Bio 2 Lab 2 Quiz

From the slides

Chlorophytes/Phylum Chlorophyta

• Not “true” plants but share many traits

• Shared traits: produce chlorphylls a and b and carotenoids, store starch, have cell wall made of cellulose, have plastids similar to chloroplasts

• Outgroups to plant phylogeny

• Green Algae and Stoneworts

• Mostly freshwater but some are marine

• About 7k species with a wide diversity of forms

• Sexual and asexual reproduction

• Found in freshwater or brackish water

• Unicellular to multicellular

• Bears a greater resemblance to true plants

Anthophyta

• Largest and omst diverse division of plants as it includes all flowering plants

• Defined by their reproduction via flowers and production of seeds in an enclosed ovary/fruit

• Double fertilization as one sperm fertilizes the egg to make a zygote while the other fuses with a polar nuclei to form a triploid endosperm which is a nutrient-rich tissue to feed the developing embryo

• Includes the monocots (single cotyledon which is the first embryonic leaves to emerge from a germinating seed) and dicots (two cotyledons)

• Includes the magnolia which lack flagellated gametes ad microphyll leaves but have everything else (cuticle, stomata, sporophyte leaves, megaphyll leaves, xylem/phloem, tracheids, sporophyte dominance, xylem vessels, pollen tube, seed, and flowers)

• Also includes the gladiolus which has the same characteristics

• Both magnolia and gladiolus are angiosperms

Embryophytes

• The true plants

• Bryophytes are non-vascular plants

• Lycophytes and monilophytes are non-seeded vascular plants

• Gymnosperms are naked seeds but vascular plants

• Angiosperms are covered seeds that are flowering vascular

Earth Before Land Plants

• Before 500mya, plants were entirely aquatic and were adapted to this environment

• Water contains dissolved gasses and nutrients that can easily diffuse into cells

• Water has a high heat capacity which helps reduce temperature fluctuations

• Water protects from solar radiation

• Buoyancy helps counteract gravitational forces

• Water can be a medium for gamete transmission

• Plants colonized land around 500 million years ago

• Before this time, Earth’s surface would have been barren, dry, and rocky

• The Earth was warmer than today so UV radiation was intense

Challenges of Living on Land and Adaptations

• Need a system of absorption — roots/rhizoids

• Prevent desiccation — waxy cuticle

• Gas exchange other than diffusion — stomata aka openings in the cuticle

• Gamete transmission that didn’t need water — pollen

• Conduction aka movement of materials — xylem for water and minerals from roots to leaves vs phloem to transport sugars from leaves to roots

• Support since air lacks buoyancy — woody/fibrous structures

Alternation of Generations

• “The oscillation between haploid (gametophyte) and diploid (sporophyte) phases”

• Fertilization and meiosis are the transitions between generations

• Sporophyte is 2n which produces spores whilst gametophyte is n which produces gametes

• All plants do this

• Bryophytes (mosses/liverworts) are gametophyte dominant

• All other land plants clades are sporophyte dominant

Bryophytes

• Gametophyte dominant — sporophyte parasitic

• Often with separate sexes aka are dioecious

• Antheridia produce flagellated sperm while archegonia produce eggs whilst also housing the developing embryos (sporophytes)

• Antheridia and archegonia or modifications thereof are found in all early plant groups through ferns

• Water is required for sperm transfer where sperm are flagellated and swim on a film of water

Tracheophytes

• Named for the vascular tissue cells called tracheids

• Xylem transport water and dissolved minerals which also provides support

• Phloem which transports sugars produces by photosynthesis

• Sporophyte dominant meaning that the gametophytes in vascular plants is much smaller than sporophytes

Lycopodiophyta

• First true stems, roots, and leaves

• Microphylls are simple elaves that only contain a single vein

• Strobilus is a cluster of sporophylls which are specialized leaves bearing sporangia at trips of branches (lycopodium) or along branches (selanginella)

• Free-living gametophyte

Monilophyta

• Horsetails (equistetum): Equisetum is the only living genus, ribbed/jointed stems with silica crystals = “scouring rushes”, non-photosynthetic microphylll, have terminal strobili, and free-living gametophyte

• Whisk ferns: Psilotum, well-developed xylem and phloem in stem, no true roots or leaves - secondarily lost, rhizome (underground stem - absorptive), sporangia fused into synangia and borne on shoots which is a unique character, free-living gametophytes (non-photosynthetic)

• Ferns: Have true roots and stems (underground rhizomes) and leaves (megaphylls called fronds), sporangia are clustered in sori which are protected by indusium, free-living gametophytes

Seed Plants

• A seed is a plant embryo protected by integument (seed coat)

• Two major clades are the gymnosperms (naked seeds aka seeds without protective ovary surrounding) and angiosperms (the covered seeds with hard or fleshy layer developed from the ovary)

• Sporophyte dominant meaning the gametophyte is reduced to a small size

Cycadophyta

• Tropical or subtropical seed plants

• Palm-like with large, pinnate leaves

• Terminal cones (strobili) — plants are dioecious

• Strobili and seeds might take 10 years to mature

• Pollination is by insects, primarily beetles and have flagellated sperm

Ginkophyta

• Only one species living is the ginko biloba (common ornamental and tolerant of pollution)

• Fan-shaped elaves

• Dioecious (plants are male or female) and have foul smelling female seeds so usually male seeds are planted

• Ginkgos are wind pollinated and have flagellated sperm

• Non-flowering seed plants that are gymnosperms

Coniferophyta

• 500-600 of “evergreens” like pines, fires, larches, spruce, etc.

• Tallest = redwood around 372 feet

• Oldest = bristlecone pine around 4,900 years

• Most massive = sequoia around 102.6 feet circumference at the base

• Characteristics are: cuticles, stomata, sporophyte leaves, megaphyll leaves, xylem/phloem, tracheids, sporophyte dominance, pollen tubes, and seeds

Pine Reproduction

• Monoecious meaning both male and female on one plant

• Strobili are cones where staminate cones are male and female cones are ovulate

• Wind-blown pollen enters the ovulate cones where two sperm nuclei in pollen tube but only one is functional and the other degenerates and sperm in pines are not flagellated

Charophyta

• One type is the spirogyra which lacks the following: flagellated sperm, cutcile, stomata, sporophyte leaves, microphyll leaves, megaphyll leaves, xylem/phloem, tracheids, sporophyte dominance, xylem vessels, pollen tubes, seeds, and flowers

• Another type is a chara which lacks everything above except for flagellated gametes which it has

• Freshwater green algae that is terrestrial

• Spirogyra is long and unbranched filaments with cylindrical cells and spiral-shaped chloroplasts

• Chara has a main central axis with nodes from which whorls of smaller branches extend and it anchored by root-like structures called rhizoids

Bryophyta

• A type of non-vascular land plants commonly known as the mosses which along with liverworts and hornworts makes up “bryophytes”

• Small, flowerless plants that absorb water from their leaves due to lack of true roots or complex vascular tissue

• The dominant/visible form i the haploid gametophyte and the spore-bearing structures grow directly out of the gametophyte

• Has these characteristics: flagellated sperm, cuticles, and stomata

• Lacks: sporophyte leaves, microphyll leaves, megaphyll leaves, xylem/phloem, tracheids, sporophyte dominance, xylem vessels, pollen tube, seeds, and flowers

Hepatophyta

• Often called the liverworts

• Non-vascular land plant that has a gametophyte-dominant life cycle where the plant carries only one set of genetic information

• Characteristics include flagellated gametes and cutcicle only

Construct a character matrix

• Across: flagellated sperm, cuticle, stomata, sporophyte leaves, microphyll leves, megaphyll leaves, xylem/phloem, tracheids, sporophyte dominance, xylem vessels, pollen tube, seeds, flower

• Down: spirogyra (charophyta), chara (charophyta), marchantia (hepatophyta), polytrichum (bryophyta), lycopodium (lycopodiophyta), pinus (coniferophyta), magnolia (anthophyta), gladiolus (anthophyta)

When presented with an image of a plant structure, be able to identify the name or function of that structure. Important structures: antheridia, archegonia, gametophyte, sporophyte, gemmae cups, stomata, cuticle, vascular tissue, microphyll, megaphyll, strobilus, sporangia, sori, spore, seed, pollen. Terms related to structures: dioecious, monoecious.

• Antheridia: Male reproductive organ in non-flowering plants that produces and holds sperm cells

• Archegonia: Multi-cellular, flask-shaped female reproductive organs in bryophytes, ferns, and gymnosperms that produce and house the egg

• Gametophyte: Sexual phase in the life cycle of plants and algae that is a multicellular organism that is haploid and response for producing haploid gametes

• Sporophyte: Diploid, spore-producing phase in the life cycle of plants and algae that develops from a fertilized egg and produces haploid spores via meiosis which then grows into the next generation being the gametophyte

• Gemmae cups: Cup-shaped structures on the upper surface of some liverworts and mosses that are used for asexual reproduction

• Stomata: Microscopic pores on the surfaces of plant leaves/stems that act as the breathing system

• Cuticle: Waxy layer that helps prevent desiccation (excessive water loss) and is an armor against environmental factors like heat, UV, pathogens, and pests

• Vascular tissue: Transport system that moves fluids/nutrients/waste and can be either xylem for water/minerals or phloem for sugars/organic products from photosynthesis

• Microphyll: Type of leaf with a single, unbranched vein and lacks a “leaf gap” in the stem

• Megaphyll: A type of plant leaf that features a complex, branching system of veins with a leaf gap (separation of vascular tissue from stem to which it connects)

• Strobilus: Reproductive structure in land plants with sporangia-bearing structures densely aggregated along a central stem aka a cone which is spirally arranged

• Sporangia: Specialized sac/receptable in which reproductive spores are formed and stored

• Sori: A cluster of sporangia on the bottom side of a fern leaf that appear as rows of dots

• Spore: Dust-like particle that is usually single celled that germinates once released and can spread over long distances easily

• Seed: Contains a complete embryonic plant, stored food, and protective outer seed coat which allows it to remain dormant until conditions are perfect for growth

• Pollen: Pollen grains are male reproductive microspores produced by seed plants that carry male genetic material to female structures of plants to facilitate fertilization