Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.
Algae and their spores exhibit enormous diversity and they vary greatly in their level of specialisation. Asexual reproduction by spores and their types are described below.
(i) Zoospores : Certain algae produce motile flagellated asexual spores called zoospores in sac called zoosporangium. Zoospore formation occurs during favourable conditions. During zoospore formation, flagella are withdrawn and organism comes to rest. The protoplasm undergoes repeated divisions and forms 8-16 daughter protoplasts. These daughter individuals called zoospore develop their individual cell wall and flagella, the parent cell wall is lost and new individuals attain independent existence. E.g., Chlamydomonas.
(ii)Aplanospores : These are non-motile asexual spores. They are formed by contraction of protoplasm and formation of new cellulose walls around it. These spores are formed under mildly unfavourable conditions. During favourable conditions, they germinate to form new filaments. E.g., Spirogyra.
(iii)Hypnospores : These are resting spores. These are thick walled aplanospores which develop in adverse conditions. Under favourable growth conditions, the spore can germinate to a new plant, e.g., Vaucheria.
(iv)Autospores : They are non-motile thin walled spores formed by parent cell division. These are similar to mother cell in the morphology and structure. E.g., Chlorella.
(v) Endospores : These are derived either from single cell or by fusion of several cells. After rupture of mother cell,under favourable conditions, endospores can spread, attach to substratum and germinate.
Neurospora—an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora so important as a genetic tool?
Neurospora – an ascomycetes fungus has been used as a biological tool to understand the mechanism of plant genetics much in the same way as Drosophila has been used to study animal genetics. What makes Neurospora so important as a genetic tool?
Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of kingdom Monera as per the "Five Kingdom Classification"even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why?
How is the five-kingdom classification advan-tageous over the two kingdom classification?
The common name of pea is simpler than its botanical (scientific) name Pisum sativum. Why then is the simpler common name not used instead of the complex scientific/ botanical name in biology?
Peat’ is an important source of domestic fuel in several countries. How is ‘peat’ formed in nature?
Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.
Peat' is an important source of domestic fuel in several countries. How is ‘peat' formed in nature?
Biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms. Justify the statement taking any two examples.
What observable features in Trypanosoma would make you classify it under Kingdom Protista?
Algae are known to reproduce asexually by variety of spores under different environmental conditions. Name these spores and the conditions under which they are produced.
Apart from chlorophyll, algae have several other pigments in their chloroplast. What pigments are found in blue-green, red and brown algae that are responsible for their characteristic colours?
Cyanobacteria and heterotrophic bacteria have been clubbed together in Eubacteria of Kingdom Monera as per the “Five Kingdom Classification” even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why?
There is a myth that immediately after heavy rains, in forest, mushrooms appear in large number and make a very large ring or circle, which may be several metres in diameter. These are called as’Fairy rings’. Can you explain this myth of fairy rings in biological terms?
Biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms. Justify the statement taking any two examples.
Apart from chlorophyll, algae have several other pigments in their chloroplast. What pigments are found in blue-green, red and brown algae that are responsible for their characteristic colours?
Make a list of algae and fungi that have commercial value as source of food,
chemicals, medicines and fodder.
There is a myth that immediately after heavy rains in forest, mushrooms appear in large number and make a very large ring or circle, which may be several metres in diameter. These are called as ‘Fairy rings'. Can you explain this myth of fairy rings in biological terms?
At a stage of their cycle, ascomycetes fungi produce the fruiting bodies like apothecium, perithecium or cleistothecium. How are these three types of fruiting bodies different from each other?
Make a list of algae and fungi that have commercial value as source of food, chemicals, medicines and fodder.
What observable features in Trypanosoma would make you classify it under Kingdom Protista?
A virus is considered as a living organism and an obligate parasite when inside a host cell. But virus is not classified along with bacteria or fungi. What are the characters of virus that are similar to non-living objects?
What is the principle underlying the use of cyanobacteria in agricultural fields for crop improvement?
Polluted water bodies have usually very high abundance of plants like Nostoc and Oscillatoria. Give reasons.
Suppose you accidentally find an old preserved permanent slide without a label. In your effort to identify it, you place the slide under microscope and observe the following features:-
(a) Unicellular
(b) Well defined nucleus
(c) Biflagellate – one flagellum lying longitudi-nally and the other transversely.
What would you identify it as? Can you name the kingdom it belongs to?
At a stage of their cycle, ascomycetes fungi produce the fruiting bodies like apothecium, perithecium or deistothecium. How are these three types of fruiting bodies different from each other?