Write a note on economic importance of algae and gymnosperms.
Economic importance of algae is as follows:
The group Algae plays both economically beneficial as well as harmful roles.
Beneficial importance :
(i) People of coastal countries have been using sea weeds & certain other algae as source of food, e.g., Porphyra, Ulva, Laminaria, etc.
(ii)Some algae are used as food for marine as well as domestic animals, e.g., Sargassum, Macrocystis.
(iii)Algae are useful source of many commercial products like agar, a jelly like substance (complex polysaccharide) is extracted form species of red algae belonging to the genera Gelidium, Gracilaria etc. Agar is also used as base in culture media. Carrageenin occurs as a cell wall polysaccharide, esterified with sulphate. It is extracted from red alga like Chondrus Crispin, etc. is used in pharmaceutical emulsifier and textile, leather, cosmetic industries. Alginates are salts of alginic acid found in the cell wall of phaeophyceae (brown algae) like Fucus, Laminaria etc.
(iv)Algae are also useful in medicine industry. Antibiotic chlorellin is obtained from Chlorella. Extracts of Cladophora, Lyngbya kill strains of Pseudomonas and Mycobacterium like bacteria. Nitella is used to destroy mosquitoes growth in ponds and hence used in control of malaria.
(v) Some algae are used in agriculture like Nostoc, Anabaena etc. are used to convert atmospheric N2 into nitrogenous compounds which are absorbed by higher plants. Some sea weeds like Fucus, Litlwphyllum, Lycophyllum etc. are rich io K, P, trace elements and growth substances and are used as fertilisers by coastal people.
(vi)Some algae like Chlorella, Chlamydomonas, etc. are used in sewage disposal in ponds. These algae help in bacterial decomposition by providing 02.
(vii)Some algae like Chlorella, Synecoccus, etc are used in space travels. A person inside a spaceship will need a device to get rid of C02 and other body wastes and will require sources of Oz and food. These algae are very useful for this purpose.
(viii)A large amount of iodine (mineral element present in thyroxine hormone of thyroid gland) is extracted from kelps (brown sea weeds or members of phaeophyceae) like Laminaria, Fucus, Ascophyllum etc. Similarly red algae like Rhodomela, Polysiphonia, Rhodymenia are sources of bromine.
Harmful importance:
(i) Some blue green and green algae like Chroococcus, Oscillatoria grow over the surface of water bodies in abundance and cause water bloom. On death and decay these algae give off bad smell. Some algae secrete poisonous or toxic substances.
(ii)Parasitic algae like Cephaleuros virescens causes red rust of tea, coffee etc.
Economic importance of gymnosperms is as follows:
(i)Some species of Cycas like C. revoluta, C. rumphii look like palm tree and are used for decoration purposes as they remain fresh for long period.
(ii)Stem portion of Cycas revoluta is a good source of ‘sago’, a kind of starch used in making bread by poor people. Seeds of some species of Cycas are roasted and taken as food. Young succulent leaves of some species of Cycas are cooked as vegetable.
(iii)Many gymnospersm have medicinal value. The fresh juice extracted from the Cycas circinalis leaves is used as medicine for stomach disorders, blood vomiting and other skin diseases. Pollen grains of some Cycas plants are reported to have some narcotic effect.
(iv)Some gymnosperms like Pinus, Abies, Cedrus are the chief source of various types of woods. The wood of Juniperus is used in making pencils, scales, holders etc.
(v)Some species of Pinus is a good source of turpentine, wood gas, wood alcohol.
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.