bio102 chapter 25
TRANSCRIPT
-
7/25/2019 Bio102 Chapter 25
1/27
Chapter 25 Structure andOrganization of Plants
-
7/25/2019 Bio102 Chapter 25
2/27
Plant Structure
* Many of the same environmental pressures
that helped to shape the transition of animals
from an aquatic existence to a terrestrial
existence, have affected plant evolution aswell. Among the environmental pressures
both animals and plants face as the transition
to land occurred were:
-
7/25/2019 Bio102 Chapter 25
3/27
Structural Needs of Plants
1. here is greater need to preventdesiccation on land.
!. here is a greater need for vascular tissue
or some means of transporting fluidsthroughout the body on land.
". here is a greater need for support onland.
#. $ot only do plants need support on land,the leaves must also be held up into thesunlight.
-
7/25/2019 Bio102 Chapter 25
4/27
Plant Structure
plant morphology % the study of
the external structure of plants
plant anatomy % the study of the
internal structure of plants
-
7/25/2019 Bio102 Chapter 25
5/27
Angiosperms (owering
plants) * Angiosperms &flowering plants' are by farthe most diverse and widespread of all
plants. he two ma(or angiosperm classes
are: 1. monocots % possess a single seed leaf
&cotyledon', ex. corn
!. dicots &eudicots' % possess a double seedleaf, ex. bean
-
7/25/2019 Bio102 Chapter 25
6/27
Comparison of Monocots andDicots )haracteristic Monocot icot
1. cotyledons one two
!. leaf venation parallel netli+e ". vascular bundles scattered through stem arranged in rings
#. roots fibrous taproot present . floral parts multiples of threes multiples of fours - fives
-
7/25/2019 Bio102 Chapter 25
7/27
Monocot Dicot:
Comparisons
-
7/25/2019 Bio102 Chapter 25
8/27
Plant structure at thecellular and tissue level: )ompared to animals cells, plant cells have a cell
wall consisting of a primary cell wall, secondary cellwall, and middle lamella.
he primary cell wall is composed of cellulose, the
secondary cell wall of cellulose and lignin, and themiddle lamella pectin
chloroplasts that function in photosynthesis a protoplast consisting of the whole cell excluding
the cell wall a large central vacuole surrounded by a tonoplast plasmodesmata for intercellular transport and they lac+ centrioles.
-
7/25/2019 Bio102 Chapter 25
9/27
Types of Plant Cells
1. parenchyma cells % /typical plant cell/ with
large central vacuole, no secondary cell
walls, and thin primary cell walls.
0arenchyma cells carry out most of themetabolic functions of the plant. he flesh of
fruit and the photosynthetic mesophyll cells of
leaves are modified parenchyma cells.
-
7/25/2019 Bio102 Chapter 25
10/27
Types of Plant Cells contd!
!. collenchyma cells % lac+ secondary cell
walls but have thic+er primary cell walls than
parenchyma cells. he cell wall lac+s the
strengthening protein lignin allowingcollenchyma cells to support young stems
without restricting growth. he collenchyma
cells lengthen as the stem grows.
-
7/25/2019 Bio102 Chapter 25
11/27
Types of Plant Cells contd!
". sclerenchyma cells % have thic+ secondary
cell walls strengthened with lignin. Mature
sclerenchyma cannot grow and occur in
areas where lengthwise growth has ceased.ibers found in hemp and sclereids found in
nutshells, seed coats, and the /grit/ in pears
are two forms of sclereids.
-
7/25/2019 Bio102 Chapter 25
12/27
Types of Plant Cells contd!
#. vascular tissue % the water%conducting tissue
xylem which is made of tracheids and vessels, and
phloem consisting of sieve tubes and companion
cells. racheids have more of a supportive function,while vessels allow a continuous flow of water.
2ymnosperms have only tracheids, while
angiosperms have tracheids and vessels which
evolved from tracheids. he phloem sieve tubesconduct sap throughout the plant and because they
lac+ a nucleus or ribosomes are supported
functionally by companion cells.
-
7/25/2019 Bio102 Chapter 25
13/27
hree Plant issue !pes 1. dermal tissue &epidermis' % derived from
protoderm meristem, a single layer of tightly%pac+edcells that covers and protects the plant. !. vascular tissue % derived from procambium
meristem, a system of xylem and phloem thatfunctions in transport and support.
". ground tissue % derived from ground meristem,fills space between epidermis and vascular tissue.0rimarily parenchyma cells, but collenchyma andsclerenchyma sometimes present.
* he basic structure of a root, stem, or leaf is anouter layer of dermal tissue, an inner vascular tissue&xylem and phloem', and the tissue that fills the root,stem, or leaf &ground tissue'
-
7/25/2019 Bio102 Chapter 25
14/27
"asic plant morpholog!
3asic plant morphology consists of a rootsystem and a shoot system containing stems,leaves, and flowers both of which are
connected by vascular tissue. 3asic plant parts: 1. flowers
!. roots ". shoots #. leaves
-
7/25/2019 Bio102 Chapter 25
15/27
"asic Plant
Parts
-
7/25/2019 Bio102 Chapter 25
16/27
"! #lower structure: sepals &calyx'
petals &corolla'
stamen 4 anther and filament
pistil &carpel' 4 stigma, style, ovary
-
7/25/2019 Bio102 Chapter 25
17/27
2! Structure and Primar! $rowthof %oot 1. root cap % protects the root meristem and secretes a
polysaccharide that allows the root to move through the soil moreeasily. !. 5one of cell division % consists of the apical meristem and
derivatives. )ells of the apical meristem divide to form the threeprimary meristems: the protoderm, procambium, and groundmeristem which in turn will form the dermal, vascular, and groundtissue respectively.
". 5one of cell elongation % growth occurs by cell elongation up toten times original length.
#. 5one of cell differentiation % the three tissues systemsproduced by primary growth complete their differentiation.
-
7/25/2019 Bio102 Chapter 25
18/27
Primar! issues of %oots
1. protoderm % outermost primary meristem which gives rise to theepidermis.
!. procambium % gives rise to the central vascular cylinder &stele'. 6ncross%section, the xylem of dicots forms a cross, whereas the xylem ofmonocots occurs in a ring. 0hloem will alternate between and outsidethe xylem.
". ground meristem % gives rise to the ground tissue which fills thecortex.
endodermis % one%cell thic+ cylinder that forms the boundary betweenthe cortex and the stele.
pericycle % layer of meristematic cells (ust inside the endodermis whichgives rise to lateral roots.
* rom the interior of a root to the exterior you would find the followingstructures:
stele &xylem and phloem' % pericycle % endodermis % cortex % epidermis
-
7/25/2019 Bio102 Chapter 25
19/27
&' Shoot (stem structure)
7hoot 7ystem % consists of vegetative shoots
containing the stem and leaves and floral shoots
that bear flowers
* A stem consists of nodes where leaves areattached and internodes. A stem also contains
axillary buds which is an embryonic side shoot, and
terminal buds at the tip of the shoot which will form
leaves and8or flowers. he terminal bud usuallyexerts apical dominance &suppresses growth' on the
lateral buds.
-
7/25/2019 Bio102 Chapter 25
20/27
Shoot (stem structure)contd'
terms 1. bar+ !. cor+ cambium
". vascular cambium
#. primary xylem
. secondary xylem
9. primary phloem . secondary phloem
;. annual ring
-
7/25/2019 Bio102 Chapter 25
21/27
Modied stems
* Modified stems with various functions
include:
the stolons or runners of the strawberry,
rhi5omes &underground stems' found in irises,
tubers illustrated by the white potato, and
bulbs of tulips or onions.
-
7/25/2019 Bio102 Chapter 25
22/27
Modied stems * e+amples
-
7/25/2019 Bio102 Chapter 25
23/27
,' -eaf structure
* A leaf is the ma(or photosynthetic organ of
most plants consisting of a blade attached to
the stem by a petiole.
-
7/25/2019 Bio102 Chapter 25
24/27
-eaf structure contd'
*
-
7/25/2019 Bio102 Chapter 25
25/27
-eaf structure contd'terms
epidermis
palisade mesophyll
spongy mesophyll
vascular bundle &vein' xylem
phloem
stomata guard cells
-
7/25/2019 Bio102 Chapter 25
26/27
#eaf structure
-
7/25/2019 Bio102 Chapter 25
27/27
-eaf structure contd'
* Modified leaves with various functions
include
tendrils of plants such as beans or grape,
the spines of cacti,
succulent leaves for water storage, and
leaves adapted to attract pollinators such
as those in poinsettia.