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photosynthesis
converts solar energy into chemical energy
autotrophs
sustain themselves without eating anything derived from other organisms
heterotrophs
obtain their organic material from other organisms
plants alternate between two multicellular stages, a reproductive cycle called:
alternation of generations
Fusion of the gametes gives rise to the diploid sporophyte, which:
produces haploid spores by meiosis
the gametophyte is haploid, and:
produces haploid gametes by mitosis
nutrients are transferred from parent to embryo through:
placental transfer cells
land plants are called:
embryophytes, because of the dependency of the embryo on the parent
the sporophyte produces spores in organs called:
sporangia
xylem:
conducts most of the water and minerals and includes dead cells called tracheid’s
phloem consists of:
living cells and distributes sugars, amino acids, and other organic products
Water-conducting cells are strengthened by:
lignin and provide structural support
roots are:
organs that anchor vascular plants
Roots may have evolved from:
subterranean stems
leaves are:
organs that increase the surface area of vascular plants, thereby capturing more solar energy that is used for photosynthesis
Phylum Lycophyta includes:
club mosses, spike mosses, and quillworts
Phylum Pterophyta includes:
ferns, horsetails and whisk ferns in their relatives
club mosses and spike mosses have:
vascular tissues and are not true mosses
Increased photosynthesis may have helped produce:
the global cooling at the end of the carboniferous period
The gymnosperms have “naked” seeds not enclosed by ovaries and consist of four phyla:
Cycadophyta (cycads)
Gingkophyta (one living species: Ginkgo biloba)
Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia)
Coniferophyta (conifers, such as pine, fir, and redwood)
fossil evidence reveals that by the late Devonian period some plants, called:
progymnosperms - had begun to acquire some adaptations that characterize seed plants
living seed plants can be divided into two clades:
gymnosperms and angiosperms
Gymnosperms:
appear early in the fossil record and dominated the mesozoic terrestrial ecosystems
phylum coniferophyta:
this phylum is by far the largest of the gymnosperm phyla
Three key features of the gymnosperm life cycle are:
-Dominance of the sporophyte generation
-Development of seeds from fertilized ovules
-The transfer of sperm to ovules by pollen
angiosperms are seed plants with:
reproductive structures called flowers and fruits
the flower is an:
angiosperm structure specialized for sexual reproduction
A flower is a specialized shoot with up to four types of modified leaves:
Sepals, which enclose the flower
Petals, which are brightly colored and attract pollinators
Stamens, which produce pollen on their terminal anthers
Carpels, which produce ovules
A carpel consists of an ovary at the base and a style leading up to a stigma, where:
pollen is received
various fruit adaptations help:
disperse seeds
The female gametophyte, or embryo sac, develops within an ovule contained within an:
ovary at the base of a stigma
the ovule is entered by a pore called the:
micropyle
double fertilization occurs when the:
pollen tube discharges two sperm into the female gametophyte within an ovule
Male gametophytes are contained within:
pollen grains produced by the microsporangia of anthers
Within a seed, the embryo consists of a root and two seed leaves called:
cotyledons
Archaefructus sinensis, for example, has:
anthers and seeds but lacks petals and sepals
Primitive fossils of 125-million-year-old angiosperms display:
derived and primitive traits
The two main groups of angiosperms are:
•monocots (one cotyledon) and eudicots (“true” dicots)
The clade eudicot includes some groups formerly assigned to the:
•the paraphyletic dicot (two cotyledons) group
most of our food comes from:
angiosperms
The pine tree is the sporophyte and produces:
sporangia in male and female cones
Small cones produce microspores called pollen grains
each of which contains a male gametophyte
The two main groups of angiosperms are:
•monocots (one cotyledon) and eudicots (“true” dicots)
plants, like multicellular animals, have
organs composed of different tissues
three basic organs evolved:
roots, stems, and leaves
roots are multicellular organs with important functions:
anchoring the plant
absorbing minerals and water
storing organic nutrients
many plants have
modified roots
a taproot system consists of one main vertical root that gives rise to:
lateral roots, or branch roots
adventitious roots arise from
stems or leaves
in most plants, absorption of water and minerals occurs near the
root hairs, where vast numbers of tiny root hairs increase the surface area
roots rely on sugar produced by:
photosynthesis in the shoot system
many plants have
modified roots
a stem is an organ consisting of:
An alternating system of nodes, the points at which leaves are attached
Internodes, the stem segments between nodes
an axillary bud is:
a structure that has the potential to form a lateral shoot, or branch
an apical bud, or terminal bud, is:
located near the shoot tip and causes elongation of a young shoot
apical dominance helps
to maintain dormancy in most nonapical buds
many plants also have:
modified stems
the leaf is the main:
photosynthethetic organ of most vascular plants
leaves generally consist of a flattened blade and a stalk called:
the petiole
Monocots and eudicots differ in the arrangement of veins:
the vascular tissue of leaves
Most monocots have
parallel veins
most eudicots have:
branching veins
Some plant species have evolved modified leaves that
serve various functions
Each plant organ has dermal, vascular, and ground tissues. Each of these three categories forms a:
tissue system
In nonwoody plants, the dermal tissue system consists of the
epidermis
In woody plants, protective tissues called periderm replace the
epidermis in older regions of stems and roots
The vascular tissue of a stem or root is collectively called the
stele
In angiosperms the stele of the root is a solid central
vascular cylinder
conveys water and dissolved minerals upward from roots into the shoots
xylem
transports organic nutrients from where they are made to where they are needed
phloem
The stele of stems and leaves is divided into vascular bundles
strands of xylem and phloem
some major types of plant cells:
Parenchyma
Collenchyma
Sclerenchyma
Water-conducting cells of the xylem
Sugar-conducting cells of the phloem
ground tissue includes cells specialized for:
storage, photosynthesis and support
ground tissue internal to the vascular tissue is the
pith; ground tissue external to the vascular tissue is cortex
Mature parenchyma cells
Have thin and flexible primary walls
Lack secondary walls
Are the least specialized
Perform the most metabolic functions
Retain the ability to divide and differentiate
grouped in strands and help support young parts of the plant shoot
They have thicker and uneven cell walls
They lack secondary walls
These cells provide flexible support without restraining growth
Collenchyma cells are
grouped in strands and help support young parts of the plant shoot
They have thicker and uneven cell walls
They lack secondary walls
These cells provide flexible support without restraining growth
Sclerenchyma cells are:
rigid because of thick secondary walls strengthened with lignin
They are dead at functional maturity
there are two types of scletenchyma cells:
Sclereids are short and irregular in shape and have thick lignified secondary walls
Fibers are long and slender and arranged in threads
The two types of water-conducting cells, tracheids and vessel elements, are
dead at maturity
tracheids are found in:
the xylem of all vascular plants
Vessel elements are common to most angiosperms and
a few gymnosperms
Vessel elements align end to end to form long micropipes called
vessels
Sieve-tube elements are
alive at functional maturity, though they lack organelles
Sieve plates are
the porous end walls that allow fluid to flow between cells along the sieve tube
Each sieve-tube element has a
companion cell whose nucleus and ribosomes serve both cells
A plant can grow throughout its life; this is called
indeterminate growth
some plant organs cease to grow at a certain size. this is called
determinate growth
annuals complete their life cycle in
a year or less
biennials require
two growing seasons
perennials
live for many years
Meristems are
perpetually embryonic tissue and allow for indeterminate growth
Apical meristems
are located at the tips of roots and shoots and at the axillary buds of shoots
Apical meristems elongate shoots and roots, a process called
primary growth
Lateral meristems
add thickness to woody plants, a process called secondary growth
There are two lateral meristems:
•the vascular cambium and the cork cambium
The vascular cambium adds
•layers of vascular tissue called secondary xylem (wood) and secondary phloem
The cork cambium replaces the
epidermis with periderm, which is thicker and tougher
•Growth occurs just behind the root tip, in three zones of cells:
Zone of cell division
Zone of elongation
Zone of maturation