Integrated Principles of Zoology Study Set 3

Answer:

Cilia are tiny hairs along the outside of the cell membrane which can push the cell along, and flagella are much larger hairs which can move back and forth to propel the cell.
Cilia and flagella also differ in their beating patterns.
Pseudopodia are only temporary structures formed for the sake of movement. They are formed with the flow of cytoplasm into one part of the organism. Due to this flow, the plasma membrane extends and forms a protrusion which helps the animal to move.

Answer:

This model of the membrane consists of a fluid phospholipid bilayer with a mosaic of interspersed proteins embedded in the lipid layers. The phospholipids are not static and are in a state of constant lateral motion.
Some proteins extend through both lipid layers, while others may extend only halfway or be loosely bound to the surface of the membrane.
Hence this model is known as fluid mosaic model.

Answer:

Phagocytosis is the process where the cell engulfs large objects while pinocytosis is the process where small molecules or ions attach to cell receptors and are invaginated along with the receptors.
Phagocytosis forms phagosomes while pinocytosis forms caveolae. In phagocytosis the phagosome fuses with the lysosome. In pinocytosis this fusion does not occur.
In receptor mediated endocytosis there are pits coated with clathrin. These pits contain receptors for specific ligands. When the specific ligand attaches to its receptor, the cell membrane invaginates to form a vesicle.
In exocytosis, the debris or the waste material present in the cell is pushed into a vesicle. This vesicle is then transported to the plasma membrane where the vesicular membrane fuses with the plasma membrane. This results in the throwing out of debris out of the cell.
Endocytosis is the process of taking materials into the cell while exocytosis is the process of throwing materials out of the cell.