Species Definition A species is a group of organisms that share a genetic heritage, are able to interbreed, and to create offspring that are also fertile. Different species are separated from each other by reproductive barriers. These barriers can be geographical, such as a mountain range separating two populations, or genetic barriers that do not … Read more

Nucleotide Definition A nucleotide is an organic molecule that is the building block of DNA and RNA. They also have functions related to cell signaling, metabolism, and enzyme reactions. A nucleotide is made up of three parts: a phosphate group, a 5-carbon sugar, and a nitrogenous base. The four nitrogenous bases in DNA are adenine, … Read more

Lesion Definition A lesion is an area of inflammation in a tissue that suffered trauma or the impact of chronic illness. Typically, a lesion involves an abnormal structural change to a tissue. So, it is often defined as a site of abnormal tissue change. These changes can take place in the form of wounds or … Read more

Tertiary Consumer Definition A tertiary consumer is an animal that obtains its nutrition by eating primary consumers and secondary consumers. Usually tertiary consumers are carnivorous predators, although they may also be omnivores, which are animals that feed on both meat and plant material. Function of Tertiary Consumers Within any ecosystem, the energy that is present … Read more

The Basics The sand dollar is a group of sea urchins belonging to the order Clypeasteroida and consisting of more than twenty families. Also known around the world as sea cookies, snapper biscuits, pansy shells, and sand cakes, sand dollars are well-known for their hard, flat tests that are often found by beachcombers. General Sand … Read more

Isomer Definition Isomers are two molecules with the same molecular formula but differ structurally. Therefore, isomers contain the same number of atoms for each element, but the atomic arrangement differs. Despite having the same molecular formula, the physical properties of each molecule may differ, particularly if the functional groups associated with each molecule are different.  … Read more

The Basics Dwarf hamsters have short tails, stubby legs, and stout bodies. In general, they measure two to three inches in length, although some are smaller. Seven of the species belong to the genus Cricetulus, while the remaining three belong to the genus Phodopus. Dwarf desert hamsters are the smallest dwarf hamsters, measuring just two … Read more

Fermentation Definition In the absence of oxygen or electron transport chains, fermentation refers to the conversion of organic molecules (normally glucose) into acids, gases, or alcohol. Adenosine triphosphate (ATP) is generated in glycolysis via fermentation pathways that regenerate the coenzyme nicotinamide adenine dinucleotide (NAD+).  Through glycolysis, fermentation yields only two molecules of ATP per glucose … Read more