Gametophyte is a dominant phase in the life cycle of a bryophyte. Explain.
Bryophytes are a group of the simplest and primitive plants belonging to embryophyta gametophytic and sporophytic phases are present in the life cycle of bryophytes and both these phases are morphologically distinct (heteromorphic). Gametophytic phase in bryophytes is more conspicuous, long lived, independent, green and freely branched whereas, the sporophytic phase is short lived and dependent upon the gametophyte. The main plant body of the bryophyte is haploid and bears sex organs i.e., antheridium and archegonium.
Antheridium produces a number of flagellate male gametes called sperms or antherozoids and archegonium is flask shaped with tubular neck and swollen venter. The gametophytic plant body of bryophytes is thalloid in liverworts whereas foliose in mosses. In liverworts, the thallus is differentiated into a dorsal photosynthetic and ventral storage region. Sex organs antheridia and archegonia are either distributed on the dorsal surface of the thallus or are on distinct receptacles. In mosses, the gametophyte has two growth stages (i) Protonema stage- It is the juvenile stage represented by prostrate, creeping, green and branched filamentous structure; it develops from the spore and is only a transitory vegetative stage and (ii) leafy stage or gametophore – an erect cylindrical shoot with persistent leaves and sex organs.
Most algal genera show haplontic life style. Name an alga which is
a. Haplo-diplontic
b. Diplontic
Give an example of plants with
a. Haplontic life cycle
b. Diplontic life cycle
c. Haplo-diplontic life cycle
Food is stored as Floridean starch in Rhodophyceae. Mannitol is the reserve food material of which group of algae?
In which plant will you look for mycorrhiza and corolloid roots? Also explain w’hat these terms mean.
Heterospory, i.e. formation of two types of spores—microspores and megaspores is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in plant kingdom?
How arc the male and female gametophytes of pteridophytes and gymnosperms different from each other?
How far does Selaginella one of the few living members of lycopodiales (pteridophytes) fall short of seed habit?
Mention the ploidyof the following rprotonemal cell of a moss; primary endosperm nucleus in dicot, leaf cell of a moss; prothallus cell of a fern; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern.
The plant body in higher plants is well differentiated and well developed. Roots are the organs used for the purpose of absorption. What is the equivalent of roots in the less developed lower plants?
The plant body in higher plants is well differentiated and well developed. Roots are the organs used for the purpose of absorption. What is the equivalent of roots in the less developed lower plants?
Explain briefly thefollowing terms with suitable examples.
(i) Protonema (ii) Antheridium
(iii)Archegonium (iv) Diplontic (v) Sporophyll (vi) Isogamy
Draw labelled diagrams of
a. Female and male thallus of a liverwort.
b. Gametophyte and sporophyte of Funaria.
c. Alternation of generation in Angiosperm.
Explain why sexual reproduction in angiosperms is said to take place through double fertilization and triple fusion. Also draw a labelled diagram of embryo sac to explain the phenomena.
Lichen is usually cited as an example of‘symbiosis' in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
a. Both will survive and grow normally and independent from each other.
b. Both will die.
c. Algal component will survive while the fungal component will die.
d. Fungal component will survive while algal partner will die.
Based on your answer how do you justify this association as symbiosis.
The heterosporous pteridophytes show certain characteristics, which are precursor to the seed habit in gymnosperms. Explain.
Lichen is usually cited as an example of ‘symbiosis’ in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
(a).Both will survive and grow normally and independent from each other.
(b).Both will die
(c).Algal component will survive while the fungal component will die.
(d).Fungal component will survive while algal partner will die.
When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?
The male and female reproductive organs of several pteridophytes and gymnosperms are comparable to floral structures of angiosperms. Make an attempt to compare the various reproductive parts of pteridophytes and gymnosperms with reproductive structures of angiosperms
How are the male and female gametophytes of pteridophytes and gymnosperms different from each other?
The heterosporous pteridophytes show certain characteristics, which are precursor to the seed habit in gymnosperms. Explain.
Heterospory i.e., formation of two types of spores – microspores and megaspores is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in Plant Kingdom?
Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
Explain why sexual reproduction in angiosperms is said to take place through double fertilisation and triple fusion. Also draw a labelled diagram of embryo sac to explain the phenomena.
Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called as the ‘relic of past'. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?
Most algal genera show haplontic life style. Name an alga which is
(a) Haplo-diplontic (b) Diplontic
Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms is called as the ‘relic of past’. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?
Match the following (Column I with Column II).
Column I Column II
(a)Chlamydomonas (i)Moss
(b)Cycas (ii)Pteridophyte
(c) Selagmella (iii)Algae
(d) Sphagnum (iv)Gymnosperm
With the help of a schematic diagram describe the haplo-diplontic life cycle pattern of a plant group.
How far does Selaginella one of the few living members of Lycopodiales (Pteridophytes) fall short of seed habit.
Food is stored as floridean starch in Rhodophyceae. Mannitol is the reserve food material of which group of algae?
Give an example of plants with
(a) Haplontic life cycle
(b) Diplontic life cycle
(c) Haplo-diplontic life cycle
In which plant will you look for mycorrhiza and corolloid roots? Also explain what these terms mean.
The male and female reproductive organs of several pteridophytes and gymnosperms are comparable to floral structures of angiosperms. Make an attempt to compare the various reproductive parts of pteridophytes and gymnosperms with reproductive structures of angiosperms.
With the help of a schematic diagram, describe the haplo–diptontic life cycle pattern of a plant group.
Differentiate between the following:
(i) Red algae and brown algae
(ii)Homosporous and heterosporous pteridophytes
(iii)Liverworts and moss
(iv)Syngamy and triple fusion.
Draw labelled diagrams of
(a) Female and male thallus of a liverwort.
(b) Gametophyte and sporophyte of Funaria.
(c) Alternation of generation in Angiosperm.