Biology 102 Chapter 35
The Plant Body
1. Explain the differences between monocots and eudicots.
---monocots generally narrow-leaved flowering plants such as
grasses, lilies, orchids, and palms
---dicots are broad-leaved flowering plants such as soybeans,
roses, sunflowers, and maples
COTYLEDONS (seed leaf/leaves)
---monocot seed has only 1; eudicot seed has 2
VEINS IN LEAVES (VENATION)
---monocot usually parallel; eudicot usually netlike
FLOWER PARTS
---monocot usually in multiples of 3; eudicots usually in 4s/5s
VASCULAR BUNDLES
---monocot bundles scattered in stem; eudicot bundles arranged
in a ring
ROOT SYSTEM
---most monocots have fibrous roots; eudicots have tap root
2. Identify the three kinds of vegetative organs possessed by
flowering plants.
---vegetative organs organized into 2 systems
--shoot system: stems, leaves, and flowers
--root system
---roots, stems, and leaves
3. Explain the functions of the root system and shoot system
and describe how they work together.
---are evolutionary adaptations to living on land
---plant can be divided into 2 basic systems
--subterranean root system
--aerial shoot system (stems, leaves, & flowers)
---root system well adapted to:
--anchor plants
--absorb and conduct water & nutrients
--store food
---absorption of water greatly enhanced by
root hairs (> surface area of root)
--absorption of water/minerals > by mychorrhizae,
symbiotic associations between roots & fungi
---some plants possess root nodules (contain symbiotic
bacteria capable of “fixing nitrogen”
---adventitious roots are roots rising above ground
from stems or leaves
--form in addition to normal root system
--example is corn prop roots
---shoot system comprised of vegetative and floral
shoots
--vegetative consists of a stem & attached leaves
--floral shoots terminate in flowers
4. Identify and give the main function for the different types
of plant cells, tissues, and tissue systems.
PARENCHYMA CELLS
---most numerous cell type in young plants
---thin walls consisting of primary wall shared middle lamella
---usually not elongated or otherwise asymmetrical
---most have large central vacuole
---comprise photosynthetic cells in leaves
---some nonphotosynthetic parenchyma cells store starch/lipids
---some serve as packing material and play role in support
---others remain mitotic and capable of dividing and giving rise
to new parenchyma cells
COLLENCHYMA CELLS
---supporting cells with primary walls thickened in cell corners
---primary wall thickens but no secondary wall forms
---generally elongate cells
---provides support to leaf petioles, nonwoody stems, and
growing organs
---tissue composed of collenchyma cells is flexible permitting
stems and petioles to sway in wind without snapping
---celery strings...
SCLERENCHYMA CELLS
---have thickened secondary cell wall that performs major
function of SUPPORT
---most sclerenchyma cells function when dead
---2 types of sclerenchyma cells
--elongated fibers and variously shaped sclereids
---fibers often organized into bundles and provide relatively
rigid support in wood and other parts of the plant
--bark of tree owes much of its mechanical strength to long
fibers
---sclereids may pack together densely (nut shell/seed coat)
and can occur in isolated clumps (stone cells)
XYLEM CELLS
---may be tracheary elements, tracheids, or vessel elements
PHLOEM CELLS
---may be sieve tube members or companion cells
---a TISSUE is organized group of cells working together as
functional unit
---SIMPLE TISSUE composed of only one type of cell
--parenchyma, sclerenchyma, and collenchyma tissue
---COMPLEX TISSUE composed of different cell types
--xylem and phloem are complex tissue
---tissues are grouped into TISSUE SYSTEMS that extend
throughout body of plant from organ to organ
---vascular, dermal, and ground tissue systems in plants
VASCULAR TISSUE SYSTEM
---includes the xylem and phloem
---is conductive or “plumbing” system of plant
DERMAL TISSUE SYSTEM
---outer covering of the plant
---epidermis/periderm
GROUND TISSUE SYSTEM
---makes up rest of plant
---consists primarily of parenchyma tissue supplemented with
collenchyma or sclerenchyma
---functions primarily in storage, support, photosynthesis, and
production of defensive and attractive substances
5. Distinguish between water-conducting cells and foodconducting cells with regard to structure and function.
---xylem is the water conducting part of vascular system
---composed of two cells types: tracheids/vessel elements
---both types have secondary walls and both are dead
at functional maturity
---tracheids are long, thin, tapered cells with ligninhardened secondary walls with pits (thinner regions
where only primary walls are present)
--water flows from cell to cell through pits
--also function in support
---vessel elements are wider, shorter, thinner-walled,
and less tapered than tracheids
--are aligned end to end
--end walls perforated, permitting free flow of
water through chains of vessel elements called
xylem vessels
---food conducting cells known as phloem
---sieve-tube members are chains of phloem cells that
transport sucrose, other organic compounds, and
some minerals
--are alive at functional maturity
--protoplasts lack nucleus, ribosomes, and
distinct vacuole
---in angiosperms, end walls of sieve-tube members
have pores and are called sieve plates
--pores facilitate movement of fluid between cells
--at least one companion cell is connected to each
sieve-tube member by many plasmodesmata
-the companion’s nucleus & ribosomes may
also serve the sieve-tube member which
lacks these organelles
---companion cells also help load sugar produced
in mesophyll into sieve-tubes of leaves of
some plants
6. Discuss how plants grow.
---embryonic plant establishes basic body plan for its mature
form
---two patterns contribute to plant body plan
--apical-basal pattern is arrangement of cells and tissues
along main axis from root to shoot
--radial pattern is concentric arrangement of tissue systems
---growing stem consists of modules (units) laid down one after
another
--unit consists of node with attached leaf/leaves, the
internode below that node, and the lateral bud or buds
at base of that internode
---new units are formed as long as the stem continues to grow
---leaves are units of another sort
---roots are another unit (branching)
---growth of stems and roots is INDETERMINATE
--generated from specific regions of active cell division
and cell expansion
---localized regions of cell division in plants are called
MERISTEMS
--meristemic tissues are forever young and retain ability to
produce new cells indefinitely(stem cells in animals)
---meristemic cell divides, one develops into new meristem cell
and the other into more specialized cell
7. Distinguish between apical and lateral meristems, where they
are located in the plant body and what cells/tissues they
produce.
---growth begins with seed germination & continues for
life of plant
---growth can occur as primary growth (apical
meristems) and secondary growth (lateral meristems)
---apical meristems are located in root tips and shoot
buds
--supply cells for plants to grow in length
--shoot apical meristems supply cells that extend stems
and branches
--roots apical meristems supply cells that extend roots
---both shoot and root meristems give rise to set of
cylindrical primary meristems that produce primary tissues
of plant body
---primary meristems are protoderm, ground meristem, and
procambium
--protoderm-->dermal tissue system
--ground meristem-->ground tissue system
--procambium-->vascular tissue system
---lateral meristems (cylinders of dividing cells
extending along the lengths of roots and shoots
--results in secondary growth (increased girth)
--thickening of roots/shoots in woody plants
--cell division of lateral meristem produces
secondary dermal tissues which are thicker
and tougher than epidermis it replaces
--also adds new layers of vascular tissue
--vascular cambium tissue divides to form new xylem toward
inside of stem/root and forms new phloem toward the outside
--cork cambium tissue produces new protective cells primarily
in outward direction
-cells become impregnated with suberin = waterproof
--layer of growth produced by cork cambium called periderm
8. Explain the relationship between the two kinds of
meristem with relation to primary and secondary growth.
---apical meristems responsible for primary growth which leads
to elongation and organ formation
---all plant organs arise ultimately from apical meristem
cell division followed by expansion and differentiation
---growth in diameter of stems and roots produced by vascular
and cork cambia is called secondary growth
--source of wood and bark
--wood is secondary xylem
--bark (periderm + secondary phloem) is everything external
to the vascular cambium
9. Explain the difference between wood and bark.
---a secondary plant body results from secondary growth
---secondary plant body is comprised of secondary tissues
produced during growth in diameter
---secondary growth results from two lateral meristems
--vascular cambium and cork cambium
---vascular cambium produces secondary xylem and phloem
---cork cambium produces tough, thick covering for roots
& stems that replaces the epidermis
---vascular cambium forms when meristemic parenchyma cells
develop between the primary xylem and primary phloem of
of each vascular bundle & in the rays of ground tissue
between the bundles
---accumulated layers of secondary xylem produces wood that
consists mostly of tracheids, vessel elements, & fiber
--hardness and strength of wood results from these cells
-dead at maturity but have thick, lignified walls
-forms annual growth rings due to yearly activity of
cambium dormancy, spring wood production, and summer
wood production
---secondary phloem does NOT accumulate extensively
--secondary phloem and all tissues external to it
develop into bark
-eventually sloughs off the tree trunk