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Biology is the study of living things. It is broken down into many fields, reflecting the complexity of life from the atoms and molecules of biochemistry to the interactions of millions of organisms in ecology. This biology dictionary is here to help you learn about all sorts of biology terms, principles, and life forms.
There are countless different functions that cells must perform to obtain energy and reproduce. Depending on the cell, examples of these functions can include photosynthesis, breaking down sugar, locomotion, copying its own DNA, allowing certain substances to pass through the cell membrane while keeping others out, etc.
Tissue Definition. Tissues are groups of cells that have a similar structure and act together to perform a specific function. The word tissue comes from a form of an old French verb meaning “to weave”. There are four different types of tissues in animals: connective, muscle, nervous, and epithelial. In plants, tissues are divided into three ...
Population Definition. A population is the number of organisms of the same species that live in a particular geographic area at the same time, with the capability of interbreeding. For interbreeding to occur, individuals must be able to mate with any other member of a population and produce fertile offspring.
Invertebrate Definition. Invertebrates are animals that don’t have a backbone. The vertebral column is another name for the backbone. Over 90% of all species on Earth are invertebrates, and invertebrate species have been found in the fossil record as far back as 600 million years ago. Molecular biology studies suggest that all invertebrates ...
Competition Definition in Biology. Competition is a relationship between organisms in which one is harmed when both are trying to use the same resource related to growth, reproduction, or survivability. Competition stems from the fact that resources are limited. There are simply not enough of some resources for all individuals to have equal ...
Lysosome Definition. Lysosomes are specialized vesicles within cells that digest large molecules through the use of hydrolytic enzymes. Vesicles are small spheres of fluid surrounded by a lipid bilayer membrane, and they have roles in transporting molecules within the cell. Lysosomes are only found in animal cells; a human cell contains around ...
Autotroph Definition. Autotrophs are organisms that can produce their own food, using materials from inorganic sources. The word “autotroph” comes from the root words “auto” for “self” and “troph” for “food.”. An autotroph is an organism that feeds itself, without the assistance of any other organisms.
Organ Definition. An organ is a self-contained group of tissues that performs a specific function in the body. The heart, liver, and stomach are examples of organs in humans. The word organ comes from the Latin organum, which means “instrument”. This in turn comes from the Greek word ὄργανον (órganon), which refers to a musical ...
Macromolecule Definition. Macromolecules are large, complex molecules. They are usually the product of smaller molecules, like proteins, lipids, and carbohydrates. Another name for a macromolecule is a polymer, which derives from the Greek prefix poly- to mean “many units.”. In broken-down terms, a macromolecule is the product of many ...