
a directional change in growth or
movement in response to a stimulus
phototropism
a change in direction of a
growing plant in response to light
Other types of tropisms include
gravitropism and thigmotropism
thigmotropism
a directional change in
growth pattern in response to touch
gravitropism
a directional change in
growth pattern in response to gravity
5 plant growth regulators
Auxins, gibberenllins, cytokins, ethylene, Abscisic Acids
apical dominance
the condition in which
most shoot growth arises from the apical
bud and not lateral buds
Auxin
groups of compounds that act in similar ways on plant growth and differebtation
-Promote cell elongation
Gibberenllins
- promote cell divison and cell elongation
-Can sometimes play a role in flowering and fruit prodcution
-smaller plants are that way because of low levels of gibberenllins
Cytokins:
-Promotes cell divison
-found in the tissue that are actively dividng like meristems and many other tissues
Ethylene
regulates fruit rippening and stress responses in many plants
Abscisic acid
Abscisic acid inhibits growth and promotes dormancy in many species. It also
induces the closing of stomata during water stress.
senescence
developmental events in
a plant tissue or organ from maturity
to death
