background preloader

Biology: terms

Facebook Twitter

1670898-slide-0-evo-large.jpg 2,420×915 pixels. Here's the tiny human twig in the Tree of Life. Each Christmas, the BMJ (formerly the British Medical Journal) gets a little bit festive, releasing a special edition filled with goofy research papers.

Here's the tiny human twig in the Tree of Life

2013jcpsrep.pdf. Groundbreaking Idea Of Life's Origin. Why does life exist?

Groundbreaking Idea Of Life's Origin

Popular hypotheses credit a primordial soup, a bolt of lightning and a colossal stroke of luck. But if a provocative new theory is correct, luck may have little to do with it. Instead, according to the physicist proposing the idea, the origin and subsequent evolution of life follow from the fundamental laws of nature and “should be as unsurprising as rocks rolling downhill.” From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat. Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity.

Kristian Peters Cells from the moss Plagiomnium affine with visible chloroplasts, organelles that conduct photosynthesis by capturing sunlight. Courtesy of Jeremy England Wilson Bentley. Biological classification. The hierarchy of biological classification's eight major taxonomic ranks.

Biological classification

Intermediate minor rankings are not shown. Modern biological classification has its root in the work of Carolus Linnaeus, who grouped species according to shared physical characteristics. These groupings have since been revised to improve consistency with the Darwinian principle of common descent. With the introduction of the cladistic method in the early 20th century, formalized by Willi Hennig in the mid-20th century, phylogenetic taxonomy in which organisms are grouped purely on inferred evolutionary relatedness (based either on classical evidence of morphology, chemistry, physiology, ecology or molecular evidence or both) has become common in biology.[1] Molecular phylogenetics, which uses DNA sequences as data, has driven many recent revisions and is likely to continue doing so.

Biological classification belongs to the science of biological systematics. Definition[edit] Biological types[edit] Early systems[edit]

History of biology

Classifications of life. Cryobiology. Population biology. Population biology is a study of populations of organisms, especially the regulation of population size, life history traits such as clutch size, and extinction.

Population biology

The term population biology is often used interchangeably with population ecology, although 'population biology' is more frequently used when studying diseases, viruses, and microbes, and 'population ecology' is used more frequently when studying plants and animals. Chronobiology. Chronobiology is a field of biology that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms.[1] These cycles are known as biological rhythms.

Chronobiology

Chronobiology comes from the ancient Greek χρόνος (chrónos, meaning "time"), and biology, which pertains to the study, or science, of life. The related terms chronomics and chronome have been used in some cases to describe either the molecular mechanisms involved in chronobiological phenomena or the more quantitative aspects of chronobiology, particularly where comparison of cycles between organisms is required. Chronobiological studies include but are not limited to comparative anatomy, physiology, genetics, molecular biology and behavior of organisms within biological rhythms mechanics.[1] Other aspects include development, reproduction, ecology and evolution.

Description[edit] The circadian rhythm can further be broken down into routine cycles during the 24-hour day:[2] History[edit] Biological organisation. A population of bees shimmers in response to a predator.

Biological organisation

Biological organization, or the hierarchy of life, is the hierarchy of complex biological structures and systems that define life using a reductionistic approach.[1] The traditional hierarchy, as detailed below, extends from atoms (or lower) to biospheres. The higher levels of this scheme are often referred to as ecological organisation. Each level in the hierarchy represents an increase in organisational complexity, with each "object" being primarily composed of the previous level's basic unit.[2] The basic principle behind the organisation is the concept of emergence—the properties and functions found at a hierarchical level are not present and irrelevant at the lower levels.[3] Homeostasis. Homeostasis, also spelled homoeostasis (from Greek: ὅμοιος homœos, "similar" and στάσις stasis, "standing still"), is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.

Homeostasis

Examples of homeostasis include the regulation of temperature and the balance between acidity and alkalinity (pH). It is a process that maintains the stability of the human body's internal environment in response to changes in external conditions. The concept was described by French physiologist Claude Bernard in 1865 and the word was coined by Walter Bradford Cannon in 1926.[1] Although the term was originally used to refer to processes within living organisms, it is frequently applied to automatic control systems such as thermostats.