Q.7. Write short note on algae habitates. (2008)
Ans. Algae Habitates: -
They occur everywhere from fathomless depth of ocean to the highest peak of the world. Their presence ranges from boiling water of hot springs to be ice cold atmosphere of snow covered mountains.
On the basis of habitate, algae can be classified into the following types -
1. Terrestrial Algae: - Generally algae of various classes, e.g., Nostoc, Chlamydomonas, Fritschiella and Vucheria, grow on moist land.
2. Aquatic Algae: - Generally, algae are found in water which are of the following types :
(i) Fresh water Algae: - Many members of the class Cyanophyceae, Chlorophyceae Charophyceae and Xanthophyceae occur in fresh water few algae e.g., Rivularia, Gleotricha, Chara, etc. Are found in stagnant water of ponds, rivers and streams. On contrast to this, some algae alike Batrachospermum, Cladophora, Hydrodictyon, Volvox etc. occur of running fresh water.
(ii) Marine Algae: - Many algae of Pheophyceae and Rhodophyceae are mostly found in water, e.g., Ectocarpus, Sargassum and Polysiphonia etc.
3. Other Habitates: -
(i) Snow algae: - Some algae grow on snow peaks e.g., Chlamydomonas yellow stonesis.
(ii) Lithophytic algae: - Few algae like Sargassum etc. grow on marine rocks.
(iii) Thermal algae: - Some algae grow on these places having high temperature and are called thermal algae.
(iv) Epiphytic algae: - Few algae like Coleochaeta, Batrachospermum and Chladophora grow on other plants.
(v) Parasitic algae: - Some algae like Cephaleuros grows on tea leaves as parasites.
(vi) Endophytic algae: - Few algae are found in the body of higher plants e.g., Noctoc, Anabaena etc. Some higher algae like Zoochlorella grows on the body of Hydra.
(vii) Symbiotic algae: - Generally, the unicellular algae of classes Chlorophyceae and Cyanophyceae live symbiotically with fungi e.g., Lichens.
Q.8. Explain chromatophores in algae. (2011)
Ans. Chromatophores in algae: -
On the basis of structure and organization chromatophores of prokaryotic and eukaryotic algae are of different types.
1. Chromatophores in prokaryotic algae: - In prokaryotic algae chromatophores are made of photosynthetic lamellae which are developed from cell memberane. Prokaryotic algae chromatophores are not surrounded by any memberane. Besides quantasomes chromatophores of prokaryotic algae consist of Bilisomes also.
2. Chromatophores in Eukaryotic algae: - Chromatophores of a specialized Eukaryotic algae are surrounded by a specialized double memberane. In these chromatophores lamellae are arranged in group of 3 to 5. Whole lamellae consist of pigments, thus they do not consist of grana. Some classes of algae posses pyrenoides and stigma like structure in their chromatophores.
pigment system is different and characteristic of the chromatophores of different classes of algae. Besides this diversities are also found in their number and size.
Class chlorophyceae is divided into several genus and families, on the basis of number of chromatophores and their size. The algae of this class also consist of pyrenoids.
Algae of class Rhodophyceae posses primitive type of chromatophores. Although these are surrounded by double memberane but in them lamellae are separate.
Chromatophores of pheophyceae are surrounded with double unit memberane. Photosynthetic lamellae are found in the group of 3 to 5. Pyrenoids are of naked type.
Q.9. Differentiate between algae and Bryophytes. (2009)
Ans. Difference between algae and Bryophytes: -
