Hort phys test : key points

what is phytochrome

response to red light (sometimes blue)

what type of light does phytochrome respond to

Pr: red light (inactive form)

Pfr: far red light (active form)

what is chromophore

a light reaction

light responses

1. very low fluence responses (VLFRs)

2. Low fluence responses (WFRs)

3. High irradance reponse (HIR)

what do VLFRs do

seed germination

inhibit mesocotyl growth (monocots) - not photoreversible

what do WFRs do

seed germination

inhibit hypocotyl elongation - dicot

leaf movements

what do HIRs do

prolonged/contiunous exposure

flowering

(full sun)

chryptochromes location, where does it go and for what

cytoplasm to nucleus for gene expression

what is chrptochrome activated with

blue and UVA light

what does chryptochrome influence

seed germination

leaf sensence

stress response

seedling detoilation

plant height

flowering tim3

protein synthesis

what are the blue light repsonses

all blue light UV-A responses

ZTL

FKP1

LKP1

what is ztl

a blue light resonse for crycadium rthym

acts as a clock for the plants internal system for flowering or hypocoytl growth

what is FKP1

a blue-light sensor that measures day length to trigger photoperiodic flowering

promotes flowers during long days

what is LKP2

a blue light response

helps the plant distinguish between day lengths — timing the transition from vegetative growth to flowering

what does UVR8 do

cellulose biosynthesis

change gene expression

motify antioxidant function

stomatl movement: opening and closing

chlorophyll a → b ratio in a plant

what type of light does UVR8 respond to

Red light UV-B

what is the location of UVR8

nucleus

embryogenesis: dicot phases

1. zygot phase

2. globular phase

3. heart stage

4. mature stage

explain zygot phase in embryogenesis: dicots

fusion of the egg and sperm to form the zygote

polar growth:

a) apical cell is the top

b) basal cell is the bottom

explain the globular phase in embryogenesis :dicots

two vertical cell divisions

1. central embryo region

2. hypophysis

3. suspendor: energy supply

what are the divisons of the globular stage in embryogenesus for dicots

1, 8, 16, early globular ( 4 stages)

what is the heart stage of embryogenesis for dicots

begins fusion of cotyldeons → apical meristem develops

draw the heart stage of embryogensus for dictos

explain the mature phase in embryogenesis :dicots

accumulation of storage compounds

**starch and oils

(vivivary can occur)

1. loss of water ( needs to dry out)

2. metabolically inactive

3. storage compounds (oils and starch)

4. onset of dormancy

types of seed

endospermic and non-endospermic

explain non-endospermic seeds

rely on cotyldeons for storage (food)

explain endospermic seeds

rely on endosperm for storage

how do seeds break dormancy

exogenous

endogenous

explain breaking dormancy for exogenous seeds

seed coat protection

1.scarification: break down the seed coat mechanically

2. stratification: cold period, time, temp (10-0), moisture

explain breaking dormany for endogenous seeds

dormany relating to the embryo

balance of GA and ABA (hormone balance theory) to break dormancy

what does the hormone balance theory relate to

breaking dormancy for embryos

balance of GA and ABA

seeds go from ____ to ____

heterotropic to autotropic

what are the seed germination phases

phase 1: inhibition

phase 2: Initiation of metabolic and respiration processes

phase 3: stored food

what happens in the first phase of seed germination

phase 1: rapid water uptake

what happens in the second phase of seed germination

phase 2 : initiation of metabolic processes and respiration

(mitochondria repair and multiplication)|

1. transcription

2. embryo expands

3. radicle emerges

4. H2O inhibition slows

what happens in the third phase of seed germination

phase 3:

h2o uptake resumes

stored food for reserve

hetertropic defintion

dependant on endosperm or cotyledons for food sources

autotropic defintion

relies on photosynthesis. produces its own food

What causes elgonation of the hypocotyl (shoot)

GA

or brassinosteroids (a combination of GA and Ba)

what causes hook opening

photochrome sense light,

what inhibits hook opening

ethylene and auxin

what are the four developmental root zones

1. root cap zone

2. meristematic zone

3. elongation zone

4. maturation zone

explain the first zone of the root

root cap: RAM (root apical meristem) base of root

secreting compound

what is the secreting compound for in the root cap

it’s a viscus to go through the soil — it allows it to go through particles like oils and produce root cap cells

explain the second zone in the root

meristematic zone: rapid cell division, undifferentiated cells

explain the third zone in the root

elongation zone:

cell elongation

differentiation of cells to specific tissues

explain the fourth zone of the root

maturation zone:
a. fully differentiated cells

b. Cell division and elongation not needed anymore

c. root hair develops

Which hormones affect or help root hair

ethylene enhances root hairs

jasmonic acid enhance root hair

brassinosteroids decrease root hairs

roots will grow towards ____

the higher water potential

what are amyloplast

in root tip to sense gravity

what are geotropism

response to gravity

amyloplast location and where will they go

located in columella cells (in root cap)

will settle in higher auxin concenetratuins

what will happen after amyloplast settle

development of Pin proteins

what hormone affects apical dominace

Auxin inhibits axillary buds from budding

explain and describe zone theory of the shoot apical meristem

1. central zone: gives rise to other cells

2. peripheral zone: rapid cell division (leaves and lateral organs, noted, thorns)

3. rib zone: internal tissues (stem, vascular tissues)

draw the zone theory

explain and describe the layer theory in shoot apical meristem

internal tissues:
L1: anticlimal division (epidermis)

L2: anticlimal division (sub-epidermal tissues)

L3: more random cell division (callus)

draw the layer theory

what influences the phylloxay arrangement

sugar (sucrose)

what hromone is essential for leaf primorida

auxin

what hormones are involved in lead phyllotacy arrangement

auxin: responsible for the formation

Cytokinin: meristem zone for cell division

Ga: expansion of present cells → results in expansion

what hormones are involved in apical dominance

Auxin and strigolactones block synthesis

BUT keep bud dormancy

• They prevent lateral growth

how can you aid in bud growth

low concentration of auxin leads to bud growth

how does light influence pf and pfr

in shade: no red light

sun: Pfr dominant

scenescne def

process of aging for plants

active, genetically controlled developmental processes

what is the end of result of scenesence

abscission: shedding of flowers, fruits, leaves

what happens to structures and macromolec when a plant scenescne and where do they do

structures and macromolecules are

broken down

translocated ( to leaves)

• go to actively growing sinks (roots and stems (storage))

what is scenescne controlled with

regulated hormoned and environmental cues

main types of senescence

1. programmed cell death: xylem

2. organ senescence: organs such as leaves, flowers, fruits

3. whole plant: annunals

senescence types

1. sequential senescence: oldest leaves falls first

2. seasional senescene: dicious

3. stress induced: flucating temp, nutrient defiences, water

hormones involved in senescne and direction

1. caused by a decrease of photosynthesis:

Downregulated: Cytokinin, GA, Auxin

increase/ up: ABA, JA, Ethylene

2. ROS: breaking down

catalases, superoxide, desmutase, peroxidase

explain abscission phases and hormones present

Phase 1: remains fully present, auxin prevents ethylene

Phase 2: abscission induction, auxin up, ethylene down

Phase 3: abscission phase: separation and degrading enzymes, cell death, separation of organs

plant developmental phases

Juvenile

aduly vegetative

adult reproductive

what is floral evocation

process of turning the apical meristem from reproductive to reproductive

pathway of floral evocation

shoot apex → apical meristem→ flowers (SAM)

what is photoperiod

a biological response to length and time of day and night

what does photoperiod respond to

1. flowering

2. asexual repro

3. formation of storage organs

4. dormancy - shorter days

photoperiod responses

short day plants

long day plants

day neutral

long short day

short long day

explain short-day plants

during late summer and fall

qualitative: only flower on short days

quantitative: accelerate

example of short day plants

mum, poinsettias

explain long day plants

late spring and summer

qualitative: only flowers on long days

quantitative: accelerated on long days

example of long day plants

snapdragon, coneflowers

exlain day neural plants

insensitive to day length

day neutral plant examples

sunflowers, corn

explain long short day planst

must follow a sequential order of long to short days to flower

example of long short day plants

kalanchoes, lettuce

explain short long day plants

must follow the sequential order of short days then long days to flower

example of short day long day plants

clover

photoperiod responsible for

phytochrome ( response to light )

response may take 8-12 weeks so for production its important to time

vernalization def

no moisuture. period of cold temperature for flowering

floral meristem pathway

1. signal for FT gene

2. FT gene moves to sieve cell (was in cc)

3. FT gene movies via phloem

4. FT and FD interact for gene expression

5. FT and FD cause floral expression for flowering

6. Expression of floral genes

what hormones can induce flowering synchronously

ethylene and braseosteroids

draw the floral meristem wholrs

what are floral meristem identity genes

positive regulators

floral (Organs) identity gene

3 classes of genes : sepals, petals, etc.

ABC class

explain what ABCE do

a: produce sepals

b. produce petals

c. stamen produced

e. pistil produced

in the ABCE which block each other

A and C block each other

cause an interference

what is parthenocarpy

fruit without seed ex: banana , citrus

what are apomixis

clones

what can occur in apomixis

some are 100% clones

However, some seeds can have multiple embryos and will produce 1 clone (apomixic) and 1 se—xual plant