Chapter 11 Flashcards
Growth and Development
definition of Growth
an irreversible increase in mass due to the division and enlargement of cells
Differentiation
the cells develop different forms adapted to specific functions, such as conduction, support or secretion.
development
the coordination of growth and differentiation into a single cell into multicellular tissues and organs
enzymes
proteins that catalyze every metabolic step within cells
Nutrients
furnish the elements and energy for plant growth and maintenance
vitamins play an important role in reactions _________ __ _______
catalyzed by enzymes
Most vitamins are _________
coenzymes, or parts of enzymes
what are coenzymes?
organic molecules that participate in catalyzed reactions
Carotene pigments in chloroplasts act as __________
precursors
what is a precursor?
simple molecules that produce new molecules after reacting with other molecules
Hormones
organic substances that differ from enzymes in structure.
signal transduction pathway
A signaling molecule is activated by an outside stimuli, which begins a chain reaction. the end result is the plant’s response to the stimuli
Major plant hormones (5)
- Auxins
- Gibberellins
- cytokinins
- abscisic acid
- ethylene
growth promoting hormones
- auxin
- gibberellin
- cytokinin
growth inhibiting hormones
- abscisic acid
2. ethylene
coleoptile
tubular sheaths that protected the shoots of grass seedlings
agar
a substance obtained from marine algae
Auxin came from the greek word ______, which means __ ________
Auxein, to increase
Auxin production occurs mainly in
apical meristems, buds, young leaves, and other active young parts of the plant
Bioassays
relate the response of a sensitive plant part to the amount of hormone applied to the part
auxins promote
cell enlargement and stem growth, cell division in the cambium, initiation of roots and differentiation of cell types.
auxins inhibit
fruit and leaf abscission, as well as fruit ripening, lateral branching
When auxins inhibit lateral branching, this leads to
A taller plant with fewer buds, AKA APICAL DOMINANCE
Gibberellin was found in the form of a ______ on ____ in _____
Gibberellin was found in the form of a FUNGUS on RICE in JAPAN
there are well over 100 gibberellins, which are abbreviated to
GA
growth retardants
inhibit or block GA
What is coconut milk?
a liquid endosperm
Cytokinins are
various stimulants to cell division
cytokinins are synthesized in
root tips and germinating seeds
if auxin is present during the cell cycle, cytokinins _____…..
promote cell division by speeding up the progression from the G2 phase to the mitosis phase, but no such effect takes place in the absence of auxin
cytokinins also play a role in
enlarging of cells,
differentiation of tissues,
the development of chloroplasts,
the stimulation of cotyledon growth
and the delay of aging in leaves, as well as
many of the growth phenomena that are brough about in auxins and gibberellines
abscisic acid is abbreviated
ABA
ABA is synthesized in
plastids, apparently from carotenoid pigments
ABA is particularly common in ______ ______, where it…….
ABA is particularly common in fleshy fruits, where it prevents seeds from germinating while they are still on the plant
Thigmomorphogenesis
responses that are controlled by touch
Calmodulin
constitutes up to 2% of a plasma membrane and is activated when it binds to calcium
Fruits that respond to ethylene usually have a major increase in ___________ before ripening occurs
respiration
The accompanying major increase in respiration is called
climacteric
fruits that exhibit the respiration phenomena in response to ethylene are called
climacteric fruits
oligosaccharins
released from cell walls by enzymes, influence cell differentiation, reproduction, and growth in plants
Senescence
the breakdown of cell components and membranes that eventually leads to the death of a cell
nutations
movements resulting primarily from internal stimuli
Nodding movements
seen in the legume family. A crook is formed in the hypocotyl, which exhibits a slow nodding movement as the seedling pushes through the soil
twining movements
occur when cells in the stems of climbing plants elongate to differing extents, and a shrinking of cells on the other side, causing a visible spiral effect
contraction movements
seen in roots that pull plant deeper into soil
nastic movements
non directional movements
tropisms
movements that are permanent resulting from external stimuli
Tropisms can be divided into 3 phases
- In the initial PERCEPTION PHASE, the organ receives a greater stimuli on one side
- Then, TRANSDUCTION occurs, during which one or more hormones become unevenly distributed across the organ
- Finally, ASSYMETRIC GROWTH occurs as a result of greater cell elongation on one side
Positive phototropism
plant bends toward light
negative phototropism
plant bends away from light
the shoots exhibit ________ phototropism, while the roots are either insensitive to light or ________ phototropic
Positive phototropism=shoots
negatively phototropic=roots
Gravitropisms
growth responses to the stimulus of gravity
the primary roots of plants are __________ gravitropic while the shoots of plants are __________ gravitropic
roots: positively gravitropic
shoots: negatively gravitropic
What does a clinostat do?
uses a motor and wheel to rotate a potted plant slowly about a horizontal axis
statoliths
gravity sensors
thigmotropism
a plant or plant part’s response to contact with a solid object
Ex: squash vines wrapping on strings
hydrotropism
movement in response to water
chemotropism
movement in response to chemicals
thermotropism
movement in response to temperature
traumotropism
movement in response to wounding/trauma
electrotropism
movement in response to electricity
skototropism
movement in response to darkness
aerotropism
movement in response to oxygen
geomagnetotropism
movement in response to magnetic forces
turgor movements result from
changes in internal water pressure and are often, but not always, initiated by contact with objects outside of the plant
The cells concerned with turgor movement
may be located in parenchyma tissue of the cortex or PULVINI, special swellings located at the bases of leaves or leaflets
Circadian rhythms
folding and unfolding of leaves which takes place during normal day cycles
Ex: Prayer Plant
Solar tracking
leaves often twist on their petioles and orient themselves perpendicular to a light source
Some scientists have referred to solar tracking movements as ____________
heliotropism
Water conservation movements
Bulliform cells in leaves lose their turgor in times of drought and roll up on themselves
Taxis
a type of movement using flagella or cilia that moves a plant toward or away from stimuli
flagella
whiplike appendages
cilia
short, whiplike appendages
An example of a chemotaxic response is
sperm swimming toward a chemical being released from the spot where fertilization can occur
photoperiodism
length of night is related to onset of flowering
short day plants
plants that will not flower unless the day length is shorter than the critical length
long day plants
plants that will not flower unless periods of light are longer than the critical length
intermediate day plants
will not flower if the days are too short or too long
day neutral plants
will flower under any amount as light as long as they receive the minimum amount they need
phytochrome
a light sensitive pigment that can affect the ability for a plant to flower
Phytochrome appears in two forms
Pred and Pfarred
etiolated oat seedlings are….
spindly and pale from having been grown in the dark
cryptochromes
respond to blue light
thermoperiodism
a plant’s growth is effected by temperature
dormancy
a period of growth inactivity
Quiescence
a seed cannot germinate unless environmental conditions normally required for growth are present
