Bacterial flagellar arrangement is classified based on the number and position of flagella. Bacteria that do not possess any flagella are referred to as atrichous. Monotrichous bacteria have a single flagellum, while lophotrichous bacteria have a tuft of flagella at one end.

In many algae, particularly during sexual reproduction, gametes aggregate into groups before fertilization occurs. This specific phenomenon of gametes clustering together is referred to as clump formation, which facilitates the subsequent fusion process.

Trichoblasts are delicate, colorless, hair-like lateral branches that arise from the apical cells of Polysiphonia. These structures are often branched and are typically associated with the reproductive organs or serve as protective structures for the growing tips of the algal thallus.

The cell membrane serves as a selective barrier that protects the internal environment of the cell from external stressors. Additionally, it plays a vital role in organizing the cell by compartmentalizing various biochemical processes and regulating the transport of molecules into and out of the cytoplasm.

Conjugation is a mechanism of horizontal gene transfer in bacteria. It requires physical contact, usually mediated by a sex pilus, allowing a donor cell to transfer a copy of its plasmid or chromosomal DNA to a recipient cell, contributing to genetic diversity.

The main axis of the Chara thallus is differentiated into nodes and internodes. Each internode consists of a single, elongated, cylindrical cell. In many species, this internodal cell is covered by a layer of cortical cells, but the internode itself remains a single cell structure.

Algae exhibit immense morphological diversity, ranging from microscopic unicellular forms like Chlorella to massive, multicellular organisms like giant kelp that can reach lengths of over 50 meters. Therefore, body size is highly variable.

The capsule is a major virulence factor for many pathogenic bacteria. It helps the bacteria evade the host's immune system by preventing phagocytosis by white blood cells, thereby allowing the bacteria to survive, multiply, and cause disease within the host.

Chlorella is a well-known genus of unicellular green algae. Unlike kelp or many brown algae, which are multicellular and complex, Chlorella consists of single spherical cells that reproduce rapidly, making them a common subject for biological research.

Many filamentous algae exhibit growth through cell division occurring in a single plane. This type of division leads to the formation of unbranched, linear filaments. While some complex algae divide in multiple planes to form parenchymatous or pseudoparenchymatous thalli, the basic mode of division for simple filamentous forms is restricted to one plane.