Lecture 3

What are seed plants (names)

• Gynosperms

• Angiosperms

What is an angiosperm?

• flowering plants

when did anthophyta appear?

around 150 mya

What is the angiosperm terrestrial revolution?

the diversification of the angiosperms coincided with a dramatic diversion of other organisms

How do you explain angiosperm diversity and species number?

• insect pollination

• flexibility in seed production and dispersal

• greater genetic and phenotype flexibility in cell and shoot elongation

• more complex mechanisms for activating and repressing the genes

• great complexity of the flower

What is the division of anthophyta?

FLOWERING PLANTS

• Around 400K species

• Reproductive organs in flowers

• Sporophyte dominant

• Hetersporous

• Microgametophyte = pollen

• Megagametophyte = 8 nuclei

• Triploid (3n) endosperm

What is an endosperm?

basis of food for humans

• more than half of (direct) daily calories worldwide

• it is the principle foodstuff of civilisation

How many whorls are on modified leaves

4

what are whorls?

a set of structures that come out of the same spot

what is a mature ovary called?

Fruit

What is a stigma?

where pollen lands & transfers down to make the ovules go

What is the stamen made up of?

• Anther

• Filament

What si the carpel made up of?

• Stigma

• Style

• Ovary

When did angiosperms split into monocots and eudicots?

around 125 mya

What are monocots?

plants that have a single leaf that comes out when germinates

Examples of monocots?

• maize

• wheat

• bamboo

• rice

• orchids

• irises

• lillies

• palms

what are eudicots?

are seeds that have 2 little leaves when germinated

examples of eudicots?

• oaks

• maples

• dandelions

• sunflowers

• legumes

• melons

• potatoes

• poppies

• roses

What is hermaphroditic?

male and female sex organs within a flower

what is monoecy?

(means one house)

separate male and female flowers on the same individual

what is dioecy?

(means 2 houses)

Male and female sex organs on different individuals

what is pollination?

arrival of pollen on stigma (flowering plants) or on receptive female cone (conifers)

ONLY ON SEED PLANTS

How do conifers pollinate?

wind

How do flowering plants pollinate?

• Insects (bees, moths, butterflies, etc)

• Birds (hummingbirds, etc)

• Bats

• Wind

What is the “reward” for the pollinator in angiosperms?

• nectar (sugar water)

• pollen

how do angiosperms advertise to get pollinted?

• showy flower

• possibly odor

what are pollination syndromes?

integrated sets of floral traits (morphology, color, odor, size, rewards) associated with particular pollinator groups

What type of evolution do pollination syndromes show and how?

convergent evolution

• the traits have evolved seperatly many times. can thus occur in unrelated species.

Pollination by bees syndrome; explain:

• Shape: various: can be highly specialized or not

• Color: various, including yellow, blue, orange, NOT RED

• Odor: none or highly specialized

Pollination by bats or moths syndrome; explain:

shape: tubular, open at night

color: yellow or white (can be seen in the night)

odor: strong and sweet

nectar: large quantity

Pollination by birds syndrome; explain:

shape: tubular

color: red most common, also yellow

odor: none

nectar: large quantity, oftern weak (20% sugar)

Pollination by wind syndrome; explain:

shape: not showy (very reduced petals)

odor: none

nectar: none

pollen: very large quantity

what is deceit pollination?

a strategy where plants trick insects into pollinating them without providing them any rewards (pink lady’s slipper orchid)

What is double fertilization?

Very important feature in flowering plants

2 sperm nuclei in pollen

• 1 fertilizes egg => embryo (2n, diploid)

• 1 fertilizes central cell => endosperm (3n, triploid)

What do angiosperm ovules become?

seeds

what do angiosperm ovaries become?

fruits

What examples of dispersal of seeds and fruits in the wind?

• maple

• cottonwood

What examples of dispersal of seeds and fruits in the water?

• coconut

• water lily

What examples of dispersal of seeds and fruits in animals?

• blueberry

• cockleburr (velcro)

what are some examples of fruits with 1 or more seed?

• watermelon

• squash

• banana

• tomato

• apple

what are some examples of fruits with 1 seed?

• coconut

• grass grain (wheat, corn, rice)

• cherry

• acorn (oak)

• peach

how do angiosperms nourish the embryo?

endosperm (3n)

what needed to happen before angiosperms came on land?

• cuticle

• sporopollenin

• jacketed sex organs (archgonia, antheridia)

• embryo retention

• stomates (= stomata)

• vascular tissue (xylem, phloem)

• seed & pollen

• flower

• fruit

The difference between conifers and flowering plants: reproductive structure

Conifers: cone

Flowering Plants: Flower

The difference between conifers and flowering plants: microgametophyte

Con.: Pollen

Flo:Pollen

The difference between conifers and flowering plants: rpollen dispersal

Con: wind

Flo: wind, animals, water…

The difference between conifers and flowering plants:megagametophyte

Con: many cells

Flo: 8 nuclei, 7 cells

The difference between conifers and flowering plants: Nourishing embryo

Con: Megagametophyte

Flo: endosperm

The difference between conifers and flowering plants: seed

Con: naked
Flo: covered (by fruit)

What are the 3 variations on alternations of generations?

1. SPorophyte dependent on gametophyte (mosses - brynophta)

2. Large sporophyte and small independent gametophyte (ferns)

3. Reduced gametophye dependent on sporophyte (seed plants)

What are the 5 derived triats of seed plants?

1. Reduced gametophytes

   1. Microscopic male and female gametophytes (n) are noursihed and protected by the sporophyte (2n)

2. Heterospory

   1. Microspore gives rise to the male gametophyte and megaspore gives rise to the female gametophyte

3. Ovules (gymnosperm)

   1. Integument (coating)

   2. Megasporangium (2n)

   3. Megaspore (n)

4. Pollen

   1. Pollen grains make water uneccsary for fertilization

5. Seeds

   1. Survive better than unprotected spores, can be transported long distances

What are the 2 systems in vascular plants?

• Shoots

• Roots

What are cell walls mostly made up of?

Cellulose!

2 kinds:

1. Primary wall - thin, in all cells but sperm

2. Secondary wall - thicker, in some cells (strength)

Functions of a plant cell wall

1. Maintains cell shape

2. Provides support + strength

3. Prevents the cell membrane from bursting (resists water pressure)

4. Controls the rate and direction of cell growth

5. Regulates cell volume

6. Reason why the plant looks the way it looks

7. Physical barrier to protect themselves (but the wall is very porous, and allows the free passage of small molecules)

8. Carbohydrate storage - the components of the wall can be reused in other metabolic processes

What are thr 3 kinds of polysaccharides?

1. Cellulose

2. Cross-linking glycans (hemicellulose)

   1. Bonds with cellulose

3. Pectin

   1. Jelly-like glue

What is the middle lamella?

• Material between cells

• Made of pectin substances

3 tissues in vascular plants

1. Dermal

   1. Single layer; secretes cuticle (waxy)

2. Vascular

   1. Xylem & phloem

   2. support & supply

3. Ground

   1. Bulk of young plant

   2. Fills space between dermal and vascular tissues

   3. Mostly parenchyma

   4. Storage, Photosynthesis & Support

Types of Dermal tissue in plant cell types

• Epidermis

Types of Vascular tissue in plant cell types

• Tracheids & vessel elements

• Sieve elements

Types of Ground tissue in plant cell types

• Parenchyma

• Collenchyma

• Sclerenchyma

What are epidermal cells

• Outermost cells

• single layer covering leaves, stems, roots of non-woody plants or plant parts

• CREATES THE CUTICLE

  • Protects againts:

    • WATER LOST

    • PATHOGENS

    • UV RADIATION

Functions of epidermal cells

• waterproofing

• protection from pathogens: viruses, bacteria, fungi

- Other specialized roles:

• Hairs (tricomes)

• Nectary

• Guard cells: gas exchange