Biology: Single-Celled Organisms

Study Notes

Organism

An individual living thing that performs basic life functions.
Examples include ducks, trees, and algae.
Basic unit of life is the cell; organisms can be unicellular (simple) or multicellular (complex).

Bacteria

Single-celled organisms without organized nuclei.
Found on and inside the human body, in soil, water, and plants.
Some bacteria are harmless; others can cause illness.

Amoeba

A type of single-celled organism from kingdom Protista capable of movement.
Changes shape while moving and can only be seen with a microscope.
Moves by extending parts of its body, resembling living gelatin.

Functionality of Single-Celled Organisms

Single-celled organisms carry out all life processes within one cell.
They can eat, grow, respond to the environment, and reproduce.
Requires a microscope for visibility.

Microorganism

Organisms too small to be seen with the naked eye.
Present in air and water; can be unicellular or multicellular.
Some microorganisms are disease-causing, while others are beneficial.

Cell and Nucleus

The basic unit of life where all organisms are composed of cells.
The nucleus functions as the cell's "brain," controlling activities and holding DNA.
Contains hereditary information influencing physical traits.

Abdomen

The body part located between the thorax and pelvis in animals.
Also refers to the hind section of insects or spiders.

Movement of Single-Celled Organisms

Amoebas move by shifting cytoplasm to form pseudopods that capture food.
Some bacteria use flagella (long tails) for movement.

Cytoplasm

The liquid interior of a living cell that supports organelles and cellular processes.

Cilia

Tiny hair-like structures that move back and forth to facilitate movement, seen in organisms like paramecium.

Harmful and Helpful Aspects of Single-Celled Organisms

Some bacteria can spoil food and cause diseases like pneumonia.
Certain amoebas in contaminated water can lead to severe health issues.
Bacteria in the intestines aid digestion and vitamin production.
Phytoplankton produce oxygen through photosynthesis and form the base of ocean food chains.

Description

Explore the fascinating world of single-celled organisms with this quiz. From bacteria to amoeba, learn about their characteristics, functionalities, and roles in the ecosystem. Understand how these microorganisms contribute to life as both harmful and beneficial entities.