Test #2 Flashcards
Roots
-portion of the plant designed to absorb water and minerals
- Water uptake
- Mineral uptake
- Plant anchorage
- Food storage
- Vegetative propagation
Tap Root
- one central root, more common with dicots - grow deep, more energy in a main root
Fibrous roots
- numerous branches - protection against erosion - large surface area - common among monocots
Adventitous: structures arising from other than expected places
Ex. Brace roots, climbing roots, propagating roots
Stems
-axis of plant which develops from the epicotyl of the embryo or from a but
Support and display
- photosynthesis - storage - vegetative propagation
Node= the often enlarged portion of a stem from which buds and leaves arise
Internode=portion between two nodes
Bud
- dormant shoot meristem
- a unelongated stem with meristem for leaves, lateral buds, flowers or all of the above
Types of Buds
Terminal, Axillary, Adventitious
Terminal
at the apex, responsible for primary growth
Axillary
borne laterally at nodes in angle between leaf and stem
Adventitious
at sites other than nodes or stem apicles (aka sucker or watersprout
Tiller: shoot branch of a grass root, rises from the rhizome
Crown: bottom of the stem… top of the root
Stolon (runners): grows parallel to the ground- horizontal above ground stem
Monocots and dicots
Rhizome: horizontal below ground stem
Bulb
Swollen underground stem
-nodes- linear order
Leaves
- vegetative lateral outgrowth of stems typically specially adapted for photosynthesis
- primary organ of food synthesis allow evaporative cooling
- storage, vegetative propagation
- thorn, tendrils, traps
Leaf Types
Simple
Pinnate- Compound
Palmate- Compound
Two sets of modified leaf like structure
- petals (corolla)
- sepals (calyx)
A complete flower contains (P.S.P.S)
Incomplete Flowers -lack one of the four parts
- Pistil
- Stamen
- Petals
- Sepals
Plants with Imperfect flowers
Dioecious- staminate and pistillate flowers on separate plants
Monoecious- staminate and pistillate flowers on the same plant
Perfect flower= contains both stamen and pistil in the same unit- can be incomplete though
Imperfect flower= lacks either a stamen or pistil
Pistillate flower - only female structures
Staminate flower -only male structures
Pollination
transfer of pollen from the anther to the stigma
Self-pollination: pollen from anther to stigma of same flower or different flower of same plant
- Only one plant to make new generation
- No dependence on wind or pollinators
- Offspring are similarly adapted
Cross-pollination: pollen from anther of one plant to the stigma of another plant (same species)
- Allows new combinations of traits that can be better adapted
- Dioecious
Prevention of Self-fertilization
- Structural barrier
- Developmental barrier
- Genetic barrier
Insect vs Wind pollination
- Flower size (wind flowers tend to be small)
- Odor
- Pollen size
- Nectar production
Fruit
fertilized, developed ovary (and attached parts)
Ovule
structure that bears the embryo sac and will mature into a seed.. Typically inside the fruit
Carpel
innermost part of the flower bearing one or more ovules
Pericarp (Fruit wall)
Ex A peach
Exocarp- outer layer
Mesocarp- middle part
Endocarp- inner layer
Function of Fruit
- Distribution of seeds
* Physical protection
Fleshy- a soft, thick pericarp
Dry- pericarp is hard and dried at maturity
Dehiscence
opening of a structure at maturity
e.g. Anthers Dry Fruits
Dehiscent: carpel spits along
Definite seams at maturity
Indehiscent: fruit wall does not split at any definite suture
The Seed
- Seedcoat or testa
- Food source: endosperm, cotyledon
- Embryo or germ
Zygote
a fertilized egg; a cell resulting from the fusion of gametes
Gamete
Female and male sex cell
Juvenile
Before sexual reproductive maturity
i.e. Vegetable growth, roots, stems, leaves
Mature
Producing Flowers
Vegetative Development- Tropism
Tropism-directional growth in response to a stimulus
• Positive = toward the stimulus
or
• Negative = away from the stimulus
Types of Tropism
-photo- light
(ie. Leaves (positive), stems of ivy on a wall (negative)
-gravi-tropism gravity (plant can detect the pull of gravity)
• thermo- temperature
• thigmo- touch
Dicot Seedling Development
- Stem apex near top of plant
* Axillary buts are aboveground if epigeal emergence
Monocot Seedling Development
- Steam apex near the base of plant
* Below ground axillary buts exist
Primordium=
embryonic or early developmental stage of an organ
Branching-
roots into favorable environment
Shoots from bud primordium
Greater at low plant densities
Apical Dominance
suppression of branching by the tip of the plant, removing the TERMINAL BUDS
Elimination of apical dominance stimulates development of axillary buds or branch roots
Ex- Trim mums because you want small flowers. Trim hedges for fuller hedges.
Developmental Variations
Dwarfing= Reducation or inhibition of height by shortening of internodes.
Rosette= Naturally short internodes, leaves in a tight whorl
Bolting = developmental process in which Rosetted plants produce a flower stalk and seed
Ie Biennials
Determinancy
The pattern of stem development
• Determinate growth - stem terminates as an inflorescence
Inflorescence- the arrangement of flowers on a floral axis
-Won’t grow another node there
• Indeterminate growth- apical meristem remains vegetative during flowering
-can continue to had nodes even after flowering has begun
Determinate Growth
Stem produces leaves at new nodes until it produces an inflorescence
Indeterminate growth
Stem produces leaves at new nodes while flowers develop in leaf axils
Differences due to determinacy
• Period of flowering
○ Uniformity
○ Vulnerability to brief stress
• Number of nodes on a stem
○ Height
○ Leaf number
• Partitioning and rate of seed fill
Reproductive Development
Plants regulate time of flowering
- To assure sufficient support
- To synchronize cross-pollination
- To complete life cycle in season
Photoperiodism= developmental responses of plants to relative length of light and dark periods
N S
L E L
S L E
Photoperiods
○ Days are longer in summer, shorter in the winter
○ Day length varies farther away from the equator
○ Day length is 12 hours everywhere twice per year
○ Days get longer in the spring, shorter in summer
Long Day plants- flower in the spring -before the longest day of the year
Short Day plants- flower in summer- after the longest day- when days are getting shorter… causing it to flower
Flowering is induced when night length passes a certain ‘trigger’ duration - It’s actually night length that influences it
Photoperiodism of flowering signals a plant to begin flowering on a specific calendar day but the date of the signal depends on latitude.
Thus flowering occurs at an appropriate time in only a limited range of latitude.
Vernalization=
induction of flowering exposure to cool temperatures for a required period of time
Vernalization causes flowering to be delayed until a ‘winter’ period has passed
E.g. bolting could be induced by vernalizaton
Ie Brocoli- plant later
Apples- can’t grow in Georgia
Radicle
the embryonic root
Secondary Root
a branch root (aka lateral root)
Tap Root
primary root that persists and maintains its dominance
Fibrous Root System
root system with many adventitious and lateral roots
Adventitious
structure arising from an unusual place; e.g. roots from stems
Node
Swollen portion of the stem from which leaves, branches, and flowers arise
Internode
region of stem between the nodes
Tiller
branch of a grass plant arising from basal nodes
Culm
hollow stem of a grass
Terminal Bud
growing point at stem apex responsible for primary growth
Axillary Bud
dormant shoots in the angle between the leaf and stem
Crown
short stems or the region where stem and root join
Stolon
an above ground horizontal stem
Rhizome
a below ground horizontal stem
Bulb
compact stem enclosed in fleshy or papery leaves
Tuber
enlarged tip of a fleshy underground stem
Tendril
coiling leaf or stem structure adapted for climbing
Blade
flattened or expanded portion of leaf
Sheath
Portion of grass leaf that surrounds the stem
Collar
junction of blade and sheath of a grass leaf
Auricles
ear-like appendages at junction of sheath and blade of grass leaf
Ligule
membranous or fringed structure at top of the sheath
Petiole
stalk that attaches a leaf blade to a stem; common in dicot leaves
Stipules
flattened, leaflike appendages at the petiole base
Sessile
attached directly; e.g. without petiole or pedicel
Leaf Type: Cotelydon
the embryonic leaf
LT: Unifoliolate
blade forms a single unit (aka simple)
LT: Trifoliolate
leaf blade formed of three leaflets
LT: Palmate
leaflets arise from a common point
LT: Pinnate
leaflets on each side of a common axis in a feather like arrangement
Leaf Arrangments:
Alternate
one leaf per node with adjacent leaves forming on opposite sides
Opposite
Two leaves per node formed on opposite sides of the node
Whorled
three or more leaves developed at a node
Pistil
the female reproductive organ of a flower
Stamen
the male reproductive organ of a flower
Inflorescence
the arrangement of flowers on a flower axis; flower cluster
I.T. Rachis
central axis of an inflorescence
I.T. Peduncle
stalk supporting the whole inflorescence
I.T. Spike
flowers attached directly to the floral axis
I.T. Raceme
Flowers borne on short stalks from a single floral axis
I.T. Panicle
Flowers borne on compound branches
I.T. Head
Flowers attached directly to an enlarged stem tip
Grasses- parallel veins in a narrow blade
Broad-leafs- net of veins branching from the midrib
Abscission
natural separation of an organ.
A layer of thin-walled cells forms: an abscission layer
Senescence
The stage of development during which deterioration occurs leading to death
-sometimes defined by specific criteria
e.g. decline in chlorophyll, dry weight
Annuals: whole plant senescence
Perennials: may involve only certain organs
Deciduous: sheds leaves at end of a growing season
Perennials that are not “evergreens”
Agronomic crops
whole plant senescence of annuals allow easy harvest and storage
Horticultural produce
can result in loss of quality if not suspended
Climacteric
developmental process of certain ripening fruits marked by an increase in respiration and a softening of fruit tissues
Climatic Apple Banana Tomato Cantaloupe
Non-Climacteric Bean Cherry Orange Grape
Phytohormones=
Compounds produced by a plant in minute amounts, that coordinate growth and development in different parts of the plant, and let the plant respond to environmental signals
• Compounds are synthesized by the plant
• Site of synthesis may not be site of activity
• Active in micro quantities (e.g. 10^-9 M)
• Responses are usually formative (irreversible such as a new branch or a discarded organ)
i.e. Apical dominant plant is producing hormones in the tip that are sent to the root
Plant Growth Regulator (PGR)
chemical analogs of phytohormones
(Human-synthesized compounds with similar activity
Bioassay
the use of living organisms to quantitatively estimate the amount of biologically active substances present in a sample
Oat coleoptile bioassay- 1920’s
Diffusible substance cause tip curvature
-proportion of concentration of substance
Challenges of studying phytohormones
• Detection in the plant is difficult
• Threshold concentration varies with site and growth stage
• Same compound has different effects in different part of the plants
• Interaction common: effects change if other compounds present
Chemistry- science of the composition and properties of substances and reactions by which they are produced or converted.
Physiology- study of the normal functioning of organisms, and of activities that maintain and transmit life
I.e. the science of essential living processes
Biochemistry vs ‘lab’ chemistry
• Biochemistry exclusive use of organic molecules • Faster reactions at low temperatures • Precision in products from a reaction • More complex reaction combinations - Control rate and ratio of reactions
Catalyst
A substance that changes the rate of a reaction without itself undergoing a permanent chemical change
Enzyme
protein molecule that acts as a catalyst for a specific biochemical reaction
-lowers the trigger energy- lower barrier
Metabolic reactions involve a transfer of energy
Thermodynamic Principles
- Synthesis requires energy
- Decomposition releases energy
- Activation energy is required to break chemical bonds
A reduction in root length, function, and available energy supply would be most likely caused by a loss of function in the…
Phloem
Plant cells have a selectively permeable membrane:
between the cell wall and the protoplasm
A toxic chemical that prevented respiration would least affect mature
fiber cells
Mature Cells are moved further from soil level by the action of
Intercalary Meristem
A significant difference between plants and animals is…
every plant cell has cell wall
Formation of cells occur in the
Cambium
The tissue system with the greatest difference between how it functions in the root and how it functions in the stem would be the…
Dermal
The successful practice of science results in:
ideas that may change in the future
Substrate= reactants in an enzymatic reaction
Product= that results from a reaction between chemicals
Enzymes provide
Rate control
and
Precision
Coupled Reactions=
pairing of energy- releasing reaction to an energy-requiring reaction of compounds.
Types of Coupled Reactions
Exergonic and Endergonic energy- Enzymes are the key to coupling reactions
Energy transfer will be greater in the reaction. if Enzymes couple.
A common exergonic (energy-supplying) component of coupled reactions in plants is ATP and ADP
-enzyme couples reactions
Adenosine Triphospate ATP
ADP- unused and can be reused to transform into ATP (ready and available)
Glucose-storage ATP- available
Photosynthesis converts light energy into available and then stored chemical energy
Cellular respiration converts stored chemical energy to available chemical energy
Photosynthesis
-A chemical process in which light energy is absorbed by a pigment and converted into stale chemical potential
H₂O+ CO₂+ -> C₆H₁₂O₆+ O₂
Inputs Products
Water Carbohydrate
Carbon Dioxide Oxygen
Light reactions- light energy to available chemical energy
Dark Reactions- available chemical energy to stored chemical energy
