Much of human knowledge of the diversity of life has been based on what can be seen. Early attempts at classifying life considered just plants and animals, with fungi part of the plant kingdom.
Arthropods are a phylum within the animal kingdom. They include four classes: Chelicerates (such as spiders, mites, ticks, scorpions, and horseshoe crabs), the extinct Trilobites, Crustaceans (such as lobsters, crabs, and shrimp), and Uniramians (millipedes, centipedes, and the most numerous group of all, the insects).
In order for the immune system to protect the body against attack by foreign organisms, it must be able to distinguish between the body's own proteins (autoantigens) and proteins from foreign cells (foreign antigens). When the immune system turns against autoantigens, thus attacking its own tissues, the resulting condition is an autoimmune disease.
Hundreds of thousands of bacterial species exist on Earth. They can be found in very diverse environments ranging from cold to hot and alkaline to acid.
Bacteria get a bad reputation for causing disease when, in reality, very few species of bacteria infect humans. The ones that do, however, are the ones most often written about in magazines and newspapers.
There are hundreds of thousands of bacterial species in existence on Earth. They grow relatively quickly, and most reproduce by binary fission, the production of two identical daughter cells from one mother cell.
There are viruses that infect all types of cells: animal cells, plant cells, and unicellular organisms. Those that infect bacteria are called bacteriophage or just phage ( phage means "to eat").
Beer is made by fermentation of grains, principally barley (Hordeum vulgare). Other grains, including wheat and rice, may be added to develop particular flavors.
A debate raged throughout the twentieth century, and probably will continue, about the relative influences of heredity and experience on human behavior. Behavioral scientists today largely regard this "nature versus nurture" debate as an outmoded dichotomy.
There are millions of different species of animals, and each species behaves somewhat differently. Nevertheless, there are common patterns of behavior exhibited by many species, and a few behavior patterns that are exhibited by all species.
A biochemist is a scientist primarily concerned with the chemistry of biological processes. The four main branches of biochemistry are: a) nucleic acids, b) proteins, c) carbohydrates, and d) lipids.
Biodiversity is the sum total of life on Earth; the entire global complement of terrestrial, marine, and freshwater biomes and ecosystems, and the species—plants, animals, fungi, and microorganisms—that live in them, including their behaviors, interactions, and ecological processes. Biodiversity is linked directly to the nonliving components of the planet—atmosphere, oceans, freshwater systems, geological formations, and soils—forming one great, interdependent system, the biosphere.
Biogeochemical cycles refer to the movement of chemical elements between living (biotic) and nonliving (abiotic) forms in the environment. Although many elements undergo this type of cycling to some extent, four elements—carbon, nitrogen, phosphorus, and sulfur—are most commonly discussed because of their importance (along with hydrogen and oxygen) for living organisms.
An enormous variety of species live in the thin layer on Earth's surface that makes up the biosphere. None of these species is found everywhere on Earth's surface.
Bioinformatics is a new field that centers on the development and application of computational methods to organize, integrate, and analyze gene-related data. The Human Genome Project (HGP) was an international effort to determine the deoxyribonucleic acid (DNA) base sequence of the entire human genome, which includes about thirty thousand protein-encoding genes, their regulatory elements, and many highly repeated noncoding sections.
Biological weapons are organisms or their by-products used to deliberately spread disease. They include bacteria, viruses, rickettsiae, protozoa, fungi, and their toxins.
Biology is defined as the "study of life." The term life refers to all organisms (plants, animals, bacteria, fungi, and protists) inhabiting Earth and its atmosphere. Both scientists and laypeople are drawn to biology because it seeks to answer the question of how life began.
The biological definition of race is a geographically isolated breeding population that shares certain characteristics in higher frequencies than other populations of that species, but has not become reproductively isolated from other populations of the same species. (A population is a group of organisms that inhabit the same region and interbreed.) Human racial groups compose a number of breeding units that in the past remained geographically and perhaps temporally isolated, yet could interbreed and produce viable offspring within the species Homo sapiens sapiens.
Earth's major terrestrial, marine, and freshwater ecosystems are known as biomes. They are classified according to similarities in species composition of plants and animals, and by environmental attributes.
The term "biotechnology" was coined in 1919 by Hungarian scientist Karl Ereky to mean "any product produced from raw materials with the aid of living organisms." In its broadest sense, biotechnology dates from ancient times. Approximately 6000 B.C.E., the Sumarians and Babylonians discovered the use of yeast in making beer.
Birds are warm-blooded vertebrates with feathers. They are thought to have evolved over 150 million years ago from a Mesozoic reptilian ancestor.
Birth control refers to the practice of deliberately controlling the number of children born, especially by reducing or eliminating the possibility of conception. While there are many forms of birth control, they can be broadly classified as follows: behavioral methods; surgical methods; barrier methods; hormonal methods; and methods that prevent the continuation of pregnancy, namely abortion.