Lecture Exam 2 Flashcards
Leaves, Water in plants, plant metabolism
what is the primary function and origin of leaves?
Function: site of photosynthesis
Origin: primordia in buds
What is the equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What are the types of leaves?
simple, compound
what are the types of compound leaves
pinnately compound
bipinnately compound
palmately compound
what is the venation in monocots?
parallel venation
what type of venation do dicots have?
netted venation
what are rachis?
extensions of the petiole
where are waxes found?
on the cuticle, on stem, on fruits
how does environment affect anatomy and morphology?
leaves in the sun have more chloroplasts and palisade mesophyll, plants in shade are larger
what is a stomate?
pore in the epidermis of a plant
what are guard cells?
cells that surround the stomata and open/close depending on conditions
what are the typical layers of a leaf?
cuticle
epidermis
palisade mesophyll
spongy mesophyll
epidermis
how do pine leaves differ from deciduous leaves?
pine have a hypodermis (to provide rigidity), no distinction between palisade and spongy mesophyll, sunken stomata, resin canals (to carry resin), and an endodermis
what is resin?
thick “sap” secreted from pines that have antiherbivore and antibacterial properties
How do leaves conserve water?
orient leaves to/from sun
bulliform cells fill with water so grass can receive direct sunlight (and the opposite)
what does the compass plant do?
pulls leaves perpendicular to avoid sun
What are tendrils?
terminal leaflets of pea plants that are modified (whole leaves, petioles, stipules can be modified as tendrils)
what do spines of barberry (modified leaves) do?
provide shelter for mice that carry the ticks that carry lyme disease
what are throns?
modified stems in the axils of leaves
what are flower pot leaves?
modified leaves where roots grow inside the leaves
what are window plants?
plants with modified “window” leaves that are transparent at the tip
stone plants, succulents
what are reproductive leaves?
modified leaves with plantlets growing along the margins
(plantlets genetically identical to parent)
mother of thousands
what is inflorescence?
a group of flowers
what are floral leaves?
colored bracts (modified leaves) that fulfill the function of petals on a flower
Why is clary’s sage special?
have small flowers below and large modified leaves (bracts) above
what is a pitcher plant?
carnivorous plant with insect trapping leaves (downward pointing hairs to help trap)
grow in wet bogs where soil is acidic and low in mineral nutrients and get their nutrients from the insects
What is sundew?
a carnivorous plant that traps insects via the mucilage on hairs
What is a venus flytrap?
a carnivorous plant with open traps that have trigger hairs that will close around an insect
what is a bladderwort?
an aquatic carnivorous plant that traps small crustaceans (daphnea) in “bladders”, suck them in very quickly
what are the photosynthetic pigments and what color are they?
chlorophyll A: blue-green
Chlorophyll B: yellow-green
carotenoids (carotene, xanthophyll): yellow
anthocyanins: red
how does color change in the fall work?
chlorophyll breaks down, unmasking the yellow carotenoids
why do leaves turn red?
the leaf interior changes pH as chlorophyll degrades which stimulates the production of anthocyanins, which protect from UV
what is the process by which leaves are shed?
abscission
what does deciduous mean?
leaves fall off the trees in the fall
list the human uses of leaves
pennyroyal: pungent oil
shade for homes
food: cabbage, lettuce, parsley, spinach
dyes: henna (red) bearberry (yellow)
fibers for rope: agave
medicines derived from leaves: atropine, marijuana, aloe
cocaine, tobacco, belladonna
lobelia: smoking cessation
tea
fuel
insecticides: nicotene, neem
carnauba wax: palm tree
what do the edges of some grasses possess?
“teeth”
why do plants need water? 1-6
- young cells can be 90% water
- enzymatic processes and other chemical reactions take place in water
- some H2O used in photosynthesis
- mesophyll cell surface in leaves must be moist for CO2 from air to diffuse into cell
- water is needed for cell turgor, important to give rigidity to herbaceous plants
- some evaporative cooling of leaves takes place
what is diffusion?
movement of particles from a region of higher concentration to a region of lower concentration
what is osmosis?
specialized diffusion of water molecules from high to low concentration that occurs across a semipermeable membrane
what is osmotic potential of a solution?
a measure of the potential of water to move from one cell to another as influenced by solute concentrations
what is turgor pressure?
(pressure potential)
the pressure of the cell contents against the cell wall as a result of water entering the vacuole of the cell
what is water potential?
osmotic potential and pressure potential added together, water moves from cell with high potential to cell with lower potential [weird greek letter equation: water potential=osmotic+ pressure]
what is a turgid cell?
cell filled with water, turgor pressure develops against the walls of the cell
what is plasmolysis?
cells lose water and shrink in a hypertonic solution
what is imbibition?
absorption of water and swelling of organic material due to the adhesion of water to the charged molecules of the internal surfaces of the cell,
what is hypertonic, isotonic and hypotonic?
Hyper: higher solute concentration outside cell
iso: equal concentrations no net movement
hypo: higher solute concentration in cell
How do mangrove roots work?
utilize active transport of molecules into root cells follow by osmosis
they concentrate mannitol and amino acids (proline) in root cells to prevent water loss to the environment
what is transpiration?
water enters the air by way of leaf
What is the path of water from soil to plant ?
soil to root hairs to xylem (upwards-roots) to xylem (stems) to mesophyll to stomates back out into air
how much water passes through a plant?
90% passes through and evaporates
5% lost through cuticle
what is the cohesion tension theory?
water moves from less negative to more negative potentials: water moves via capillary tubes and in endodermal cells water passes through endodermis into xylem
how is transpiration regulated?
stomates regulate transpiration and gas exchange
guard cells change depending on the turgor pressure when exposed to changes in light, CO2 or water concentration
what does water follow?
potassium that enters via active transport
how do stomates respond to water stress?
- stomates close when plant isnt getting enough water
- abiscisic acid (hormone) is produced in leaves subject to water stress causing membrane leakage from cells
- potassium ions leave guard cells, water follows and the cells deflate
what is guttation?
the loss of water in liquid form from within the plant through hydathodes at the tips of veins some some herbaceous plants
How does guttation work?
minerals cause water to flow into xylem, pressure builds and water is released from hydathodes
what is the pressure flow hypothesis?
flow of sugars through phloem from source to sink via active transport in sieve tube members
(where leaf is source and roots are sink), water osmoses into sieve tubes and pushes from low conc yo high conc sugar down to sink
what is metabolism?
the sum of all chemical reactions that take place in a cell
what are the two types of metabolism?
anabolism and catabolism
what is anabolism?
enzymes help form chemical bonds and build molecules [PHOTOSYNTHESIS]
what is catabolism?
enzymes help break chemical bonds and break down molecules [CELLULAR RESPIRATION]
What is endergonic?
energy stored
what is exergonic?
energy released
What is oxidation-reduction?
oxidation= loss of electron
reduction= gain of electron
transfer of electrons often accompanied by transfer of H+
Explain the visible spectrum
wavelengths of light visible to the human eye (ROYGBIV)
in the middle of the spectrum between short wavelength+high energy (gamma) and long wavelength+ lower energy (radio)
What are the 2 chemical pathways in plants?
C3: first stable molecule to hold CO2 in this pathway is a 3 carbon molecule (normal climate, lower temp)
C4: first stable molecule to hold CO2 is a 4 carbon molecule (hot, dry environment, higher temp)
What is hlorophyll?
pigment that absorbs light energy
WHat reactions do chloroplasts run?
light dependent and light independent rxns
what are the light dependent rxns
occur in thylakoid membranes where chlorophyll is held, makes ATP and NADPH, H2O is an important reactant
what are the light independent rxns
occur in stroma
calvin cycle, CO2 fixed C-C bonds will form and glucose will be formed
what are the reactions of photosynthesis?
first light dependent then light independent
what is Engelmann’s experiment?
algae exposed to light, bacteria were attracted to O2 produced cells in certain color regions
which of the chlorophylls is more abundant?
chlorophyll a
b transfers energy to a
what are the colors of the carotenoids?
carotene= yellow
xanthophyll= pale yellow
What does RUBISCO do?
Ribulose Biphosphate Carboylase Oxygenase enzyme can fix CO2 through activity as a carboxylase or can fix O2 through activity as an oxygenase
What is photorespiration?
process where 5C RuBP combines with oxygen and a subsequent pathway that releases CO2
What is the positive role of photorespiration?
allows C3 plants to survive hot, dry conditions (dissipates ATP and accumulated electrons from light reactions, prevents photooxidative damage)
what is the first stable product in the calvin cycle?
3 carbon molecule 3-PGA
What is the equation for aerobic cellular respiration?
glucose + oxygen –Enzymes–> carbon dioxide +water + energy
C6H12O6 +6O2—-> 6CO2 +6H2O+ENERGY
what are the 4 phases of complete glucose breakdown?
glycolysis, preparatory rxn, citric acid cycle, E.T.C.
What is assimilation?
conversion of sugars to lipids, proteins or other carbohydrates (sucrose, starch, cellulose)
what is digestion?
conversion of starch and other insoluble carbohydrates to soluble forms (through hydrolysis)
How are thylakoid membranes organized?
Chemiosmosis occurs in the mitochondria (cristae), electrons are passed to the acceptors, and H+ ions are passed up the electron chain and flow through the ATP complex to form ATP
What is phosphorylation?
ADP+P=ATP
What is the Calvin cycle?
Discovered by physiologist Melvin Calvin who used the experimental apparatus and isotopically labeled CO2 to discover the nature of the cycle
What does glucose plus fructose equal
Sucrose
How does the C4 pathway work?
CO2 enters the mesophyll cells and C3 binds to CO2 creating C4 molecules to move into bundle sheath cells, where the Calvin cycle occurs
increasing the CO2 affinity
What does increasing the affinity for CO2 do?
Makes less photorespiration more photosynthesis (c fixation is more stable)
Do stomates open after C4 pathway?
No, they stay closed to reduce water loss
What is the CAM pathway?
Crassulacean acid metabolism occurs in tropical plants, the stomates open at night and CO2 enters combines to CO3 and forms C4
Occurs in one cell
What is cellular respiration
Glucose + oxygen —enzymes—> CO2 + H2O + energy
Aerobic
Glucose is reduced
What is glycolysis?
Occurs in cytoplasm
Splits sugars from 6C—> (2) 3C molecules
Net generation of 2 ATP and release of 2 NADH
What happens in the preparatory rxn?
Occurs in mitochondria
3C molecules lose CO2 and become 2C molecules
What is the citric acid cycle?
Happens in mitochondria
Makes 2 ATP, NADH, FADH2 comes out
What is the electron transport chain?
Occurs in mitochondria
Cristal release NADH and FADH2 which allows the release of electrons and H+ to electron receptors which generates ATP
32-34 ATP
How much ATP is produced in cellular respiration?
36-38 net total made in whole process
Not all energy transformed from glucose to ATP due to second law of thermodynamics
Also produced NADH which uses 3 ATP and FADH which uses 2 ATP
What is fermentation?
Occurs in environments without oxygen, anaerobic, glycolysis occurs and 2 ATP is made per glucose
Plants whose leaves fall off at the end of the growing season are
Deciduous
All leaves originate as
Primordia
The plant part that facilitates a leaf blade being oriented at right angles to the Sun is a/an
Petiole
A _____ leaf has a single expanse of blade tissue
Simple
Which statement about Venation is INCORRECT
Some flowering plants have leaves that lack venation even though the stems and roots have vascular bundles
Which of the following do guard cells and palisade mesophyll cells have in common?
Chloroplasts
Leaf veins are located in which of the following?
Mesophyll
The epidermis of leaves normally is coated with
Cutin
The opening and closing of stomata is governed by _______ levels in the guard cells
Water
The spongy mesophyll is so named because it
Has numerous intercellular spaces
Pressure that develops within a living cell as a result of water entering the cell is called
Turgor
Osmosis is a special kind of diffusion in which water molecules
Move across a selectively permeable membrane
If the concentration of solutes outside the plant cell is greater than the concentration on the inside water will
Move out of the cell
When a solute is dissolved in water the _______ of the water is lowered
Osmotic potential
Which of the following plays a role in plasmolysis
Water potential, vacuole, plasma membrane, protoplasm
Inbibition is responsible for
Breaking open the seed coat of germinating seeds
Substances are absorbed and retained against a concentration gradient, through the expenditure of energy, by
Active transport
Which of the following is not involved in guard cell regulation of stomata opening
Imbibition
Many studies leading to our present knowledge of translocation of food in plants utilized radioactive tracers and
Aphids
The direction of movement of food molecules in plants is
From source to sink
Oxidation is the
Loss of electrons
Photosynthesis is an example of a/an _____ set of chemical reactions in plants
Anabolic
The oxygen liberated by green plants during photosynthesis comes from
Water molecules
Several antenna pigments function in photosynthesis. Which is found in flowering (higher) plants
Both carotenoids and chlorophyll b
The longest wavelengths of light useful in photosynthesis are those of
Red light
Which list gives the products of the light reactions of photosynthesis
NADPH, ATP, and an oxygen molecule
In the process of photosynthesis which molecule becomes reduced
CO2
In glycolysis
Glucose is broken down into simpler compounds
The citric acid cycle takes place in the
Mitochondria
In aerobic respiration, how many ATPs are produced from complete respiration of one molecule of glucose
36
Oxidative phosphorylation takes place when protons flow across the inner membrane of a mitochondrion. This is called
Chemiosmosis
Which of the following is a correct comparison between photosynthesis and respiration
Photosynthesis is an energy storing process whereas respiration is an energy releasing process
