ĐỀ THAM KHẢO KÌ THI TUYỂN SINH VÀO LỚP 10 MÔN TIẾNG ANH FORM 50 CÂU TRẮC NGHI...
Phaeophyceae Brown Algae
1.
2. o It contain’s 240 Genera & 1500
Species.
o Golden Brown Xanthophyll
Fucoxanthin (C40H54O6) Pigments.
o It also contains chlorophyll A & C.
o 99.7% marine & few are fresh
water, Pleurocladia &
Lithoderma(Freshwater).
3. o Plant body is multicellular and
highly differentiated both
externally and
internally.Unicellular,colonial
&unbranched filamentous forms
are Completely absent.
oSize ranges from few
cm(Ectocarpus) to
100m(Macrocystis pyrifera) largest
form known as kelps or Rockweed.
4. oRoot-like structure called
a holdfast.
oSmall Stalk , stem like structure
called Stipe.
oflattened structure called the
lamina, blade or frond which
performs photosynthesis.
oSome contain special gas-filled
bladders called pneumatocysts.
5. oThe cell wall is differentiated into
outer and inner layers. The outer
mucilaginous layer has fucinic and
alginic acid, but the inner layer is
mainly cellulosic.
oThe reserve foods are commonly
laminarin and mannitol. Sucrose
and glycerol are also present in
some members.
6. oReproduce by all three means:
vegetative,sexual & asexual.
oFragmentation (Sphacelariales)
oAsexually by motile zoospores(pear
shaped 2 unequal flagella.)
oSexually by motile gametes
(biflagellated with 2 laterally attached
flagella)
oSexual reproduction may be
oogamous, isogamous or anisogamous.
9. Economic Importance
oWidely used as edible sea weeds:
Laminaria, Sargassum.
oAlginic Acid used as thickening agent in
food industry.
o Alginic Acid is also used in batteries, pills
, surgical threads.
oKelps are used for making soap & glass.
oLaminaria used for treating iodine
deficiency.
