A dynamic complex of plant, animal and microorganism communities and their non-living environment all interacting as a functional unit.

An organ or cell that acts in response to a stimulus

Rate of flow of electric charge .

(of a species) seriously at risk of extinction

 A species which is at risk of becoming extinct because it is either few in number, or threatened by changing environmental or predation parameters

Data which has been shown to be valid.

The act of ending the existence of a plant or animal

A fair test is one in which only the independent variable has been allowed to affect the dependent variable.

A hormone secreted by the anterior pituitary gland which promotes the formation of ova or sperm.

Fuels such as oil, natural gas, and coal that are made from decayed plants and animals that lived millions of years ago. These fuels are made of hydrogen and carbon (hydrocarbons).

A hormone produced by the anterior lobe of the pituitary gland that stimulates the growth of the ovum-containing follicles in the ovary and activates sperm-forming cells —abbreviated to  FSH

A nuclear reaction in which two or more atomic nuclei join together to form a single heavier nucleus

Heat energy obtained from the hot areas under the surface of the earth.

Increase in the average temperature of the earth's surface.

A gravitational field due to a body is a region in space in which another body placed in the region experiences a force of attraction by the first body.

 A turning or growth movement by a plant or fungus in response to gravity.

Gases such as carbon dioxide and methane that trap heat in the atmosphere. These gases are emitted from a variety of natural sources like forest fires, and human sources like the combustion of gasoline and natural gas.

The natural home of an animal or plant

The process in which natural habitat is rendered functionally unable to support the species present.

The natural homes or environments of an animal, plant, or other organism

The force needed to cause an extension/compression in a spring is directly proportional to its extension/compression.

Regulatory substances produced in organisms and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action.

Electrical energy produced by moving water

Energy or power produced by moving water.

A proposal intended to explain certain facts or observations.

Ignaz Semmelweis was a Hungarian physician whose work demonstrated that hand-washing could drastically reduce the number of women dying after childbirth. Until the late 1800s surgeons did not scrub up before surgery or even wash their hands between patients, causing infections to be transferred from one patient to another. Through vigorous statistical analysis, Semmelweis figured out where the problem lay and introduced rigorous hand-washing rules in the maternity ward. Deaths were drastically reduced and Semmelweis became known as the ‘saviour of the mothers’.
 
REF :  http://www.sciencemuseum.org.uk/broughttolife/people/ignazsemmelweis.aspx

A procedure in which eggs (ova) from a woman's ovary are removed. They are fertilized with sperm in a laboratory procedure, and then the fertilized egg (embryo) is returned to the woman's uterus.

The independent variable is the variable for which values are changed or selected by the investigator.

The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body

Disorders caused by organisms — such as bacteria, viruses, fungi or parasites