Theme 2C: Plant Classification

What are the defining characteristics of land plants?

Eukaryotes, photoautotrophic, multicelular, sessile, cell walls, alternation of generations, embryo retained on gametophyte tissue

What features do all cell walls share?

Primary cell wall surrounding plasma membrane, and cell contents, cellulose fibers, rigid but flexible

Which parts of a plant have secondary cell walls?

Xylem and schlerenchyma

What provides the cell rigidity?

Turgor pressure

What provides turgor pressure

Central vacuole

which state are plant cells usually in? How/why?

turgid state, the central vacuole

why don't plant cells burst when submerged in water?

the primary cell membrane neutralizes the pressure of water

what will plant cells do in hypertonic situations?

be plasmolyzed (shrink)

what will plant cells do in isotonic situations?

be flaccid

what will plant cells do in hypotonic situations?

be turgid

explain the alternation of generations of life cycle?

plants alternate between haploid and diploid

which phase, haploid or diploid, is the gametophyte stage? which is the sporophyte stage?

gametophyte=haploid, sporophyte=diploid

explain embryo retention?

after fertilization, the embryo is retained on the female gametophyte

what does a sporophyte produce? what does a gametophyte produce?

spores. gametes

which process do sporophytes use to form spores? why?

meiosis. do get from diploid to haploid

which process do gametophytes use to form gametes? why?

mitosis, because they are already haploid

which form are spores, are they uni or multicellular, what do they turn into and how?

haploid, unicellular, gametophyte through germination

how are land plants classified?

by vasculature and seeds

what do vascular bundles consist of?

xylem, phloem, parenchyma cells and fiber cells

what is lignin and where is it?

a strong polymer, hydrophobic and aromatic, linked with cell wall polysaccharides. inside the secondary cell wall

what are fiber cells?

sclerenchyma that provide rigid support to the xylem and phloem

what are xylem? are they alive or dead at maturity? do they have secondary cell wall? what does that mean? can they move things both or one direction? are they inner or outer circle?

water conducting cells. dead. yes, meaning rigid. one direction. inner.

what are phloem? are they alive or dead at maturity? do they have secondary cell wall? what does that mean? can they move things both or one direction? Are they inner or outer circle?

sugar transporting cells. alive. no, meaning not rigid. both directions. outer

what is the cotyledon? what does it do?

embryonic leaf, stores energy for plant to use when germinating, part of seed classification

what are the 5 extant diversity groups?

bryophytes, pterophyte and lycophytes, gymnosperms and angiosperms

what are the 3 main groups in classification of land plants?

nonvascular plants, vascular seedless plants, vascular seed plants

what is haploid/diploid proportion for nonvascular plants? Example?

dominant haploid generation, small diploid organism. bryophytes

what is haploid/diploid proportion for vascular seedless plants? Example?

dominant diploid generation, small haploid organism. lycophytes and pterophytes

what is haploid/diploid proportion for vascular seed plants? Example?

diploid generation is dominant, very small haploid organism. gymnosperm and angiosperm

what is an observation looking at comparing the 3 groups of land plants?

as plants evolved to have seeds and vasculature, they evolved to spend more time as diploid, and grew larger

what is an important note when comparing haploid vs diploid?

there is no fitness advantage between the two, but if a haploid gets a deleterious mutation it might die, whereas a diploid would survive

what is an important note regarding mutations in haploids and diploid? what is the term associated with this?

diploids can acquire more mutations because they are usually non-lethal, unlike mutations for haploids. genetic load

what are bryophytes?

mosses, nonvascular, poikilohydric, dominant haploid phase,

what is poikilohydric?

lack of ability to control/maintain internal water content

what are the gametophytes in bryophytes? subgroups? Which produce eggs and which produce sperm?

gametangia: antheridia: sperm and archegonia: eggs

what are rhizoids?

root-like anchoring structures

what is filamentous protonema? what happens with this?

spores can't directly turn into gametohpytes, so they germinate and produce this, then they produce buds and turn into gametophytes

what are important details about the bryophyte life cycle?

require water, gametophyte is dominant phase, flagellated sperm, sporophyte retained on gametophyte (embryo protection), protonema produces multiple buds and many gametophytes

what are biggest disadvantages for bryophytes?

staying longer in haploid phase, need water for almost all life cycle

what new part did seedless vascular plants evolve?

microphylls and megaphylls

what are microphylls? which group are they in?

offshoot of main vertical stem, basically leaves. only in lycophytes

what are megaphylls? what is an advantage?

broader leaf with multiple veins, more surface area for photosynthesis

what is summary of seedless vascular plants?

have cone or strobilus where spores are produced, microand megaphylls

what are pterophytes? summary?

have vasculature roots and can survive without continuous moisture. Ferns, have finely divided fronds, sporangia often in sori, still have antheridia and archegonia

what produces spores in bryophytes? pterophytes?

gametangia, sori

where do antheridia and archegonia develop in pterophytes?

underside of gametophytes

compare bryophyte and pterophyte?

bryo: no vasculature, small, no roots or veins. ptero: vasculature, large, roots, megaphyll

what is info about the antheridia and archegonia important slide?

once egg cells formed on bisexual, a hormone is released called antheridiogen to shut down notch and egg formation in neighbouring plants to maximize fertilization from the non-egg producing plants

what is the main classification difference between gymnosperms and angiosperms?

gymno=naked seeds, angio=covered seeds

compare sporophyte and gametophyte phase in gymnosperms? which is dominant? what is gametophyte in gymnosperms?

dominant phase is sporophyte and very large, gametophyte phase is very small (pollen)

what are details about vascular seed plants? most important?

spores protected with resistant coat, spores not released to produce gametophyte, pollen tube, no flagella in sperms, no need for external water

why was evolution of pollen so important?

allowed non-water related reproduction

which thing sporophyte or gametophyte produces female gametophyte?

sporophyte

what becomes the seed?

fertilized ovule

what is released, spores or gametophytes? what is it?

gametophytes. pollen

how many megaspores survive?

1 of 4

what is important about the fertilization of gymnosperms?

each fertilization event creates 4 embryos that compete with each other, one will dominate and survive.

at seed maturity how many embryos are inside the seed

1

what happens at seed maturity?

seed goes through desiccation process, it's dormant, dry but still alive to protect it until it gets to soil and water

what do both seeds and pollen have in gymnosperms?

wings to flow in the wind

what are major gymnosperm reproductive adaptations?

spores that produce gametophytes are not shed anymore, ovule becomes seed, 1/4 megaspores survive, 2-4 archegonia, 4 embryo per archegonia

summarize gymnosperm seed diagram

seed coat(maternal)=2n, embryo sporophyte(one from each parent)=2n, nutritive tissue(maternal)=n

what are some angiosperm adaptations

efficient transport of water and nutrients, double fertilization, ovary protects ovule

explain double fertlization?

found a way to use second unused sperm cell (endosperm)

summarize angiosperms

flowering plants with covered seeds, ovaries protect ovules and seeds, fruit structure nourishes and disperses seeds, seeds acquire dormancy as they mature

why are pollen tubes so important?

they are very efficient, they place plugs while growing so only the front part is functional, second sperm cell forms primary endosperm cell

what is suspensor?

placenta of plants, supports nutrition to the embryo

what is main difference between monocots and eudicots?

mono: parallel veins, eudi: reticulate veins

what is the ploidy of the products of double fertilization

haploid egg+haploid sperm=diploid embryo. diploid central cell+haploid sperm=triploid endosperm

summarize the red vs far red experiment/info

in the forest canopy, lots of plants at the bottom don't receive a lot of light because the plants above them absorb all the light, they wait until just the right amount of light to germinate

what is phytochrome? what things does it have (2)? which are they? How does it work?

pigment like chlorophyll with an active and inactive form: Pfr and Pr. When enough red light hits the pigment it activates (Pfr) and the seed germinates. If far-red light hits it, it quickly reverts back to Pr