quiz tmw

6-3 & 6-4 READING ASSN #22: 22.1 (all and Figure 22.1)---382-388

(differences between types of algae)---23.1(all)---23.3 (all)

-Protists have eukaryotic cells.

-Endosymbiosis hypothesis: explains how mitochondria and chloroplasts became part of eukaryotic cells—mitochondria likely came from aerobic bacteria and chloroplasts from cyanobacteria, both engulfed separately by a eukaryotic cell.

-Protist diversity: vary in size/complexity—kelp (multicellular brown algae), volvox (colonial green algae), spirogyra (filamentous green algae).

-Amoeboids and ciliates have a contractile vacuole for water regulation.

-Nutrition: Algae are photosynthetic. Protozoans are heterotrophic—some use endocytosis (food vacuoles), others are parasitic. Slime molds absorb decaying matter like protozoans via endocytosis.

-Reproduction: Usually asexual (mitosis); in harsh conditions, sexual (meiosis).

-Cysts: Some protozoans form cysts as a resting stage; in parasites, cysts help transfer to a new host.

-Ecological/medical importance: Photosynthetic protists produce oxygen and serve as producers in aquatic food chains (plankton = food for others).

-Symbiosis: Protists form relationships ranging from parasitic to mutualistic.

-Classification: May change; currently based on nutrition—algae (autotrophic like plants), protozoans/slime molds (heterotrophic by ingestion like animals), and water molds (heterotrophic by absorption like fungi).

-Algae = diverse group of photosynthetic protists. Classified as plants. All have chlorophyll a and perform photosynthesis in plastids.

-Phylum Chlorophyta = ~7,500 species of green algae. Symbiotic with plants, animals, fungi. Mostly unicellular; some filamentous/colonial. Not always green.

-Chlamydomonas = unicellular green alga in still freshwater. <25μm. Cell wall, cup-shaped chloroplast with pyrenoid (makes starch), 2 flagella (breaststroke motion).

• Asexual: mitosis → up to 16 daughter cells released by enzyme.

• Sexual (unfavorable conditions): gametes fuse → zygote → zygospore → dormancy → meiosis → 4 flagellated zoospores.

-Filaments = chains of cells formed by division in 1 plane.

-Spirogyra = unbranched filamentous alga with spiral chloroplasts. Found in green masses. Sexual repro by conjugation (genetic exchange).

-Plants and green algae similarities = cellulose, chlorophyll a/b, store starch.

-Ulva (sea lettuce) = multicellular; thallus is 2 cells thick. Has alternation of generations (gametes identical in appearance).

-Stoneworts = freshwater green algae, possibly closest to plants. Covered in calcium carbonate. Main axis = long cells, anchored by rhizoids. Whorls of branches at nodes. Reproductive structures grow at nodes: male = flagellated sperm; female = egg.

-Volvox = colonial green alga. Hollow sphere with many Chlamydomonas-like cells. Some specialize in reproduction and form daughter colonies asexually.

-Colony = loose group of independent cells.

-Phylum Rhodophyta (red algae) = over 5,000 multicellular species. Mostly in warm seas. Often smaller than brown algae, some unicellular. Range from filaments to complex branches.

• Coralline algae = red algae with calcium carbonate, help form coral reefs.

• Uses:

Agar (Gelidium, Gracilaria): capsules, cosmetics, food

Carrageenin (Chondrus crispus): chocolate, cosmetics

Porphyra: used in Japanese aquaculture

Phylum Phaeophyta (brown algae) = over 1,500 multicellular species (no unicellular/colonial forms). Range in size, found in cold ocean waters. Contain chlorophyll a, c, and brown pigment.

• Found on rocky coasts (e.g., Laminaria = kelp, Fucus = rockweed).

• Provide food/habitat for marine life, used as food and fertilizer.

Seaweeds = general term for green, red, and brown algae.

Algae & Protists Reproduction

• Algae reproduce both sexually and asexually.

• Protists usually reproduce asexually in favorable environments.

• Asexual reproduction:

  • Involves 1 parent.

  • Offspring are identical to the parent.
    
    

• Sexual reproduction:

  • Occurs more when the environment is unfavorable or changing.

  • Creates genetic variation, which can help survival in extreme conditions.

  • Involves 2 parents and gametes.

  • Gametes fuse to make a diploid zygote.

  • If gametes look alike: isogamous (isogametes).

  • If gametes look different: oogamous (heterogametes).

  • Meiosis is part of sexual reproduction.

Life Cycles:

• Haploid cycle (e.g., algae):

  • Zygote undergoes meiosis → haploid spores → haploid individuals.

  • Zoospores common in algae.

  • Zygote = only diploid stage.

• Diploid cycle (e.g., animals):

  • Diploid individuals undergo meiosis → haploid gametes.

  • Gametes fuse → diploid zygote → diploid individual.

  • Gametes = only haploid stage.
    
    

Phylum Chrysophyta

• Includes:

  • ~11,000 diatom species.

  • 500 golden-brown algae.

  • 600 yellow-green algae.

• Mostly free-living photosynthetic cells.

• Diatoms:

  • Most numerous unicellular algae in oceans & freshwater.

  • Major part of phytoplankton (food & oxygen for heterotrophs).

  • Cell wall made of two silica valves.

  • Asexual reproduction → each gets 1 old valve → smaller offspring until ~30% size.

  • Then sexual reproduction restores size.

  • Zygote grows and divides by mitosis into full-size diatoms.

  • Silica walls → diatomaceous earth used in filters, soundproofing, and abrasives.
    
    

Phylum Pyrrophyta (Dinoflagellates)

• ~4,000 unicellular marine/aquatic species.

• Cells usually have:

  • Cellulose plates with silicates.

  • Two flagella.

• Provide food for small ocean animals.

• Zooxanthellae = symbiotic dinoflagellates in corals.

  • Provide corals with organic nutrients.

  • Corals provide waste (fertilizer).

• Usually reproduce asexually (mitosis and longitudinal division).

• Can also reproduce sexually.

• Major marine producers.

• In polluted water, population explosions (up to 30,000/mL) → red tide.

  • Kills fish and causes paralytic shellfish poisoning in humans.
    
    

Phylum Euglenophyta (Euglenoids)

• ~1,000 species of small freshwater unicellular organisms.

• ⅓ have chloroplasts; others ingest or absorb food.

• Produce paramylon (a unique carbohydrate).

• Euglena:

  • Can photosynthesize and ingest food.

  • Considered both plant- and animal-like.

• Reproduce by longitudinal cell division.

• No known sexual reproduction.

Kingdom Fungi

• Over 80,000 known species; could reach 1.5 million.

• Heterotrophic (absorb organic matter).

• Most are saprotrophic decomposers.

• Cause crop loss and human diseases.

• Economically important:

  • Food: mushrooms, truffles, cheeses.

  • Antibiotics (e.g., penicillin), anticancer agents.

• Can be:

  • Parasitic (on animal/plant tissue).

  • Mutualistic (e.g., with seed plant roots).

Fungal Structure:

• Mostly multicellular, some unicellular.

• Body = mycelium (network of hyphae).

• No chloroplasts.

• Cell walls contain chitin (not cellulose).

• Nonmotile (no flagella or basal bodies); grow toward food.

• Hyphae types:

  • Septate (with cross-walls).

  • Nonseptate (multinucleated).

Fungal Reproduction:

• Asexual and sexual.

• In sexual reproduction:

  • Hyphae of 2 mating types fuse.

  • Nuclei may fuse right away or later.

  • Hyphae with 2 haploid nuclei = dikaryotic.

• Spores:

  • Reproductive cells that don’t require fusion.

  • Germinate when landing on food.

• Asexual reproduction includes:

  • Spore production, fragmentation, and in yeasts, budding.

Lichens

• Symbiotic relationship: fungus + cyanobacteria/green algae.

• Crustose lichen body:

  • Thin tough upper layer.

  • Loosely packed lower layer.

  • Middle layer with photosynthetic cells.

  • Fungal hyphae transfer nutrients.

• Asexual reproduction by releasing fragments with hyphae and algal cells.

• Fruticose lichens may reproduce sexually via sac fungi.

• Algae may not benefit:

  • Grow better alone.

  • Fungus doesn’t grow naturally alone.

• 3 types:

  • Crustose (compact, on rocks/bark).

  • Fruticose (shrublike).

  • Foliose (leaflike).

• Survive in extreme conditions.

• Help form soil.

• Absorb pollutants; die in polluted air → indicate clean air.

Mycorrhizae

• Mutualistic relationships between soil fungi and plant roots.

• Plants with mycorrhizae grow better in poor soil.

• Fungi increase mineral absorption.

• Fungi receive carbohydrates from plants.

• Truffles are mycorrhizal sac fungi:

  • Found with oak/beech roots.

  • Once found with pigs, now grown by inoculating seedlings.

• Mycorrhizae may have helped plants adapt to land.

6-3 and 6-4 practice questions: 

1. Green algae a)store reserve food as lipid b)do not give off energy c)possess chlorophylls a and b d)have a cell wall that contains pectin 

2. Classification of algae according to color a)can no longer be justified b)is based on the type of pigments they contain c)suggests that they do not have chlorophyll d)means that some algae are colorless

3. Volvox a)does not reproduce b)is a colonial alga c)produces daughter colonies d)both b and c are correct 

4. Which of these is NOT true of spirogyra? a)has a spiral chloroplast b)is filamentous c)carries out conjugation d)reproduces asexually by forming spores

5. Some brown algae a)live at sea b)are quite large c)produce algin d)all of these are correct

6. Which is (are) true of euglenoids? a)they have flagella b)some have chloroplasts c)they reproduce asexually d)all of these are correct

7. Most fungi a)are plant parasites b)form mycorrhizae c)are saprotrophic d)are unicellular 

8. Club fungi a)include mushrooms b)have basidiocarp that looks like a cup c)include more parasites than all the other types of fungi d)all of these are correct

9. In fungi, the gametes are a)heterogametes b)flagellated c)the ends of hyphae d)produced by meiosis 

10. Which of the following is NOT a characteristic of lichens? a)soil formers b)algal cells and fungal hyphae c)form a type of moss d)can live in extreme conditions 

11. Which of the following is NOT true of fungi? a)saprotrophic nutrition b)eukaryotic cells c)reproduce by means of spores d)are always multicellular

12. A fruiting body is a)a special type of vacuole found in fungi b)a symbiotic relationship between algae and bacteria c)a reproductive structure found in fungi d)always the same shape

Long notes/original ones: 

• protists=have eukaryotic cells

• endosymbiosis hypothesis=suggests how mitochondria and chloroplasts became part of the eukaryotic cell (mitochondria may be derived from aerobic bacteria and chloroplasts mya be from cyanobacteria that were engulfed by a eukaryotic cell on 2 separate occasions) 

• Protists can vary in size and complexity (Ex:kelp, a brown algae, is multicellular, volvox, a green algae, is colonial, and spirogyra, a green alga, is filamentous)

• Amoeboids and ciliates (protists) have unique organelles-their contractile vacuole is an organelle assisting water regulation

• Protists get nutrients in different ways like algae being photosynthetic and getting energy from sun, protozoans are heterotrophic and some get food by endocytosis (food vacuoles) and some are parasitic and absorb nutrients meant for their host, and smile molds creep on forest floors and eat decaying plant material in the same manner are protozoans doing endocytosis

• Usual reproduction for protists=asexual reproduction by mitosis

• Reproduction for protists in hostile environments=sexual reproduction with meiosis

• Some protozoans form cysts (another resting stage). In parasites, a cyst can serve as a mean of transfer to a new host

• Protists are important medically but also ecologically as the photosynthesizers give off oxygen and function as producers in freshwater and saltwater. They’re part of plankton, organisms suspended in water serving as food for heterotrophic protists and animals

• Protists enter symbiotic relationships anywhere from parasitism-mutualism. Protist classification may be split up even more in the future. Now, they’re grouped based on modes of nutrition. Protists include algae, which are autotrophic like plants; protozoans and slime molds and heterotrophic by ingestion like animals; and water molds are heterotrophic by absorption like fungi. 

• algae=diverse group of photosynthetic protists. Classified as plants. All have chlorophyll a and carry on photosynthesis within a membrane bounded plastid

• Phylum Chlorophyta includes ~7,500 species of organisms known as green algae. They form symbiotic relationships with plants, animals, and fungi. Most are unicellular but some are filamentous and colonial forms. Green algae isn’t always green. 

• chlamydomonas=actively moving green alga that inhabits still freshwater pools. Its fossil ancestors date back over 1 billion years. It’s less than 25 micrometers long. It has a cell wall and a cup shaped chloroplast containing a pyrenoid, a body where starch is synthesized. 2 flagella protrude from the anterior and move w/a breaststroke motion

• Chlamydomonas reproduce asexually and mitosis makes up to 16 daughter cells which escape by secreting an enzyme that digests the parent cell wall. Sometimes chlamydomonas reproduce sexually when growth conditions are unfavorable. 2 dif mating gametes form a zygote, then a wall forms around the zygote, it becomes a resistant zygospore, goes through dormancy, zygospore germinates, and produces 4 zoospores (flagellated spores) by meiosis. 

• filaments=end to end chains of cells formed after cell division happens in 1 plane

• Spirogyra=filamentous unbranched green alga. Has spiralled chloroplasts. Found in green masses. Undergoes conjugation in sexual reproduction (cells exchange genetic material)

• Plants may be most closely related to green algae bc both have cellulose, chlorophylls a and b, and store food as starch

• Ulva=multicellular green alga often called sea lettuce. Thallus (body) is 2 cells thick. Has generations (like plants) expect they look exactly alike and gametes all look the same

• Stoneworts (may be most closely related to plants)=green algae living in freshwater lakes and ponds that have calcium carbonate deposits encrusting them. Its main axis is a single file of long cells anchored by rhizoids (hairlike filaments). Whorls of branches occur at multicellular nodes (regions between giant cells of the main axis). Reproductive structures grow at nodes (male produces flagellated sperm and female makes single egg)

• Volvox=colonial green alga. Hollow sphere with thousands of cells in a single layer around a watery interior (each cell resembles a Chlamydomona cell). Some cells are meant for reproduction and they can divide asexually to make a daughter colony 

• colony=loose association of independent cells

• Phylum rhodophyta has over 5,000 species of multicellular organisms called red algae. Mainly live in warm sea waters. Usually smaller than brown algae, but can be long. A few species are unicellular. 

• Some red algae are simple filaments but others are complexly branched

• Coralline algae=red algae w/cell walls impregnated by calcium carbonate and contribute to coral reef growth

• Red algae are economically important (ex: agar made from gelidium and gracilaria is used for vitamin capsules, cosmetic bases, food preparation, and carrageenin made from chondrus crispus is used in chocolate and cosmetic making, and porphyra is the base of an aquaculture industry in japan)

• Phylum phaeophyta has over 1,500 species of seaweeds+other algae called brown algae. NO unicellular or colonial ones. Range from simple small forms to large multicellular ones. Usually found in cold ocean waters. They have chlorophyll a and c and a pigment that gives them their color. 

• Brown algae are found along rocky coasts in north temperate zones (ex: laminaria which is kelp, and fucus which is rockweed) and dry slowly. Brown algae provide food and habitat for marine organisms and are harvested for human food and for fertilizer.  

• Seaweeds=green, red, and brown algae forms

• Algae reproduce sexually and asexually

• Protists frequently reproduce asexually when the environment is favorable to growth

• Asexual reproduction=requires only 1 parent and offspring are identical to the parent

• Sexual reproduction is more likely to occur with protists if the environment is changing and has unfavorable growth. Recombination of genes may create individuals who can survive extremes in environments

• Sexual reproduction=requires  parents and each of their chromosomes contribute to offspring by way of gametes. The gametes fuse and make a diploid zygote. Reproductive cycle is isogamous when gametes look alike (isogametes) and oogamous when they dont look alike (heterogametes)

• Meiosis happens in sexual reproduction

• In haploid cycle, zygote divides by meiosis and forms haploid spores which become haploid individuals 

• In algae, spores are typically zoospores. The zygote is only the diploid stage in this life cycle and the haploid gives rise to gametes

•  In diploid life cycle (usually animals), diploid individuals produce gametes by meiosis and gametes are only haploid stage in this cycle. They fuse to make a zygote which becomes a diploid individual. 

• Phylum Chrysophyta has ~11,000 species of diatoms, 500 species of golden=brown algae, and 600 species of yellow-green algae. Most of these members are free-living photosynthetic cells. 

• Diatoms are the most numerous unicellular algae in oceans/freshwater. They're a significant part of phytoplankton (photosynthetic organisms that are suspended but sink slowly in water. They’re a source of food and oxygen for heterotrophs in marine water and freshwater)

• Diatom structure and reproduction=diatoms have a cell wall with 2 valves. When they reproduce asexually, each receives 1 old valve and the new diatoms are smaller than the og ones. This happens until the new ones are ~30% of the og ones, then they reproduce asexually. The zygote grows, then divides mitotically to make normal size diatoms

• Diatom cell walls have an outer layer of silica (ingredient in glass). Remains of diatoms (diatomaceous earth) accumulate on ocean floor and are used for filtering agents, soundproofing materials, and gentle polishing abrasives

• Phylum Pyrrophyta has ~4,000 species of aquatic and marine unicellular organisms called dinoflagellates. The cell usually has protective cellulose plates impregnated w/silicates and they also usually have 2 flagella

• Dinoflagellates are important bc they provide food for small ocean animals. 

• Symbiotic dinoflagellates are called zooxanthellae. Corals have high amounts of zooxanthellae and they provide their hosts w/organic nutrients and corals provide wastes that fertilize algae.

• Dinoflagellates usually reproduce asexually by mitosis and longitudinal division, but sometimes they reproduce sexually.

• Dinoflagellates are 1 of the most important producers in marine environments (like diatoms). Sometimes in polluted waters though, they undergo population explosion and have a density of ~30,000 in a single milliliter. As a result “red tide” may happen which kills many fish and causes some ppl so suffer paralytic shellfish poisoning. 

• Phylum Euglenophyta has ~1,000 species of small freshwater unicellular organisms called euglenoids. ⅓ have chloroplasts and the rest don't. If they don't, they ingest or absorb their food. Euglenoids produce an unusual carbohydrate called paramylon

• Euglena is a type of euglenoid and it can undergo photosynthesis and ingest food which is why it's treated like a plant and an animal like organisms in botany and zoology

• Euglenoids reproduce by longitudinal cell division. It believe that there's no sexual reproduction 

• Kingdom fungi has over 80,000 species of mainly multicellular eukaryotes sharing common mode of nutrition (mycologists,fungi studiers,say may go over 1.5 mil in future)

• Fungi=heterotrophic and consume organic matter like animals (but animals ingest food while fungi absorb food)

• Most fungal species are saprotrophic decomposers that feed on waste products and dead remains of animals and plants

• Fungal diseases are responsible for large loss of crops and many human diseases

• Fungi are economically important (mushrooms, truffles, cheeses)

• Fungi are important in antibiotic production like penicillin and 1 has an anticancer agent

• Some fungi are parasitic, living off tissues and some are mutualistic w/seed plant roots, giving inorganic nutrients and getting organic ones in return

• Fungi structure=some unicellular, most are multicellular. Mycelium (body of fungi) is a network of filaments called hyphae, facilitating absorption of nutrients in the fungus body. Fungal cells don't have chloroplasts and their cell wall has chitin instead of cellulose. Fungi are nonmotile (don't have basal bodies or flagella). They move toward food by growing toward it. 

• Hyphae with cross walls=septate and nonseptate fungi=multinucleated

• Fungi reproduction=sexual and asexual. In sexual, hyphae from 2 dif mating types fuse. Some species nuclei fuse immediately and some don't for a while. 

• Hypha that has paired haploid nuclei=dikaryotic

• Spore=reproductive cell that becomes a new organism without needing to fuse w/another reproductive cell (when it lands on a food source, it germinates and grows)

• Asexual reproduction usually involves production of spores by specialized part of a single mycelium. Asexual reproduction can also happen by fragmentation. Unicellular yeasts reproduce asexually by budding (small cell forms and gets pinched off when full sized)

• Lichens are an association between a fungus and a cyanobacteria or green alga. 

• Body of crustose lichen=thin tough upper layer and loosely packed lower layer to shield photosynthetic cells in the middle layer. The fungal hyphae in/around the photosynthetic cells transfer nutrients to the rest of the fungus. 

• Lichens can reproduce asexually by releasing fragments containing hyphae and an algal cell. In fruticose lichens, sac fungi sexually reproduce. 

• Lichens may involve parasitism of the  algal cells by fungus as the algae does not benefit from the association. Evidence is growing them separately/alone. Algae grows faster alone and the fungus doesn't grow naturally alone. 

• 3 lichen types: compact crustose (on bare rocks or tree bark), fruticose (shrublike), and foliose (leaflike)

• Lichens can live in extreme conditions and contribute to formation of soil Lichens take up pollutants and cant live in polluted air areas (indicate healthy air to breathe for ppl)

• Mycorrhizae=mutualistic relationships between soil fungi and roots of most plants 

• Plants w/soil invaded by mycorrhizae grow better in poor soils than those without

• Presence of fungus gives plants a greater absorptive surface to intake minerals. Fungus also benefits from association bc it receives carbohydrates from the plant

• Truffle is a mycorrhizal sac fungus living in association with oaks and beech tree roots. Pigs used to be used to find them, but now they inoculate roots of seedlings

• Mycorrhizae may have helped plants to adapt and thrive on land