Botany Exam 2

Water loss that occurs by evaporation from the above ground parts of plant

a minute opening, bordered by guard cells, in the epidermis of leaves and stems through which gases pass

The potential energy that water has in a particular environment compared with the potential energy of water at room temperature and atmospheric pressure

tendency of water to move in response to differences in solute concentrations

tendency of water to move in response to differences in pressure

the diffusion of water across a selectively permeable membrane

solute potential inside cell and in surrounding solution is the same. No net movement of water.

Cell is placed in pure water. Its solute potential is low relative to its surroundings. Water moves into cell via osmosis.

Referring to a solution that has a concentration of solute particles high enough to gain water across a selectively permeable membrane from another solution.

a flaccid cell has no turgor pressure ( pressure potential = 0)

outward pressure exerted on the plasma membrane by the fluid contents of a plant cell

resistance of the plant cell wall to increase in turgor pressure

the movement of water up a narrow tube

the elastic like force existing in the surface of a body, especially a liquid, tending to minimize the area of the surface, caused by asymmetries in the intermolecular forces between surface molecules

the sticking together of unlike objects or materials

the mutual attraction of molecules of the same substance

the pressure developed in roots as the result of osmosis, which causes guttation of water from leaves and exudation from cut stumps

a model for the ascent of water in vascular plants. According to this theory, water is pulled up through the plant body in the xylem. This pull, or tension, is brought up about by transpiration and/or use of water by the leaves, which results in a gradient of water potential from the leaves to the soil solution at the surface of the roots

the cell wall continuum of a plant or organ; the movement of substances via the cell walls is called apoplastic movement or apoplastic transport

the interconnected protoplasts and their plasmodesmata; the movement of substances in the symplast is called symplastic movement, or symplastic trnasport

the exudation of liquid water from leaves; caused by root pressure

In plants, the long-distance transport of water, minerals, of food; most often referred to as food transport

the assertion that assimilates are transported from sources to sinks along a gradient of turgor pressure developed osmotically

the process by which substances (primarily sugar) are actively secreted into the sieve tubes

the process by which sugars and other assimilates transported in the phloem exit the sieve tubes of sink tissues

the overall movement of water or some other liquid induced by gravity, pressure, or an interplay of both

the process by which organisms take in and utilize food material.

Chemical elements essential for normal plant growth and development

Inorganic chemical elements required in large amounts for plant growth, such as nitrogen, potassium, calcium, phosphorus, magnesium, and sulfur.

Inorganic chemical elements required only in very small, or trace, amounts for plant growth, such as iron, chlorine, copper, manganese, zinc, molybdenum, nickel, and boron.

the sum of all chemical processes occurring within a living cell or organism

- requires energy input

- complex molecules are broken down into simpler ones

- releases energy

- complex molecules are broken down into simpler ones

- substance loses electrons

- releases energy

- substance gains energy

- requires energy

- (energy currency)

a nucleotide consisting of adenine, ribose sugar, and three phosphate groups

a coenzyme that, in the form of NADPH, functions as an electron donor in many of the reduction reactions of biosynthesis

an intracellular process in which molecules, particularly pyruvate entering the citric acid cycle, are oxidized with the release of energy. The complete breakdown of sugar or other organic compounds to carbon dioxide and water is termed aerobic respiration, although the first steps of the process are anaerobic.

the process by which an organism uses light energy to drive the synthesis of carbohydrates

the reactions of photosynthesis that require light and cannot occur in the dark.

the energy captured by the light reactions will be used to fix carbon to synthesize simple sugars

The series of enzymatically meditated photosynthetic reactions during which CO_2 is reduced to glyceraldehyde 3-phosphate and the CO_2 acceptor, ribulose 1,5-biphosphate, is regenerated.

a plastid that contains chlorophylls; the site of photosynthesis.

a saclike membranous structure in cyanobacteria and in the chloroplasts of eukaryotic organism; in chloroplasts, stacks of thylakoids form the grana

Structures within chloroplasts, seen as green granules with a light microscope and as a series of stacked thylakoids with an electron microscope

the ground substance of plastids

the entire spectrum of radiation, which ranges in wavelength from less than a nanometer to more than a kilometer

a substance that absorbs light, often selectively

the green pigment of plant cells

a class of fat-soluble pigments that includes the carotenes and the xanthophyll's

the spectrum of light waves absorbed by a particular pigment

the spectrum of light waves that elicits a particular reaction

when a pigment involved in photosynthesis absorbs light, the electrons are temporarily boosted to a higher energy state- the excited state

the transfer of light energy from an excited chlorophyll molecule to a neighboring chlorophyll molecule, exciting the second molecule and allowing the first one to return to is ground state

- the chlorophyll a in the reaction center are called P_700

- optimal absorption peak at 700 nm

- the chlorophyll a in the reaction center are called P_680

- optimal absorption peak at 680 nm

the portion of a photosystem that consists of pigment molecules (antenna pigments) that gather light and "funnel" it to the reaction center

the complex of proteins and chlorophyll molecules of a photosystem, capable of converting the light energy to chemical energy in the photochemical reaction.

the primary electron acceptor

the light-dependent oxidative splitting of water molecules that takes place in Photosystem II of the light reactions of photosynthesis

electrons that reach phenophytin

formation of ATP in the chloroplasts during photosynthesis

- In chloroplasts, the light-induced flow of electrons originating from and returning to Photosystem I

- the light-induced flow of electrons from water to NADPH in oxygen-evolving photosynthesis

the oxygenase activity or Rubisco combined with the salvage pathway, consuming O_2 instead of CO_2

- plants that employ only the Calvin cycle, or C3 pathway, in the fixation of CO2

- Plants in which the first product of CO2 fixation is a four-carbon compound

a variant of the C4 pathway

starting and ending compound of Calvin cycle

RuBP carboxylase/oxygenase the enzyme that catalyzes the initial reaction of the Calvin cycle, involving the fixation of carbon dioxide to ribulose 1,5-biphosphate (RuBP).

layer or layers of cells surrounding a vascular bundle; may consist of parenchyma, collenchyma, or sclerenchyma.

the ground tissue (parenchyma) of a leaf, located between the layers of epidermis; mesophyll cells generally contain chloroplasts.

an organic substance produced, usually in minute amounts, in one part of an organism and transported to another part of that organism where it has a specific effect; hormones function as highly specific chemical signals between cells.

a class of plant hormones that control cell elongation, among other effects

a class of plant hormones that promotes cell division, among other effects.

a simple hydrocarbon, H2C=CH2; a plant hormone involved in the ripening of fruit.

a plant hormone that brings about dormancy in buds, maintains dormancy in seeds, and brings about stomatal closing, among other effects

a class of plant hormones, the best known effect of which is to increase the elongation of plant stems

a group of growth-promoting steroid hormones in plants that play essential roles in a wide range of developmental processes, such as cell division and cell elongation in roots and stems, vascular differentiation, responses to light (photomorphogenesis), flower and fruit development, resistance to stresses, and senescence

a hormone produced by plants in response to leaf damage

activates production of proteinase inhibitors

(from tip to bottom)

- undirectional transport of IAA

- IAA is always transported toward the base (basipetally)

- via vascular parenchyma cells

development or (differentiation) that proceeds toward the base (away from the apex) of an organ; the opposite of acropetal development (or differentiation)

the influence exerted by a terminal bud in suppressing the growth of lateral, or axillary, buds

toward the stimulus

away from the stimulus

growth in which the direction of the light is the determining factor, such as the growth of a plant toward a light source; turning or bending in response to light

the response of a shoot or root to the pull of the Earth's gravity

a response to contact with a solid object

- when the root cap is removed from root tip, the root does not respond to gravity

- gravity sensing cells are in the root cap

- statoliths are gravity sensors

- gravity pulls heavy amyloplasts to the bottom of the plant cell

a leucoplast (colorless plastid) that forms starch grains

- auxin is relocated to the lower side of the root

- auxin inhibits cell elongation on the lower side of the root

- root consequently bends downward

regular rhythms of growth and activity that occur in an approximately 24-hour cycle

response of organisms to duration and timing of day and night; a mechanism that has evolved for measuring seasonal time.

a phycobilinlike pigment, found in the cytoplasm of plants and a few green algae, that is associated with the absorption of light; photoreceptor for red and far-red light; involved in a number of timing processes, such as flowering, dormancy, leaf formation, and seed germination

plants that must be exposed to light periods shorter than some critical length for flowering to occur; they usually flower in autumn

plants that must be exposed to light periods longer than some critical length for flowering to occur; they flower in spring or summer

plants that flower without regard to daylength

pressure within the cell resulting from the movement of water into the cell

joint like thickening at the base of the petiole of a leaf or petiole of a leaflet, having a role in the movements of the leaf or leaflet

- water loss that occurs by evaporation from the above ground parts of plant

- most water is last through stomata

- occurs when stomata are open and when air surrounding leaves is drier than leaves

- loss of water when stomata are open

- the potential energy that water has in a particular environment compared with the potential energy of water at room temperature and atmospheric pressure

-differences in water potential determines the direction water will move

- water moves from regions of high water potential to regions of low water potential

- the diffusion of water across a selectively permeable membrane

- water moves from region go greater water potential (i.e., lower solute concentration) to one of lesser water potential (i.e., higher solute concentration)

- the movement of water up a narrow tube

- capillary action occurs in response to 3 forces:

*Surface tension (stick to surface)

*Adhesion (stick to walls)

*Cohesion (stick together)

- cell in isotonic solution => nothing happens

- cell in hypotonic solution => cell enlarges

- water absorption takes place through epidermis of roots (lower water potential there)

- water moves from epidermis to cortex to endodermis to vascular cylinder

- apoplastic = between cells (this reaction)

- symplastic = through cells

- At night, roots accumulate ions through the soil

- ions move into xylem, lowering xylem water potential below that of surrounding cells

- water flows into xylem, generating positive pressure that forces water up the xylem

- more water moves from xylem into leaves than is lost by transpiration

(not due)

water is forced out of pores on the edge of the leaf by root pressure (short distance water movement)

water is pulled through the xylem to the tops of plants along a water potential gradient due to

- pulling forces created by transpiration

- bonding between water molecules

- movement of sugars through the plant from sources to sinks

- phloem sap moves down a steep pressure potential gradient

- source: tissue where sugar enters the phloem

- sink: tissue where sugar exits the phloem

- Macronutrient: an essential element that is required in a fairly large amount for normal plant growth

- Micronutrient: an essential element that is required in very small amounts for normal plant growth

- Criteria 1: element is required for normal growth and reproduction; element is needed to complete life cycle

- Criteria 2: element is required for a specific structure of metabolic function

- macronutrients: oxygen, carbon, hydrogen, nient: oxygen, carbon, hydrogen, nitrogen, potassium, phosphorus, calcium, magnesium, sulfur

- micronutrients: chlorine, manganese, boron, nickel, iron, zinc, copper, molybdenum

- Growth of plants is often limited by the availability of nitrogen (N) or phosphorous (P)

- deficiency usually causes yellowing (chlorosis)

anabolic

- requires energy input

- complex molecules are synthesized from simpler ones

- (Calvin cycle?)

catabolic

- releases energy

- complex molecules are broken down into simpler ones

oxidation

- substance loses electrons

- releases energy

reduction

- substance gains electrons

- requires energy

photosynthesis

- uses CO2 and H2O, C is reduced

- occurs in photosynthetic autotrophs

- solar energy is converted to chemical energy

cellular respiration

- releases CO2 and H2O, C is oxidized

- occurs in all organisms

- chemical energy released from sugars and stored in ATP

- the process by which an organism uses light energy to drive the synthesis of carbohydrates

- energy from light is transformed into chemical energy

- the energy to do the above comes from certain light waves captured by certain pigments

- light-dependent reactions (thylakoid membrane)

- calvin cycle (stroma)

- Chloroplast

pigments

- substances that absorb light

- pigments are efficient in absorbing certain wavelengths

photosynthetic pigments

- chlorophylls (chlorophyll a is required)

- Carotenoids

- phycobilins

- photosynthetic action spectrum is very similar to absorption spectra of chlorophyll

- action spectra is wavelength vs. biological activity seen (rate of photosynthesis)

- absorption spectra is wavelength vs. absorption of energy

excitement, the electrons are temporarily boosted to a higher energy state. starts spinning faster.

- cyclic: photosystem I is involved, the active reaction center is p700, only ATP is produced, oxygen is not evolved.

- noncyclic: photosystems I and II is involved, the active reaction center is p680, ATP and NADP is produced, oxygen is evolved.

- the movement of ions across a selectively permeable membrane, down their electrochemical gradient. (generation of ATP)

- electrons that reach phenophytin are down an ETC in thylakoid membrane. triggers synthesis of ATP. NADPH into O2

- P680 replaces its lost electrons one at a time by extracting them from water

-this process liberates O2

- Generates a proton gradient across thylakoid membrane

- light-dependent reaction: (thylakoid) chlorophyll is embedded in the thylakoids of chloroplasts in units called photosystem I and II.

- Calvin cycle: (stroma) requires more ATP (3:2),

- products: NADPH, ATP

1. water is dissociated into electrons, protons, and free oxygen. ATP and NADPH is produced.

2. (Calvin cycle) actual fixation of carbon is carried out. ATP and NADPH is consumed.

stages: fixation, reduction, regeneration

- CO2 is combined with RuBP via the enzyme ribulose bisphosphate carboxylase oxygenase (Rubisco)

- the resulting 6-C compound breaks down into two molecules of 3-phosphoglyceric acid (PGA).

>PGA is the first detectable product of the Calvin cycle

- PGA is reduced to glyceraldehyde 3-phosphate (G3P)

- this step uses ATP and NADPH

- Fate of G3P

> In 6 turns of the Calvin cycle, 2 "extra" molecules G3P is produced. This G3P is transported to the cytosol and converted to gluclse or other sugar.

- RuBP is regenerated from G3P

- ATP is used

(bad!)

When Rubisco fixes O2 rather than CO2

- C3 maybe C4 (?)

C3: 3 ATP/fixed CO2, photorespiration very common, 85% plants have C3, (Wheat)

C4: 5 ATP/fixed O2, additional ATP to regenerate PEP, increases CO2 concentrations around the Calvin cycle resulting in less photorespiration, (Corn)

CAM: plants separate pathways in time rather than space (<C4), (Pineapple, Cacti)

- organic compounds that are produced in small quantities by plants, serves as a communication mechanism between cells, tissues, and organs

- some hormones are synthesized in one part of the plant, transported to another part of the plant, where it induces a chemical response

- other hormones are produced in the same tissue where they elicit a physiological response

- transport: polar-from tip to bottom & non polar-via sieve tubes of phloem

- functions: apical dominance, vascular tissue, differentiation, induction and arrangement of leaves, lateral and adventitious root formation, fruit development

- function of synthetic auxin: weed killer

- transport: via xylem from roots to shoots

- functions: regulation of cell division, root and shoot development, delay leaf senescence

- Gas, synthesized in most tissues

- transport: by diffusion

- functions: cell expansion, fruit ripening, promotes abscission

- Growth response involving bending or curving of a plant part in response to an external stimulus

- growth of plants toward the direction of light, caused by elongation of cells, under the influence of auxin, on the shaded side of the tip. blue light mediates phototropic response

- growth in response to gravity.

- roots exhibit positive gravitropism

- shoots exhibit negative gravitropism

- starch-statolith hypothesis: when root cap is removed, root doesn't respond to gravity. amyloplasts are the primary gravity sensors. statoliths are gravity sensors

Starch-stotolith hypothesis: when root cap is removed, root doesn't respond to gravity

-amyloplasts are the primary gravity sensors

-statoliths are gravity sensors

- weight of amyloplasts activates sensory proteins that trigger gravitropic response

- Growth in response to touch

- Coiling of tendrils

- initiated by touch with a solid object

- caused by uneven rates of growth

- regular cycles of growth and activity that occur on approximate 24-hr basis

- daily rhythms consist of photosynthesis, hormone production, and cell division

- response of plant to relative length of day and night

- phytochrome senses light, red and far-red (the active form), acts as an on/off switch, in the dark P_FR reverts back to P_r

short-day: flower only when day are shorter than a critical period; spring or fall

long-day: flower only when days are longer than a critical period; mid-summer (flashlight can trigger flowering)

day neutral: flower regardless of day length

response to movement (stimulus)

- thigmonastic movement: due to changes in turgor pressure of parenchyma cells in the pulvinus