Acquired immune deficiency syndrome, a disease in which there is a severe loss of the body's cellular immunity, greatly lowering the resistance to infection and malignancy. The cause is a virus (the human immunodeficiency virus, or HIV) transmitted in blood and in sexual fluids.

evolution of a structure, behavior, or internal process that

enables an organism to respond to environmental factors and live

to produce offspring. 

information obtained from experiments, sometimes called

experimental results.

the passing on of traits from parent organisms to their offspring. (Descent with modification coupled with natural selection is Darwin’s theory of Evolution)

Hormone produced by the pituitary gland in the brain. It is usually released during sleep in response to positive and negative signals from the hypothalamus. Also known as the master hormone of the body, hGH affects growth, development, immunity, and metabolism.

explanation for a question or a problem that can be formally

tested.

mechanism for change in populations; occurs when organisms

with favorable variations survive, reproduce, and pass their

variations to the next generation.

means false science. Pseudoscience is any scheme of assertions, beliefs and methods, wrongly considered as scientific. It differs from antiscience in the nonattendance against real science and the scientific method.

group of organisms that can interbreed and produce fertile

offspring in nature. 

An explanation based on many observations during repeated

experiments that is valid only if it is consistent with

observations, makes predictions that can be tested, and is the

simplest explanation of observations.

slow, steady changes over time. Someone who believes in this thinks that species change at a slow steady rate over time.

variation in genes that occurs both within and among populations. Genetic variation is important because it provides the “raw material” for natural selection. Genetic variation is brought about by mutation, a change in a chemical structure of a gene.

Each level on the energy pyramid receives about one-tenth (or 10%) of the energy from the level below it. 

Physical, chemical and other non-living environmental factors. They are essential for living plants and animals of an ecosystem, providing the essential elements and nutrients that are necessary for growth. The abiotic elements also include the climatic and soil components of the ecosystem

the total mass or weight of all living matter in a given area.

An animal or plant (particularly insect- and invertebrate-eating plants) that requires a staple diet consisting mainly or exclusively of animal tissue through predation or scavenging.

symbiotic relationship in which one species benefits and the

other species is neither harmed nor benefited. 

The competitive exclusion principle, sometimes referred to as Gause's Law of competitive exclusion or just Gause's Law, states that two species that compete for the exact same resources cannot stably coexist. 

An organism that generally obtains food by feeding on other organisms or organic matter due to lack of the ability to manufacture own food from inorganic sources; a heterotroph.

interactions among populations in a community; the community’s physical surroundings, or abiotic factors. 

A graphical model that is shaped like a pyramid to show how the energy flows through a food chain, how the amount of energy is decreasing and becoming less available for organisms as it enters each trophic level, and how much of the energy in the ecosystem is lost to the atmosphere as heat.

An animal that consumes herbaceous vegetation. Any animal that feeds chiefly on grass and other plants; horses are herbivores; the sauropod dinosaurs were apparently herbivores. Animals that consume plant material as a source of obtaining energy.

a symbiotic relationship in which both species benefit. 

role or position a species has in its environment; includes all biotic and abiotic interactions as an animal meets its needs for survival and reproduction. 

symbiotic relationship in which one organism benefits at the expense of another, usually another species. 

A form of symbiotic relationship between two organisms of unlike species in which one of them acts as predator that captures and feeds on the other organism that serves as the prey.

herbivores that feed on primary producers

(1) An autotrophic organism capable of producing complex organic compounds from simple inorganic molecules through the process of photosynthesis (using light energy) or through chemosynthesis (using chemical energy).

(2) The first trophic level in a food chain in which it serves as a food source for consumers or for higher trophic levels.

consumers that feed on primary consumers and/or producers

permanent, close association between two or more organisms of

different species. 

consumers that feed on secondary and primary consumers, as well as on producers... (also called tertiary consumers)

A position in a food chain or Ecological Pyramid occupied by a group of organisms with similar feeding mode.