Understanding Amoeba Movement and Feeding

Amoeba is a single-celled organism that belongs to the group of protozoa. One of its most characteristic features is its ability to constantly change its shape. This ability is crucial for both its movement and how it obtains food.

The question asks about the finger-like projections that the amoeba pushes out. These projections serve a dual purpose: helping the amoeba move from one place to another and capturing food particles.

Identifying the Finger-like Projections: Pseudopodia

The finger-like or temporary projections that an amoeba extends from its body are called pseudopodia (singular: pseudopodium). The word "pseudopodia" comes from Greek words meaning "false feet".

• Movement: Amoeba moves by extending a pseudopodium in the direction it wants to go. The rest of the cytoplasm then flows into this projection, effectively pulling the amoeba along. This process is called amoeboid movement.
• Food Capture: When an amoeba encounters a food particle, it extends pseudopodia to surround and engulf the food. The food particle is then enclosed within a membrane-bound sac called a food vacuole. This process of engulfing food is known as phagocytosis.

Therefore, pseudopodia are the key structures responsible for both the locomotion and feeding mechanism of an amoeba.

Analyzing the Other Options

Let's look at why the other options are not the correct answer for the finger-like projections used for movement and food capture:

• Contractile vacuole: This is an organelle found in amoeba that helps regulate the water content within the cell. It collects excess water from the cytoplasm and expels it out of the cell, preventing the amoeba from bursting. It is not involved in movement or capturing food.
• Food vacuoles: These are temporary sacs formed within the cytoplasm of the amoeba after food has been engulfed by pseudopodia. Digestion of the food takes place inside these vacuoles. They are a result of food capture, not the projections themselves.
• Endoplasm: This refers to the inner, more granular part of the cytoplasm of the amoeba. The cytoplasm is the material filling the cell, excluding the nucleus. While the flow of endoplasm and ectoplasm (the outer, clearer part) is involved in forming pseudopodia, endoplasm itself is not the finger-like projection.

Comparison of Amoeba Structures

Based on the functions described, the finger-like projections used by amoeba for movement and capturing food are clearly pseudopodia.

Revision Table: Key Amoeba Parts

Additional Information: Amoeboid Movement Details

Amoeboid movement using pseudopodia is a fascinating process involving the streaming of cytoplasm. The conversion between the jelly-like gel state (ectoplasm) and the more fluid sol state (endoplasm) of the cytoplasm, driven by the assembly and disassembly of actin filaments, is key to extending and retracting the pseudopodia. This mechanism allows the amoeba to navigate various surfaces and capture food particles effectively.