<\/span><\/h3>\n(a) heterotrophic bacteria<\/strong><\/p>\n(b) archaebacteria<\/strong><\/p>\na) Heterotrophic bacteria are used in the production of vitamins, antibiotics, cheese and curd.<\/p>\n
They help fix nitrogen and are used in the formation of humus.<\/p>\n
b) Archaebacteria are used in Biogas production.<\/p>\n
They are used in the bioleaching of mines.<\/p>\n
<\/span>3. What is the nature of cell walls in diatoms?<\/strong><\/span><\/h3>\nIn diatoms, cell walls are embedded with silica imparting characteristic patterns onto the walls, and are indestructible. These diatoms leave large amounts of cell wall deposits in their habitat to accumulate to form the diatomaceous earth.<\/p>\n
<\/span>4. Find out what the terms \u2018algal bloom\u2019 and \u2018red tides\u2019 signify.<\/strong><\/span><\/h3>\nAlgal blooms are found in contaminated water. They are an overgrowth of algae, especially blue-green algae (cyanobacteria). Their growth leads to water pollution. They inhale carbon dioxide and exhale oxygen.<\/p>\n
Rapid multiplication of red-pigmented dinoflagellates, such as Gonaulax<\/em>, gives the sea a red color, a phenomenon known as red tides. These algae produce toxins that kill fish and other aquatic organisms.<\/p>\n<\/span>5. How are viroids different from viruses?<\/strong><\/span><\/h3>\n(i) Viroids are small infectious agents with single-stranded RNA without a protein coat, but viruses have single-stranded or double-stranded RNA bound with protein coat.<\/p>\n
(ii) Viroids are very small in size compared to viruses.<\/p>\n
(iii) Viroids infect only plants, while viruses infect plants, animals, and microorganisms.<\/p>\n
<\/span>6. Describe briefly the four major groups of Protozoa.<\/strong><\/span><\/h3>\nFour major groups of Protozoa are as follows<\/strong><\/p>\nAmoeboid protozoans:<\/strong> Found in aquatic environments; they move and catch their prey using pseudopodia.<\/p>\nFlagellated protozoans:<\/strong> These protozoans are free-living or parasitic. Their locomotory structure is flagella.<\/p>\nCiliated protozoans:<\/strong> They live in aquatic environments and the presence of cilia makes them actively moving.<\/p>\nSporozoans:<\/strong> They contain a wide variety of organisms, producing infectious spores throughout their life cycle. Their spore-like phase helps them move from one host to another.<\/p>\n<\/span>7. Plants are autotrophic. Can you think of some plants that are partially heterotrophic?<\/strong><\/span><\/h3>\nInsectivores and carnivorous plants are partially heterotrophic, these organisms are green and autotrophic, but they prey on and digest small components for their nitrogen supply.<\/p>\n
Ex; Utricularia, Drosera, Nepenthes.<\/em><\/p>\n<\/span>8. What do the terms phycobiont and mycobiont signify?<\/strong><\/span><\/h3>\nLichens are a symbiotic association of fungi and algae. Phycobiont is part of algae and part of mycobiont fungi. Mycobiont provides structural cover that protects the algae from unfavorable conditions. Similarly, phycobionts prepare food by the process of photosynthesis, which is used by both organisms.<\/p>\n
<\/span>9. Give a comparative account of the classes of Kingdom Fungi under the following:<\/strong><\/span><\/h3>\n(i) Mode of nutrition (ii) Mode of reproduction<\/strong><\/p>\n\n
\n\n\n| <\/td>\n | Phycomycetes<\/td>\n | Ascomycetes<\/td>\n | Basidiomycetes<\/td>\n | Deuteromycetes<\/td>\n<\/tr>\n |
\n| Mode of nutrition<\/td>\n | Saprophytic or parasitic<\/td>\n | Decomposers, Saprophytic or parasitic or coprophilous<\/td>\n | Saprophytic<\/td>\n | Decomposers, Saprophytic or parasitic<\/td>\n<\/tr>\n |
\n| Mode of reproduction<\/td>\n | Asexual reproduction by zoospore (motile) and Aplanospore (non-motile)\n Sexual reproduction \u2013 zygote can be similar or dissimilar in morphology<\/p>\n<\/td>\n | Asexual spores called conidia and sexual spores are known as ascospores<\/td>\n | By vegetation reproduction through budding.\n The fusion of two somatic cells for the formation of basidiospores is Plasmogamy<\/p>\n<\/td>\n | Through asexual spores called conidia.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/span>10. What are the characteristic features of Euglenoids?<\/strong><\/span><\/h3>\nThe typical features of Eugenoids are:<\/p>\n (i) Absence of cell wall.<\/p>\n (ii) Their body is flexible because there is a protein-rich layer called a pellicle.<\/p>\n (iii) Two flagella of different lengths are found.<\/p>\n (iv) They are autotrophic in the presence of sunlight and heterotrophic in the absence of sunlight.<\/p>\n <\/span>11. Give a brief account of viruses with respect to their structure and nature of genetic material. Also, name four common viral diseases.<\/strong><\/span><\/h3>\nViruses are infectious agents that crystallize in structure when found outside the host cell. The genetic material is either DNA or RNA (never both) and they are located within the protein core. If the virus that infects plants has single-stranded RNA, then the viruses that infect animals are single or double-stranded DNA or RNA. Capsid is their protein coat, which in turn is made up of small subunits called capsomers, which protect nucleic acid.<\/p>\n Common viral diseases are \u2013Influenza, AIDS, Herpes, and Rabies.<\/p>\n |
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