chapter5( plantlifecycle: flowers( tradescan(a*ohiensiscparis/pbio006/chap5_flowers.pdf ·...
TRANSCRIPT
Chapter 5 Plant Life Cycle:
Flowers
Lecture Outline Structure of a flower Alterna(on of genera(ons, the plant life cycle • Gametophyte and sporophyte defined Meiosis – cell division that halves the # of chromosomes Double fer(liza(on in flowering plants Flowers, fruits and seeds movie Pollina(on -‐ wind-‐ and animal-‐pollinated plants
Tradescan(a ohiensis
The evolu?onary success of the angiosperms is due in large part to
flowers and fruits
basal angiosperms monocots eudicots
Vegeta?ve Body
Reproduc;ve Body
Root
Shoot
Stamen Anther
Filament
Petal
Receptacle
Stigma Style
Ovary
Carpel
Sepal
Structure of an idealized flower
Monocot Characteris;cs
Eudicot Characteris;cs
Vascular ;ssue usually arranged
in ring
Veins usually parallel
Vascular ;ssue scaBered
Leaf vena;on
One cotyledon
Embryos
Two cotyledons
Stems
Veins usually netlike
Roots
Pollen
Root system usually fibrous (no main root)
Pollen grain with three openings
Pollen grain with one opening
Floral organs usually in
mul;ples of three
Flowers
Floral organs usually in mul;ples of four or five
Monocot Characteris;cs
Eudicot Characteris;cs
Taproot (main root) usually present
pollen contains the sperm (male gamete)
the ovule contains the egg (female gamete)
A flower that has both stamens and carpels is called perfect.
Painted trillium, Trillium undulatum
A flower that is lacking either stamens or carpels is imperfect.
Begonia staminate (male) carpellate (female)
Water lily: symmetry is radial
Radial symmetry
orchid: symmetry is bilateral
Bilateral Symmetry
Key
Haploid (n)
Diploid (2n)
Gametes (eggs, sperm)
n
n
n
2n 2n Zygote
MEIOSIS FERTILIZATION
Mitosis
Diploid multicellular organism
The life cycle of an animal (like humans)
• gametophyte = the mul?cellular haploid form that produces haploid gametes by mitosis
• sporophyte = the mul?cellular diploid form that results from the union of gametes and produces spores by meiosis
Alterna(on of genera(ons, the plant life cycle
Fig 5.6
Meiosis is special type of cell division that results halving the number of chromosomes.
MEIOSIS FERTILIZATION
Diploid 2n
Haploid n
diploid (2n) à haploid (n)
Mitosis occurs in meristems
Meiosis occurs in sexual organs
Pollina(on – the transfer of pollen from an anther to a s?gma
Moth pollina?ng flower Bumblebee pollina?ng goldenrod
Who are the major animal pollinators?
insects birds
bats
Stigma
Pollen tube
2 3 1
2 sperm Style Ovary Ovule
Pollen grain
Polar nuclei Egg
Ovule Polar nuclei
Egg
2 sperm
Endosperm
Zygote (2n)
Double fer?liza?on
Hazel staminate flowers (stamens only)
Hazel carpellate flower (carpels only)
Wind-‐pollinated plants usually have small, inconspicuous flowers & produce abundant pollen
Corylus species
Common dandelion under normal light
Common dandelion under ultraviolet light
Animal-‐pollinated plants usually have large, showy flowers
with rewards
Pollinator rewards
pollen Resin-‐gathering bee
1. Pollen (protein and lipids) 2. Nectar (water, sugar, amino acids) 3. Oils (lipids, an?-‐fungal agent)
Hummingbird sipping nectar
Importance of pollina;on
Necessary for food produc?on! • Almonds • Apples • Blueberries • Cucumbers • Squash • Melons • Strawberries • Apricots • Pears • Plums • Some citrus (tangerines, lemons) • Honey
Lecture Review, Chapter 5 • Iden?fy and describe the func?on of the following floral structures:
sepals, petals, stamens, carpel, filament, anther, s?gma, style, ovary, and ovule.
• Compare and contrast the life cycles of animals and plants. • Diagram the generalized life cycle of an angiosperm; indicate which
structures are part of the gametophyte genera?on and which are part of the sporophyte genera?on
• What cell division process occurs in the sporophyte? What does it produce?
• What cell division process occurs in the gametophyte? What does it produce?
• What is pollina?on? Is pollina?on the same as fer?liza?on? Provide examples of pollinator rewards in animal-‐pollinated plants.
• What is double fer?liza?on? Why is double fer?liza?on advantageous to the plant?