Download and Plants

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Unit 15 PLANT NOTES 2015
Ch. 20-22
Chapter 20: Plant Diversity
20.1 Origins of Plant Life
Plant life began in the water and became adapted to land.
Green Algae (Domain Eukarya, Kingdom Protista) and
Plants (Domain Eukarya, Kingdom Plantae) share many characteristics:
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photosynthetic eukaryotes
contain chlorophyll—green pigment that captures energy from sunlight during
photosynthesis
use starch as a storage product
have cell walls with cellulose (all plants and most green algae)
are multicellular
reproduction involving sperm and egg
Green algae are not currently classified with plants since algae do not have roots, stems or leaves,
and most species are aquatic.
Plants have 4 major adaptations that allow them to live on land.
1. Retaining moisture (prevent desiccation)
 cuticle—clear waxy, waterproof layer that helps hold in moisture
 stomata—holes in the cuticle surrounded by special cells allowing the
stomata to close to prevent water loss or to open to exchange gases with
the air (bring in CO2 and release O2 and water vapor).
2. Transporting resources
 vascular system—a collection of specialized tissues that bring water and
mineral nutrients up from the roots and transport sugars to where they are
used or stored
 vascular system allows the plants to grow taller
 nonvascular plants must remain small because water moves by osmosis
3. Growing upright
 tall plants compete better for light
 lignin—hardens the cell wall of some tissues to provide support, such as in
wood
4. Reproducing on land
 pollen grain—contains a cell that will form sperm; structure of the pollen
allows it to be carried by wind or animals and not require water
 seed—storage device for a plant embryo; the seed coat protects the
embryo from drying out
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20.2 Classification of Plants
The Plant Cell: Review
•
•
•
•
Are plants autotrophic or heterotrophic?
– autotrophic (plants are producers and they make their own food via photosynthesis;
have chloroplasts)
Are plants prokaryotic or eukaryotic?
– eukaryotic (eukaryotes have a nucleus just like we do and YOU are EUkaryotic)
Are plants multicellular or unicellular?
– multicellular
Plant cell walls are made of….
– cellulose
The Plant
Cell: Label
Not in
animal cells:
Nonvascular Plants (3 phyla)
Vascular Plants (6 phyla)
 do not have a system for transporting  contain structures with vascular tissue
water and other nutrients within their
(roots, stems and leaves)
body
 vascular plants (also known as
– nonvascular plants are small
tracheophytes) are composed of:
and lack vascular tissue
– tissue (roots, stems, leaves)
(xylem and phloem);
– each plant part – tissue, root,
therefore cannot develop
stem, leaf - has a specific role
stems, roots, and leaves
in keeping the plant alive
– include mosses (bryophytes),
through photosynthesis
liverworts, and hornworts
– include club mosses, ferns,
gymnosperms, &
angiosperms
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Plants are divided into two major groups:
Nonvascular Plant - moss
Sphagnum moss is commonly used by humans. It does not decay when it dies and thick deposits
of this are known as peat. Peat has many uses:
 can be burned as fuel
 absorb water, so often used to make soil more productive
 antibacterial properties (which prevents decay)
 serves as carbon reservoirs in the carbon cycle
Question: If nonvascular plants don’t have roots or stems, why do
we find most of them near water?
Answer:
They don’t have the structures to transport
water so in order to get water they have to be
near it to “absorb” it directly; it moves cell to
cell by osmosis
Vascular Plants - contain
vascular tissue (xylem & phloem—
discussed later)
 There are two types of vascular
plants:
- seedless plants
- seeded plants
 Plants with seeds can be grouped
into two additional categories:
- gymnosperms and
angiosperms
– Advantages of conducting
tissue
o transportation of water and sugar within a plant
o development of true roots, stems, and leaves
o grow taller (gaining more sunlight) and deeper (gaining more water)
o store sugars for future use
o don’t rely on osmosis and diffusion
Seedless Vascular Plants:
– spore – haploid asexual reproductive cell that divides by mitosis
into a multicellular haploid organism
– spores have thickened walls that prevent the cells from drying out
– diagram shows spores growing in clusters called sori on the back
of the fern
– Examples: ferns, club mosses, horsetails, and whisk ferns
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Seeded Vascular Plants:
seed- adaptation to terrestrial life composed of a plant embryo, stored food and a protective coat
• advantages of seeds
• seeds allow reproduction without free-standing water
• seeds protect and nourish a plant’s embryo.
• seeds disperse the offspring and delay the growth of the embryo until conditions are
favorable.
ovulate conefrom a pine tree
Types of seeded vascular plants:
(female)
• Gymnosperms
• seed plants whose seeds are not enclosed in fruit
• the cone is the reproductive structure;
contains pollen in males and ovules (eggs) in females
• Examples: conifers (pine, fir, cedar cypress),
staminate conecycads, ginkgoes, and gnetophytes
from a pine tree
(male)
• Angiosperms
• seed plants that have seeds enclosed in some type of fruit
• the flower contains the reproductive structures
• Examples: monocots and dicots.
Angiosperm are categorized by seed type:
• Monocots:
– one cotyledon—food source for baby
plant before it has true leaves for photosynthesis
– veins in leaf parallel
– vascular bundles in complex arrangement (scattered)
– fibrous root system
– floral parts in multiples of three
– Ex) grasses, corn, wheat, tulips, lilies
• Dicots:
– two cotyledons
– leaf veins netlike
– vascular bundles arranged in ring
–
–
–
taproot usually present
floral parts in four or five
Ex) most deciduous trees, roses, daisies, peanuts
Angiosperm are also categorized by
stem type and lifespan:
– stem type: woody or herbaceous
– lifespan:
o annual (life cycle in one year),
ex. petunias and pansies
o biennial (life cycle in two years)
ex. carrots
o perennial (lives more than 2
years) ex. trees and shrubs
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Chapter 21: Plant Structure & Function
21.1 Plant Cells & Tissues
 organ-group of tissues working together to perform a common function
 tissue-group of cells working together for a common purpose
 Plants have three main organs—leaves, stems, and roots.
 These three organs are made up of three tissue systems—dermal, ground, and vascular.
 These three tissue types are made up of three basic cell types—parenchyma, collenchyma, and
sclerenchyma.
3 basic plant cell types:
– parenchyma – found throughout the plant and store starch, oils, and water; also house
chloroplasts in the leaves; makes up most of fruits, stems, and roots
– collenchyma – found in younger tissues of leaves and roots; provide support while the
plant grows.
– sclerenchyma — strongest of these cell types that have a second cell wall hardened by
lignin; provide support; cells are dead at maturity and make up wood, nut shells, seed
coats
3 tissue systems in plants:
– dermal tissue system – covers the plant; epidermal (outer)
layer of cells of plants.
– ground tissue system – specialized for photosynthesis in
leaves and for storage and support in stems and roots.
– vascular tissue system – internal system of tubes and
vessels that transports water, mineral nutrients, and organic
compounds to all parts of the plant.
 2 types of vascular tissue: xylem and phloem
1. xylem – transports water and minerals
UP from the roots to the shoots
(memory trick—remember “wxyz”…water
carried by the xylem (xy sounds like a z))
2. phloem – transports sugar (food) from
where it’s made (leaves) or stored (cells in
leaves or roots) to where it’s needed
(remember phloem (ph sounds like an f) transports food).
21.2 & 21.3 The Vascular System and Stems & Roots
Stems
Function: support, storage, and transport
Support:
– stems can be woody or herbaceous
– stems support leaves, flowers, and fruits
Storage:
– stems can store food and water (ex. cacti, potatoes, ginger)
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Transport:
xylem – transports water and minerals up
from the roots to the shoots
 forces responsible for the
movement of fluids through
xylem are transpiration,
cohesion, adhesion, and
absorption.
See Figure 2.2 p. 622 and watch
Animated Biology--Movement
Through A Plant:
http://tinyurl.com/msun9zk
What process is the main force for
the movement of fluids through
xylem? transpiration
phloem – transports sugar (food) from where
it’s made (leaves) or stored (cells in leaves or
roots) to where it’s needed
The transport of sugar down the plant requires
energy. Plants pump sugar from a source into
the phloem. The change in the concentration
causes water to follow sugars into the phloem,
increasing the pressure and pushing the sugars
through the phloem into a sink.
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Roots
Function- support the plant, absorb water and
nutrients, transport water and nutrients to the
stem, and store nutrients
Roots are either fibrous or form a taproot.
Main parts of the root:
– vascular cylinder (or stele) is in the
center; contains the xylem and phloem
– root hairs—tiny projections of epidermal
cells on the roots that increase the
surface area which increases absorption
of water; microscopic
–
–
root cap—protects the growing tip
meristem—where the new cells are produced (aka zone of cell
division)
Remember that nitrogen fixation happens near the roots where bacteria live.
(Nitrogen fixation is when nitrogen in the atmosphere is converted by
bacteria into nitrogen compounds like ammonia, nitrates and nitrites.)
Nitrogen is important for making nucleic acids, proteins, and chlorophyll.
21.4 Leaves
Leaves absorb light and carry out photosynthesis.
blade
Leaves
Function - site of sunlight absorption and photosynthesis
– flat structure increases surface area
Leaf Characteristics:
• composed of blade and petiole
• simple or compound (based on the how many leaves/leaflets are
coming off of the main branch)
• venation- types of veins – parallel or net-like (palmate or pinnate)
• palmate- veins meet/touch at the base of the leaf
• pinnate- veins attach to one large vein that is throughout leaf
• parallel- veins run parallel to one another down the
length of the leaf (like a blade of grass)
petiole
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Leaf Tissues (layers of the leaf):
• cuticle – clear, waxy layer that protects leaf from drying out (desiccation); secreted by
the epidermis
• epidermis – outer layers of leaf, made of dermal tissue
• mesophyll – layer of ground tissue in the leaf in between the epidermal layers,
surrounds the vascular tissues (xylem and phloem) and is divided into two layers:
• palisade layer – rectangular cells below the upper epidermis that capture the
majority of sunlight; where the majority of photosynthesis occurs; ground tissue
• spongy layer – loosely packed cells with air spaces that connect to the
stomata; where some photosynthesis occurs; ground tissue
• stoma(ta) – site of transpiration and gas exchange; holes in the upper and lower
surfaces of leaves; surrounded by guard cells
• guard cells - control water loss by closing a plant’s stomata when water is scarce
stomata
guard cells
Cross-section of a Leaf
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Ch. 22: Plant Growth, Reproduction, and Response
Plants reproduce either sexually or asexually and hormones help regulate their growth, development,
and response to their environment.
22.1 Plant Life Cycles
Alternation of Generations
Plant life cycles alternate between
producing spores and gametes; this
is known as alternation of
generations.
•
•
•
gamete- a haploid (unpaired
chromosome) reproductive cell that
unites with another haploid
reproductive cell to form a diploid
zygote (fused cell)
gametophyte- haploid structure that
makes gametes; microscopic in most
plants
sporophyte- diploid structure that
makes spores; most plants
Spore vs. Seed
Spores:
• nonvascular plants– water needed for fertilization
– reproduces with spores
• vascular seedless plants
– water needed for fertilization
– reproduces with spores
Seeds:
• vascular seeded plants
– gymnosperms- cones
– angiosperms
• make pollen and ovules
(ovaries)
• once fertilized, the ovules
produce fruit
• fruit houses/protects seeds
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22.2 Reproduction in Flowering Plants (Angiosperms)
Reproduction of flowering plants takes place within flowers.
Flowers have four layers—sepals, petals, stamens, and pistils.
• sepals- modified leaves that are the outermost structures that protect the developing
flower; often green but can
be brightly colored.
• petals- modified leaves that
are the innermost structures that
are colorful to attract pollinators
• stamen- male reproductive
structure
– anthers produce pollen
• pollen grains contain
sperm
– filaments holds anthers up
to make accessible to wind
or pollinators
• pistil- female reproductive
structure; made of one or more
carpels that have three parts:
– stigma- top of the style, sticky so pollen sticks
– style- tube that leads from the stigma to the ovary
– ovary- where ovules (eggs) develop
• Ovaries with ovules become fruits with seeds after the ovule (egg) is
fertilized by sperm from the pollen; See Figure 2.3 page 647.
pollination – when a pollen grain reaches the stigma of the same plant species
fertilization – the process of the sperm combining with the egg to form the diploid zygote and
the food for the growing plant embryo that is within the seed (read p. 646 if you would like to learn about
the more complex details of double fertilization in plants)
Parts of a seed
– seeds contain an embryo (baby plant),
which is a new sporophyte, and a supply
of stored nutrients for the embryo
– cotyledons of a seed help transfer
nutrients to the embryo
– seed coat covers and protects a seed
Fruit or Veggie?
• fruit - ripened ovary; contains seeds
• botanically, tomatoes, peppers, squash, olives, and cucumbers are FRUITS, not vegetables
• vegetables – edible parts of plants not involved in reproduction (leaves, stems, roots)
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o
o
o
other plant
o
o
roots – carrots, turnips, radishes
stems – celery, bok choi, rhubarb, garlic, broccoli, onions, potatoes
leaves – lettuce, cabbage, parsley
parts we eat:
seeds – pinto beans, peas, sunflower seeds, corn, pepper corns, rice, pecans, coconut
flowers – anise flowers (licorice), basil
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22.3 Seed Dispersal and Germination
Seeds are spread (dispersed) by many vectors, including:
 Wind- some seeds are shaped to be carried by the wind easily
 Animalso some seeds stick to animals that brush past it
o when insects drink nectar, they get coated in pollen which will,
in turn, be passed on to the next flower the insect gathers
nectar from
o animals eat seeds or fruit with seeds; seeds are dispersed when
solid waste is excreted by the animal
 Water- can easily carry seeds miles away from parent plant
Seeds begin to grow when environmental conditions are favorable:
 dormancy – state of inactivity during which an embryo is not growing but is alive; Ex. A 2000 year

old seed from an extinct date palm was discovered; scientists put it in favorable conditions and the
seed began to sprout.
germination – the process of the embryo breaking out of the seed coat and growing (sprouting)
into a seedling when the conditions are favorable; usually triggered by water
22.4 Asexual Reproduction
Plants can produce genetic clones of themselves through asexual reproduction.
Plants can reproduce asexually with stems, leaves, or roots:
 regeneration - process in which plants grow a new individual from a fragment of a stem, leaf, or
root; ex. prickly pear cactus
 vegetative propagation – a process in which stems, leaves, or roots attached to the parent plant
produce new individuals; ex. irises, strawberries, potatoes, bulb plants
o humans often produce plants with desirable traits using vegetative propagation techniques
22.5 Plant Hormones and Responses
Plant hormones regulate plant functions.
 hormone – a chemical messenger produced in one part of an organism that stimulates or
suppresses the activity of cells in another part. Ex. gibberellins, ethylene, cytokinins, auxins

(if you would like to know more about the various plant hormones, read pages 656-657)
tropism--plant response to the an environmental stimulus such as direction of light, gravity, and
touch
o result of hormone action ex) hormones trigger cell division on one side of a stem making the
stem curve
o can be positive (toward the stimulus) or negative (away from the stimulus)
Plants can respond to light, touch, gravity, and seasonal changes.
 phototropism – the growth of a plant toward a light source
 thigmotropism – turning or bending of a plant in response to contact with an object;
response to touch; Ex: vines growing up latticework or the side of a house
 gravitropism- growth of plants in response to gravity; plant stems grow upward, against gravity
(negative), and roots grow toward the gravitational pull (positive)
 rapid responses – response that does not involve growth, but is an adaptation that helps protect
plants from predators; ex. mimosa plant quickly folds its leaves together after being touched; Venus
flytrap closing its leaves on an insect.
 photoperiodism – the response of an organism to changes in the length of the day; ex. shorter
days and longer nights trigger the leaves of deciduous trees to change color; poinsettia plants
flower when the days are short
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Kingdom Plantae
Bryophytes
*nonvascular:
No internal system of
tubes or vessels to
transport materials
throughout plant.
Characteristics:
1. no true ROOTS,
STEMS OR
LEAVES
2. need WATER to
reproduce
Examples:
MOSSES
LIVERWORTS
Seedless
Pteridophytes
Examples:
FERNS
HORSETAIL
ALL AUTOTROPHIC
MULTICELLULAR
EUKARYOTIC CELLS
HAVE CELL WALLS &
CHLOROPLASTS
Tracheophytes
*vascular system:
Internal Transport System of
interconnected vessels
XYLEM H20 & Minerals
PHLOEM Sugars
Seeded
Angiosperms
(Covered seeds)
Characteristics:
1. Produce Flowers
2. Seeds in Fruit
3. Lose leaves annually
(most)
Examples:
Wildflowers, Oak, Maple,
Grass
Gymnosperms:
First seed plants
(Naked seed)
Characteristics:
1. Seeds are in cones
2. Keep Leaves all
year long (most)
3. Leaves needle-like
Examples:
Pines, Juniper
Monocot (One Cotelydon)
Dicot (Two Cotelydons)
1. Flowers in 3’s
2. Leaves have parallel veins
3. Vascular bundles scattered
4. Diffuse Root system
Ex: grasses, palms, orchids
1. Flowers in 4’s or 5’s
2. Leaves have netlike veins
3. Vascular bundles form a ring
4. Tap root system
Ex. Shrubs, most trees, cactus
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