bio 3 exam

Part 8:

Protist: Any organisms that are eukaryotic (have a nucleus) but are not animals, plants, or fungi.

• Animal-like protists: Hunt and move around for prey
• Fungi-like protists: live as heterotrophs and form sheet-like colonies of cells like a fungus
• Plant-like protists: they are multicellular and photosynthetic like a plant
• Eukaryotic:

5 big areas of diversity among protists

1. Single vs multi-cellular: Some protists are single-celled while some are multicellular

   1. Diatoms are single-celled and have a silica-based cell wall

   2. Algae are multicellular that form large kelp forests underwater

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2. Terrestrial vs. aquatic: Some protists are terrestrial while some are aquatic

   1. Many live in soil, on trees & rocks, etc. love damp environments

   2. Many live in water, including diatoms, water molds, green algae,& red algae

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3. Motile vs. stationary: some protists are motile while some are stationary

   1. Most diatoms are stationary due to their thick silica cell wall

   2. Dinoflagellates have flagella tails that can propel them through water

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4. Sexual vs. asexual: Some protists reproduce asexually while some reproduce sexually

   1. Many protists reproduce asexually through binary fission (cell division)

   2. Some reproduce sexually: 2 individuals contribute genetic material to offspring that is genetically different from both parents. (no sex organs involved)

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5. Autotropic vs. Heterotrophic: some protists are autotrophic while some are heterotrophic (some are both)

   1. Protists that undergo photosynthesis are autotrophic (self-feeding) & are generally called algae

   2. Heterotrophic protists get nutrients from their surroundings by either: absorbing nutrients directly through cell membranes or ingesting food

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Protists that ingest food are predators

• Use extensions of the cell membrane called pseudopods to surround & engulf prey
• Other predatory protists create tine currents that sweep food particles into the mouth-like openings in the cell.

Protists that absorb nutrients directly from the surrounding environment are 2 types:

1. Free-living types in the soil that decompose organic dead matter

2. Parasites that live inside the bodies of other organisms, sometimes harming the host

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Protists & other organisms/environment:

• Photosynthesis (pos)
  • Capture sunlight, turning it into fuel for all living things
  • Produce oxygen, allowing us to continue breathing
  • Pull carbon dioxide from the air, reducing dangerously high levels in the atmosphere
• Food sources (pos)
  • Protists (plankton) are the most important organism in the ocean food chain
• Commercial uses (pos)
  • Agar is a gelatinous substance derived from algae & is used as a: vegetarian substitute for gelatin
• Some protists act as pathogens, causing illness & disease (neg)
  • Parasitic protists cause some common and sometimes deadly ailments in humans
  • “light blight” caused the Irish potato famine of 1840
  • “downy mildew” is a parasitic water mold that can destroy crops like grapes
  • Marine protists that release toxins that can accumulate to harmful levels in coastal areas “red tide”

Part 9

Fungi characteristics

• Heterotrophic -Secrete enzymes to absorb nutrients
• Multicellular
• Mycelium body structure
  • Reproduce using spores
  • Hyphae- threadlike filaments
  • Septa- divide cells into partitions and pores to allow nutrients to pass through each cell
• Chitin- in cell walls. It is tough and flexible
• Fruiting bodies = reproductive spore-producing structures such as mushrooms, puffballs, or truffles

Important relationships: endophytes, mycorrhizae, & lichens

• Symbiotic relationships and photosynthesis to absorb nutrients
• Endophytes live with plants and provide benefits to the plant
• Mycorrhizae roots of plants
• Lichens live on or with protists or bacteria

Fungi & other organisms/environment:

The good:

1. Provide antibiotics

   1. Not all but many antibiotics are derived from fungi
   2. The 1st antibiotic discovered, penicillin, is produced by a mold
   3. Other medications are derived from fungi as well (cyclosporin)

2. Some fungi provide food

   1. Mushrooms, such as morels and truffles, are eaten by many animals
   2. Certain molds impart flavor to some of the world’s most famous cheeses

3. Yeast is useful in baking and brewing

   1. Wine is produced when yeasts ferment fruit sugars
   2. Beer is derived when yeasts ferment sugars in germinating grains (barley)
   3. Bread rises when yeasts ferment sugar that has been added to bread dough

4. Most fungi are important decomposers

   1. Fungal Saprophytes feed on dead organisms

      1. Secrete substances that digest the tissues of dead organisms, liberating nutrients that can be reused by plants
      2. Important for recycling minerals, nutrients, & energy on earth

The bad:

1. Parasitic

   1. Fungal parasites cause the majority of plant diseases

      1. Rusts & smuts = parasites that cause considerable damage to grain crops

2. Mold and mildew

   1. Some molds & mildews cause wooden structures to rot
   2. Some damaged cotton and wool fabrics

3. Poisonous

   1. Claviceps purpurea produces several toxins. It infects rye plants and causes a disease called ergot.
   2. Ergot symptoms= vomiting twitching hallucinations, & death.

4. Pathogenic

   1. Jock itch is caused by fungi that affect the skin

Part 10

Plant Characteristics

1. Plants exist nearly everywhere

   1. Form the basis for complex food webs & provide diverse habits for all other organisms

2. Plants are autotrophic

   1. Self-feeding through photosynthesis

3. Plants are multicellular

4. Plants are immobile

5. Most plants reproduce sexually (& some asexually)

   1. Some plants can make offshoots, giving rise to identical offspring: asexual reproduction
   2. Most plants reproduce sexually ( sperm and egg) Alternation of generations (sporophyte, gametophyte, embryo, haploid, diploid…)

A multicellular diploid generation alternates with a multicellular haploid generation

• Full plant = sporophyte -diploid (2 sets of genes)
• Sporophyte produces Spores (through meiosis) Haploid (1 set of genes)
• Spores grow into Gametophytes, not a full plant- haploid
• Gametophytes produce gametes (egg and sperm)
• A fertilized egg develops into an Embryo -diploid
• The embryo turns into a full plant

Plants & other organisms/environment: 7 positives

1. Provides food for animals, fungi, & other heterotrophic organisms

   1. Energy moves 1-way coming from the sun to the earth into plants
   2. Organisms eat plants and other organisms to stay alive

2. Plants maintain the atmosphere

   1. Through the process of photosynthesis. They pull CO2 from the atmosphere and release O2

3. Plants build & maintain the soil

   1. Dead plant material is decomposed into organic matter, adding nutrients that soil makes more fertile.
   2. They hold the soil together preventing erosion

4. Plants keep water in ecosystems

   1. They absorb stored water from the soil & release it slowly

5. Plants provide shelter and homes for organisms

6. Plants provide important medicines

   1. Asprin
   2. Taxol

7. Plants provide useful materials for fuel & other commercial goods

   1. Fuel, twine, canvas, clothing, pigments, alcohol, cleaners, oils, cosmetics

Major groups: Nonvascular & Vascular

Nonvascular:

• No way to conduct water around the plant
• No seeds: sperm & egg must meet in the water
• MUST be around water

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Vascular plants:

• Have tube-like cells to spread water
• Provide support & transport water
• Allows for larger size and can move away from water

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Seeded vs. seedless

Vascular seedless

• Plants have no seeds, so they still require sperm & egg to meet in the water
• Some stay near water to continue reproduction

Vascular seeded

• Pollen= tiny grains for reproduction
  • Dispersed by wind or pollinators
  • Eliminates the need for sperm to swim to the egg, so they can live and reproduce on dry land
• Seeds protect the embryo as it grows and provide it with nourishment

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Gymnosperms vs. angiosperms:

Gymnosperms = vascular seeded plants that do NOT have flowers or fruits

Angiosperms= vascular seeded plants with flowers & fruits

• Most Diverse & widespread of all plants
  • Flowers= reproductive structures in which gametophytes are formed

The evolution of angiosperms exploded when gymnosperm ancestors formed an association with animal pollinators

• Fruits: contain developing seeds
• Edible fruits entice animals to eat them: seeds pass through the digestive tract unharmed
• Burr fruits cling to animal fur
• Winged fruits are carried through the air

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