Explain briefly thefollowing terms with suitable examples.
(i) Protonema (ii) Antheridium
(iii)Archegonium (iv) Diplontic (v) Sporophyll (vi) Isogamy
(i) Protonema : It is the first, usually branched, green and filamentous structure produced by a germinating moss or fern spore. The protonema of mosses bears buds that develop into the gametophyte plant. In fern the protonema becomes the prothallus.
(ii)Antheridium : The male sex organ of cryptogams (algae, fungi, bryophytes and
pteridophytes) is known as antheridium. It produces the male gametes or anthero- zoids. It may consist of a single cell or it may have a wall that is made up of one or several layers forming a sterile jacket around the developing gametes.
(iii)Archegonium : The multicellular flask shaped female sex organ of bryophytes, pteridophytes and many gymnosperms is known as archegonium. Its dialated base called the venter contains the female gamete or egg or oosphere. The cells of the narrow neck of archegonium liquify to allow the male gametes to swim towards the oosphere.
(iv)Diplontic : It is the kind of life cycle in which the diploid sporophyte is dominant and this diploid phase is photosynthetic. The gametophytic phase is represented either by gametes only, that are formed through meiosis or by a highly reduced few celled gametophyte. E.g., all seed-bearing plants (gymnosperms and angiosperms).
(v) Sporophyll : It is a type of leaf bearing sporangia. In ferns, the sporophylls are the normal foliage leaves, but in other plants the sporophylls are modified and arise in specialised structure such as the strobili of club-moss, gymnosperms and the flower of angiosperms. In most plants sporophylls are of two types – microsporophylls and megasporophylls.
(vi)Isogamy: It is a type of sexual reproduction where fusion takes place between two identical gametes. The gametes are similar in size and structure and they show equal motility during sexual reproduction, e.g., Spirogyra (algae).
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.
Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.
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?
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.