Test: Amoeba - 2 (Old NCERT) - NEET MCQ

Amoeba orients in directive illumination and is negative in strong light and probably positive in very weak light, since strong light causes inhibition in the formation of pseudopods .

Pseudopodia is a temporary cytoplasm-filled projection of a eukaryotic cell membrane or a unicellular protist.
Pseudopods may be used for motility, or for ingesting nutrients or other particulate matter. It senses the prey that can then be engulfed; the engulfing pseudopodia are called phagocytosis pseudopodia. Hence, pseudopodia in amoeba help in locomotion, engulfment and ingestion.
Hence the correct option is B.

Pseudopodia are temporary finger like projections with blunt rounded tips which are constantly being given out or withdrawn by the body. Many pseudopodia are formed simultaneously. Amoeba exhibits movement by the pseudopodia. It also helps in food capture.

Amoeba takes in its food through this process. Initially, it pushes out its pseudopodia so that it can encircle the food. After this, it engulfs the food, thus forming a bag-like structure called food vacuole. The process is known as “phagocytosis”.

Amoeba is a fresh water unicellular organism. In amoeba the excretory waste is ammonia. The excretory waste present in the cytoplasm is collected by contractile vacuole then this excretory waste i.e NH3 is excreted through plasma membrane by diffusion.
So, the correct answer is 'Plasmalemma'.

For, binary fission, Amoeba requires one parent cell. In the process of binary fission, a fully grown cell divides into two equal halves forming two daughter cells.

It is the most common method of asexual reproduction that occurs in prokaryotes and some single-celled eukaryotes, i.e.,  Amoeba.

Budding is a type of asexual reproduction  which do not involve fusion of gametes. A new organism develops from an outgrowth or bud due to cell division at one particular site. The bud remains attached to the parent plant and separates after it gets mature. It leaves a scar at the point of separation. The newly developed organism is a clone to its parent cell. 
Sporulation is the process of production of spores which germinates under favorable condition. During favourable condition the encysted amoeba divides by multiple fission and produces pseudopodiospores. This phenomenon is known as sporulation. In order to survive, the unfavorable condition amoeba develops a tough wall around it known as cyst. When the favorable condition approaches the cyst wall bursts out, and the spores are released in the surrounding medium to grow up into many amoebae.
Fragmentation is a mode of asexual reproduction which involves breaking the parent body into several fragments and each fragment develops into a new individual.
Regeneration is the process of development of lost or damaged part.
So, the correct answer is option C.

Mast in 1926

Amoeba proteus contains a central elongated fluid portion (plasmasol), a rigid layer surrounding this (plasmagel), a thin elastic surface layer (plasmalemma), and a hyaline layer between the plasmagel and the plasmalemma which is fluid at the tip of active pseudopods and in certain other regions.

The plasmasol is an emulsion. It consists of a fluid in which various vacuoles and granuoles are suspended. The plasmagel is probably alveolar in structure. It contains the same kinds of substances as the plasmasol, but some of the fluid appears to be gelated so as to form alveoli. The plasmalemma probably consists of interwoven protein fibers and a lipoid which fills the interstices.

The plasmasol is probably hypertonic; the plasmagel and the plasmalemma are probably semipermeable. This and other factors result in an excess inflow of water, stretching the plasmagel and the plasmalemma. When a pseudopod is formed, the inner portion of the plasmagel liquefies locally. This produces a local decrease in elastic strength resulting in the formation of a protuberance, a pseudopod. As this is formed there is contraction at the posterior end, resulting in forward flow of the plasmasol and extension of the pseudopod.

If the pseudopod is attached, the plasmalemma, being attached to the substratum and to the adjoining plasmagel, slides over the plasmagel above and remains stationary below, rolling movement results. If it is free, the plasmalemma is stretched out with movement in it equal on all sides. If the free pseudopods become attached to the substratum at the tip after they are thus formed, walking movement results.

During locomotion of either type, the plasmasol continuously gelates at the tip of the extending pseudopods forming plasmagel, and the plasmagel continuously solates at the posterior end forming plasmasol.

Response is due largely to changes in the elastic strength of the plasmagel in the adhesiveness of the plasmalemma and in turgidity.

Locomotion in Amoeba verrucosa is in principle the same as it is in Amoeba proteus.

Option A is correct as because cockroach uses it's legs for movement and locomotion similarly amoeba uses the pseudopodia for its movement.

Amoeba Proteus reacts negatively when touched at any point with a solid object, the part affected contracts and the animal moves away. A floating Amoeba with spread pseudopodia, responds positively to contact with the solid object by fastening to it.

Contractile vacuole helps in regulation of osmotic pressure. as entamoeba histolytica has no contractile vacuole, it cant regulate osmotic pressure and hence dies.