1. Plant Structure and Function
Chapters 35-39

2. Evolution of Plants All Plants…
multicellular, eukaryotic, autotrophic, alternation of generations

3. Alternation of Generations
Sporophyte (diploid)
produces haploid
spores via meiosis
Gametophyte (haploid)
produce haploid
gametes via mitosis
Fertilization
joins two gametes to
form a zygote

4. Angiosperms Monocots vs. Dicots named for the number
of cotyledons present on
the embryo of the plant
+ monocots
- orchids, corn,
lilies, grasses
+ dicots
- roses, beans,
sunflowers, oaks

5. Plant Morphology Morphology (body form) shoot and root systems
+ inhabit two environments
- shoot (aerial)
+ stems, leaves, flowers
- root (subterranean)
+ taproot, lateral roots
vascular tissues
+ transport materials between
roots and shoots
- xylem/phloem

6. Plant Anatomy Anatomy (internal structure) division of labor
+ cells differing in structure and function
- parenchyma, collenchyma, sclerenchyma (below)
- water- and food-conducting cells (next slide)
Parenchyma
St: “typical” plant cells
Fu: perform most metabolic functions
Collenchyma
St: unevenly thickened primary walls
Fu: provide support but allow growth
in young parts of plants
Sclerenchyma
St: hardened secondary walls
(LIGNIN)
Fu: specialized for support; dead

7. Plant cell types Parenchyma cells Collenchyma cells Cell wall
Sclerenchyma cells

8. Plant cell types Xylem Phloem Vessel Tracheids Tracheids and vessels
WATER-CONDUCTING CELLS OF THE XYLEM
Vessel
Tracheids
Tracheids and vessels
element
Pits
SUGAR-CONDUCTING CELLS OF THE PHLOEM
Companion cell
Sieve-tube
member
Sieve-tube members:
longitudinal view
Sieve
plate
Nucleus
Cytoplasm
Companion
cell

9. Water- and Food-conducting Cells
Xylem (water)
dead at functional maturity
tracheids- tapered with pits
vessel elements- regular tubes
Phloem (food)
alive at functional maturity
sieve-tube members- arranged
end to end with sieve plates &
Companion cells

10. Plant Tissues Three Tissue Systems dermal tissue + epidermis (skin)
- single layer of cells that
covers entire body
- waxy cuticle/root hairs
vascular tissue
+ xylem and phloem
- transport and support
ground tissue
+ mostly parenchyma
- occupies the space b/n
dermal/vascular tissue
- photosynthesis, storage,
support

11. Plant Growth Meristems
perpetually embryonic tissues located at regions of growth
+ divide to generate additional cells (initials and derivatives)
- apical meristems (primary growth- length)
+ located at tips of roots and shoots
- lateral meristems (secondary growth- girth)

12. Roots A root Is an organ that anchors the vascular plant
Absorbs minerals and water
Often stores organic nutrients
Taproots found in dicots and gymnosperms
Lateral roots (Branch roots off of the taproot)
Fibrous root system in monocots (e.g. grass)
Figure 35.3

13. Modified Roots Many plants have modified roots (a) Prop roots
(b) Storage roots
(c) “Strangling” aerial roots
(d) Buttress roots
(e) Pneumatophores
(a) Prop roots
(b) Storage roots

14. Primary Growth of Roots
apical meristem
+ root cap
+ three overlapping zones
- cell division
- elongation
- maturation

15. Stems A stem is an organ consisting of
Nodes (could be opposite or alternate)
Internodes

16. Modified Stems Stolons Storage leaves Rhizomes Stem Node Root Bulbs
Tubers
(c)
Bulbs
Stolons
(a)
Storage leaves
Stem
Root
Node
Rhizome

17. Buds
An axillary bud
Is a structure that has the potential to form a lateral shoot, or branch
A terminal bud
Is located near the shoot tip and causes elongation of a young shoot
Gardening tip:
Removing the terminal bud stimulates growth of axillary buds

18. Primary Growth in Shoots
apical meristem (1, 7)
+ cell division occurs
+ produces primary meristems
- protoderm (4, 8)
- procambium (3, 10)
- ground meristem (5, 9)
axillary bud meristems
+ located at base of
leaf primordia
leaf primordium (2, 6)
+ gives rise to leaves

19. The leaf
Is the main photosynthetic organ of most vascular plants
Leaves generally consist of
Blade
Stalk
Petiole

20. Leaf Morphology In classifying angiosperms
Taxonomists may use leaf morphology as a criterion
Petiole
(a) Simple leaf
(b) Compound leaf.
(c) Doubly
compound leaf.
Axillary bud
Leaflet

21. Modified Leaves Tendrils Spines Storage leaves Bracts
Reproductive leaves. The leaves of some succulents produce adventitious plantlets, which fall off the leaf and take root in the soil.

22. Leaf Anatomy Epidermal Tissue upper/lower epidermis
guard cells (stomata)
Ground Tissue
mesophyll
+palisade/spongy
parenchyma
Vascular Tissue
veins
+ xylem and phloem

23. Cutaway drawing of leaf tissues
Leaf Anatomy
Key
to labels
Dermal
Ground
Vascular
Guard
cells
Stomatal pore
Epidermal
cell
50 µm
Surface view of a spiderwort
(Tradescantia) leaf (LM)
(b)
Cuticle
Sclerenchyma
fibers
Stoma
Upper
epidermis
Palisade
mesophyll
Spongy
Lower
Vein
Xylem
Phloem
Bundle-
sheath
Cutaway drawing of leaf tissues
(a)
Air spaces
Guard cells
100 µm
Transverse section of a lilac
(Syringa) leaf (LM)
(c)

24. The Three Tissue Systems: Dermal, Vascular, and Ground

25. Dermal Tissue Protects plant from: Physical damage Pathogens
H2O loss (Cuticle)

26. Vascular tissue
Carries out long-distance transport of materials between roots and shoots
Consists of two tissues, xylem and phloem

27. Ground Tissue
Includes various cells specialized for functions such as storage, photosynthesis, and support
Pith = ground tissue internal to the vascular tissue
Cortex = ground tissue external to the vascular tissue

28. Secondary Growth Lateral Meristems vascular cambium
+ produces secondary xylem/phloem (vascular tissue)
cork cambium
+ produces tough, thick covering (replaces epidermis)
secondary growth
+ occurs in all gymnosperms; most dicot angiosperms

29. The Vascular Cambium and Secondary Vascular Tissue
Is a cylinder of meristematic cells one cell thick
Develops from parenchyma cells

30. 2° Growth As a tree or woody shrub ages
The older layers of secondary xylem, the heartwood, no longer transport water and minerals
The outer layers, known as sapwood
Still transport materials through the xylem

31. Cork Cambium Periderm protective coat of secondary plant body
+ cork cambium and
dead cork cells
- bark
cork cambium produces
cork cells

33. Plant Transport
Chapter 36

34. A variety of physical processes
Are involved in the different types of transport
Sugars are produced by
photosynthesis in the leaves. 5
Through stomata, leaves take in CO2 and expel O2. The CO2 provides carbon for
photosynthesis. Some O2 produced by photosynthesis is used in cellular respiration. 4
CO2 O2
Light
H2O
Sugar
Transpiration, the loss of water
from leaves (mostly through
stomata), creates a force within
leaves that pulls xylem sap upward. 3
Sugars are transported as
phloem sap to roots and other
parts of the plant. 6
Water and minerals are
transported upward from
roots to shoots as xylem sap. 2
Roots exchange gases
with the air spaces of soil,
taking in O2 and discharging
CO2. In cellular respiration,
O2 supports the breakdown
of sugars. 7
Roots absorb water
and dissolved minerals
from the soil. 1 O2
H2O
CO2
Minerals

35. The Central Role of Proton Pumps
Proton pumps in plant cells
Create a hydrogen ion gradient
Contribute to membrane potential
CYTOPLASM
EXTRACELLULAR FLUID
ATP H+
Proton pump generates
membrane potential
and H+ gradient. – +

36. (Membrane potential and cation uptake
Plant cells use energy stored in the proton gradient and membrane potential
To drive the transport of many different cations +
CYTOPLASM
EXTRACELLULAR FLUID
Cations ( , for
example) are driven into the cell by the membrane potential.
Transport protein K+ –
(Membrane potential and cation uptake

37. Figure 37.6b Soil particle – K+ Ca2+ Mg2+ Cu2+ H+ H2CO3 HCO3– +
(b) Cation exchange in soil. Hydrogen ions (H+) help make nutrients available by displacing positively charged minerals (cations such as Ca2+) that were bound tightly to the surface of negatively charged soil particles. Plants contribute H+ by secreting it from root hairs and also by cellular respiration, which releases CO2 into the soil solution, where it reacts with H2O to form carbonic acid (H2CO3). Dissociation of this acid adds H+ to the soil solution.
H2O + CO2
H2CO3
HCO3– +
Root hair K+
Cu2+
Ca2+
Mg2+ H+
Soil particle –

38. Cotransport A transport protein couples the passage of H+ to anions –
NO3–
NO3 – – +
Cotransport of anions
of through a
cotransporter.
Cell accumulates
anions ( , for
example) by
coupling their transport to the inward diffusion

39. Contransport of a neutral solute
Cotransport
Is also responsible for the uptake of sucrose by plant cells H+ S
Plant cells can
also accumulate a
neutral solute,
such as sucrose
( ), by
cotransporting
down the
steep proton
gradient. – +
Contransport of a neutral solute

40. Water potential
Is a measurement that combines the effects of solute concentration and pressure
Determines the direction of movement of water
Water
Flows from regions of high water potential to regions of low water potential

41. Quantitative Analysis of Water Potential
The addition of solutes
Reduces water potential
0.1 M
solution
H2O
Pure
water
(a)

42. Negative pressure
Decreases water potential
H2O
(d)

43. Application of physical pressure
Increases water potential
H2O
(b)
H2O
(c)

44. Aquaporin Proteins and Water Transport
Aquaporins
Are transport proteins in the cell membrane that allow the passage of water
Do not affect water potential

45. Fluid Movement
Movement of fluid in the xylem & phloem is driven by pressure differences at opposite ends of the xylem vessels and sieve tubes

46. Water and minerals ascend from roots to shoots through the xylem
Plants lose an enormous amount of water through transpiration, the loss of water vapor from leaves and other aerial parts of the plant
The transpired water must be replaced by water transported up from the roots

47. Pushing Xylem Sap: Root Pressure
At night, when transpiration is very low
Root cells continue pumping mineral ions into the xylem of the vascular cylinder, lowering the water potential
Water flows in from the root cortex
Generating root pressure

48. Root pressure sometimes results in guttation

49. Transpiration produces negative pressure (tension) in the leaf
Which exerts a pulling force on water in the xylem, pulling water into the leaf
The transpirational pull on xylem sap
Is transmitted all the way from the leaves to the root tips and even into the soil solution
Is facilitated by cohesion and adhesion

50. Upper epidermal tissue
The stomata of xerophytes
Are concentrated on the lower leaf surface
Are often located in depressions that shelter the pores from the dry wind
Lower epidermal
tissue
Trichomes
(“hairs”)
Cuticle
Upper epidermal tissue
Stomata
100 m

51. Translocation through Phloem
Is the transport of organic nutrients in the plant
Phloem sap
Is an aqueous solution that is mostly sucrose
Travels from a sugar source to a sugar sink

52. Sugar Source & Sink A sugar source
Is a plant organ that is a net producer of sugar, such as mature leaves
A sugar sink
Is an organ that is a net consumer or storer of sugar, such as a tuber or bulb

53. Transpiration Lab

54. Control of Transpiration
Photosynthesis-Transpiration Compromise
guard cells help balance plant’s need to conserve water with its
requirement for photosynthesis

55. Stomatal closing
1. Potassium ions move out of the vacuole and out of the cells.
2. Water moves out of the vacuoles, following potassium ions.
3. The guard cells shrink in size.
4. The stoma closes.
Stomatal opening
Potassium ions move into the vacuoles.
Water moves into the vacuoles, following potassium ions.
The guard cells expand.
The stoma opens.

56. Chapter 37
Plant nutrition

57. Plant Nutrition What does a plant need to survive?
9 macronutrients, 8 micronutrients
+ macro- required in large quantities
- C, H, N, O, P, S, K, Ca, Mg
+ micro- required in small quantities
- Fe, Cl, Cu, Mn, Zn, Mo, B, Ni
+ usually serve as cofactors
of enzymatic reactions

59. The most common deficiencies
Are those of nitrogen, potassium, and phosphorus
Phosphate-deficient
Healthy
Potassium-deficient
Nitrogen-deficient

60. Hydroponics
Remove only one macronutrient to see effects on plant

61. Soil Texture and Composition texture depends on size of particles
+ sand-silt-clay
- loams: equal amounts of sand,
silt, clay
composition
+ horizons
- living organic matter
- A horizon: topsoil, living
organisms, humus
- B horizon: less organic, less
weathering than A horizon
- C Horizon: “parent” material
for upper layers
soil conservation issues
+ fertilizers, irrigation, erosion

62. Soil
Aeration
A mixture of mineral particles, decaying organic material, living organisms, air, and water, which together support the growth of plants

63. Soil Bacteria and Nitrogen Availability
Nitrogen-fixing bacteria convert atmospheric N2
plants absorb ammonium (NH4+), nitrate (NO3-)
Atmosphere N2
Soil
Nitrogen-fixing bacteria
Organic material (humus)
NH3 (ammonia)
NH4+ (ammonium)
H+ (From soil)
NO3– (nitrate)
Nitrifying bacteria
Denitrifying bacteria
Root
NH4+
Nitrate and nitrogenous organic compounds exported in xylem to shoot system
Ammonifying bacteria

64. Nutritional Adaptations
Symbiotic Relationships
symbiotic nitrogen fixation
+ Legume root nodules contain bacteroids (Rhizobium bacteria)
- mutualistic relationship
- Crop rotation (Legumes
mycorrhizae
+ symbiotic associations of fungi and roots
parasitic plants
+ plants that supplement their nutrition from host
- mistletoe, dodder plant, Indian pipe
carnivorous plants
+ supplement nutrition by digesting animals

65. Mycorrhizae and Plant Nutrition
Are modified roots consisting of mutualistic associations of fungi and roots
The fungus
Benefits from a steady supply of sugar donated by the host plant
In return, the fungus
Increases the surface area of water uptake and mineral absorption and supplies water and minerals to the host plant

66. Staghorn fern, an epiphyte Mistletoe, a photosynthetic parasite
Unusual nutritional adaptations in plants
Staghorn fern, an epiphyte
EPIPHYTES
PARASITIC PLANTS
CARNIVOROUS PLANTS
Mistletoe, a photosynthetic parasite
Dodder, a nonphotosynthetic parasite
Host’s phloem
Haustoria
Indian pipe, a nonphotosynthetic parasite
Venus’ flytrap
Pitcher plants
Sundews
Dodder

68. Phytoremediation
Poplars remove nitrates
Mustard removes uranium

70. Wetlands Pesticide Levels (ppb) in
Ground Water Before & After Phytoremediation Activities
Wetlands

71. Uptake of Soil Solution
Symplastic Route
continuum of cytosol based
on plasmodesmata
Apoplastic Route
continuum of cell walls and
extracellular spaces
Lateral transport of soil
solution alternates between
apoplastic and symplastic
routes until it reaches the
Casparian strip

72. Casparian Strip
A belt of suberin (purple) that blocks the passage of water and dissolved minerals.

73. Chapter 38
Plant Reproduction

74. Plant Reproduction Sporophyte (diploid) produces haploid
spores via meiosis
Gametophyte (haploid)
produce haploid
gametes via mitosis
Fertilization
joins two gametes to
form a zygote

75. (a) An idealized flower.
An overview of angiosperm reproduction
Anther at
tip of stamen
Filament
Anther
Stamen
Pollen tube
Germinated pollen grain
(n) (male gametophyte)
on stigma of carpel
Ovary (base of carpel)
Ovule
Embryo sac (n)
(female gametophyte)
FERTILIZATION
Egg (n)
Sperm (n)
Petal
Receptacle
Sepal
Style
Ovary
Key
Haploid (n)
Diploid (2n)
(a) An idealized flower.
(b) Simplified angiosperm life cycle. See Figure for a more detailed version of the life cycle, including meiosis.
Mature sporophyte
plant (2n) with
flowers
Seed
(develops
from ovule)
Zygote
(2n)
Embryo (2n)
(sporophyte)
Simple fruit
(develops from ovary)
Germinating
seed
Carpel
Stigma

76. Mechanisms That Prevent Self-Fertilization
Stigma
Stigma
Pin flower
Thrum flower
Anther
with
pollen
The most common anti-selfing mechanism in flowering plants
Is known as self-incompatibility, the ability of a plant to reject its own pollen

77. Preventative Selfing Some plants Recognition of self pollen
Reject pollen that has an S-gene matching an allele in the stigma cells
Recognition of self pollen
Triggers a signal transduction pathway leading to a block in growth of a pollen tube

78. Double Fertilization Double Fertilization pollen grain lands on stigma
+ pollen tube toward ovule
+ both sperm discharged down the tube
- egg and one of the sperm
produce zygote
- 2 polar nuclei and sperm
cell produce endosperm
+ ovule becomes the seed coat
+ ovary becomes the fruit

79. Seed Structure and Development

80. The radicle In many eudicots
Is the first organ to emerge from the germinating seed
In many eudicots
A hook forms in the hypocotyl, and growth pushes the hook above ground
Foliage leaves
Cotyledon
Hypocotyl
Radicle
Epicotyl
Seed coat

81. Monocots The coleoptile
Use a different method for breaking ground when they germinate
The coleoptile
Pushes upward through the soil and into the air
Foliage leaves
Coleoptile
Radicle

82. Plant Responses to Internal and External Signals
Chapter 39
Plant Responses to Internal and External Signals

83. Tropisms Growth toward or away from a stimulus Gravitropism (Gravity)
Phototropism (Light)
Thigmotropism (Touch)

84. Etiolation
The stems of plants raised in the dark elongate much more rapidly than normal, a phenomenon called etiolation.

85. Signal Transduction Pathway
Figure 39.3
CELL
WALL
CYTOPLASM
  1 Reception
2 Transduction
3 Response
Receptor
Relay molecules
Activation
of cellular
responses
Hormone or
environmental
stimulus
Plasma membrane

86. Plant hormones help coordinate growth, development, and responses to stimuli
Are chemical signals that coordinate the different parts of an organism

88. Photoperiod, the relative lengths of night and day
+ Is the environmental stimulus plants use most often to detect the time of year