Transcript Plant Biology Review ()

Botany
SAT II Review
Things to know that we’ve already
covered…
• Plant cell structure (Chapter 4)
• Photosynthesis (Chapter 7)
• Angiosperm reproduction and double
fertilization (31.9-31.15)
2 major divisions of land plants
I. Non vascular plants
II. Vascular plants
I. Non vascular plants
(bryophytes)
• No vascular tissue
• Small, inhabiting shady, moist areas
• Include mosses, liverworts, hornworts
II. Vascular Plants
Have vascular tissue - tubelike, elongated
cells through which water (xylem) and
sugars (phloem) are transported. Has true
roots, stems and leaves.
Grow in a variety of environments-why?
2 major divisions of VASCULAR plants
I. Seedless plants
II. Seed plants
I. Seedless plants
Must have a moist environment in which to grow.
Includes Club Mosses- Lycophyta
Horsetails/Sphenophyta,
Ferns/Pterophyta
All reproduce by
forming spores.
Let’s move on to the other division of vascular plants…
II. Seed plants
Reproduce by seeds. A seed is an embryo
with a food supply (endosperm) enclosed
in a tough, protective coat.
2 major divisions of
VASCULAR SEED plants
I. Gymnosperms
II. Angiosperms
I. Gymnosperms
• Most are conifers (cone-bearing trees)
• Seeds are formed in cones
• Plants contain some “female” cones that make spores
and some “male” cones that make pollen
II. Angiosperms
Anthophyta = Flowering Plants
This is the most successful group of plants.
Why?
Seeds are protected within
flowers and develop inside
fruit.
2 major divisions of
VASCULAR PROTECTED SEED/FLOWERING plants.
I. Monocots
II. Dicots
Angiosperms:
Divided into two classes, based on the number of seed
leaves (cotyledons) within the seed.
Monocots: (non-wood)
grasses, lilies, palms
Dicots:
Shrubs, trees, herbs and flowers.
Dicot and monocot stems
14
Summary
PLANTS
Kingdom
Plantae
Vascular
Seeded Plants
Angiosperms
P
rotected Seeds
Monocot
Dicot
Non-Vascular
Seedless Plants
UGymnosperms
nprotected Seeds
Chapter 31
Plant structure, reproduction, and
development
Body plant – roots, stems, and leaves
17
General
Tissue types
• Dermal tissue –
outer protective
covering
• Vascular tissue –
xylem and phloem
• Ground tissue –
between epidermis
and vascular
18
Vascular tissue
• Xylem
– Conducts water and minerals upward in the plant
– Dead at maturity – do not consume water
• Phloem
– Carries sugars that have been produced in the
leaves and/or stems.
– Barely alive – require ATP from companion cells to
assist in transport
Transporting water up the xylem
(Chapter 32)
• Root pressure
• Capillary action
• Transpiration-cohesion
theory
– Water evaporates from
the leaf surface
– Water molecules are
connected to each other
by hydrogen bonds
– Water is pulled up the
xylem from the root
20
Transporting sugar through the
phloem (Chapter 32)
• Sucrose is pumped
into phloem cells at
the source
• Water enters from the
adjacent xylem cells
via osmosis
• The sugar solution is
forced down the
phloem cells under
pressure.
21
Leaf structure
• Mesophyll is between epidermis layers
– Palisade layer is more ordered to maximize
photosynthesis
– Spongy layer is
more diffuse,
leaving space for
gas movement
22
Stomata
• Pores in the leaf
surface
• Regulated by guard
cells
23
Growth
• Primary growth
– Apical meristem on root and shoot extend the
vertical length of the plant
Growth
• Secondary growth
– Lateral meristems
increase the girth of
woody plants
– Vascular cambium
• One cell thick, between
primary xylem and
phloem
• Produces new
secondary xylem
(inside) and phloem
(outside) each year
• Growth is not
continuous throughout
the year, creating rings
Growth
• Secondary growth
– Cork cambium
• Forms cork (bark),
which replaces the
epidermis (from
original shoot)
• Forms protective
covering for root and
shoot
Reproduction Alternation of generations
27
Alternation of generations
• Sporophyte – Main body of the angiosperm
plant
• Immature male gametophyte = pollen grain
• Mature male gametophyte = pollen tube
• Female gametophyte = egg sac
– Enclosed in the ovule
– the ovule is a section of the ovary
28
Double fertilization
• The pollen tube
enters the ovule
• One nucleus
fertilizes the center
two nuclei
• Results in triploid
(3n) endosperm
nucleus
29
30
Asexual reproduction –
Vegetative propagation
• Tubers (like potatoes) – underground storage
equipped with buds on the surface
• Runners (like strawberries) – horizontal stems
that can give rise to new roots and shoots
• Bulbs – underground buds (contains several
buds that can be new plants)
• Grafting – two young plants are joined
Chapter 33
Plant hormones and behaviors
32
One group of hormones stimulates
growth and development
• Auxin – origin: apical meristem of the shoots
– Stimulates cell elongation in stems
– Retards cell elongation in roots.
• Gibberellins – origin: buds and leaves
– Breaks dormancy in buds by stimulating mitosis
– Stimulates mitosis in developing leaves
• Cytokinins – origin: roots
– Works with auxins to stimulate cell division
– Delay aging (used on freshly cut flowers)
33
The other group stimulates aging and
death or dormancy
• Abscisic acid (inhibitors)
– Retards growth
– Causes dormancy in seeds
• Ethylene
– Causes fruit ripening
– May work along with auxin to retard elongation of
root cells
– Causes leaf falling
34
Phototropism
• Plants bend toward light – auxin migrates to
the dark side, elongating those cells
35
Gravitropism
• Response to gravity – roots grow downwards,
shoots grow upwards
36
Thigmotropism
• Response to touch – caused by changes in
water pressure
– Coiling around a support
– Tree trunks grow thicker in response to winds
Photoperiodism – flowering regulated
by light
• Short day plants (long night plants)
– Flower in early spring or autumn (when nights are
longer)
• Long day plants
– Flower in summer (when nights are shorter)
• Day neutral plants
– Flowering begins when the plant has a certain
number of branches and flowers until frost
38