Transcript (gene expression)-allowing plants to produce flowers.

Angiosperms
• Two Groupings:
– Monocot and Dicot
• Based off:
– Morphological characteristics
– DNA analysis
How does a plant flower?
Light Controlled  photoperiodism (is the plants response to light.)
Plants response to light involving
relative lengths of day/night
Controls flowering
Happens in conjunction with
availability of pollinators and
necessary resources
Plant Type
Long-day
plants
Flowering and Light
Bloom when days are
longest and nights
shortest (midsummer)
Examples
Radishes, spinach,
and lettuce
Short-day
plants
Bloom in spring, late
summer, and autumn
when days are shorter
Poinsettias,
chrysanthemums,
and asters
Day-neutral Flower without regard to
plants
day length
Night length is
controlling factor
Roses, dandelions,
and tomatoes
Inactive (Pr)
Active (Pfr)
Phytochrome red
Pr
Pr
DAY TIME
660 nm
Slow conversion
730 nm
Pfr Rapid conversion
Plants time dark
period
Inhibitor for shortday plants
Pfr
Pfr
Phytochrome Far-red
Promoter for
long-day plants
Activates specific genes in
shoot apex
Changes DNA transcription
(gene expression)-allowing
plants to produce flowers.
• Methods for controlling flowering:
– Controlled greenhouses
– Covering plants for appropriate time periods
Animal Pollinated Flower
Anther: Part of stamen
which produces the make
sex cells, pollen
Filament: Stalk of
stamen that holds up
the anther
Stigma: Sticky top of carpel on which
pollen lands
Style: Structure of the carpel that
supports the stigma
Ovule: Base of carpel in which
the female sex cells develop
The entire female part
is called the “carpel”.
The entire male part is
called the “stamen”.
Petal: Often
are colorful
to attract
pollinators
Sepal: Protect
the developing
flower while in
the bud
Receptacle
Complete vs Incomplete Flowers
• Complete: has all 4 basic parts: sepal, petals
carpel, and stamen.
•
Incomplete: lacks one of the 4 basic parts
• Staminate flowers: only have stamens and no
carpels
• Carpellate flowers: only have carpels
Pollination
Flower colors:
Red- conspicuous to birds
Yellow and orange- noticed by
bees
Scented: can be located at
night.
Pollen Movement: wind/animal vector/water
Coevolution of insects and flowers
Attraction: color/smell
2 types:
Self-pollination: same plant
pollination  less genetic
variance
Cross-pollination: pollen
from one plant goes to
stigma of another 
increases variation
Problem: harder
to pollinate 
travelling pollen
Fertilization
1. Pollen germinates to
produce pollen tube
2. Pollen tube grows
down style
3. Within pollen tube is the
nucleus that will produce the
sperm.
4. Pollen tube
attaches to ovary
opening
5. 2 sperm moves
into ovule
1 – fertilizes egg  zygote
2 – fertilizes 2 polar nuclei 
endosperm  cotyledon
Plants have 2 different generation
cycles.
• Gametophyte generation- which is haploid
– Produces the plant gametes by mitosis
• Sporophyte generation- which is diploid
– Produces spores by meiosis.
• These generations alternate with each other.
Internal Structure of Seeds
Hypocotyl: separate
root from shoot
Embryonic shoot
and root: Become
the new plant when
germination occurs
Micropyle: Scar of
the opening where
the pollen tube
entered the ovule
Testa: Tough, protective
outer coat
Cotyledon: Seed
leaves that
function as
nutrient storage
structures
Seed maturation:
 Dehydration (10-15% of weight)
 Dormancy period (variable)
Conditions needed for germination:
1. Water – rehydrate the dried seed tissues
2. Oxygen – aerobic respiration to produce ATP
3. Appropriate temperature enzyme action
4. Other specific conditions
No light needed
Germination:
Absorb water to rehydrate the seed
Release gibberellin
(gibberelic acid)
Plant Hormone
Produces Amylase- caused by the release of gibberellin
Hydrolyzes Maltose into glucose, which can be used in
cellular respiration
Cell respiration
Further hydrolyzed
into glucose
Converted into cellulose-so that
the cell walls may be produced.
Pollination vs fertilization
• They are 2 very different things!!!
• Pollination- is the process by which pollen is
places on the female stigma.
• Fertilization-happens when the male and
female sex cells unite to form a diploid zygote.
Next Class
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•
•
•
Quiz 9.4
Review
Plant dissection  possibility
Start seed germination
• EXAM TUESDAY!!!