Chapter 29: Plant Diversity I How Plants Colonized Land
BY 124 w/ Dr. Cusic
1) What are the four things land plants and charophytes have in common? Phragmoplast Formation
Flagellated Sperm Structure
Rings of cellulose making proteins
2) What are the five traits that land plants have and charophytes don’t? Alternation of Generations
Walled Spores Produced in Sporangia Don't forget about the age old question of Robert koch is famous for what?
3) Explain the alternation of generations (and review picture from the textbook!) The life cycle has stages between multicellular sporophytes and gametophytes. ∙ In the beginning, the gametophyte produces haploid gametes.
∙ Two haploid gametes (from a male and female) come together and are fertilized, creating a diploid zygote.
∙ This diploid zygote becomes a multicellular sporophyte.
∙ The mature sporophyte produces haploid spores through meiosis. ∙ These haploid spores become haploid gametophytes and the cycle repeats.
4) What are two traits that land plants have derived? Explain their function. Cuticle waxy covering that prevents excessive water loss from aboveground plant organs We also discuss several other topics like What is the single most important regulator of calcium?
Stomata pores in cells that regulate gas exchange between air and plant. This is where water evaporate from. Also minimizes water loss by closing in hot & dry conditions
5) List the sequence in which plants evolved as well as how many years ago each event occurred.
Origin of the land plant 470 MYA
Origin of vascular plants 425 MYA
Origin of seeds 305 MYA
Origin of flowers 160 MYA
6) What is a vascular system?
Where cells joined into tubes transport water and nutrients throughout the plant body
7) What are vascular plants commonly referred to? Tracheophytes
8) Name the two main divisions of vascular plants
Seedless vascular plants vs. seeded vascular plants
9) What are the two phyla under seedless vascular plants (and their common names)? Phylum Lycophyta (lycophytes) If you want to learn more check out How did microbiology develop?
Phylum Monilophyta (monilophytes)
10) What are the two types of seeded vascular plants?
Gymnosperms & Angiosperms If you want to learn more check out How does scientific knowledge compare to conventional wisdom or common sense?
11) What are the 4 phyla under Gymnosperms (and their common names)? Phylum Gnetophyta (gnetophytes)
Phylum Cycadophyta (cycads)
Phylum Coniferophyta (conifers)
Phylum Ginkgophyta (ginkgo)
12) What is the single phylum under Angiosperms (and its common name)? Phylum Anthophyta (flowering plants)
13) What are nonvascular plants commonly referred to?
14) Nonvascular plants have no divided groups, consisting only of 3 phyla. What are they and what are their common names?
Phylum Anthocerophyta (hornworts)
Phylum Hepatophyta (liverworts)
Phylum Bryophyta (mosses) We also discuss several other topics like What are biological molecules?
15) Distinguish vascular plants from nonvascular plants.
Vascular plants have true stems, roots, and leaves while nonvascular plants don’t.
Vascular plants have diploid sporophytes as their dominant generation. Nonvascular plants have haploid gametophytes as their dominant generation
16) What is the dominant generation of the moss life cycle?
Haploid gametophytes because mosses are nonvascular.
17) Explain the process of the moss life cycle. (and review picture from the textbook!)
∙ Haploid spores are released from the capsule
∙ Spore develops into a haploid protonemata which produces buds ∙ Buds on protonemata divide by mitosis and grow into male and female gametophytes
∙ Antheridia on haploid male gametophyte releases sperm which swims through moisture
∙ Sperm reaches the egg inside the archegonia of the haploid female gametophyte ∙ FERTILIZATION*** inside archegonia
∙ Diploid zygote sporophyte embryo is created
∙ Sporophyte grows inside archegonia attached by its foot as a seta (stalk) and becomes
nutritionally dependent on its haploid gametophyte mother
∙ MEIOSIS*** inside capsule (sporangium) at the head of the sporophyte ∙ Mature capsule releases haploid spores created inside
∙ These spores develop into protonemata. We also discuss several other topics like Which agencies support federalism?
∙ CYCLE REPEATS Bryophyte sporophyte remains attached to gametophyte mother for its entire lifespan.
18) What is a peristome?
Toothlike structures found on the sporangium capsule at the sporophyte head. It opens under dry conditions and closes under moist conditions.
The spores are released from here slowly to ensure some of them are passed on/survive.
19) What is peat moss?
Made of moss remains, found in peatlands
These peatlands do not have oxygen, have a low pH and temperature that inhibit decay
20) What are baby liverworts called?
21) What are nonvascular hornworts more closely related to?
22) What were the first vascular plants like?
Seedless, became taller with support
Include monilophytes and lycophytes
23) Explain the process of the fern life cycle. (and review picture from the textbook!) ∙ Haploid spores are released from sporangia of sporophyte
∙ Spores develop into bisexual gametophytes known as rhizoids
∙ These rhizoids produce sperm in antheridia and eggs in archegonia at different times
∙ This is done so egg is fertilized by sperm of another gametophyte and to ensure genetic diversity
∙ Sperm is directed by archegonia secretions to its eggs where fertilization occurs ∙ Diploid zygote develops in archegonia and develops into sporophyte ∙ Sporophyte grows out from parent archegonia
∙ Mature sporophyte contains sori spots on the underside of its leaves, which contain clusters of sporangia
∙ Meiosis occurs in the sporangia of the sori
∙ Haploid spores are released from the sporangia
24) What are the two types of vascular tissue found in vascular plants? Xylem conducts water and minerals
Phloem this tissue arranges cells into tubes, distributing sugars, amino acids, and organic products
25) Name six factors why lignified vascular tissue is important.
∙ Ensure vascular tissue grows tall
∙ Stems are strong enough to support against gravity
∙ Allows high water and nutrient transport
∙ Tall plants outcompete short plants for sunlight
∙ Tall plant spores disperse farther, colonizing new environments more rapidly. ∙ Taller forms favored by natural selection
26) What are sporophylls?
Modified leaves that have sporangia
27) What do roots do?
They anchor vascular plants to grow taller
28) What is the importance of leaves?
They increase plant body surface area and are the primary photosynthethic organ of
29) What are the two types of leaves?
Microphylls and Megaphylls
30) Where are microphylls found and what is their structure?
Found only in lycophytes
They’re small and supported by one strand of unbranched vascular tissue. (ex. ordinary leaf)
31) Where are megaphylls found and what is their structure?
Found in most vascular plants
They’re larger and more photosynthetic with branching vascular tissue (ex. Maple leaf)
32) Explain the process of Homosporous Spore Production
Occurs in most seedless vascular plants (ferns)
Sporangiun on Sporophyll
Single Type of Spore created
Gametophyte (includes male and female gametophyte)
33) Explain the process for Heterosporous Spore Production
Two types of sporangia create two kinds of spores
All seed plants are heterosporous
megasoporophyll Megaspore Female
34) What is a strobilus?
Area where spores are made
35) Are club mosses (lycophytes) true mosses?
36) In which two major time periods did plants develop vascular systems? Devonian & Carboniferus
37) What happened to the forests in the Carboniferus period? They turned into coal after a major cooling period occurred.
Chapter 30: Plant Diversity II – The Evolution of Seed Plants Tarana Sidhu
BY 124 w/ Dr. Cusic
1) Problems with what arose as the environment became drier? Flagellated Sperm
2) What does a flagellated sperm indicate about its needs?
Requires water/ moist environment to reach the egg (flagella indicates swimming)
3) Name some important evolutionary events.
a. Pollen grain replaces swimming sperm
b. The gametophyte is reduced and maintained in the sporophyte where it is protected.
The gametophyte nourishes new sporophyte in its development c. The seed encloses embryo for protection and contains food supply. The seed is what distributes the species
4) What now contains the male gametophyte instead of spores? Pollen grain 5) What trait does the male gametophyte contain to discharge sperm through to fertilize egg?
The pollen tube
6) What has the ovule become and what does it include?
The ovule is a seed which includes sporophyte embryo, food supply, and evolved protective seed coat
7) What is the oldest living tree (include the phylum)
The Bristlecone Pine – Phylum Coniferophyta
8) In plants that make spores, what distributes the species?
9) In plants that make seeds, what distributes the species?
10) What are some important background facts about the Pine Life Cycle? Multicellular diploid sporophyte – dominant generation
Seed Plant Evolution shown in this cycle:
Seed is dispersible
Appearance of pollen to bring gametes together, not spores The Conifer is heterosphorous like all seed plants are
Two types of spores are produced by small pollen cone (male) and large ovulate cone (female)
Both cones are found on the same tree.
11) Summarize the steps of the pine life cycle (and review picture from the textbook!)
Ovulate cone contains 2 ovules, each with megasporangium Pollen grain reaches ovule and germinates
Pollen tube goes through diploid megasporangium
Diploid megasporocyte in megasporangium goes through meiosis, creating 4 haploid cells
One survives as a haploid megaspore
This megaspore goes to the archegonia and egg is formed
Sperm cells develop within the pollen tube that extends to the female gametophyte
FERTILIZATION occurs – more than a year after pollination Usually one zygote becomes an embryo
Overall ovule is a seed which acts as an embryo, food supply, as well as a seed coat.
The embryo is a diploid sporophyte with diploid seed coat & haploid gametophyte food supply
Seedling becomes a diploid sporophyte with pollen cone and the ovulate cone/cycle repeats
PS: Male (pollen cone) has diploid microsporangia. The diploid microsporocytes under meiosis creating haploid microspores which become pollen grain.
This pollen grain = male gametophyte within pollen wall.
12) What are two statistics about angiosperms?
They make up 90% of all plant species
The dominant plant today
13) What are two facts about flowers?
They’re a structure unique to angiosperms
Structures specialized for reproduction
14) Where are the sepals in a flower and what do they do?
At the base of the flower, enclose flower before it opens
15) What do petals do?
Brightly colored to attract pollinators such as bees
16) What do petals and sepals have in common that no other plant structure does? Infertile, neither have reproductive organs. All other structures are fertile.
17) What are the stamens and what is their function?
The “male” part of the flower, produce microspores which develop into pollen grains containing male gametophytes.
18) What two structures do stamens consist of and what are their functions? Anther produces pollen / appear bulbous
Filament – stalk that has anther at its head
19) What are carpels and what is their function?
The “female” part of the flower, produce megaspores and their products are female gametophytes.
Also where seeds are enclosed
20) What two structures do carpels consist of and what are their functions? Stigma – receives pollen / the sticky tip of carpel
Style – bridges stigma to ovary / slim middle structure
Ovary – contains several round ovules / when fertilized these ovules become seeds / round structure below Style
21) What two types of symmetry may be present in flower structure? Radial Symmetry & Bilateral Symmetry
22) What is radial symmetry?
Where any imaginary line would divide flower into two equal parts This is primitive
23) What is bilateral symmetry?
One imaginary line divides flower into equal parts
This is more advanced
24) Name some methods that enhance seed dispersal and explain them Explosive action – when seeds mature in pod and pod pops, tossing seeds far from parent plant
Seed Wings – carry seeds over long distances
Feces – berries (holding seeds) eaten, organism moves around as seeds pass through body, seeds dispersed far from parent plant
Burrs – cling to fur of pets / clothes of humans and seeds are transported
25) What is a pericarp?
The wall of the ovary becomes
Thickened part of fruit
26) Distinguish cotyledon count in monocots and eudicots
Monocots have 1 / eudicots have 2
27) Distinguish leaf structure between monocots and eudicots
Monocots – leaf veins run parallel
Eudicots – leaves run netlike (think of a maple leaf – veins aren’t not parallel)
28) Distinguish vascular tissue composition between monocots and eudicots Monocots – scattered tissue / no specific arrangement
Eudicots – vascular tissue arranged in a ring around edge
29)Distinguish root appearance between monocots and eudicots Monocots – roots are fibrous, no one main visible root
Eudiocots – taproots, main root can be seen (multiple roots come off this one middle root)
30) Distinguish pollen grain openings
Monocots – 1 opening
Eudicots – 3 openings
31) Distinguish handle size between monocots and eudicots
Monocots – short handle
Eudicots – long handle
32) Distinguish floral organ count between monocots and eudicots Monocots – appear in multiples of 3
Eudicots – appear in multiples of 4/5
Chapter 35: Plant Structure – Growth and Development
BY 124 w/ Dr. Cusic
1) Where does the root system of a plant thrive?
2) Where does the shoot system of a plant thrive?
3) Why is branching important for a plant?
Increases its surface area
4) What is an adventitious root?
Any root that arises after the embryonic stage of a plant
5) What are the 3 functions of a root?
Anchors vascular plant in the soil
Absorbs water & minerals
Stores carbs, etc.
6) Name the structures in the shoot system as well as their functions Shoot – photosynthesis
Flowers – reproduction
Buds – where plants grow from
Nodes – points at stem where leaves are attached
Internodes – stem segments/space in between nodes
Stem – center of the vascular system in charge of transport
Rhizome – horizontal stem
7) What are the 3 types of differentiated plant cells?
Parenchyma cells, Collenchyma cells, Sclerenchyma cells
8) Name an important structure that Parenchyma cells include? A central vacuole which stores water and nutrients
9) What are some functions of Parenchyma cells?
Perform most of plant’s metabolic activities
Mature ones may divide (ex. wound repair)
10) Where are Parenchyma cells found?
Roots, stems, leaves, etc.
11) Why do Parenchyma cells have no secondary cell walls? Need flexibility to be able to store water and nutrients in vacuole
12) What are the primary cell walls of Collenchyma cell walls like as compared to Parenchyma cells?
Much more rigid and thick primary cell walls
13) What do Collenchyma cells and Parenchyma cells both lack? A secondary cell wall
14) What do Collenchyma cells support?
15) What is the appearance of Collenchyma cells?
16) What two things do neither Parenchyma nor Collenchyma cells have regarding their cell walls while Sclerenchyma cells do have this?
Lignin & secondary cell walls
17) What is the composition like for Sclerenchyma cells in comparison to Collenchyma cells?
Much more rigid
18) Can Sclerenchyma cells elongate?
19) Where in the plant are Sclerenchyma cells found?
Within the plant regions that have stopped growing
20) While Sclerenchyma also provides support like Parenchyma and Collenchyma cells do, is it alive like them?
No. Sclerenchyma cells are dead.
21) What remains of dead Sclerenchyma cells so that they still provide a “skeleton” for the plant?
Their cell walls
22) What are the two types of Sclerenchyma cells?
Sclereids and Fibers
23) What do sclereids provide?
Support, also strengthen
24) A sclereid has secondary walls. What are they like?
Thick and lignified
25) The hardness of sclereids can be contributed to what, for example? Nutshells
26) Describe fibers.
Long and slender
27) What are the two types of waterconducting cells of the Xylem? Tracheids
28) Are tracheids and vessel elements living?
29) Contrast tracheids and vessel elements
Tracheids – long/thin and found in all vascular plants
Vessel Elements – wide/short and found only in angiosperms
30) Are tracheids and vessel elements lignified?
31) What do both of these waterconducting cells do?
They form nonliving tubes through which water is carried
32) In what manner does the water migrate?
Laterally through pits
33) How do pits interrupt water flow?
They’re thin with only primary walls (acting as a barrier of sorts). Water has to make it through and travel between neighboring cells through these pits.
34) What are the two types of sugarconducting cells of the phloem? Sieve Tube Elements
35) What is a major difference between the waterconducting cells of the xylem and sugarconducting cells of the phloem (besides location in the plant and function)? The sugarconducting cells of the phloem are alive/living
36) Where are these sugar conducting cells found?
In seedless vascular plants and gymnosperms
37) What are sieve tube elements like in size?
Long and narrow
38) What really is a sievetube element?
“A bag of cytoplasm”
39) How is it a “bag of cytoplasm”?
It lacks a nucleus, ribosomes, vacuole
40) Why has it evolved to be this way?
To allow nutrients to pass through more easily
41) What connects the end walls of sievetube elements?
42) What is the function of sieve plates?
They assist fluid flow from cell to cell through sieve tube
43) What acts as a “life support” to sieve tube elements?
44) Where are companion cells located?
Next to each sieve tube element
Connected by numerous plasmodesmata
45) What are the two functions of companion cells?
Direct sievetube cells
Share their nucleus and ribosomes with sievetube cells to sustain them
46) What are the 3 types of plant tissue?
Dermal Tissue – outermost
Ground Tissue – surrounds middle
Vascular Tissue – middle
47) What are two things dermal tissue does?
Acts as outside covering/”skin”
Protects the plant
48) What three things does ground tissue do?
49) What two things does vascular tissue?
Water + sugar transport
50) What must be located in vascular tissue if water and sugar is being transported? Xylem and Phloem
51) What is indeterminate growth?
Growth that occurs throughout the plant’s lifespan as long as meristematic growth is present. (happens in most plants, and they grow continuously)
52) What are meristems?
Unspecialized tissues that divided to create new cells which elongate and become specialized
53) What is determinate growth?
Plant organs stop growing after reaching a certain size.
54) Name a part of the plant that faces determinate growth.
Leaves, they don’t keep growing
55) What are the 2 types of meristems?
56) Where are Apical Meristems located and what are they? At the tips of shoots and roots
Additional cells to enable growth in length
57) What type of growth do Apical Meristems cause?
58) What is primary growth?
Where roots and shoots extend downwards/upwards as they grow in length
59) Name a plant that has only primary growth
Herbaceous (nonwoody plant)
60) Where are Lateral Meristems found?
Extend along length of roots and stems
61) What do Lateral Meristems consist of?
62) What type of growth do Lateral Meristems cause?
63) What is secondary growth?
Where plants grow in width/thickness when they no longer grow in length
64) What plant group exhibits secondary growth?
65) What does the vascular cambium do?
Adds layers of secondary xylem (wood) and secondary phloem
66) Where is the cork cambium located in relation to the vascular cambium? External to the vascular cambium
67) What does the cork cambium do?
Replaces epidermis with thicker and tougher periderm
68) What are the three types of plants based on life cycle?
69) Summarize the lifespan of an annual.
Completes reproductive cycle in 1 year from germination to flowering to seed production to death
70) Summarize the lifespan of a biennial
Grows for the 1st year and then grows the 2nd year
They only flower and seed in the 2nd year
71) Summarize the lifespan of a perennial
Grow, flower, and seed repetitively
Live many years
Most favored plant
72) What are the 3 functions of a root cap?
Covers root tip
Protects apical meristems as root pushes through soil
Secretes slime into soil
73) What is the importance of a root cap secreting slime?
Lubricates area surrounding roots so they can be pushed through more easily
74) Name the 3 cell zones
Zone of Cell Division
Zone of Elongation
Zone of Differentiation (aka Maturation)
75) What happens in the zone of cell division and what is located there? Cells divide here, creating new root and root cap cells
Apical Meristems in this zone
76) What’s the significance of the cells in the zone of elongation? Most of their growth occurs there, as this is where cells elongate
77) What does the elongation of cells do to the root tip? Causes it to be pushed farther into soil
78) What’s the significance of cells entering the zone of differentiation? It’s where they become distinct and differentiable cell types
79) What do xylem cells in a eudicot cross section of a root look like? Light/larger cells near the middle
80) What do phloem cells in a eudicot cross section of a root look like? Darker/smaller cells arranged externally to xylem cells
81) Where is the xylem and phloem here in the eudicot? The vascular cambium
82) What are pericycle cells located?
Cells just under the endodermis
83) What does the pericycle consist of?
Vascular tissue with xylem and phloem
84) What does the pericycle remain (as well as in monocots)? Meristematic
85) What does the endodermis do?
Has a waxy covering which blocks out substances
86) What is any endodermis like and why?
A gatekeeper – regulates opening, has a selective nature
87) Where is the phloem in a monocot?
Also like in a eudicot, external to xylem
88) What does the xylem do in terms of cell arrangement? Forms rings
89) Are the endodermis from a monocot and eudicot different? No, have the same “gatekeeper” composition
90) Differentiate eudicots and monocots in terms of their appearance in the cross section of a stem.
Eudicots have vascular bundles creating a ring
They have ground tissue torwards the inside called the pith Monocots have vascular bundles scattered throughout entire stem instead of eudicots concentrated around edges of circle in a ring.
91) As always, what do eudicots and monocots have in common in terms of xylem and phloem?
The phloem is always external to the xylem
92) Do monocots have secondary growth?
93) Do eudicots have secondary growth?
94) What does the vascular cambium do to the oldest phloem cells as it accumulates?
Pushes them outward
95) What does the vascular cambium do the oldest xylem cells as it accumulates? Pushes them inwards to the center where the pith is
96) As the occurs, what is happening to the tree trunk?
It’s expanding in size (diameter)
97) Differentiate between heartwood and sapwood.
Heartwood – clogged with resin
can no longer transport water and minerals
turns into tree support
center of the tree / “heart is closer to the center”
older layers of secondary xylem
Sapwood – not clogged with this “inhibitory” resin
can still transport sap / why it’s called sapwood
lighter in appearance than sapwood
outer layers of tree
newest layers of secondary xylem
98) What is significant about secondary phloem?
It DOES NOT accumulate
99) What is the function of secondary phloem?
100) What does the cork cambium consist of?
Cork and cork cells
101) Where is the cork cambium located and what does it do? Outside vascular cambium
Helps protect tree
102) How does the cork cambium replace fallen epidermal cells? By destroying the oldest phloem
103) What does the cork cambium give rise to and where do they accumulate? Cork cells which accumulate to the cork cambium’s exterior
104) What do cork cells deposit?
A waxy, hydrophobic layer
105) What is this waxy, hydrophobic layer called?
106) What are 3 function of suberin?
Protective barrier for the root and stem
Prevents water loss
Protection against pathogens
107) What are lenticels?
Holes in the periderm
108) What is the function of lenticels?
Enable living cells in woody stem/root to exchange gases with the outside air
109) What can this structure be compared to?
110) What does (tree) bark actually consist of?
Cork and secondary phloem
111) What is the common name for cork?
Chapter 36: Resource Acquisition
& Transport in Vascular Plants
BY 124 w/ Dr. Cusic
1) In plant photosynthesis, where does the plant get CO2?
Through the leaves
2) How does water travel in a plant?
Travels up into leaves from the roots
3) Where are glucose and oxygen released from?
From stomata on the leaves
4) In cell respiration, what do plants need?
Oxygen and CO2
5) Where can sugar be produced?
Can be produced in the leaves
6) How does sugar move?
Moves down roots
7) What is one important difference between sugar and water travel within a plant?
While water can only move up, sugar can actually move up & down
8) Where are proton pumps located?
Plasma membrane of plant cells
9) What does using ATP in the pumps do?
Pushes hydrogen ions
10) From where to where do those hydrogen ions do?
From the inside (cytoplasm) to the outside (extracellular fluid)
11) What is being done to hydrogen ions in the plant?
12) What does this cotransport with hydrogen ions responsible for? Neutral solutes such as sucrose moving across the membrane
13) Why do plants use energy in the hydrogen gradient and membrane potential?
To drive active transport of solutes
14) What cell state should plant cells be in to be able to bring in stuff? Hypertonic
15) What should their ideal physical shape be?
They need their cells to have central vacuoles filled with water ions
17) Define what a turgid cell is.
A walled cell with greater solute concentration than its surroundings
18) What are aquaporins?
Waterspecific transport proteins
19) What do aquaporins do?
Facililate the transport of water molecules across plant cell plasma membranes
20) From what concentration to what concentration do aquaporins go? High to low
21) If you go from high to low concentration, what is never required? Energy
22) More specifically, what type of transport do aquaporins engage in? Passive, facilitated transport
23) Name the 3 routes for transport within a plant tissue/organ Apoplastic Route
24) How does water travel through via the apoplastic route?
Water moves along cell wall only, while never entering any cell membrane
25) How does water travel through via the symplastic route?
Water goes through plasma membrane upon entering, then moving from cell to cell through plasmodesmata which connect the plasma membrane
26) How does water travel via the transmembrane route?
Water moves out of one cell, across cell wall, and into next cell, while never needing plasmodesmata
27) Which of the three routes goes through every single cell in the root? Transmembrane route
28) Which of the 3 routes has the most flexibility?
29) What is bulk flow?
Movement of fluid driven by pressure
30) What 2 types of relationships are exhibited between plants and fungus? Mutualism and parasitism
31) Explain how fungus can be mutualistic with plants?
Wraps around plant roots
Increases plant surface area
Allows more water to move into the plant
32) Where does the majority of water go through to get to the endodermal cells? Root hairs
33)How can things move freely into any cell?
As long as they’re small enough and in water to go in
34) What does water have to cross?
35) Why can water not move freely there?
Coated in a Casparian Strip
36) Where does water travel after endodermal cells?
37) When water and minerals are discharged, what happens to them? Xylem vessels carry them through bulk flow
38) Where are they carried to?
Upwards into the shoot system
39) In small plants, what is beneficial?
40) What is guttation?
The movement of pressure of water through a small plant
41) Where does guttation exist and not exist?
Exists in small plants, never in trees
42) Explain guttation
More water enters leaves than transpired leading to excess water This excess water becomes water droplets that are seen on leaves
43) Are these water droplets found on leaves dew?
No, dew has nothing to do with guttation
44) What is transpiration?
The loss of water and process of transporting xylem sap
45) What is cohesiontension hypothesis?
Transpiration provides pull of ascent of xylem sap
Cohesion of eater molecules transmits pull along xylem length from shoots to roots
leaves, not roots, begin transpirational pull
46) What is the mechanism behind all of these factors?
TranspirationalPull CohesionTension Mechanism
47) Explain the ascent of xylem sap.
Water moves into the roots of the tree
(Polar Covalent & Hydrogen Bonds exhibited here)
Cohesion – when molecules are clinging together
Adhesion – molecules attracted to anything with a charge (water’s holding hands)
Water goes up into the xylem
Everything clings to xylem cell
Creates a “continuous column” of water going upwards
Water moves out to mesophylls and goes out stomata (evaporates) Transpiration
As water evaporates, water is pulled from xylem to make more water come into the xylem
48) How much water is actually used for photosynthesis in a plant? 2%
49) Where does a plant’s energy coming from?
Sun (solar powered)
50) What does this mean?
Plant uses no energy
Plant isn’t anything of its own, using just what it acquired from the sun
52) What does plant’s energy from the sun cause?
Evaporation of water out of stomata
53) What is a stomata and what does it mean?
A hole, means “mouth”
54) What flanks both sides of a stomata?
55) What do guard cells?
Allow stomata to open or close
56) If water is needed for photosynthesis, water is lost, or there is not enough water, what does the stomata do?
57) When the stomata is closed, how are the guard cells in terms of shape? Flaccid
58) If there’s enough water inside guard cells, what does the stomata do? Opens
59) When the stomata is open, how are the guard cells in terms of shape? Turgid
60) What is water doing when the stomata is open?
Water follows in
61) What is water doing when the stomata is closed?
Water goes out (water is being lost)
62) What is happening with potassium when the stomata is open?
Guard cells accumulate K+ from neighboring epidermal cells
H+ actively transported out of cell
63) What is happening with potassium when the stomata is closed? Guard cells are losing K+ cells to neighboring epidermal cells
64) What activates the pump and opens stomata?
65) What must be absent for the stomata to be open?
66) What time of day is the stomata open?
67) What are circadian rhythms?
Cycles with intervals of 24 hours, plants have internal clocks
68) What do circadian rhythms cause the stomata do?
69) What is abscisic acid and what does it do the stomata?
Produced in roots and leaves, signals guard cells to close stomata
70) What are some other instances in which the stomata may be closed (during the daytime)
71) Explain how sucrose is loaded into the phloem
Sucrose made in mesophyll cells and travels through a symplastic route to sievetube elements
then travels through apoplast
accumulates from apoplast by sieve tube elements and companion cells
72) What is the mechanism responsible for this process?
Chemiosmotic Mechanism – actively transports sucrose into companion cells and sieve tube elements
Sucrose then couples with transport of hydrogen ions back into the cell
73) Explain bulk flow in a sievetube
Water from xylem wants to go from high to low concentration Moves into phloem
Puts positive pressure on sugar to drive it down phloem (this is an example of bulk flow)
Water goes back into the xylem
74) What is happening in the plasma membrane with this process? ATP is used to pump more hydrogen ions to use energy to pump more sucrose into the phloem
Water still in phloem is next to water in xylem
That water in phloem then moves back into xylem via proton pump