THE GREEN ALGAE Flashcards
green algae
Supergroup
Clade
Division
(Supergroup Archaeplastida, Clade Chlorophyta, Division Chlorophyta
are considered most
advanced among algae and most closely related to land plants.
green algae
Asexual reproduction may be by
fission (splitting), fragmentation or by formation of zoospores (motile spores).
Sexual reproduction is very common and may be (3)
isogamous
anisogamous
oogamous
gametes both motile and same size
isogamous
both motile and different sizes - female bigger
anisogamous
female non-motile and egg-like; male motile
oogamous
some green algae may have an alternation of haploid and diploid phases.
true
haploid phases form gametangia
diploid phases form zoospores by reduction division
true
green algae can grow even in snow and produce blooms known as the
watermelon snow
8,000 species of green algae, of which only about 1000 species are in marine waters, the rest in freshwater habitats.
true
is a unicellular motile green alga that inhabit freshwater habitats.
Reproduction in this organism is done both sexually and asexually.
Chlamydomonas
Chlamydomonas has the following
major parts:
cellulosic cell wall, the central nucleus, one cup-shaped chloroplast, the eyespot, the pyrenoid
(starch body in the lower part of the chloroplast), contractile vacuole, mitochondria and two anterior flagella.
Chlamydomonas Asexual reproduction is through production of ________ that develop into gametes in response to adverse environmental conditions.
biflagellated zoospores
represents the peak of evolutionary development of the colonial motile type of green algae.
The coordinated movement of the
flagella of all cells allows the entire colony to behave like one individual organism, moving forward as it also spins in a vertical axis. The colony varies from spherical to ovoid. A gelatinous envelope holds all cells together.
Volvox
The number of cells in the colonies of various species of _______ ranges from 500 to 50,000.
Volvox
shows some specialization and division of labor among the cells.
Volvox
__________cells occur at the base or hind end of the colony while the forward or leading end has only _________cells.
Reproductive cells
vegetative cells
in the vegetative cells are
larger than those of the reproductive cells.
Eyespots
Sexual reproduction in volvox
oogamous
Male gametes are formed in large
numbers by multiple subdivisions of the protoplasts of certain adult vegetative cells. These cells are the
antheridia
Only one or a very few of them are formed within any one parent volvox
cell.
female gamete, the egg
which result from either sexual or asexual reproduction are usually seen floating in the center of the larger parent colony. volvox
Small daughter colonies
daughter colonies of volvox are called
gonidia
each cell of the volvox colony is Chlamydomonas-like.
true
volvox
When the parent colony disintegrates, the _________ are released and become mature colonies.
daughter colonies (gonidia)
filamentous green alga named for the helical or spiral arrangement of the chloroplasts.
Spirogyra
Cells of Spirogyraa contain one to several spiral, ribbon-like and parietal ______, containing row of conspicuous
_____________
chloroplasts
pyrenoids
Spirogyra Reproduction is by conjugation between two adjoined filaments called
scalariform or ladder-like conjugation
Spirogyra Reproduction is by conjugation between cells of the same filament
lateral or side conjugation
2 Spirogyra Reproduction
lateral or side conjugation
scalariform or ladder-like conjugation
explain conjugation
The contents of one cell flow or are squeezed through connective tube to unite with the contents of the other cell. The resulting zygote forms a thick walled, sometimes much decorated, zygospore, which lies dormant before it generates into a
new filament.
simple, unbranched filamentous green alga that reproduces by oogamy.
Cells in the filament are
mostly elongated. The chloroplast is reticulate, that is, in a delicate meshwork. Pyrenoids are located at the intersections of the reticulum. You can see the scattered dark bodies in the cell. The nucleus is usually centrally placed. A holdfast is present in some species.
Oedogonium
among the elongated vegetative
cells in the filament are groups of smaller disc-like cells. Each of the short disc-like cells is an
antheridium
Each antheridium form two protoplasts. After release, these protoplasts become _____
sperm
They are small, ovoid cells with a ring of flagella at one end. antheridium
sperm
is a single cell whose entire protoplast has become a large, globose opaque egg. It has a fertilization pore through which a sperm cell can enter to fertilize the egg. Oedogonium
oogonium
After fertilization, the zygote remains within the oogonium. It develops a thick wall, goes dormant and is known as an____. Oedogonium
oospore
As the filament decays, the oospore
is released but remains dormant for several months. Oedogonium
true
Later the oospore divides by meiosis to ___________. These have a ring of flagella at one end. They resemble sperm but are larger cells. They swim about and later each grows into new filaments. Oedogonium
four haploid zoospores
unicellular or filamentous green algae whose cells are divided into two symmetrical portions (semi
cells)
the content only of the cells is symmetrically divided and there
is no median constriction. The wall is complex in its ornamentations, spines, granules and other decorations. There
may be mucilage pores in the wall and the cells are often enclosed in a wide sheath of mucilage.
Desmids
Desmidsusually with a conspicuous constriction at the mid-region, The wall is in two sections that meet
and slightly overlap at the
isthmus
common representative of desmids
Cosmarium and Closterium
a charophyte, represents the most advanced group of green algae.
has a stem-like body divided into
nodes and internodes, with whorls of branches arising at internodes
body is several cells thick, composed of true parenchyma tissue derived from cell division of the apical meristem.
Chara
Although chara features seem to
correspond to those of flowering plants, virtually all of the resemblance is spurious, because the earliest vascular land plants had no nodes, internodes or branches. The ultrastructural and morphological data suggest that the Charophytes are a paraphyletic assemblage.
true
The egg and sperm cells in chara are protected by a
sterile jacket of cells.
in chara, the egg is formed within a structure called ________, the sperms in the _______.
nucule
globule
macroscopic specimens of green algae
Acetabularia, Caulerpa spp, Halimeda spp, Enteromorpha, Ulva
