In Ulothrix meiosis takes place in
cells of the filament
holdfast
zygote
zoospores.
C.
zygote
In Ulothrix sexual reproduction is of isogamous type. Two isogametes of + and - strain come together and fuse as a result a quadriflagellate zygospore is formed which floats on water after sometime it rests on the bottom of the pond at this time its four flagella disintegrate and a wall is formed surrounding it from all sides. After taking rest for a long period this zygote divides meiotically and gives rise to 16 zoospores. These zoospores come out of sac and give rise to the new plants of Ulothrix.
Mossess and ferns are found in moist and shady places because both
require presence of water for fertilization
do not need sunlight for photosynthesis
depend for their nutrition on microorganisms which can survive only at low temperature
cannot compete with sun-loving plants.
People recovering from long illness are often advised to include the alga Spirulina in their diet because it
makes the food easy to digest
is rich in proteins
has antibiotic properties
restores the intestinal microtlora
Azolla is used as a biofertilizer because it
multiplies very fast to produce massive biomass
has association of nitrogen - fixing Rhizobium
has association of nitrogen - fixing cyanobacteria
has association of mycorrhiza
In oogamy, fertilization involves :
a small non- motile female gamete and a large motile male gamete
a large motile female gamete and a small non-motile male gamete
a large non- motile female gamete and a small motile male gamete
a large non-motile female gamete and a small non-motile male gamete
In angiosperms, triple fusion results in the formation of:
zygotic nucleus
polar nucleus
secondary nucleus
primary endosperm nucleus
Read the following statements (IV) and answer the question which follows them
I. In liverworts, mosses and ferns gametophytes are free living.
II. Gymnosperms and some ferns are heterospores.
III. Sexual reproduction in Fucus, Volvox and Albugo is oogamous.
IV. The sporophyte in liverworts is more elaborate than that in mosses.
How many of the above statements are correct?
One
Two
Three
Four
The most common type of ovule found in angiosperms is
Anatropous ovule
Atropous ovule
Campylotropous ovule
Hemitropous ovule