Exam #3

Eukarya

Include protists, plants, animals, and fungi.

Eukaryotes

Have a nuclear envelope and organelles.

Tend to be multicellular and reproduce via meiosis/mitosis.

Eukaryotic Cells

• Nucleus

• Mitochondria

• Endomembrane system

• Extensive cytoskeleton

• Chloroplasts (some)

• Other organelles

Protists

Include all Eukaryotes except plants, fungi, and animals.

All protists live in…

aquatic environments:

• Open ocean

• Shallow coastal waters

• Intertidal habitats

• AND…inside our bodies!!

Protists are responsible for diseases like…

Malaria

Photosynthetic protists called _____ can form toxic blooms.

dinoflagellates

Protists are integral to aquatic _______.

food webs

Protists also play an important role in the marine ________.

carbon cycle

Many, but not all protists have elaborate ________ and _________.

cell walls, shells

Some protists are _______ and produce energy via ________.

autotrophs, photosynthesis

Some protists are _________ and produce energy via __________.

heterotrophs, phagocytosis (engulfing food)

Some protists feed using ______ and a specialized ___________.

cilia, gullet

Some protists move in a sliding ____________ with the help of ___________.

amoeboid motion, pseudopodia

Some protists move by __________ with the help of large ___________ or many small _______.

swimming, flagella, cilia

Protists macroevolution includes four important morphological

innovations unique to eukaryotes:

1. the nuclear envelope

2. the mitochondria and chloroplast

3. multicellularity

4. s*x and alternation of generations

Becoming eukaryotes (1)

The ____________ evolved via infolding of the plasma membrane. This allowed eukaryotes to better regulate gene expression.

nuclear envelope

Becoming eukaryotes (2)

The ___________ of Eukaryotes evolved via _____________. An ancient Achaean cell

engulfed an ancient Bacterial cell. This early Eukaryote had a _______ cell and more _______.

mitochondria, endosymbiosis, larger, energy

Becoming eukaryotes (3)

The ________ evolved multiple times. In __________, an

ancient protist engulfed a cyanobacterium (plants). In ____________, another protist engulfed a cyanobacterium-containing protist (others).

chloroplast, primary endosymbiosis, secondary endosymbiosis

What allowed eukaryotes to specialize for different functions?

Multicellularity

Alternation of Generations

Includes multicellular haploid and diploid phases

Opisthokonta

Includes fungi and animals

Plantae

Includes plants

The Seven protist lineages are divided into 2 major groups:

Unikonta - have one flagellum

Bikonta - have two flagella

Green plants include:

• Green algae

• Land plants

Scientists study land plants because…

We can’t live without them!

And some can be harmful!

Excavata > Euglenics

Habitat: freshwater.

Characteristics: single-celled; lack

mitochondria but have chloroplasts, asexual

Impact: phytoplankton important in aquatic

foodwebs.

Key Lineage: Excavata

▪ unicellular

Euglena velata

▪ most have flagella

▪ includes free-living,

symbiotic & parasitic

▪ some photoautotrophic

Key Lineage: Alveolata

▪ unicellular w/alveoli

▪ motile (cilia or flagella)

or non-motile

▪ include free-living,

parasitic

Alveolata > Apicomplexans

Habitat: oceans.

Characteristics: unicellular, have

chloroplasts from secondary

symbiosis.

Impact: the most important

primary producer in marine

ecosystems.

Key Lineage: Stramenopila

uni- & multicellular

▪ flagella with hollow “hairs”

▪ parasites, decomposers

& photoautotrophs

Stramenopila > Brown Algae

Habitat: oceans.

Characteristics: contain

chloroplasts from secondary

endosymbiosis, multicellular,

alternation of generations.

Impact: largest protists, form

kelp forests.

Key Lineage: Plantae

▪ All plants + 3 protist lineages

– descended from common ancestor

– all photoautotrophic

▪ Glaucophyte, Red, & Green algae lineages:

– protists, not plants

– unicellular & multicellular

Plantae > Red Algae

Habitat: oceans and hotsprings.

Characteristics: multicellular,

alternation of generations

Impact: major component of coral

reefs.

Amoebozoa > Slime Molds

Habitat: wet forests

Characteristics:

amoeboid movement

Impact: important for

carbon cycling in

forests; model organism

for multicellularity .

Rhizaria > Foraminiferans

Habitat: oceans.

Characteristics: have shell,

feed by phagocytosis,

reproduce asexually by

mitosis.

Impact: major component

of aquatic carbon cycle;

form limestone, chalk, and

marble.

The fossil record suggests that _________ evolved 700 MYA,

when oxygen increased in the atmosphere.

green algae

Land plants evolved following the _____________.

Cambrian Explosion

Fossil record suggests that _________ evolved 475 MYA.

land plants

What are some of the challenges for the very first terrestrial

land plants?

▪ Drier conditions

▪ Intense light

▪ A lack of supporting tissues

Plants then evolved from five major radiations starting 475 MYA, with ___________ allowing them to live on land.

morphological innovations

Nonvascular Plants

Bryophytes: mosses, liverworts, hornworts

● Very successful: widespread; ~16,000 species

● Small; rhizomes (root-like anchors);

● Produce spores

● No vascular tissue (no xylem & phloem)

○ Absorb nutrients through cells

Seedless Vascular Plants

ferns, club mosses, horsetails

Evolution of vascular tissue provided plants with better support. This allowed:

○ Taller upright growth

○ More efficient transport of water upwards

Seed plants

Gymnosperms: conifers, cycads, Gingko

Angiosperms: flowering plants

Which adaptations address each problem of life on land?

1. avoid drying out.

2. grow upright to capture

sunlight.

3. transport water to different

parts of the plant.

4. reproduce without water.

Photosynthesis

6CO2 + 6H2O ––light→ C6H12O6 + 6O2

Cuticle

A waxy cuticle to prevent water loss + UV protection in nonvascular plants

Stomata

pore to let out water vapors/perform gas exchange, prevent water loss in nonvascular plants

Nonvascular plants characteristics

● AKA Bryophytes

○ No vascular tissue → this is

the tissue that plants use to

move water & nutrients

■ Instead, they absorb

H2O & nutrients directly

■ Need to live in moist

habitats

○ No seeds → spores or

asexual reproduction

● Habitat: moist forests & fields

● Life cycle: gametophyte-dominated

alternation of generations

● Impact: among the world’s most

abundant plants

Seedless Vascular Plants characteristics

•No seeds

•Have vascular tissue

•Xylem (conducts water)

•Phloem (conducts sugar)

•Include:

• Ferns

• Horsetails

• Club mosses

• Whisk ferns

● These do have vascular tissue, but no seeds

● Habitat: moist forests

● Life cycle: sporophyte-dominated alternation of generations

● Impact: used as food & landscaping

Seed plants characteristics

● Have vascular tissue and seeds

● Seeds = embryos surrounded by

nutritive tissue

● This group includes Gymnosperms

(plants that produce “naked” seeds

like pines and firs) and

Angiosperms (flowering plants)

Seed plants - GYMNOSPERMS

● Habitat: dry fields & forests

● Impact: dominant trees in many

forests; key food source for many

animals

● Life cycle: sporophyte-dominated

Seed plant adaptations

Seed plants evolved more efficient

ways of transporting water with

tracheids and vessel elements

○ These structures allow seed plants to grow

tall in drier environments

● Provide the rigid structure plants need

to grow tall (aka WOOD)

● Allow transport of water and sugar up

(and down) the plant

○ Xylem- Transport H2O from roots upwards

○ Phloem- Transport sugars from the leaves

to the rest of the plant

● In some plants the tracheids & vessel elements form wood!

○ Extremely strong support material

○ Important for organisms & humans

● Seeds have a protective coat and

a nutrient supply to protect and

provide for the fertilized embryo

Seed plants - ANGIOSPERMS

● Habitat: most habitats except deep

oceans and poles

● Impact: most diverse group of land

plants, supply food & housing for

many terrestrial animals

● Life cycle: sporophyte-dominated

● Flowers contain a stamen (produce

pollen with sperm→ male gametes)

● Flowers also contain a carpel for

(produce ovules with eggs→

female gametes)

Some angiosperms evolved ________ that contains 1+ seeds

fruit

Fruit

• Fruits attract animals that will

disperse their fertilized seeds

• Helps move their seed to a new

location and not compete with the

“mother” plant

Fungi and Animals are members of

the __________.

Ophisthokonta

What are fungi?

Fungi include mushrooms, molds, mildews, and yeasts.

Fungi are ___________ that obtain nutrients via __________.

chemoorgano-heterotrophs, extracellular digestion

Fungi are…

decomposers

Fungi comes in two forms…

1. Single-celled yeasts.

2. Multicellular mycelia.

Mycelia are composed of filamentous _________. These hyphae are divided into porous _________.

hyphae, septa

Fungi impact human…

agriculture and health.

Fungi are responsible for

several types of crop disease

and ___________.

spoilage

Many ________ are derived

from fungi. (e.g. penicillin)

antibiotics

Fungi play an important role in

______________. Fungi breakdown carbon from

other organisms – especially ________. They release this carbon into the

__________. This is nutrient recycling.

decomposition, trees, atmosphere

Like plants, fungi are _________ and live

in moist habitats.

But fungi are much more closely

related to _______ than they are to

plants.

For example, morphologically, fungi and

some animals share ______ in their cell

walls

sessile, animals, chitin

Each sexually reproducing lineage has its own unique ________ and ________.

mycelia, sporangia

_____ is a tough structural component of cell walls. It is found in both fungi and arthropods.

Chitin

Fungi are classified based

on how they obtain food:

1. Saprophytic

2. Endophytic

3. Mycorrhizal

Saprophytic: How do fungi eat?

• Saprophytic fungi digest

dead plants.

• They secrete enzymes

that break down tough

lignin and cellulose.

• This recycles carbon and

other nutrients for other

organisms.

Endophytic: How do fungi eat?

• Endophytic fungi grow

on the surface of plants.

• They are mutualistic and

protect the plant.

• They produce antibiotics

and pesticides.

Mycorrhizal: How do fungi eat?

• Mycorrhizal fungi live in

association with plant roots.

• They transfer nitrogen from

the soil in exchange for

sugar.

• Without them, the world

would be a lot less green.

There are five lineages of fungi.

Distinguished by adaptations

for:

1. Obtaining Food

2. Reproduction

Key lineage: Fungi > Chytrids aka “water molds”

Food: digests plants or

parasitize amphibians.

Life Cycle: live in wet

environments; sexual

reproduction.

Impact: responsible for

decline of amphibian

populations.

Key lineage: Chytrids

▪ saprophytes

▪ pathogens

Zygomycetes

▪ terrestrial

▪ filamentous

▪ Coenocytic

▪ Don’t have septa between

cells, meaning each hyphal

thread has hundreds to

thousands of nuclei

▪ saprophytes,

pathogens

▪ Most well knows is

▪ Black bread mold

Fungi > Zygomycetes: exemplified by Rhizopus—Black Bread Mold

Food: saprophyte that digests plants.

Life Cycle: usually asexual

reproduction, though can undergo

sexual reproduction via zygosporangia.

Impact: common cause of food

spoilage.

Basidiomycota

▪ terrestrial

▪ most filamentous (septate)

– some yeasts

– (i.e. single celled)

▪ sexual reproduction

– basidiospores

▪ asexual reproduction

– conidiospores

Fungi > Basidiomycota

exemplified by the “mushrooms”

we all can recognize

Food: saprophytes that digest wood.

Life Cycle: sexual or asexual.

Impact: cycle nutrients in forests;

many species used as food; some

have hallucinogenic properties

Ascomycota

▪ terrestrial

▪ filamentous (septate)

& yeasts (i.e. single celled)

▪ sexual reproduction

– ascospores

▪ asexual reproduction

– conidiospores

▪ saprophytes, symbionts,

pathogens

Fungi > Ascomycota > Lichens

Food: mutualistic

association with algae.

Life Cycle: sexual or

asexual.

Impact: common in the

Arctic and Antarctic

tundras; sensitive to air

pollution and used an as

indicator species.

___________ are related to fungi

and single-celled protists.

Animals

All animals share several key

synapomorphies:

1. Multicellularity

2. Chemoorganoheterotrophs

3. Motile

4. Neuron and muscle cells

Animals are divided into two

groups based on their symmetry

and development.

Nonbilaterians

1. Sponges

2. Jellyfish

Bilaterians

1. Protostome (e.g. insects)

2. Deuterostome (e.g. chordates)

Key events in animal

macroevolution include:

1. Multicellularity

2. Multiple tissue layers

3. Bilateral symmetry

4. Cephalization / CNS

5. Body cavity / coelom

6. Segmentation

The ancestors to animals were single-celled ________ organisms

similar to __________.

colonial, Choanoflagellates

Multicellularity allows for cellular _________.

specialization

Diploblasts have two germ layers:

• Outer ectoderm

• Skin, nervous system, muscle

• Inner endoderm

• Digestive tract/organs

• Reproductive organs

Non-Bilaterian > Porifera

Bodyplan: asymmetrical

Feeding: suspension feeder

Movement: sessile, limbless

Reproduction: asexual or

sexual

Non-Bilaterian > Cnidaria

Bodyplan: two germ layers, radial

symmetry

Feeding: suspension feeder,

predator; uses a cnidocyte to sting

prey.

Triploblasts have three germ layers:

• additional inner mesoderm

• Muscle

• circulatory system

• Skeletal system (bone)

• non-digestion organs

The diploblastic nonbilaterians exhibit _______ symmetry.

radial

Triploblasts evolved ________ symmetry.

bilateral

radial symmetry:

– only in diploblasts

– evolved before bilateral

symmetry

bilateral symmetry:

– all triploblasts & some

diploblasts

Nervous system: Non-bilaterians

▪ Sponges: no nerve cells (?)

▪ Others: ✓ nerve cells

▪ nerve net or ganglia

Nervous system: bilaterians

central nervous system (CNS )

– > 1 ganglia &/or tracts

– Nerve tracts: carry

information through the body

– encounter environment at

one end ∴ many neurons at

that end

Cephalization

• Head: feeding; sensing

environment; processing

information

• cerebral ganglion or brain

• Evolution of CNS coincided

with cephalization

• rapid, directed movement