Protists and plants

Protists characteristics

• include any eukaryote that is not plant, animal or fungus

• Diverse

• some photosynthesize or produce bacteria

• Live in multitude of ecosystems but mostly aquatic

• Unicellular except: brown algae, slime molds, etc.

Movement

• Can be amoeboid, cilia, or flagella-based

• Range in size from 1 um to 3 feet

• 4 different groups based on locomotion:

  -Flagellates

  -Ciliates

  -Amoeba

  -Sporozans: non-motile

Different types of protists have different methods of getting food

_can photosynthesize

-engulf particles of organic matter of bacteria

_some do both

Protist Asexual reproduction

Binary fission

-Multiple fission

Budding: one cells separates from a larger cell

Protist sexual reproduction

=happen in extreme conditions

-Conditions are so bad that they figure a combo of their genes would give their offspring a chance

How do we classify protists?

• Classifying protists is challenging due to their diversity.

• DNA sequencing advances have revealed six eukaryotic supergroups.

• Protists are found in all six supergroups.

• Similar protist morphology results from convergent evolution, not a common ancestor.

• These factors make protist classification complex.

Archaeplastida

• Formed from a heterotrophic protist and a cyanobacterium in an endosymbiotic relationship.

• Land plants evolved from their common ancestor..

• Includes red and green algae.

• Can be single-celled, multi-celled, or colonial.

Red Algae

• Found mainly in clear tropical oceans.

• Multicellular, photosynthetic, and mostly marine.

• Pigments range from red to black.

• Some help build reefs by depositing calcium carbonate.

• Contain useful gelatinous substances like agar.

Green Algae

Mostly in ponds and lakes
 Photosynthetic
 Multicellular or unicellular

Amoebozoa

• Can be unicellular, multinucleated, or multicellular.

• Move using pseudopodia.

• Pseudopodia extend and anchor to surfaces.

• Includes free-living and parasitic species.

• Live in both water and land environments.

• Slime molds belong to this group.

• Act as decomposers on forest floors.

• Form a multinucleated mass called plasmodium to engulf food.

Opisthokonta

• Named for a single rear flagellum used for movement.

• Choanoflagellates resemble the ancestor of sponges and animals.

• Can be unicellular or colonial.

• Use a collar to filter and ingest bacteria.

• Similar feeding method to sponges.

Rhizaria

• Includes amoebas with thin, threadlike pseudopodia.

• Play key roles in carbon and nitrogen cycles.

• Forams in this group resemble snails.

• Useful for detecting pollution and climate changes.

Chromalveolata

-Diverse subgroup

-Apicomplexans

-Stromatolites

Alveolates

• Includes parasites, predators, and phytoplankton.

• Single-celled with small cavities under their cell surface.

• Examples: Dinoflagellates (cause red tide) and ciliates.

Apicomplexans

• Sporozoans are parasites that live inside host cells.

• They do not have any way to move on their own.

• An example is Plasmodium, the parasite that causes malaria.

Stramenopiles

• Include both photosynthetic and non-photosynthetic organisms.

• Have fine, hair-like projections on their flagella.

• Can be single-celled or multicellular.

• Examples: Water molds, diatoms, and brown algae.

Excavata

• Most protists belong to this supergroup.

• Asymmetrical, single-celled organisms with a feeding groove on one side.

• Includes heterotrophic predators, photosynthetic species, and parasites.

• Some species lack mitochondria.

• Euglena is a well-known example.

• Found mostly in freshwater, they swim using flagella.

• Some have an eyespot to sense light and move towards it for photosynthesis.

Bioluminescent waves

• The bluish-green glow in the ocean comes from tiny dinoflagellates.

• These single-celled organisms range from 30 micrometers to 1 millimeter in size and are found worldwide.

• Individual dinoflagellates have a glow too dim to see, but large populations create a noticeable glow.

• In U.S. coastlines, dinoflagellate populations grow in summer to fall when water temperatures rise and seas are calmer.

Key characteristics of plants

• Eukaryotic and multicellular.

• Autotrophs that make their own food through photosynthesis.

• Mostly reproduce sexually.

• Have cell walls made of cellulose.

• Live on land and in water.

• Do not move from place to place.

• Large and diverse group with 300,000 cataloged species.

Transition from water to land

• Originally only aquatic.

• Transitioning to land required overcoming several challenges.

• Advantages of land:

  • Unlimited sunlight

  • Abundant CO2

  • Few pathogens and herbivores at first.

• Challenges to overcome:

  • Water loss: developed a cuticle (waxy covering).

  • Some still need to live near water.

  • Obtaining resources from soil and air: development of vascular tissue.

  • Support: development of root systems.

  • Reproduction: development of spores, seeds, and fruits.

Plant organ systems

• Similar cells make tissues; different tissues make organs.

• Vascular plants have two main organ systems:

  • Shoot system:

    • Vegetative parts: stem and leaves

    • Reproductive parts: flowers and fruit  

  • Root system

Shoot systems -stems

• Vary in size and shape  

• Support plant and hold leaves, flowers, buds  

• Transport water and minerals (xylem) and products of photosynthesis (phloem)

Shoot system -Leaves

• Photosynthesis occurs here

• Gas exchange via stomata

• Cuticle prevents water loss

• Vein patterns help distinguish monocots/dicots

Root systems

• Two types: tap (vertical) and fibrous (network)

• Absorb water and minerals

• May store food

• Mycorrhizae (fungi) help with nutrient absorption

Reproductive adaptations for the move to land

• Ways to keep gametes/embryos moist without water

• Protection for gametes from drying out

• Mechanisms to lure animals for pollination and seed dispersal (e.g., nectar, flower color)

Reproductive adaptations for the move to land pt-2 more confusing

• They alternate between a haploid stage (gametophyte) and a diploid stage (sporophyte), and both are multicellular.

• It starts with a diploid zygote, which becomes a sporophyte.

• The sporophyte produces haploid spores, which become a gametophyte.

• The gametophyte produces gametes (sex cells).

• Gametes fuse to form a zygote, starting the cycle again.

Plants as resources

• Agriculture (food)

• Lumber (construction, paper)

• Flowers (perfume, decoration)

• Medicine (many drugs)

• Ecosystem services (oxygen, habitats, soil stability)

• Fossil fuels (coal)

Major division of land plants

• Non-vascular plants: lack vascular tissue and seeds (e.g., bryophytes - liverworts, mosses, hornworts)  

• Vascular plants: have vascular tissue

  • Seedless: lycophytes (club mosses) and pterophytes (ferns, horsetails, whisk ferns)

  • Seeded: gymnosperms (conifers) and angiosperms (flowering plants)

Nonvascular plants

• Lack vessels for water and food transport

• Require external water for fertilization; live in moist places

• Gametophyte is the dominant stage

• Include:

  • Bryophyta (mosses)

  • Marchantiophyta (liverworts)

  • Anthocerotophyta (hornworts)

Phylum Marchaniophyta -Liverworts

• Closest relatives to the ancestors of vascular plants that adapted to land  

  • Have colonized every terrestrial habitat  

  • Have a flat body (thallus) that looks like lobes of a liver  

  • Over 7,000 species  

Phylum Anthocerotophyta -Hornworts

• Colonized various land habitats but are never far from a water source

• Characterized by a narrow, pipe-like sporophyte

• About 100 species

Phylum Briophyata -Moses

• Most numerous non-vascular plants (over 10,000 species)

• Anchored by rhizoids

• Rhizoids absorb water

• Have leaf-like structures but lack vascular tissue

• Sporophyte is a brown, stem-like structure

• Water travels up the outside of the plant

• Can withstand drying

• Abundant in Arctic and Antarctic, rare in deserts

• Sensitive to pollutants

Vascular plants

• Vascular plants are divided into seedless and seeded.

• Seedless plants include lycophytes (club mosses, etc.) and pterophytes (ferns, etc.).

• Ancient seedless vascular plant forests became coal.

Club mosses

Lycophytes:

• Earliest group of seedless vascular plants

• Dominated landscapes in the Carboniferous period

• Small, evergreen plants with stems and microphylls

• About 1,200 species

• Include:

  • Quillworts (Isoetales)

  • Club mosses (Lycopodiales)

  • Spike mosses (Selaginellales)

Horsetails

Equisetopsida:

• Found in damp environments and marshes

• Characterized by joints or nodes

• Most photosynthesis occurs in the green stem

Whisk Ferns

Psilotopsida:

• Lack roots and leaves

• Photosynthesis takes place in green stems that branch dichotomously

True Ferns

Polypodiopsida:

• Most advanced seedless vascular plant

• More than 20,000 species

• Found in various habitats (tropics to temperate forests)

• Mostly in moist, shaded spaces

• Expanded during the Carboniferous period

Fern Cycle

• Ferns have spores under their leaves.

• Spores are haploid and grow into a haploid gametophyte (prothallus).

• The gametophyte produces sperm (in antheridium) and eggs (in archegonium).

• In ferns, sperm use flagella to swim to the egg for fertilization when water is available.

• The resulting diploid zygote stays attached to the gametophyte.

• The zygote develops into the diploid sporophyte.

Seed plants

• Gymnosperms are seed plants with naked seeds, appearing in fossils about 425 million years ago.  

• Seeds have a protective coat, food storage, and dispersal adaptations.  

• Gymnosperms include conifers, cycads, gnetophytes, and ginkgo

  .  

Gymnosperm characteristics

• Gymnosperms have naked seeds, separate male/female gametophytes, and pollen/ovulate cones.

• Pollination is by wind/insects.

• The sporophyte is the dominant stage.

• Gymnosperms include conifers, cycads, gnetophytes, and ginkgo.

Angiosperms

• Angiosperms are flowering plants (Phylum Anthophyta) and the most diverse plant group.

• They include basal angiosperms, monocots, and dicots.

• Their success is due to flowers and fruits.

Flowers

• Flowers function to ensure pollination and protect the embryo.

• They use colors, patterns, and scents to attract specific pollinators (e.g., sweet scents for bees, rotting scents for flies).

Flower anatomy

Flower structure – can be one sex
or both
 Stamen – male reproductive
structure
 Anthers – produce pollen
 Filaments – hold up anthers
 Pistil – female reproductive
structure
 Ovary – where ovules are
produced
 Stigma – where pollen lands
 Style – tube connecting the
stigma to ovary
 Petals – attract pollinators
 Sepals – protect flower

fruit

Contain seeds
 Not just the sweet tasting foods
 Eggplants, zucchini, string beans,
tomatoes, bell peppers
 Fruit can be fleshy or dry
 Fleshy: berries, peach, apples, grapes
 Dry: rice, wheat, nuts
 Goal is to get your seed dispersed to
another place

Vegetables

Roots, stems and leaves
 Normally more savory
 Beets, potatoes, turnips, spinach, kale,
lettuce, celery, broccoli