Question

Amoeba moves by_____
a. Pseudopodia
b. Cillia
c. Flagella
d. Axopodia

Answer 1

Hint: Amoeba is simple eukaryotic organisms classified not in protozoa but also in fungi, animals. It has a characteristic feature of crawling fashion.

Complete Answer:
Amoeba are simple eukaryotic organisms that move in a characteristic crawling fashion as contraction and relaxation of pseudopods. Pseudopodium is an arm-like projection of a eukaryotic cell membrane which is developed towards the direction of movement temporarily. It is filled with cytoplasm, actin filaments, microtubules and intermediate filaments. This movement strategy produces forward movement via the following steps:
1. Ballooning: the plasma membrane forward. This distinct rearrangement is known as a pseudopodium or “false foot”, which is very similar in nature to that of the lamellipodium generated in higher vertebrates.
2. The pseudopodium attaches to the substrate and is filled with cytosol.
3. The attachment to the substrate is released by amoeba and is propelled forward.

Cilia are the external appendages found in protozoa like paramecium. In protozoa, it is used for motility. Flagella are found in all flagellated eukaryotic cells and bacteria. Flagella are helpful in such organisms in movement. Cilia and flagella in eukaryotic cells are composed of microtubules and cytosol. Microtubules undergo polymerization and depolymerisation during movement. Bacterial flagella also help in movement but consist of protein named as flagellin. Amoeba lacks flagella.

Axopodia is also known as actinopoda. It is a semi-permanent type of pseudopodium. They are containing complex arrays of microtubules enveloped by cytoplasm. It consists of an axial rod, found in Protists like Radiolaria and Heliozoa. It is used for phagocytosis or ingestion of food particles by rapidly retracting in response to physical contact with substance.
Thus the correct choice is A as pseudopodia.

Note: Pseudopodia are used for movement by amoeba cells while axopodia are used for phagocytosis. Flagella and cilia are found in protozoa which are helpful for movement.