UAB BY 124 Exam 1

charophytes

(aquatic) green algae land plants evolved from

3 key traits land plants share with charophytes

1. rings of cellulose-synthesizing proteins embedded in plasma membrane

2. formation of a phragmoplast (helps form cell wall)

3. structure of flagellated sperm (not all will have this)

adaptations enabling plants' move to land: why?

1. CO2

2. sunlight

3. soil- nutrients

4. fewer predators/pathogens (never been seen before)

adaptations enabling plants' move to land: problems?

1. lack of structural support

2. scarcity of water

adaptations enabling plants' move to land: adaptations?

1. survive periods when not submerged

2. charophytes have a layer of durable polymer (sporopollenin) that prevents exposed zygotes from drying out

natural selection

can only act on traits present in population

phylogenetic tree of ancestral algae

a. red algae

b. chlorophytes

c. charophytes

d. embryophytes

4 derived traits (unique to) of plants

1. alteration of generations and multicellular, dependent embryos

2. walled spores produced in sporangia

3. multicellular gametangia

4. apical meristem

alteration of generations

n (gametophyte) <-> 2n (sporophyte)

multicellular, dependent embryos

supported by maternal tissue, placental transfer

walled spores produced in sporangia

adaptation

multicellular gametangia

through mitosis:

female (n) -> eggs (n)

male (n) -> sperm (n)

archegonia

female gametangia

antheridia

male gametangia

apical meristem

where growth occurs (up or down)

other derived traits of plants

5. cuticle (waxy covering of the epidermis)

6. stomata (open & close for gas exchange)

7. mycorrhizae (symbiotic relationship between fungi and land plants -> nutrients)

8. secondary compounds (deter herbivores and pathogens)

origin and diversification of plants

-evident in fossilized spores & sporophyte (2n) tissue

-see image for phylogenetic tree

life cycles of mosses & other nonvascular plants: dominated by?

gametophytes (n)

3 phyla of byrophytes (small, herbaceous (non-woody) plants)

1. liverworts (Phylum Hepatophyta)

2. hornworts (Phylum Anthocerophyta)

3. mosses (Phylum Byrophyta)

location of gametophyte (n) & sporophyte (2n)

-can be in close proximity

-sporophyte arises from gametophyte

life cycle of moss

sporophyte (2n) -> meiosis -> spores (n) -> mitosis -> gametophytes (n) (male- sperm and female- egg) -> fertilization within archegonium (sperm has flagella and swims to egg) -> zygote (2n) -> embyro (2n) -> sporophyte (2n)

asexual reproduction in mosses

brood bodies

ecological and economical importance of mossess

1. peat -> fuel

2. acidity -> preservation of tissue

restrictions of mosses

1. moist environment necessary

2. unsubstantial root system

like carpet on the floor

1st plants to grow tall

ferns and other seedless vascular plants

1st (ancestral) vascular plant

Aglaophyton major

traits of living vascular plants

1. life cycles with dominant sporophytes (2n)

2. vascular tissues called xylem and phloem (plumbing system)

3. well-developed roots & leaves

xylem

(non-living) conducts water & minerals

1. trachieds

2. lignin

phloem

(living) distributes sugars, amino acids, and other organic compounds

life cycle of ferns

sporophyte (2n) (sorus underneath) -> sporangium -> meiosis -> spore (n) -> gametophyte (n) -> mitosis -> egg and sperm -> fertilization -> zygote (2n)n -> new sporophyte (grew from gametophyte)

evolution of roots

-organs that anchor vascular plants and absorb water and nutrients from soil

-tap root (pine trees) vs. fibrous root (oak trees)

evolution of leaves

1. microphylls (single vein)

2. megaphylls (highly branched) (more efficient)

sporophylls

modified leaves with sporangia

sori

clusters of sporangia of underside of sporophylls

strobili

cone-like structures formed from groups of sporophylls

homosporous spore production (most seedless vascular plants)

sporangium on sporophyll -> single type of spore -> typically bisexual gametophyte -> egg and sperm

heterosporous spore production (all seed plants and some seedless)

-megasporangium -> megaspore -> female gametophyte -> egg

-microsporangium -> microspore -> male gametophyte -> sperm

2 phyla of seedless vascular plants

1. Phylum Lycophyta (club mosses, spike mosses, and quillworts)

2. Phylum Monilophyta (ferns, horsetails, and whisk ferns and relatives)

distinguishing common name of mosses from mosses

height, roots, and chromosome number (haploid or diploid)

significance of seedless vascular plants

1. great heights during the Devonian and Carboniferous forming 1st forests

2. removed CO2 from atmosphere and may have contributed to global cooling at the end of Carboniferous (->carbon<-)

3. decaying plants of these Carboniferous forests -> coal

best adaptation of land plants

flowering plants (250,000 species)

key adaptations of plants for life on land

seed and pollen grains

common to all seed plants

1. reduced gametophytes (microscopic)

2. heterospory (distinct male- microspore and female- megaspore)

3. ovules (egg) (in gymnosperm, there's integument (2n), megaspore (n), and megasporangium (2n))

4. pollen (sperm) (water no longer needed for transportation)

5. seeds (survive better than unprotected spores, can be transported longer distances)

moses and other nonvascular plants

gametophyte: dominant

sporophyte: reduced, dependent

ferns and other seedless vascular plants

gametophyte: reduced, independent (photosynthetic and free-living)

sporophyte: dominant

seed plants

gametophyte: reduced (microscopic)

sporophyte: dominant

heterospory

-the rule among seed plants

-megaspore (female) -> egg

-microspore (male) -> sperm

development of female gametophyte within ovule (unfertilized)

1. megasporangium (2n)

2. megaspore (n)

3. 1 or more protective integuments (2n)

development of male gametophyte in pollen grain

1. microspores -> pollen with male gametophytes

2. pollination- transfer of pollen to part of seed plant containing ovule

fertilized ovule

1. female gametophyte (n)

2. egg nucleus (n)

3. discharged sperm nucleus (n)

4. pollen tube

5. inserted pollen grain/male gametophyte (n)

gymosperm seed

1. seed coat

2. spore wall

3. food supply (n)

4. embryo (2n)

evolutionary advantages of seeds over spores

1. may remain dormant for days to years until conditions are favorable for germination

2. supply of stored food

3. increased transportation by wind or animals

gymnosperms

-bear "naked seeds" typically on cones (formed by seeds exposed on sporophylls)

-4 phyla:

1. Cycadophyta (cycads)

2. Gingkophyta (1 living species= Ginko biloba)

3. Gnetophyta

4. Conifera

angiosperms

-seeds found in fruits (mature ovaries)

-single phylym: Anthophyta

-flowers & fruits- 2 key adaptations

life cycle of a pine

sporophyte (2n) -> a. microsporangia (2n) -> meiosis -> pollen and b. megasporangium (2n) -> meiosis -> megaspore -> egg <- pollen -> fertilization -> embryo (2n) -> seeds -> seedling (2n) -> sporophyte

angiosperm structure

1. sepal (leaf)

2. petal

3. carpel- stigma, style, and ovary

4. ovule

5. stamen- anther and filament

life cycle of angiosperm

sporophyte (2n) -> a. microsporangium -> meiosis -> microspore (n) -> pollen -> growing pollen tube and b. ovary -> meiosis -> megaspore (n) -> egg <- pollen -> fertilization -> zygote (2n) (nucleus of developing endosperm (food for egg) is 3n) -> seed -> germinating seed -> sporophyte

triploid endosperm

sperm fusing with egg and nucleus

angiosperm diversity

-more than 250,000 living species

-2 main groups:

1. monocot (1)- parallel veins, scattered vascular tissue, fibrous root, pollen with 1 opening, and flowers (3)

2. dicot (2)- netlike veins, ring-arranged vascular tissue, taproot, pollen with 2 openings, and flowers (4-5)

phylogenetic tree of angiosperms

evolution of flowering plants

(basal angiosperms)

1. amborella

evolution of vessel elements

2. water lillies

3. star anise

(core angiosperms- all connected)

1. magnolias

2. monocots

3. eudicots

types of taxon

1. monophyletic- includes a group of organisms who all arose from 1 common ancestor

2. polyphyletic- composed of unrelated organisms who arose from more than 1 ancestor

3. paraphyletic- includes most recent common ancestor but not all its descendents

human welfare greatly depends on seed plants: how/why?

1. most of our food comes from angiosperms

2. wood

3. medicines

4. fuel

5. animal diversity

selective breeding = artificial selection

humans have been doing it for years

(ex: corn)

genetic modification

leads to seeds with high-yielding crop but the seeds it produces can't reproduce

growth in plants

indeterminate (not predetermined) (but can still be ordered such as in broccoli)

basic hierarchy of plants

cell -> tissue -> organ

3 basic plant organs

1. roots

2. stems

3. leaves

2 types of systems in plants

1. root system (down)

2. shoot system (up)

roots can be modified: how?

to store energy (starch)

roots

-anchor

-absorb nutrients (because nutrients from the seed are used up fast)

function changes structure

specialized functions of roots

1. prop roots (corn)

2. storage roots (beet)

3. "strangeling" aerial roots (strangler fig)

4. pneumatophores (aquatic plants)

structures that have determine growth in plants

leaf blades, petioles, internodes, and flowers

stem

-bears leaves and buds

-elongates plant

specialized functions of stems

1. rhizomes (horizontal shoot) (ginger)

2. stolons (strawberry)

3. tubers (potato)

parts of leaf

1. leaf blade

2. petiole (joins leaf to stem)

types of leaves

1. simple

2. compound

3. double compound

4. wood-like

simple leaves

have single blade and petiole

compound leaves

have a blade divided into leaflets

double compound leaves

-have leaflets arranged along the middle vein

-large yet rarely damaged by wind or rain

needle-like leaves

characteristic of species adapted to extreme hot or cold temperatures

arrangements of leaves

1. alternate

2. opposite

3. whorled

4. rosette (upward staircase)

leaves: shade vs. sun?

-shade: larger leaves (more surface area) because of less sunlight

-sun: smaller leaves because of max sunlight

specialized functions of leaves

1. tendrils (climb)

2. spines (protect)

3. bulbs (storage) (onion)

4. reproductive

5. bracts (pollination) (poinsettias)

6. traps

3 types of tissues in plants

1. dermal (exterior)

2. vascular ("veins and arteries")

3. ground (the in-between)

dermal tissue system: in nonwoody plants

-has a single tissue called the epidermis

-the cuticle in stems and leaves helps prevent water loss

dermal tissue system: in woody plants

periderm replaces epidermis in older regions of stems and roots

dermal tissue system: trichomes

highly specialized epidermal cells

vascular tissue system: xylem

conducts water and dissolves minerals up

vascular tissue system: phloem

transports sugars and products of photosynthesis up and/or down (wherever needed)

vascular tissue of a stem or root: collectively called?

stele

ground tissue system: pith

ground tissue internal to vascular tissue

ground tissue system: cortex

ground tissue external to vascular tissue

ground tissue: includes?

-cells specialized for storage, photosynthesis, and support

-made up of: parenchyme, collenchyme, and sclerenchyme

major types of plant cells

1. parenchyma

2. collenchyma

3. sclerenchyma

4. water-conducting cells of xylem

5. sugar-conducting cells of phloem

parenchyma

(leaf)

-primary cell walls are thin and flexible

-perform most metabolic functions

-synthesize and store organic products

-where photosynthesis occurs (within chloroplasts)

-retain ability to divide and differentiate into other types of cells

collenchyma

(celery)

-thicker cell walls

-support young parts of the plant

-provide flexible support without restricting growth

-living and flexible when mature

sclerenchyma

(pear)

-function in support

-thick secondary cell walls with large amount of lignin

-mature cells can't elongate

-occur in regions where plant has stopped growing

trachieds/vessels

-in xylem of vascular tissue system

-nonliving

-move water up by cohesion and adhesition

siete tube/companion cells

-living

-provide nutrients (products of photosynthesis)

-in phloem of vascular tissue system

meristems: generate what?

cells for primary and secondary growth