Download Ch 20-21

Chapter 20
Plant Anatomy and Growth
Chapter 21
Plant Responses and Reproduction
20.1 Plant Cells and Tissues
Figure 20.3a Ground tissue cells.
 Parenchyma—least
specialized
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• May contain chloroplasts
and carry on
photosynthesis
• May contain colorless
plastids that store
products of
photosynthesis
×100
a. Parenchyma cells
© Biophoto Associates/Photo Researchers, Inc.
Figure 20.3b Ground tissue cells.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
 Collenchyma—
give flexible
support to
immature regions
of plant body
×340
b. Collenchyma cells
© Biophoto Associates/Photo Researchers, Inc.
Figure 20.3c Ground tissue cells.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
 Sclerenchyma—most
nonliving, contain
lignin, primary
function is to support
mature regions of
plant
×340
c. Sclerenchyma cells
© Biophoto Associates/Photo Researchers, Inc.
Figure 20.5 The vegetative body of a plant.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
terminal bud
lateral bud
blade
vein
petiole
leaf
node
Shoot
system
internode
node
vascular tissues
lateral root
Root
system
primary root
root hairs
root tip
• Monocot versus eudicot plants
 2 major groups of flowering
plants
 Names based on cotyledons—
first embryonic leaves present
in seeds
• Monocots, or
monocotyledons, have 1
cotyledon.
 Store some nutrients and
transfer nutrients stored
elsewhere
 Grasses, lilies, orchids,
palm trees, rice, wheat,
corn, etc.
Figure 20.7 Flowering
plants are either monocots
or eudicots.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Seed
Monocots
one
cotyledon
in seed
• Eudicots, or
eudicotyledons, have 2
cotyledons.
 Supply nutrients to
seedlings
 Dandelions, oak trees, and
many others
Eudicots
two
cotyledons
in seed
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 20.7
Flowering plants
are either
monocots or
eudicots,
continued.
Seed
Monocots
Eudicots
Root
Stem
one
cotyledon
in seed
root xylem and
phloem in a ring
vascular bundles
scattered in stem
root phloem between
arms of xylem
vascular bundles
in a distinct ring
two
cotyledons
in seed
 Location and arrangement of vascular tissue
differs
•
•
•
•
Xylem—water and mineral transport
Phloem—organic nutrient transport
In stems, vascular tissue forms vascular bundles
In leaves, forms leaf veins
 Differences in the
number of flower
parts
• Monocots have
flower parts in threes
and multiples of
three
• Eudicots have flower
parts in fours or fives
or multiples of four
or five
Figure 20.7 Flowering plants are
either monocots or eudicots,
continued.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Flower
Monocots
flower parts in threes
and multiples of three
Eudicots
flower parts in fours or
fives and their multiples
Leaves
• Blade—wide portion of leaf
• Blade may be simple or
compound
• Petiole—stalk that attaches
blade to stem
Figure 20.8a Simple versus compound leaves.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
blade
lateral bud
Simple leaf
Figure 20.8b Simple versus compound leaves.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
leaflet
blade
petiole
lateral bud
Compound leaf
Figure 20.8c Simple versus compound leaves.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
blade
lateral bud
Twice compound leaf
Figure 20.9 Leaf structure, continued.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
guard cell
O2 and H2O
exit leaf
through stoma.
CO2 enters leaf
through stoma.
epidermal cell
Stoma and guard cells
Figure 20.10a, b, c Leaf and stem diversity.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
leaves
tendril
stem
a. Cucumber
b. Venus’s flytrap
c. Cactus
(a): © Michael Gadomski/Photo Researchers, Inc.; (b): © Steven P. Lynch; (c): © Nature Picture Library
• Leaves also have other purposes
 Tendrils for attachment
 Some capture insects
 Thorns for protection
Figure 20.10c, d Leaf and stem diversity.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
leaves
tuber
stem
c. Cactus
d. Potato
(c): © Nature Picture Library; (d): © The McGraw Hill Companies, Inc./Carlyn Iverson, photographer

Stems may also function as
•
•
Primary photosynthetic organ and
water reservoir—cactus
Store food—potato
Figure 20.11 Nonwoody (herbaceous) stems.
Figure 20.12 Organization of a woody stem.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
cork
cork cambium
cortex
Bark
phloem
Vascular Cambium
summer
wood
secondary
xylem
annual
ring
spring
wood
Wood
Pith
(bottom, circular): © Ed Reschke/Peter Arnold/Photolibrary
• Bark
 Contains cork, cork cambium, cortex, and
phloem
 Cork cambium located below epidermis
 Cork cells impregnated with suberin
• Wood
 Secondary xylem
 In trees with a growing season, annual rings
formed by spring and summer wood
Roots
 Functions
• Support plant by anchoring it in the soil
• Absorb water and minerals
 Rule of thumb—root system equivalent in size
and extent to shoot system
• Also depends on environment
 Root hairs found in zone of root tip
• Increase absorptive capacity of root
• Constantly being replaced
Figure 20.15a, c Root diversity.
 Root types
• Taproot, fibrous roots, prop roots
 Perennial plants regrow each year from the
roots.
Figure 20.13 Eudicot root tip, continued.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
zone of
cell division
apical meristem
protected by
root cap
root cap
Root tip
(right): © Visuals Unlimited/Corbis
Micrograph of root tip
Figure 20.18 Cohesion-tension model of xylem transport.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Evaporation of water
(transpiration)
creates tension that
pulls the water
column from the
roots to the leaves.
H2O
Cohesion and
adhesion of water
molecules keeps
the water column
intact within xylem.
Water enters a
plant at root cells.
H2 O
Figure 20.19 Opening and
closing of stomata.
• Opening and
closing of stomata
 Plants are able to
open and close
epidermal cell
stomata by changing
nucleus
turgor pressure
within guard cells.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
 When water
enters the guard
cells, turgor
pressure is
created and
stomata open.
thickened
inner wall
H 2O
H 2O
guard
cell
Open
 When water
leaves the
guard cells,
turgor
pressure is
lost and
stomata
close.
Figure 20.19 Opening and
closing of stomata, continued.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H2O
H2O
H2O
H2O
Closed
21.2 Plant Responses
• Tropism
 Growth toward or away from a directional
stimulus
• Positive tropism—growth toward stimuli
• Negative tropism—growth away from stimuli
 Phototropism—response to light
 Gravitropism—response to gravity
Figure 21.7a Phototropism.
Positive phototropism
•The accumulation of auxin on the shady side of the
stem causes the plant to curve toward light
Figure 21.8a Gravitropism.
The corn seed was germinated in a sideways orientation and
in the dark. The shoot is growing upward (negative
gravitropism) and the root downward (positive gravitropism).
21.3 Sexual Reproduction in
Flowering Plants
• Alternation of generations—2 multicelluar
stages in life cycle
 Sporophyte (2n) produces haploid spores by
meiosis
• Spores develop into gametophytes
 Gametophytes (n) produce gametes
 Upon fertilization, the cycle returns to the 2n
sporophyte
Figure 21.14 Jatropha
plants are monoecious.
The flowers of the
mature Jatropha plant
are monoecious with
both female (left) and
male flowers (right) on
the same plant.
• Monocots versus eudicots
 Eudicot embryos
• Have 2 cotyledons
• All endosperm absorbed into cotyledons
 Monocot embryos
• Have 1 cotyledon
• Endosperm retained
• Cotyledon functions in food storage and passes
food from endosperm to embryo
Figure 21.18 Examples of
fruits.
• Fruit types
 Seeds develop from ovules
 Fruits develop from ovaries (and other parts of
flower)
• Dry fruit—thin, dry ovary; wheat, rice, walnuts, peas
• Fleshy fruits—juicy and brightly colored
 Drupe—inner stony layer, peach, cherry, olive
 Berry—contains many seeds, tomato
 Pome—dry ovary covers seeds while fleshy part derived
from receptacle, apple
Germination of seeds
 Doesn’t usually take place until conditions are
right
• Enough water, warmth, oxygen, moisture
 Some seeds require a trigger to germinate
• Cold period, fire, removal of fruit
• Eudicot versus monocot germination
Figure 21.20a Common garden bean, a eudicot.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
embryo
seed coat
cotyledon
Eudicot—between 2 cotyledons is the embryo
•Shoot hook-shaped to protect immature leaves
•Cotyledons shrivel up as true leaves begin function
Figure 21.20b Common garden bean, a eudicot.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
first true
leaves
cotyledons
(two)
seed coat
seed coat
withered
cotyledons
roots
Figure 21.21a Corn, a monocot.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
fruit and seed coat
endosperm
cotyledon
embryo
Monocot—corn kernel is a fruit
•Both immature leaves and root covered by sheaths
•Immature leaves become first true leaves
Figure 21.21b Corn, a monocot.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
true leaf
first leaf
sheath
roots
21.4 Asexual Reproduction and Genetic
Engineering in Plants
• Can reproduce asexually due to
undifferentiated cells in meristem
• Complete strawberry plants grow from
nodes of stolons
• Iris plants grow from nodes of rhizomes
• Seedless fruits can be produced several
ways
 Usually some stimulus prompts fruit to
develop without fertilization
Figure 21.22a
Structures for asexual
propagation.
Figure 21.22b
Structures for asexual
propagation.
QUIZ in one minute