Biological Classification Test - 21

Pseudopodia are organs of locomotion and food capture in class Sarcodina of phylum Protozoa. Class Sporozoa are nonmotile. Class Mastigophora have flagella and class Ciliata have cilia as the organ of locomotion. Thus, the correct answer is option B.

The protozoans possess highly efficient locomotory structures (cilia, flagella, pseudopodium etc),  competent life cycle (trophozoite to cyst stage and vice versa) and diversified nutritional modes (holophytic, holozoic, pinocytosis, saprozoic, mixotrophic and parasitic), by their specialised organelles like glycosomes, cytostomes, (9+2) microtubular flagella and cilia, hydrogenosomes, acidocalcisomes, endosomes, lysosomes and secretory organelles of the endocytic pathway etc.
Hence, the correct answer is option (D).

• Physarum is a plasmodium slime mould. 
• It is formed when many flagellated cells swarm together and fuse to form a large bag of cytoplasm with a large number of diploid nucleus. 
• Rhizopus is a fungus, which belongs to the family Rhizopodaceae. 
• Thiobacillus is bacteria, that causes denitrification. 
• Anabaena is nitrogen fixing blue-green algae.

Phytoplanktons are small photosynthetic organisms. They are primary producers of aquatic food chains. They provide food, energy and oxygen to aquatic organisms. If they are destroyed then the trophic level of primary consumers will get disturbed.

Correct Option: D

Explanation: 

The microfossils of foraminiferans are often useful in petroleum exploration. On the other hand, radiolarians skeletons are used in geological dating. Diatoms are commonly used in studies of water quality. Heliozoans are found in both freshwater and marine environments.

The correct answer is D.

The sexual reproduction of fungi involves three phases, namely plasmogamy, karyogamy and meiosis.
In plasmogamy, there is a fusion of two protoplasts that brings together two compatible nuclei within the same cell. This pair of nuclei is called as a dikaryon (resulting cell becomes bi-nucleate).
Thus, there is fusion of two haploid cells without nuclear fusion.
In case of lower fungi, plasmogamy is almost immediately followed by karyogamy but in higher fungi these two processes may be separated in time.

• Oospores are produced when male gametes (reproductive nuclei) enter a large spherical cell (oogonium) and fertilize the eggs within. The oogonia is usually penetrated by one or more hyphae (antheridia) that give rise to the male nuclei. 

• Zygospores do not occur inside any kind of enclosing structure but are produced by the direct fusion of two hyphal protrusions (suspensors) from neighbouring filaments. Usually, zygospores are recognized as large, nearly spherical, often dark brown or black, rough-walled spores with two connecting hyphae, representing the two mating gametangia. 

• Ascospores are produced within spherical to cylindrical cells called asci, most often in groups of four or eight. Usually, the asci are produced within some kind of enclosing structure and thus, are not found exposed on the hyphae.

• Basidiospores are always produced externally on a structure, called as a basidium. Basidia come in a variety of forms, but those commonly encountered on moulds will be club-shaped and bear four or eight spores on sharp projections at the apex. 

Thus, the correct answer is option D.