Unit 6
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Botany-study of plants
 Plants share a common ancestor
with algae:
 Cell walls of cellulose
 Same type of chlorophyll used in
photosynthesis
 Food stored as starch
 Scientist hypothesize that plants
originally lived under water
 Over time, plants adapted to live on
land:
 Cuticle
 Stomata
 Vascular Tissue
 Reproductive Strategies
 Cuticles
 Fatty or waxy coating covering the cell
 Helps prevents water from evaporating
 Acts as a barrier to invading
microorganisms
 Stomata
 Enable the exchange of gases
 Opening in outer layer of leaves
 Openings are controlled
by guard cells
 Vascular Tissue
 Specialized transport tissue
 Enables faster movement of substance
over greater distances
 Provide structure and support
 Two types: Xylem and phloem
▪ Xylem-carries water
▪ Phloem-carries sugar or organic compounds (food)
 Reproductive Strategies
 Some plants use spores to reproduce
 Some plants use seeds
 Alternation of generations
▪ Gametophyte
▪ Sporophyte

Gametophyte
stage- gametes
(sperm and egg)

Sporophyte
stage- results
from the
fertilization of
egg by sperm
Plant Classifications
 Nonvascular Plants
 No vascular tissue
▪ Transport water/nutrients via diffusion and osmosis
 Small, short
 Collectively called bryophytes
 Grow in moist climates
 Mosses, hornworts, and liverworts

Vascular plants
 Contain xylem and phloem
 Xylem-carries minerals and water through the
plant
 Phloem-carries sugars through the plant
 Vascular plants can be seedless or seed plants
 Seedless Vascular Plants
 Club mosses,
horsetails, ferns
 Reproduce via spores
 Spores are found on the
underside of leaves in clusters
called sori (sorus)
 Seed Vascular Plants
 Highly diverse (5 divisions)
 Do not require water for fertilization
 Seeds have cotyledons (store/absorb food
for young sporophyte)
 Sporophyte generation is dominant
 Coniferophyta:
 Wide range of shapes/sizes, climates
 Produce seeds in cones for reproduction
 Can be deciduous or evergreen
 Often referred to as
conifers or
gymnosperms
 Anthophyta:
 Flowering seed plants
 Most widely distributed
(75% of plant kingdom)
 Often referred to as angiosperms, which
can produce seeds in fruits or flowers
 Can further be divided into monocots or
dicots (eudicots)
Monocots
Dicots
have one seed leaf
have two seed leaves
Have scattered vascular bundles
Have vascular bundles arranged in a ring
along the outside edge
Have parallel venation
Have net venation
Have flower parts arranged in 3’s
Have flower parts arranged in 4’s or 5’s
Checkpoint
Review


Cell walls, chloroplasts, and a large central
vacuole set plant cells apart from animal cells
Plant cells undergo photosynthesis mainly in
the leaves where chloroplasts are numerous
 Meristematic tissue
 Dermal tissue
 Vascular tissue
 Ground tissue

Meristematic tissue:
 Regions of rapidly dividing cells
 Figure 22.3 (pg. 635)
 Apical meristems- tips of roots and stems, make
the plant grow longer (primary growth)
 Intercalary meristems- located throughout the
stem, their growth increases plant length, e.g.
mowing the grass (primary growth)
 Lateral meristems- increases root and stem
diameter (secondary growth)

Dermal cells: Epidermis
 Outer covering of the plant
 Can secrete lipids to form the cuticle
 Stomata- small openings in leaves and stems for
gas exchange; guard cells control the
opening/closing of stomata
 Root hairs- increase surface area, material uptake
 Vascular Tissue:
 Xylem- water-carrying vascular tissue,
transports materials one way (away from
roots)
 Phloem- food-carrying vascular tissue,
transports materials both directions,
 Ground Tissue:
 Functions include photosynthesis,storage,
support
 Basically any tissue that isn’t meristematic,
dermal, or vascular



Absorb materials, provide
support, anchor the plant to
the ground
Root cap- protects the root’s apical meristem
Types of roots
 Table 22.2 (pg. 641)- taproot, fibrous root,
modified root (pneumatophores, adventitious
roots)


Support, transportation of materials
Types of stems
 Table 22.3 (pg. 643)- tuber, rhizome, runner, bulb,
corm
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Primary function: photosynthesis,
transpiration
Transpiration-process in which
water evaporates from the inside of the
leaves to the outside through stomata
Petiole: attaches blade to stem
Palisade mesophyll: column-shaped, contain
many chloroplasts
Spongy mesophyll: loosely packed cells,
allows for movement of gases such as oxygen

Modifications help plants
survive in different
environments
(e.g., cactus spines)
Tropic Responses- tropism,
a plant’s growth response to an
external stimulus
 Table 22.4 (pg. 651)

 Phototropism- response to light
 Gravitotropism- response to gravity
 Thigmotropism- response to touching an object,
e.g., vines on a tree


Sepals: protect the flower bud; look like small
leaves surrounding the bud or petals
Petals: colorful structures; attract pollinators
(e.g., bees); surround the reproductive organs

Stamen: male
reproductive structure;
composed of two parts
 Filament- stalk that supports the anther
 Anther- contains the pollen grains


Pollen grain: contain plant’s sperm that will
be used to fertilize the plant’s egg
The stamen is the structure with black tips in
the picture!

Pistil: female reproductive
structure; composed of three
parts
 Stigma- tip of the pistil; where
pollination occurs
 Style- connects stigma to ovary
 Ovary- contains ovules (where eggs form)

The pistil is the big red thing in the picture!
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Self pollination vs Cross
pollination
Animal pollination: animals collect pollen on
their bodies and move it from one flower to
the next
Wind pollination: the wind blows the pollen
to the plant ovary for fertilization; these
flowers normally aren’t very colorful (i.e.,
they don’t need to attract animals to
pollinate)

The factor that affects the opening/closing of
flowers; based on the number of hours of
uninterrupted darkness
 Short-day (Long night)
 Long-day (Short night)

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Germination: when the seed begins to grow
Seedling-refers to a young plant

Endosperm- a tissue that
surrounds the embryo and provides nutrients
to the developing plant