PLANT SYSTEMS QUESTION 1973:			L. PETERSON/ECHS

	Seeds that are randomly positioned when planted in a pot of soil placed 
	on a window sill produce seedlings with downward growing roots and 
	upward growing shoots. Above ground, the shoots are oriented toward 
	light. Describe the physiological mechanisms that occur to produce:

	a)  the downward growth of the roots
	b)  the upward growth of the shoots
	c)  the bending of the shoots toward light

STANDARDS:	NOT MORE THAN FIFTEEN TOTAL POINTS WERE GIVEN.

ONE POINT FOR EACH OF THE FOLLOWING:
__  The hormone involved is auxin.
__  In vertical roots or stems, auxin is uniformly distributed.
__  In horizontally placed roots, auxin accumulates on the lower side.
__  The accumulation of auxin on the lower side in roots inhibits cell elongation in the area.
__  In horizontally placed stems, auxin accumulates on lower side.
__  Accumulation of auxin in stems is stimulatory.
__  In a laterally illuminated stem, auxin accumulated on the shady side.
__  There is lateral transport of auxin from the sunny to the shady side, or from top to
       bottom in horizontally placed stems and roots.

TWO POINTS FOR EACH OF THE FOLLOWING:
__  Auxin is produced in the stem apex.
__  Auxin causes cell elongation in stems.
__  Optimum for root growth is an amount much less than for stem growth.
__  In high concentration, auxin is inhibitory in both stems and roots.
__  Lateral movement of auxin requires energy.
__  Auxin movement is too fast to be explained by diffusion.
__  The perception of auxin in stem tips is light promoted (carotenes or flavenes).
__  Discussion of the perception of gravity.
__  Evidence that the site of perception is the tip.

FIVE POINTS FOR THE FOLLOWING:

The downward growth of roots...the geotropic response of root is dependent on the production
of a growth inhibitor or inhibitors produced in the root cap. The inhibitor(s) move from the
cap through the apex to the elongating cells. If the root is horizontal, a large part of the sub-
stance is transported laterally to the lower side. The difference in concentration produces
unequal growth,...the lower side is more inhibited and root therefore turns down.
 










PLANT SYSTEMS QUESTION 1979:			L. PETERSON/ECHS

	In relation to plants, describe in detail one way of:
	a)  measuring the rate of transpiration
	b)  measuring the rate of photosynthesis
	c)  separating pigments

STANDARDS:

A.  TRANSPIRATION:			Max. = 6 points
__  a functional and structural definition of transpiration
__  factors affecting rate in vivo (2 points)
__  mention method of measurement (2 points)
__  method discussed in some detail (3 points)

B.  PHOTOSYNTHESIS:			Max. = 6 points
__  definition by equation or by statement of function
__  factors affecting rate in vivo (2 points)
__  naming a possible method of determining rate (2 points)
__  method discussed in some detail (3 points)
__  rate of disappearance of CO2 or rate of appearance of CHO or O2

 C.  PIGMENT SEPARATION:		Max. = 6 points
__  separation method mentioned (2 points)
__  separation method discussed (3 points)
__  pigment composition
__  pigment function
__  molecular characteristics of pigments




















PLANT SYSTEMS QUESTION 1983:			L. PETERSON/ECHS

	Relate the structure of an angiosperm leaf to each of the following:
	a)  Adaptations for photosynthesis and food storage
	b)  Adaptations for food translocation and water transport
	c)  Specialized adaptations to a desert environment

STANDARDS:


PART A
__  Cuticle transparent to allow light in
__  Palisade Parenchyma - site of photosynthesis
__  Spongy Parenchyma - site of photosynthesis
__  Altered leaf shape + Photosynthetic efficiency
__  Stoma controls passage of gas and water
__  Turgor pressure controls guard cell behavior


PART B
__  Xxlem transports water to leaf tissue
__  Phloem transports "food" from leaf tissue to sink
__  Bulk-mass flow mechanism of phloem movement
__  Transpiration defined


PART C
__  Small leaves
__  Altered stoma behavior
__  Specialized physiology (4C)
__  Details of oxaloacetate






















PLANT SYSTEMS QUESTION 1984:			L. PETERSON/ECHS

	Define the following plant responses and explain the mechanism of 
	control for each. Cite experimental evidence as part of your discussion.
	a)  Phototropism
	b)  Photoperiodism

STANDARDS:
PHOTOTROPISM:	
	Max. = 9 points if experimental evidence is given
	Max. = 7 points if experimental evidence is lacking

__  Definition - movement in response to light (involving growth) - 2 points
__  Possibility of negative response

Mechanism
__  Auxins
__  Distribution (apex -> stem or lateral)
__  elongation of cells
__  stem tip or coleoptile

Evidence (2 points for any of the following)
__  Darwin - covered coleoptiles
__  Paal - cut coleoptiles - agar, uneven placement
__  Boysen-Jensen - mica
__  Went - bioassay

PHOTOPERIODISM:
	Max. = 9 points if experimental evidence is given
	Max. = 7 points if experimental evidence is lacking
__  Definition - response to light/dark periods
__  flowering (or other response)

Mechanism
__  Categories of plants (LDP, SDP)
__  Receptor in leaf
__  LDP (if night shorter than minimum)
__  SDP (if night longer than minimum)
__  night not day
__  existence of phytochrome in two forms
__  PFR/PR  interconvertible
__  PFR active form
__  ratio (PR/PFR) important
__  possible hormonal involvement

Evidence
__  light flash in dark
__  grafting
__  ratio of PR/PFR 



   
   
PLANT SYSTEMS QUESTION 1985:			L. PETERSON/ECHS
	Describe the structure of a bean seed and discuss its germination 
	to the seedling stage. Include in your essay hormonal controls, 
	structural changes, and tissue differentiation.

STANDARDS:

STRUCTURE: 			Max. = 8 points
__  Seed coat (protection)
__  Embryo (new plant)
__  Cotyledons (store food)
__  Epicotyl (new shoot)
__  Hypocotyl (new stem/root)
__  Radicle (1st root)
__  Plumule (1st leaves)
__  Hilum scar (attachment)
__  Micropyle (pollen tube entry)

GERMINATION DISCUSSION:	Max. = 12 points
__  Imbibition of water (increases metabolism)
__  Correct temperature (enzymes)
__  Oxygen (for respiration)
__  Radicle emerges 1st (establishes root)
__  Subsequent shoot (photosynthesis when stored food gone)
__  Formation of hook/arch (pulls epicotyl)
__  Epigeal germination

a.  Hormonal Control
	--  Auxin in geotropism (+ or -)
	--  More auxin, lower 1/2 axis
	--  Stem/root affected differently
	--  Gibberellins stimulate length growth
	--  Cytokinins stimulate cell division
	--  Abscisic acid inhibits root cell elongation
b.  Structural Changes (Note: some germination discussion is structural change)
	--  Formation of root cap
	--  Dropping spent cotyledons
	--  Change, dark-to-light-growth
	--  Branch root production
	--  Leaf primordia
	--  Two different foliage leaves
c.  Tissue differentiation
	--  Cell division, elongation, maturation
	--  Xylem, phloem (elaboration)
	--  Apical meristem
	--  Protoderm, ground meristem, procambium
	--  Several vascular strands, stem; one, roots
	--  Collenchyma, sclerenchyma
	--  Mesophyll, epidermis, guard cells
	--  Endodermis pericycle
	--  Root hair formation
PLANT SYSTEMS QUESTION 1987:			L. PETERSON/ECHS
	Describe the effects of plant hormones on plant growth and development.
	Deisgn an experiment to demonstrate the effect of one of these plant 
	hormones on plant growth and development.

STANDARDS:
PART I. EFFECTS:				Max. = 7 points
__  For identifying a plant hormone
__  For correctly defining a plant hormone

For correctly describing the effects of a plant hormone (most frequently mentioned hormones
and effects given below, but see addendum for a more complete master list):

AUXINS
__  Promote cellular elongation
__  Promote softening of cell walls
__  Involved in phototropism
__  Involved in geotropism
__  Involved in apical dominance
GIBERELLINS
__  Stimulate cell elongation
__  Produce bolting in biennials
__  Stimulate production of starch digestion enzymes in some seeds
__  Reverse effects of genetic dwarfism
CYTOKINETINS
__  Promote growth in size of leaf cells
__  Stimulate cell division
__  Release buds from apical dominance
ETHYLENE
__  Promotes ripening of fruit
ABSCISIC ACID
__  Promotes stomatal closure
__  Promotes resistence to water stress
__  Promotes seed and bud dormancy
__  formerly thought to promote abscission
FLORIGEN
__  May induce flowering

Extra points, up to two, awarded for each association of a hormone with a correct, specific effect.
In order for two points to be awarded, two different hormones must be associated with their
specific effects.

PART II.  EXPERIMENTAL DESIGN		Max. = 7 points
Appropriate understanding or indication of:
__  Basing design on past observations or the literature
__  Problem, statement, or question posed
__  Hypothesis
__  Use of adequate sample size or replicates
__  Maintaining uniform conditions
__  Control or understanding of the concept of control
__  Treatment of experimental group
__  Taking of data
__  Evidence supports or refutes the hypothesis

One extra point awarded for a particularly innovative experimental design and another for
especially well organized and detailed description of the experiment.  (Max. = 2 points)
ADDENDUM TO STANDARDS / MASTER LIST OF PLANT HORMONAL EFFECTS:
AUXINS					GIBBERELLINS

promote cellular elongation			stimulate cell elongation in stem
promote phototropism in stems			promote bolting and flowering in biennials
promote softening of cell walls			promote production of starch digesting enzymes
promote growth of branch or adventitious roots    in grass seeds
promote renewed cell division in cambium	promote pollen germination
promote differentiation of vascular tissue	increase size of grapes and loosen clusters
promote joining of vascular tissue of leaves	break seed and bud dormancy
 with that of stems				stimulate leaf growth in monocots
affect transcription of at leaves ten genes	inhibit root formation
 involved with growth				stimulate development of "male" flower parts
inhibit growth of main roots			stimulate auxin production
inhibit production of abscission layer		stimulate cell division at the stem apex
act as a herbicide for dicots			may stimulate the production of auxins
exert apical dominance by inhibition of cell	stimulate fruit-set in some species
 elongation					stimulate vascular cambium to produce
artificially promotes parthenocarpy		 secondary phloem
						stimulates protein synthesis

CYTOKININS					ABSCISIC ACID (ABA)
promote growth in size of leaf cells		promote stomatal closure
stimulate cell division				promote seed and bud dormancy
promote conversion of immature plastids	promote resistance to water stress
 to chloroplasts					counters effects of auxin
inhibit senescence of leaves			induces apical meristem to stop mitosis
help break dormancy in some seeds		 and cytokinesis
enhance flowering in some plants		induces leaf primordia to form protective
promote fruit development in some species	  bud scales
release lateral buds from apical dominance	keeps twigs dormant until leaching occurs
						involved in root geotropism by inhibiting
						 elongation of cells on lower side

ETHYLENE					FLORIGEN   (hypothetical)
promotes ripening of fruit			may induce flowering
promotes radial growth in stems and roots
contributes to leaf drop
produces horizontal growth of stems
affects sex expression in some monoecious species
promotes wound healing








PLANT SYSTEMS QUESTION 1988:			L. PETERSON/ECHS
	Trace the pathway in a flowering plant as the water moves from the soil 
	through the tissues of the root, stem, and leaves to the atmosphere. Explain
	the mechanisms involved in conducting water through these tissues.

STANDARDS:		
ANATOMY AND PATHWAY:				Max. = 6 points

__  Pathway....some relationship from root to leaf required for a 10
       mention of "root tissue -> transport tissue -> leaf tissue
	      e.g.  root hair -> xylem -> stomata

Max. 5 - Anatomy of Pathway
__  Soil water or capillary water
__  Root hairs or Epidermis
__  Cortex or Parenchyma
__  Plasmodesmata
__  Endodermis
__  Pericycle
__  Procambium
__  Xylem or Vessels or Tracheids or Vascular Bundle
__  Petioles
__  Mesophyll Cells or Leaf Parenchyma
__  Intercellular Spaces
__  Stomata or Guard Cells

Max. 2 - Additional Points
__  Symplastic - water moves through protoplasts, plasmodesmata
__  Apoplastic - water moves along cell walls
__  Elaboration of Sylem - e.g. dead cells, hollow cells, main water transport
__  Casparian Strip - involvement in directional or selective flow
__  10% of water through the cuticle

MECHANISMS OF WATER MOVEMENT:		Max. = 6 points
	Explanation of Mechanism = 1 point / Name alone = 0 point
__  Osmosis - diffusion of water through semipermeable membrane
__  Transpiration - evaporation of water from leaf
__  Cohesion - water forms chain through H bonding, molecules adhere to each other
__  Adhesion - water adheres to cell walls, unlike molecules attract
__  Root Pressure - water enters root due to solute accumulating in root cells, force
       exerted by root cells on water column
__  Water potential - negative pressure in leaves; positive pressure in roots;
		          flow is along gradient of decreasing water potential

Max. 2 - Additional Points
__  Root hairs - large surface area -> absorption
__  Stomatal mechanism - open stomates allow transpiration/how guard cells act to regulate flow
__  Stomate placement relative to rate of transpiration, effect on transpiration
__  Root pressure - requires an energy dependent mineral movement into xylem
__  Guttation (proof of root pressure)
__  Elaboration of water potential relative to cohesion and adhesion 


PLANT SYSTEMS QUESTION 1990:			L. PETERSON/ECHS

	Discuss the adaptations that have enabled flowering plants to overcome the
	following problems associated with life on land.

	a.  The absence of an aquatic environment for reproduction
	b.  The absence of an aquatic environment to support the plant body
	c.  Dehydration of the plant
	
STANDARDS:

A.  ABSENCE OF AN AQUATIC ENVIRONMENT FOR REPRODUCTION:		   Max. = 4 points
__  Flowers - attraction for insects - shape, color, smell, chemical, nectar.
	          Mimicry for pollination (coevolution)
__  Timing of reproduction
Male
__  Microspores - pollen / Reduced Gametophyte
__  Lack of motility of gamete - pollen grain modification for transport
				e.g. light weight/structure
__  Pollination - transport of male gametes, wind, insects (self-pollination)
Female
__  Reduced gametophyte (in megaspore or megasporangium)
__  Protected gametophyte - embryo inside ovary, carpel, pistil
__  Evolution of seed
__  Fertilization - internal - pollen tube, endosperm
__  Fruit and seed dispersal
__  Seed dormancy

B.  ABSENCE OF AN AQUATIC ENVIRONMENT TO SUPPORT THE PLANT BODY:  Max. = 4 points
__  Stem - support
__  Root - anchorage
__  Vascular tissue - xylem fibers, tracheids, vessels, heartwood, dead tissues, phloem fibers
        or Vascularization
__  Vines, Tendrils
__  Cell wall - lignin, cell wall support, cellulose
__  Cambium - secondary thickening
__  Sclerenchyma - whole wall support
       Collenchyma - corner wall support
__  Prop, buttressed roots
__  Turgor pressure

C.  DEHYDRATION OF THE PLANT:					  Max. = 4 points
__  Root hair, absorption
__  Cuticle, wax, acellular
__  Bark - suberin, cork
       Scales - bud protection
       Sepal/petals - floral part protection
__  Seed coat / Pollen grain wall
__  Stomates - function to control water movement
__  Xylem - water transport



__  Leaf/stem/root modifications (2 points max.) 
	surface area reduction in desert plants/succulents
	stomates under surface
	leaf rolling
	hairs and trichomes
	interlocked epidermal cells
	hypodermis
	cortex - water storage or retention
	loss of leaves / abscission layer
__  CAM/C4 plants - modified stomate functions
__  seed dormancy (if not mentioned in part A)