Botany Krosnick Exam 2

Asexual Reproduction

Homosporous

Sexual Reproduction

Heterosporous in seeds in flowering and cone bearing seeds

Meiosis in plants

-In all plants and in may protists, meiosis results in the formation of haploid cells that can divide vegetatively without undergoing fertilization
-These cells are referred to as spores
-In these groups, gametes are produced by mitosis

Meiosis in animals

Diploid → Meiosis → 2 Haploid → Mitosis → 4 Haploid
Results directly in gametes

Mitosis vs Meiosis

Mitosis: one division forming 2 identical cells (clones); Meiosis: two divisions forming 4 genetically different cells

Haploid (1n)

-One copy of each chromosome
-Gametes

Diploid (2n)

-Two copies of each chromosome
-Zygotes

Polyploid

-Having three or more of each type of chromosome
-Triploid (3n)
-Tetraploid (4n)
-Hexaploid (6n)

Alternation of Generations

Life cycle involving sexual reproduction that alternates between diploid sporophyte phase and haploid gametophyte phase

Sporophyte

Diploid, or spore-producing, phase of an organism

Gametophyte

Haploid, or gamete-producing, phase of an organism

Haplobiontic

Life history where only one stage (haploid or diploid) is dominant, and multicellular

H, h

Starts with a 2n zygote, spends multicellular generation as haploid

H, d

Starts with a 2n zygote, goes through mitosis and spends multicellular generation as diploid

Diplobiontic

Life cycle with both haploid and diploid multicellular generation (alternation of generation, D, h + d)

Cyanobacteria

Photosynthetic, oxygen-producing bacteria (formerly known as blue-green algae).

Cyanobacteria vs chloroplasts

chlorophyll is stored in thylakoids in their cytoplasm

Cyanobacteria vs green algae

green algae are a eukaryotic organism having a nucleus and membrane-bound organelles while cyanobacteria are prokaryotes having no nucleus and membrane-bound organelles

Cyanobacteria vs blue-green algae

Bacteria that can photosynthesize, but do not have bound membranes or nuclei

Isogamous gametes

both sperm and eggs are motile and equal in size

Anisogamous gametes

sperm and egg differ in size

Oogamous gametes

One is a large, non-motile egg and the sperm is small and motile

Gametangia

A reproductive organ that houses and protects the gametes of a plant

Antheridium

Male reproductive structure in some algae and plants

Sporangium

spore capsule in which haploid spores are produced by meiosis

Viridiplantae

Kingdom ____________would include green algae and land plants.

Chlorophyta

phylum of green algae

Streptophyta

green algae clade that gave rise to land plants; charophytes and liverworts

Charophyte

A member of the green algal group that are considered the closest relatives of land plants.
chlorophyll a and b, store carbohydrates as starch, have cell walls consisting of cellulose, and undergo similar cell-division processes.
life cycles are usually characterized as haploid with zygotic meiosis

Coleochaete

Disk-shaped (with hairs) member of the Charophyta whose cells produce a phragmoplast during cell division

Green algal ancestry

Filamentous cells developed 2D and 3D growth, creating parenchyma, eggs become large, became archegoniate (egg chamber).

Water-To-Land difficulties

-Drying out
-Ultraviolet rays
-Temperature variation
-Obtaining nutrients
-Gravity

Byrophytes

Nonvascular plants - examples are liverworms, hornworts, and mosses.

Byrophyte characteristics

-No vascular tissue
-Grow in damp and frozen/hot climates
-Rhizoids, not roots!
-Diplobiontic life cycle/ dominant haploid (gametophyte) generation

Compared to green algae?

-Oogamous reproduction only
-Archegonium
-Embryo from zygote
-Sporophytes are differentiates
-Heteromorphic alternation of generation

Bryophyte examples

mosses, liverworts, hornworts

byrophyte structure

Archegonia

Female reproductive part of a nonvascular plant

Antheridia

Structures in nonvascular plants that produce male gametes

Protonema

A mass of green, branched, one-cell-thick filaments produced by germinating moss spores.

Peristomal teeth

Opens when air is dry enough to release pores

Microphylls

leaves with a single vein

Sporophyte

Diploid, or spore-producing, phase of an organism

gametophyte

Haploid, or gamete-producing, phase of an organism

Bryophyta

-True mosses
-Have protonema
-Haploid, dominant gametophyte generation
-Budding sometimes
-Paraphyses collect water
-Several chloroplast per cell

Hepatophyta

-Liverworts
-Leafy (dichotomous branching)
-Pores for gas exchange, static unlike stomata
-Thallose (no stem/leaf distinction, elevated gametophytes, chimney cells)
-Sperm use raindrops

Anthocerophyta

-Hornworts
-Thalloid gametophyte
-Cyanobacteria present (nitrogen fixation)
-Stomata on sporophyte
-Gametophytes are within small cavities

hydroids and leptoids

-Inside vs outside
-H for water (X)
-L for nutrients (P)

Fern allies

Lycophyta, Sphenophyta, and Psilophyta

Fern ally characteristics

-Seedless
-Vascular
-Shed spores to initiate alternation of generation
-Xylem and Phloem
-Sporophyte dominate multicellular stage

Pteridopsida

-True ferns
-Sporangia arise from single epidermal cell

Sorus

cluster of sporangia on the underside of a fern frond

Annulus

-Curved sporangium covering that ejects spores when walls break

Sporocytes

-Undergo meiosis and produces spores that are released in the spring

Prothallus

-Heart-shaped gametophyte form of a fern that can make its own food and absorb water and nutrients from the soil
-Produces archegonia and antheridia

Antheridum in ferns

-Along root like rhizoids
-Circular
-Produces sperm

Archegonium in ferns

-Short neck
-Single egg close to notch of prothallus

Fern life cycle

1). Zygote develops into leafy fern plant. 2) the sporophyte. 3) Spores are released from spore cases and grow into tiny, heart-shaped gametophytes. Each gametophyte has both male and female structures. 4) Sperm swim to another gametophyte to fertilize eggs.

Enations

Tiny, green, superficially leaflike, veinless, photosynthetic flaps of tissue

Microphylls in ferns

Homospory vs. Heterospory

Exospory vs Endospory

-spore germinates and grows as an external gametophyte; ancestral condition
-Inside!

Strobilli

cone-like structures formed from groups of sporophylls

rhizoids

A thin, rootlike structure that anchors a moss and absorbs water and nutrients.

Rhyniophytes

A group of early vascular plants that appeared in the Silurian and became extinct in the Devonian. Possessed dichotomously branching stems with terminal sporangia but no true leaves or roots.

Ferns need water

-Spores do not have moisture storage, so humid environments are required

Bryophytes water needs

-Have swimming sperm, needs water to reach egg

Node

Place where leaves, branch, and stems originate

Internode

A segment of a plant stem between the points where leaves are attached.

petiole

the stalk of a leaf

blade

Broad, flat portion of a leaf.

phyllotaxy vennation

Spiraling from a center axis or stem

what the difference between edicot and monocot stems

Monocot leaves are narrow, slender, and longer than dicot leaves. Dicot leaves are broad and relatively smaller than monocot leaves.

asexual reproduction

produces plants that are genetically identical to the parent plant because no mixing of male and female gametes

sexual reproduction

through pollination when a male and female (two parent plants) come together to make a new plant containing both DNAs

What is the end result of meiosis in plants vs. animals?

Meiosis in animals produce the gametes (sperms and eggs), whereas meiosis in plants produce spores

What is the purpose of meiosis?

Meiosis is the process of chromosomal reduction in eukaryotic cells, which leads to the production gametes needed for sexual reproduction.

how does mitosis differ from meiosis

Mitosis results in two identical daughter cells, whereas meiosis results in four sex cells

What is alternation of generations?

the regular alternation between two distinct forms. The generations are alternately sexual and asexual

What is the significance of the cyanobacteria for land plants?

They are able to carry out nitrogen fixation.

what features do cyanobacteria share with chloroplasts

hey both have cell membranes constructed from a phospholipid bilayer and both have a cell wall

How are cyanobacteria similar to green algea

they occur in terrestrial and aquatic habitats. and evolved from algae and can be photosynthetic

How do cyanibacteria and green agea differ

cyanibacteria can produce and use their own food through sunlight where as green algea provide for zooplankton

Why should we not call cyanobacteria "blue-green algae"

blue-green algae aren't quite plants or algae

Haplobiontic versus diplobiontic life cycles

diplohaplontic is describing a life cycle that has alternating haploid and diploid phases while haplodiplontic is having multicellular diploid and haploid stages.

Isogamous

Similar

anisogamous

fusion of two gametes that differ in size and/or form.

oogamous gametes

Large female gamete is immobile while the small male gamete is mobile

what are the closest relative to land plants

Green-algea

Viridiplantae

Made up of green algea/ where land plants originated

Chlorophyta?

green algea that survive in extreme enviroments

Streptophyta?

aquatic green algea that live in

What are the characteristics of the charophytes that make them a good potential precursor to land plants?

have chlorophyll a and b, store carbohydrates as starch, have cell walls consisting of cellulose, and undergo similar cell-division processes.

What type of life cycle do charophytes display?

a haplontic life cycle where the only diploid cell is the zygote that then undergoes meiosis to produce haploid spores

Is Charophytes life cycle similar or different from land plants?

they are different as they dont undergo alternation of gennerations

gametophyte

gamete-producing and usually haploid phase, producing the zygote from which the sporophyte arises

sporophyte

asexual and usually diploid phase, producing spores from which the gametophyte arises

List several characteristics of the bryophytes.

Vascular tissues are absent, sexual reproduction is oogamete type, they have a heteromorphic or heterologous alternation of generations, Bottom half is haploid and upper half is diploid.

How are Bryophytes similar to the green algae, and how are they different?

Both algae and bryophytes lack a vascular system. The main difference between algae and bryophytes is the division of the plant body

Which organisms are classified within the Bryophytes?

liverworts, hornworts and mosses