Characteristics of Bacteria Quiz

Criteria for Life

• Scientists define life based on criteria such as organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and evolution.

Cell Structure and Organization

• Cells are the basic units of life, and are organized into tissues, organs, and systems.
• Homeostasis is the ability of cells to maintain a stable internal environment despite changes in the external environment.
• Cells are organized into three domains: Bacteria, Archaea, and Eukarya.
• Organelles are specialized structures within cells that perform specific functions.

Cell Membrane and Transport

• The cell membrane is the main means of transport of substances across the cell membrane in unicellular organisms.
• Cells take in nutrients through active transport, passive transport, and endocytosis.

Bacteria

• Bacteria are classified based on their reaction to the Gram stain, which distinguishes between Gram-positive and Gram-negative bacteria.
• Peptidoglycan (also known as murein) gives most bacteria support and contributes to their structure and shape.
• Bacteria can reproduce through a process called binary fission.
• Some bacteria, such as facultative anaerobes, do not need oxygen but can survive in its presence.

Unicellular Organisms

• Unicellular eukaryotes, such as protists, are typically between 10-30 micrometers in size.
• Protists are a diverse group of eukaryotic organisms that include protozoa, algae, and fungi.
• Examples of unicellular organisms include Paramecium, Amoeba, and Euglena.
• Unicellular organisms usually reproduce through binary fission or budding.

Eukaryotes and Prokaryotes

• The main feature that distinguishes prokaryotes from eukaryotes is the presence of a true nucleus.
• Prokaryotes lack a nucleus and are typically small, simple cells.

Kingdoms and Domains

• The kingdom Protista includes unicellular, eukaryotic organisms that live in aquatic habitats.
• The kingdom Plantae includes multicellular, autotrophic organisms that have cell walls made of cellulose.
• The kingdom Fungi includes non-motile, heterotrophic organisms with structurally different cell walls from plant cells.

Characteristics of Unicellular Organisms

• A defining characteristic of protists is their ability to perform both photoautotrophic and saprophytic nutrition.
• Protozoans are a group of protists that are characterized by their ability to move using flagella, cilia, or pseudopodia.
• Ciliates are a type of protozoan that are distinguished by their cilia, which are used for movement.
• Flagellates are a type of protozoan that are characterized by their flagella, which are used for movement.
• Heliozoans are a type of protozoan that are characterized by their axopodia, which are used for capturing prey.

Multicellular Organisms

• Multicellular organisms are distinguished from unicellular organisms by their ability to have more complex body processes.
• The primary energy source for diatoms is sunlight.
• The main function of the flagella in dinoflagellates is to provide movement.
• Dinoflagellates cause red tides due to their ability to produce toxins.
• Multicellular organisms are able to have more complex body processes due to their ability to specialize cells and tissues.

Test your knowledge of the characteristics of bacteria, including their size, cellular structure, and habitats. Learn about the unique features of these unicellular organisms.