Exam 3 Flashcards
Herbs
primary only, annuals
Woody
primary and secondary and perennials
Advantages of Woody Growth
Size, support, water conduction, seed production
Disadvantages of Woody Growth
Expensive defenses needed
Osmosis
net movement of water across a semipermeable membrane
Hypotonic
lower solute conc
Hypertonic
higher solute conc
net direction of water movement
hypo—> hyper
isotonic movement
none
If cell is surrounded by hypotonic solution, then cell —- water
gains
If cell is surrounded by hypertonic solution, then cell —- water
loses
xylem tissues?
tracheids and vessels, water
phloem tissues?
sieve tubes and sieve tube elements, sugars
Cohesion-Tension Theory?
evaporation of water from leaves creates a water deficit that pulls water through xylem
TACT?
transpiration, adhesion, cohesion, tension
Transpiration?
evaporation of water from leaf through stomata
Stomata - structure and function:
epidermal structures – controllable openings – allows CO2 to diffuse in; O2, H2O diffuse out – closed at night and when dry
Be able to describe the movement of water from soil to air thorough the plant
- transpiration ® water deficit in leaf – creates tension in leaf tissues * tension pulls water from leaf xylem by adhesion/cohesion * leaf xylem pulls water from stem xylem * stem xylem pulls water from root xylem * root xylem pulls water from root tissues and soil
Know the evidence that supports the TACT theory
- xylem under inward pressure – requires thicker cell wall to prevent collapse
- air embolism-air in xylem breaks water chain permanently
- flowers with bases cut underwater last longer – Prevents air from entering xylem
Equation of photosynthesis
6 CO2 + 12 H2O ————-> C6H12O6 + 6 H2O + 6 O2
What is the role of visible light?
It is what is converted to chemical energy, absorbed by chlorophyll (blue and red)
What is the role of CO2?
Oxygens from CO_2 go to sugar and water
What is the role of H2O?
Form O_2 gas
Photosynthesis R, P, B?
R: CO_2, H_2O
P: Glucose
B: O_2, H_2O
What is the role of chlorophyll? How does it work?
It is a light-harvesting pigment that absorbs red and blue light and transmits green light.
What kinds of chlorophyll are found in plants? How does their absorption differ?
5 forms, A-E, absorb different wavelengths
What is the role of carotenoid?
Light protection
Know the structure of the chloroplast and roles of each structure.
Double outer membrane, thylakoids is the inner membrane system, stroma is the watery matrix around thylakoids
Where do the light-dependent reactions occur?
Grana
Know the structure of the photosystems and how they function.
Organized clusters of light harvesting pigment molecules, chlorophyll a and b and cartenoids
Functions include antenna, funnel energy to rxn center, energy passed to ETS
What is the role of chemiosmosis? How does it work? Why are thylakoids important in this process?
Mechanisms of atp formation, energy pumps H+ across membrane, creates a charge which allows for flow of H+, this leads to formation of ATP, thylakoids are where this occurs
What are the products and by-products of the light-dependent reactions?
P: ATP, NADPH
B: O_2
What products of the light-dependent reactions are used in the light-independent reactions?
Where do the light-independent reactions occur?
Stroma
List the three phases of the light-independent reactions.
Carbon Fixation, Reduction, Regeneration
Describe what occurs in the three phases of the light independent reactions.
Carbon Fixation: CO_2 is used to make organic compounds
Reduction: ATP→ ADP, NADPH—-> NADP+
Regeneration: RUBP regenerated, allows cycle to continue
What is Rubisco? Why is it important?
Enzyme that mediates CO_2 fixation to 5C RUBP, most abundant enzyme on earth
What is the product of the light-independent reactions?
Glucose
Why are the light-dependent and light-independent reactions considered to be coupled?
The ATP and NADPH from the dependent rxn are required for independent rxns to continue.
What factors influence the light-independent reactions?
CO_2 concentration and temperature
What is photorespiration?
RUBP has a greater affinity for O_2 than CO_2 at low CO_2 concentrations and under high heat/light conditions rapid photosynthesis occurs, so RUBP uses O_2 instead of CO_2 which leads to C loss
What is energy?
Is the ability to do work
List and describe the three main types of photosynthesis, C-3, C-4 and CAM, including any structural differences any of these may have.
MODERATE ENVIRONMENTS C-3: bean, no defense against photorespiration, more efficient bc less ATP needed
HIGH LIGHT/HEAT C-4: Can overcome photorespiration, increases CO_2 concentration, 4-C compound, corn, high light/heat, defense against photorespiration, rapid photosynthesis, requires more ATP
DRY/HOT CAM: conserves water, desert plant, stomata open at night, CO_2—> malic acid, stomata close during day to conserve water loss, in the daytime malic acid releases CO_2 starts up photosynthesis
What is the importance of ATP?
The bond between last 2 phosphates is easily broken and releases energy to do work, it is the energy currency of the cell, stores energy for immediate cellular work
What is the importance of ATP in aerobic cellular respiration?
Stored for immediate use of energy
Describe aerobic cellular respiration.
Involves H_2O and CO_2, 34 ATP are made from cellular respiration, occurs in mitochondria, chemiosmosis ATP formation, requires O_2
What is alcoholic fermentation?
Occurs without O_2, no ATP formed (just 2 from glycolysis), uses CO_2 and 2C Ethyl alcohol, examples are yeasts and plants
How do aerobic respiration and alcoholic fermentation compare?
No production of ATP in alcoholic fermentation, no O_2 in alcoholic fermentation, both use CO_2
How do ethanol fermentation and lactate fermentation compare?
Both no ATP made, occurs in absence of oxygen, lactate is in animals, alcohol plants, yeast
How many ATP are produced by aerobic respiration? Fermentation?
36 aerobic, 2 fermentation
What are plant hormones?
Plant growth regulators, at low concentrations, 5 main hormones
What is lactic acid production? Why does it occur?
Works in addition to aerobic respiration in animals, O_2 deficit
Describe and give the significance of the Darwin and Darwin and the Boysen-Jensen experiments.
Identified the located where auxin is located tip to basal regions of stem
Describe and give the significance of the agar-block experiments.
Directly isolates auxin as hormone responsible for phototropism, blocks with no chemical have no effect versus resin with chemical (stimulated growth and curved shape).
What is the importance of cell elongation caused by auxin?
Causes cell to release acid into wall, softens wall which allows for cell expansion
What are tropisms? How is auxin involved? Know how phototropism and geotropism occur in plants.
They are a directional response to stimuli, there is an inhibition of auxin on lighted side of plant in phototropism, phototropism is the response to directional light, geotropism is the response to gravity, auxin is produced in the stem apex, this causes the roots to grow in the direction of the force of gravity
How does auxin cause apical dominance?
The production of auxin by the stem apex suppresses lateral bud growth, therefore the main stem is the largest element and there are smaller side branches
What is the role of auxin in fruit maturation?
The seeds in fruit produce IAA to trigger maturation, also prevents early abscission
What are the roles of cytokinins?
Stimulate cell division, bud activation, fruit and embryo development, prevents leaf senescence
Where do cytokinins originate in the spring and what affect does this have on the plant?
In spring they are transported from the roots to shoot, dormant buds activate
What are the roles of gibberellins?
Flowering, juvenile to adult conversion, pollen tube growth, stem elongation, seed germination
What can happen if a plant is deficient in gibberellin?
Suppress stem elongation
What is unique about ethylene?
It is the only gaseous growth regulator
How is it produced?
Produced by damaged or dying tissue
What are its effects?
Speeds ripening/spoilage, spreads to other fruits, one bad apple, touch activates growth response (shaking effect)
What is the role of abscissic acid?
Initiation of dormancy, resistance to stress conditions, stomatal closure, control mechanism
What is photoperiodism?
It include phytochrome which essentially detects absence or presence of light
What is phytochrome?
Two forms, far-red (active form), red (inactive form)
How does phytochrome influence flowering?
For short day plants, Pfr present at dawn inhibits flowering, long day plants, Pfr present at dawn induces flowering
What other effects does phytochrome influence?
Inhibits stem elongation, seed germination, spore germination in lycopods
What is florigen?
Induces a cascade of genes to induce flowering Produced in leaf and transported to SA
How do we know that florigen exists?
It is a mobile transcription factor
