Plant Science Exam 3

growth

an irreversible increase in volume or dry weight (biomass) of living cells

can be measured as increase in fresh or dry weight or in volume, length, height, or surface area

plant development

progress through the plant life cycle

seed germination, growth of vegetative organs and tissues

initiation and maturation of reproductive organs and tissue

fertilization, seed development and maturation

senescence and death

photosynthetic active radiation

(PAR)

400 to 700 nm

heliotropic

movements are used by some plants

leaf angles are adjusted throughout the day

maintain 90 degree angle if incidence to increase light

photomorphogenesis

highly integrated plant growth and developmental processes in response to light

de-etiolation

greening of young plants

stem growth

typically, presence or absence of light

may have more specific light spectral composition requirements and changes in leaf structure.

most photomorphogenic responses regulated by

phytochrome

phytochrome

pigment that has 2 interconvertible forms

red light absorbing

far-red light absorbing

cryptochromes

pigments involved in photomorphogenic responses and circadian rhythm

phototropin

a blue light receptor is responsible for phototropism

photoperiodism

the photomorphogenic response to variations in day length

all photoperiodically controlled processes can be categorized into 3 basics types

photoperiod plants

long day

short day

day neutral

critical day length (CDL)

flowering (other processes) induced only at day lengths longer/shorter than specific day length

stratification

some seeds require time during which the seeds are imbibed at low temps before germination is possible

chilling requirement

the duration required to break dormancy

vernalization

cold induction of flowering

determinate growth

after vegetative growth, flower bud clusters form at shoot terminals so mot shoot elongation stops

indeterminate

plants bear flower clusters laterally along the stem in the axils of the leaves

annuals

complete life cycle in one growing season

biennials

complete life cycle requires 2 growing seasons

perennials

remain alive indefinitely

annuals life cycle

germination

vegetative growth

reproductive growth

flower

fruit

seed

death (senescence)

biennials life cycle

limited stem growth 1st season

dormant

reproductive growth 2nd season

perennials life cycle

herbaceous types: shoots may die in winter, new shoots emerge in spring

woody types: root and shoot systems remain alive

shoots may go dormant in winter

juvenility

vegetative only

maturation

reproduction possible

phases of development

juvenility

maturation

senescence

death

circadian rhythms

biological rhythms that complete one cycle in approximately 24 hours

anthesis

flower opening

self pollination

same flower

same plant, different flower

different flowers, same clone

cross pollination

different plant/clone

self fertile

plant produces fruit and seed with its own pollen

self sterile

plant requires pollen from another plant

incompatibility

cross pollination between 2 cultivars can be ineffective

factors inhibiting pollen tube germination or elongation

parthenocarpy

fruit formed without pollination and fertilization

stenospermocarpy

fertilization but embryo aborts

no viable seed is produced

certain seedless grapes

simple sigmoid

slow start

period of rapid size increase

decreased rate near fruit maturity

double sigmoid

single sigmoid growth curve is repeated

climacteric fruits

as they ripen experience a burst of respiration and release high levels of ethylene

ex. apples, apricots, bananas

senescence

terminal, irreversible deteriorative change in living organisms, leading to cellular and tissue breakdown and death

plant hormone

natural chemicals that acts to control plant activities (produced by itself)

plant growth regulators

compounds applied to affect growth/development

plant growth hormone classes

gibberellin

auxin

cytokinin

ethylene

abscisic acid

gibberellin (GAs)

stimulate cell division, cell elongation or both and can control enzyme secretion

auxin

seed germination

apical dominance

one of the most widespread auxins that occurs naturally in plants INDOLEACETIC ACID (IAA)

cytokinin

primarily promote cell division

ethylene

induces fruit ripening

abscisic acid

regulation of processes in seed development (seed dormancy)

a mobile stress hormone in which ABA action initiates responses to cold and water stress

signal guard cells to close stomate and conserve water

secondary hormones

salicylic acid

jasmonates

systemin

salicylic acid

response to pathogen attack

assonates

defense against herbivores

systemin

signaling peptide that induces defense genes

basis for plant nutritional needs

carbs

lipids and fatty acids

proteins

starch

main plant stored carb

cellulose

main structural component in plants

essentially insoluble in water

glucose

6 carbons

most important and common of the sugars

fructose

5 carbon sugar

fruit sugar

sucrose

glucose + fructose

table sugar

unsaturated fatty acids

2 or more double or triple bonds between carbons (places for more hydrogens)

in human diet considered to be more healthy

saturated fatty acids

only single bonds present between carbons

in human diet considered to be less healthy

triglycerides

three fatty acids linked to glycerol

waxes, fats, oils

phospholipids

glycerol molecule with a phosphate group and 2 fatty acids

secondary products

alkaloids

phenolics

terpenoids

alkaloids

bitter taste and acts as detterents

alkaloid examples

morphine

cocaine

nicotine

caffeine

phenolics

flavanoids

anthocyanins

flavonoids

act as pigments in flowers to attract insects and birds

absorb UV light

anthocyanins

antioxidant activity

helps plant cells deal with external stresses such as cold snaps and excess light

thought to be a health component of our diet

terpenoids

rubber (latex)

carbon cycle

starts with photosynthesis (capture of solar energy)

ends with respiration (release of energy)

carbon

forms strong, stable bonds

transfer of electrons (energy) between molecules

oxidized compounds (respiration)-easily accept electrons

reduced compounds (PS)-easily donate electrons to other compounds

photosynthesis equation

6CO2+6H2O=C6H12O6+O2

PS

process of converting oxidized CO2 to reduced C

RS

process of converting reduced carbon to oxidized carbon to generate other forms of energy that are central to the function of living organisms

types of photosynthetic pigments

chlorophyll a and b

carotenoids

xanthophylls

chlorophyll a

most important pigment

absorbs blue, red, and violet wavelengths

carotenoid

yellow to orange

xanthophyll

yellow

light reactions location

grana and thylakoid of chloroplast

light rxn product

ATP and NADPH

2 phases of light rxns

photolysis of H2O

phosphorylation

dark rxns location

stroma

calvin cycle steps

carbon fixation

reduction phase

carb formation

regeneration of RuBP

classification of plants

C3 unregulated

C4 concentration regulated

CAM time regulated

C3 pathway C fixation

CO2 attached to 5C RuBP molecule resulting in 6C molecule

6C splits into 2 3C molecules (3PGA)

reaction accelerated by RuBP carboxylase (rubisco)

CO2 fixed as part of carbohydrate

C reduction

utilizing ATP and NADPH 3PGA is reduced to G3P

C3 pathway carbohydrate formation

G3P makes fatty acids, glycerols, glucose phosphate, fructose, starch, cellulose, amino acids

C3 RuBP regeneration

RuBP used in CO2 fixation must be replaced

every 3 turns of calvin cycle 5 G3P (3C MOLECULE) USED

to remake 3 RuBP (5C molecule) require ATP

C4 pathway

high light intensity, high temp, low moisture

mesophyll cells

PEP- a carboxylase PS in low [CO2]

fix CO2 to PEP (3C)

oxaloacetate (4C)

calvin cycle occurs where in C4

bundle of sheath cells

crassulacean acid metabolism

CAM

during night CAM

stomata open

fix CO2 to form 4C molecules

during day CAM

stomata closed (H2O conservation)

NADPH and ATP available

4C molecules release CO2 to calvin cycle

respiration

extracts energy stored in glucose

converts it to other forms (ATP) to perform metabolic tasks

requires carbs, oxygen and ADP

produces 36 ATP

step 1 respiration

glycolysis

conversion of glucose to pyruvate

takes place in cell cytoplasm

process of glycolysis results in

2 pyruvic acid+2ATP+2NADH

RS 2nd step is called

tricarboxylic acid (TCA) cycle

takes place in cell mitochondria

several rxns involve acids with 3 carboxyl groups