Definition A concentration gradient occurs when a solute is more concentrated in one area than another. A concentration gradient is alleviated through diffusion, though membranes can hinder diffusion and maintain a concentration gradient. Overview “Concentration” refers to how much of a solute is in a given amount of solvent. A corner of a water tank … Read more

Nervous Tissue Definition Nervous tissue is the term for groups of organized cells in the nervous system, which is the organ system that controls the body’s movements, sends and carries signals to and from the different parts of the body, and has a role in controlling bodily functions such as digestion.  Nervous tissue is grouped … Read more

Leaf Definition The term leaf refers to the organ that forms the main lateral appendage on the stem of vascular plants. In general, leaves are thin, flat organs responsible for the photosynthesis of the plant. Although photosynthesis typically only occurs on the upper surface of the leaf, it can occur on both sides in some … Read more

Dichotomous Key Definition A dichotomous key is a tool created by scientists to help scientists and laypeople identify objects and organisms. Typically, a dichotomous key for identifying a particular type of object consists of a specific series of questions. When one question is answered, the key directs the user as to what question to ask … Read more

Heterotroph Definition A heterotroph is an organism that cannot manufacture its own food by carbon fixation and therefore derives its intake of nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are secondary and tertiary consumers. Carbon fixation is the process of converting inorganic carbon (CO2) into … Read more

Anatomical Position Definition Standard anatomical position is a way of describing the anatomy of an organism so that it is easy to understand what part of the body is being talked about no matter what direction the organism is facing or where its appendages/limbs are. In humans, standard anatomical position is defined as standing up … Read more

Flagellum Definition Flagellums are microscopic organelles that help cells and microorganisms move. In Latin, flagellum means whip, similar to the whipping motion flagella (plural) frequently use for locomotion. In some organisms, specialized flagella function as sensory organelles that detect temperature and pH changes. Function of Flagellum A flagellum is a filamentous protein structure found in … Read more

The Basics In freshwater aquariums, the oscar fish (or simply oscar) is a species from the cichlid family. Oscars originate from South America – namely the Amazon River basin – but have been introduced all over the world. There are many types of Oscar fish available as aquarium species. A common variety is the “tiger … Read more

Thoracic Vertebrae Definition The thoracic vertebrae are bones located between the cervical and lumbar vertebrae. There are 12 thoracic vertebrae in humans, and these bones increase in size as you move down the body.  They are thicker and larger than the cervical vertebrae but smaller than the lumbar vertebral bones. The increase in size ensures … Read more

Cleavage Furrow Definition A cleavage furrow is an indentation that appears in a cell’s surface when the cell is preparing to divide. It marks the beginning of the cell’s “pinching” its cell membrane and cytoplasm down the middle. Eventually, the cell will pinch itself completely in two, forming two daughter cells. This furrow is created … Read more