Chapter 20 Life of a Flowering Plant. 20.1 Reproductive Adaptations Flower is a specialized shoot...
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Transcript of Chapter 20 Life of a Flowering Plant. 20.1 Reproductive Adaptations Flower is a specialized shoot...
Chapter 20
Life of a Flowering Plant
20.1 Reproductive Adaptations
Flower is a specialized shoot with modified leaves
sepals: outermost ring; covers flower bud
petals: second ring; colorful to attract pollinators
stamens and carpels: center ring; reproductive structures
Reproductive Structures
Male Gametophytes
produced in stamens
anther: sac on top of stalk of stamen
Spores develop into pollen grains
Pollen = 2 cells with protective wall
Female Gametophytes
produced in carpels Ovary at base Ovules produce 4 cells
each; 3 die Each undergo 3
cycles of mitosis embryo sac: resulting
gametophyte style: leads to ovary stigma: sticky tip
Pollination pollination: pollen grains released from
anthers land on stigma Pollen grain absorbs water and extends a
pollen tube which grows toward ovary Pollen cell divides forming 2 sperm (n)
One fertilizes egg = zygote (2n) = embryo The other fertilizes the central cell = (3n)
endosperm
Seed Dispersal
Fruits protect seeds and help disperse Travel by sticking to animal’s fur (burr) Fleshy fruit that attracts animals; seeds
are passed through digestive system Water; coconuts Wind; puffy dandelion
Seed Development Seed coat: outer layer around seed that protects
embryo and endosperm Miniature root and shoot cotyledon: storage and
transfer of nutrients to embryo Dicots = dicotyledon = 2 Monocots=
(mono)cotyledon
Embryo grows through a few
stages of mitosis and stops to be
dispersed (stage that you see in
fruit)
Seed Germination germination: embryo grows when
conditions are favorable Soak up water
split seed
coat trigger
metabolic
changes
Adaptations and Conditions Protections for developing
shoots Hooked tip Sheath covering
Seedling: young plant that has just emerged from the soil
Vary among species Desert plants: after heavy rainfall Harsh winters: only after long period of cold Fire: clears other growth
Asexual Reproduction
vegetative reproduction: asexual reproduction Cacti; dropped shoots become new plant Strawberries and grasses send out runners Some trees send out shoots from underground stems
Different Life Cycles
Annuals: complete life cycle in one year Biennials: 2 years, flower in second Perennials: multiple times per year
20.2 Plant Structure Roots fibrous root: mat of
thin roots spread out below the soil surface Increased surface area grasses
taproot: one large vertical root with smaller branches Starch-storing Carrots
Stems, leaves, and flowers stems: support leaves and flowers nodes: point where leaves and stems attach internodes: portions of stem between nodes Transport water and nutrients
Shoots
buds: undeveloped shoots Terminal bud: tip of stem Axillary: in the angles of a leaf - branches
blade: main part of the leaf Primary photosynthesis site
petiole: stalk that connects leaf to stem veins: throughout leaves to carry water and
nutrients Some plants have modified leaves
Celery stalks are leaves; onion is underground shoot
Plant Tissues
Dermal Vascular Ground
Meristematic: differentiates into the others
Dermal Tissue
Outer covering or “skin”
Epidermis: tissue of nonwoody organs One or more layers of
cells Covers and protects
young parts Secretes waxy cuticle
Periderm: older tissue
Vascular Tissue
Transports water, mineral nutrients, and organic molecules; structure
xylem: water and dissolved minerals
phloem: food; made in leaves and transported to parts that don’t photosynthesize
Ground Tissue
Fills the spaces between dermal and vascular
Most of young nonwoody plant
Photosynthesis, stoage and support
cortex: ground tissue in a root
Leaf Structure
Types of Plant Cells parenchyma: thin cell walls and large
central vacuoles Food storage Photosynthesis and cellular respiration Fruits Phloem
collenchyma: unevenly thick cell walls Grouped in strands or cylinders Support to young parts Young stems and petioles
sclerenchyma: specialized for support Die and leave behind a “skeleton” xylem
20.3 Primary Growth
Plants continue to grow their entire lives meristems: tissues that differentiate into
new dermal, vascular, and ground tissue apical meristems: tips of roots and buds of
shoots Grow in length and branches primary growth: growth in length
Primary Growth of Roots root cap: tip of the root
Protects dividing cells of apical meristem
Apical meristem Replaces cells of root cap Produces cells for primary
growth Forms 3 cylinders of
cells; dermal, ground, vascular
Cells elongate by taking up water
Primary Growth of Shoots
Apical meristem: tip of terminal bud Elongation just
below
Auxillary buds Formed as
elongating cells push upward
Cylinders of cells
20.4 Secondary Growth
Growth in plant width Woody plants; vines,
shrubs, trees Vascular cambium and
cork cambium vascular cambium:
cylinder of actively diving cells between xylem and phloem Adds secondary
vascular tissue to primary
Accumulates as wood
Cork cambium
cork cambium: meristem that develops from parenchyma cells Produces tough outer
layer of cork Dead cork cells leave
thick, waxy walls; protects and prevents water loss
bark: everything outside vascular cambium Phloem, cork, cork
cambium
Tree Rings
Rings = yearly activity of vascular cambium
Spring; cells are larger and thinner Cool and wet
Summer: cells are smaller and thicker Hot and dry
Heartwood - dead xylem
Sapwood - xylem transports water