Plant Physiology, Growth and Development Flashcards
absorb water and minerals (nutrients) from the soil
Roots
To grow, flower, and produce seeds, plants need a variety of _________ in addition to carbon dioxide and water
Inorganic Nutrients
Most important nutrients that plants need
Nitrogen, Phosphorus, Potassium, Magnesium, Calcium
______ comes from the soil, while _______ comes from the air
Water and Minerals, Carbon dioxide
What are the positively charged minerals that adhere by electrical attraction to the negatively charged surfaces of clay particles
Potassium (K+), Calcium (Ca2+), Magnesium (Mg2+)
Minerals that are negatively charged that are less tightly bound to soil particles and tend to leach away more quickly
Nitrate (NO3-), Phosphate (H2PO-4), Sulfate (SO4^-2)
are made available to the plant when hydrogen ions (H+ ) in the soil displace the mineral ions from the clay particles
Positively charged mineral ions
A process that is stimulated by the roots, which secrete H+ and compounds that form acids in the soil solution.
Cation exchange
What do cell membrane of root epidermal cells contain
Active Transport Protein (ATP)
Movement of water to the side with the greater concentration of
solute (a passive transport of water)
Osmosis
move water and minerals from the root epidermis into the cortex
Osmosis and active transport
The water and dissolved minerals pass the inner boundary of the cortex and enter the _____
Endodermis
Cells in the endodermis are made waterproof by the
Casparian strip
Each endodermal cell is surrounded on four sides by a
waterproof strip called the
Casparian strip
What kind of transportation does Casparian strip controls
Apoplastic Transport
the cytoplasmic continuum
Symplast
the continuum of cell walls plus extracellular spaces
Apoplast
pushes water through the vascular system of the entire plant
Root pressure
Water and minerals ascend from roots to shoots through the
Xylem
Water is pulled upward by
_________ in the xylem
negative pressure
Water is pulled up through the xylem
Transpiration, Adhesion, Cohesion, and Tension
generated by transpiration is largely responsible for the upward movement of water in xylem
negative pressure
According to this theory: Due to transpiration, water is lost in the form of vapor from the leaves
Transpiration Pull Theory
powers photosynthesis and these sugars are transported via the phloem (translocation)
Sunlight
Materials are translocated in the phloem from sources (usually mature leaves) to sinks (roots, immature leaves)
Phloem transport
also called mass-flow or bulk flow
Pressure flow model
Translocated solutes are mainly
Carbohydrates
It is the most common translocated sugar
Sucrose
Phloem also contains
Amino acids, proteins, inorganic ions, and plant hormones
Sugars and other organic materials are conducted throughout the plant in the phloem by means of
Sieve tube elements
is driven by a gradient of pressure.
Flow
It is required to establish the pressure gradient, but energy is not required by cells of the pathway itself.
Energy
Often occurs at night, is caused by the continued, active accumulation of ions in the roots at times when transpiration from the leaves is very low or absent
Root pressure
The exudation of water droplets (xylem sap) on tips of grass blades or the leaf margins of some small, herbaceous eudicots
Guttation
does not take place through the stomata, but instead occurs through special groups of cells located near the ends of small veins
Guttation
Are connected to the plant vascular system by a vascular bundle. It probably evolved from modified stomata
Hydathodes
The evaporation of water vapor from plant surfaces; especially in leaves (through the stomata), also in stems, flowers, and roots.
Transpiration
When is stomata usually closed
when there is too little water available, temperature is low, or there is little light.
Stomatal Control is controlled by
Guard cells
regulate water loss in plants
and the rate of CO2 uptake
Stomata
What happens to the stomata during night
No photosynthesis occurs, stomata is closed
What happens to the stomata during a sunny day
Demand for photosynthesis is high, stomata is open
What happens to the stomata when water is abundant
Stoma is wide open
What happens to the stomata when water is limited
Stomata will open less or remain closed even on a sunny day
It is what flank the stoma which also controls the diameter of the stoma by changing shape
Guard cells
Guard cells gain and loss water by
Osmosis
It is defined as an increase in the number, size, and volume of cells; definite (measurable)
Growth
It is the emergence of specialized, morphologically different body parts; indefinite
Development
In biological systems, what does growth mean
indicates a quantifiable change in size
In biological systems, what does development mean
indicates a transformation
of structure
What are the internal factors that regulate the growth of plants
Affecting growth and development of plants are the Plant Growth Regulators (PGRs)
What are the external factors that regulate growth of plants
light intensity, day length, gravity, touch, temperature, and water
Plant growth is influenced by
phytohormones (plant
growth regulators/PGRs)
is a chemical produced in one part of an organism, transported to other tissues where it has its effect
Hormone
are organic compounds produced in the meristems and transported through the vascular system of the plant
Plant Growth Regulator
It determines the formation of flowers, stems, leaves, the shedding of leaves, and the development and ripening of fruits.
Plant Growth Regulator
Four types of movement that transports PGR
- cytoplasmic streaming within cells
- slow diffusion of ions and molecules between cells
- sieve tubes of the phloem
- xylem
5 main group of PGR
- Auxin
- Gibberellin or Gibberellic acid
- Cytokinin
- Ethylene
- Abscisic Acid (ABA)
PGR that promote growth
Auxins, Gibberellin, and Cytokinin
PGR that inhibits growth
Abscisic Acid, Ethylene
PGRs are produced in what concentration
Low concentration
Synthesized in the shoot apical meristem promote cell enlargement and growth
Auxin
It inhibits cell division in some tissues (apical dominance). Stimulate cell division in vascular cambium. It helps regulate gravitropism (change in direction of growth due to gravity
Auxin
change in direction of growth due to gravity
gravitropism
In shoots, light causes auxin to move down the shaded part of the stem, causing the shoot to grow towards the sunlight
Phototropism
Are used in rooting powders
to stimulate root formation in stem cuttings
Artificial Auxins
It is used as a selective weed killer (weedicide), causing unequal growth (twisting & deforming of leaf blades and stems), thus the overall growth of the plant is retarded and eventually stopped
synthetic auxin
Promote cell division and elongation in plant shoots and cell (differentiation). It breaks seed and bud dormancy. Play a role in flowering and fruit formation in many species. Help make carbohydrates for embryo. Cause stem lengthening
Gibberellin or Gibberellic Acid
used to stimulate fruit production
Gibberellin sprays
when floral buds are initiating, the plant is sprayed with auxin or gibberellin so that the fruits do not develop seeds
artificial parthenocarpy
Promotes cell division; found in meristems, young leaves and growing seeds. Slow cell aging by inhibiting protein break down and
stimulating protein synthesis
Cytokinin
Promotes chlorophyll synthesis. Enhance stomatal opening in some species
Cytokinin
Plant growth is a balance between the action of _______ and _______
Auxins and Cytokinins
Called the plant stress hormone because it causes changes to the plant to protect itself from environmental stress
Ethylene
What are cytokinin sprays used for
Prevention of rotting
Regulates the growth of plant roots and shoots around obstacles
Triple response
Stimulates fruit ripening, leaf and fruit drop, flower and leaf
senescence
Ethylene
It breaks down chlorophyll which causes leaves to fall. It is produced when senescence or abscission (falling of leaves or
fruits) is needed
Ethylene
What happens during triple response in plants
Stem elongation slows
Thickening of stem
Curvature to stem growth
inhibits growth in response to changes in temperature and light
(e.g. seasons); causes bud and seed dormancy
Abscisin or Abscisic Acid
Controls the closing of stomata in dry conditions
Abscisin or Abscisic Acid
has great survival value because it ensures that the seed will germinate only when there are optimal conditions of
light, temperature, and moisture
Seed dormancy
Are steroids chemically similar to
cholesterol and the sex hormones of animals
Brassinosteroid
When was Brassinosteroid first isolated
Brassica Pollen in 1979
Induce cell elongation and division in stem segments and seedlings. They also retard leaf abscission and promote xylem
differentiation
Bassinosteroid
External Factors that affect plant growth
Light, Food, Water, Temperature, Soil pH
It is limited by environmental factors
Quantity
Quality of light is influenced by
– Shade from other plants
– Cloud cover
– Time of day
– Seasons
_______ in meristems increases the potential for growth
Cell Division
It is the irreversible change in size of cells and plant organs due to both cell division and cell enlargement
Growth
Accounts for the actual increase in plant size
Cell expansion
when an organ or part or whole
organism reaches a certain size and then stops growing
Determinate Growth
when cells continue to divide
indefinitely
Indeterminate Growth
Cell division only takes place in areas called
Meristem
Where are meristems found
Roots and Shoots
It is the progression from earlier to later stages in maturation
Development
Development involves what
Growth, Morphogenesis, Cell Differentiation
These three act in concert to
transform the fertilized egg into a
plant
Growth, morphogenesis, and
cellular differentiation
Plants pass through developmental phases
Phase Changes
