[plants]: ALGAE Flashcards
General description of algae
chlorophyll-bearing simple thalloid autotrophic largely aquatic(both freshwater and marine) organisms
habitats
mainly aquatic
moist stones, soils, wood
in association with fungi(lichens) or animals(eg sloth bear)
example of colonial form
volvox
examples of filamentous forms
ulothrix, spirogyra
example of plant body-like formations
few marine forms like kelps
aspects of reproduction
vegetative, asexual,sexual
vegetative reproduction is by
fragmentation
each fragment develops a
thallus
thallus
a plant body that is not differentiated into stem and leaves and lacks true roots and a vascular system. Thalli are typical of algae, fungi, lichens, and some liverworts.
asexual reproduction is by
formation of different types of spores, the most common being the zoospores
their zoospores are
flagellated(motile) and on germination give rise to new plants
sexual reproduction takes place through
fusion of two gametes
example of same sized flagellated(motile) gametes
ulothrix
example of same sized non-flagellated(non-motile) gametes
spirogyra
isogamy
Isogamy is a form of sexual reproduction that involves gametes of similar morphology.
Because both gametes look alike, they generally cannot be classified as male or female.
anisogamy
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes, which differ in size and/or form. The smaller gamete is male, a sperm cell), whereas the larger gamete is female, typically an egg cell. Anisogamy is common and widespread in multicellular organisms.
example of anisogamous species
eudorina
example of isogamous species
ulothrix, spirogyra
example of oogamous species
volvox, fucus
oogamy
It is a form of anisogamy (heterogamy) in which the female gamete (e.g. egg cell) is significantly larger than the male gamete and is non-motile.
uses of algae
- half of CO₂ fixation on earth by photosynthesis
- increase the level of dissolved oxygen in the atmosphere
- primary producers of energy-rich compounds for aquatic life forms
- 70 marine species are edible like laminaria, sargassum,porphyra
- certain marine red and brown algae produce hydrocolloids like algin(b.a) and carrageen(r.a)
- agar used in jellies and ice cream from Gelidium and Gracilaria
- chlorella, unicell alga, rich in proteins, used as a food supplement
hydrocolloids
water-holding substances
three main classes of algae
Chlorophyceae
Phaeophyceae
Rhodophyceae
the common name of Chlorophyceae
green algae
pigments of grp 1
chlorophyll a,b