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Parasitism

Parasitism is a form of one-sided symbiosis. The parasites live off the host. They may, or may not, harm the host. Parasitoids, on the other hand, usually kill their hosts. A parasitic relationship is the opposite of a mutualistic relationship. E ...

                                               

Cuckoo bee

Cuckoo bees lay their eggs in the nests of other bees, rather like cuckoo birds. They are kleptoparasites, a term which means parasitism by theft. In this case the theft is of food stored for the host larvae. Females of cuckoo bees lack the speci ...

                                               

Hyperparasite

A hyperparasite is a parasite which is parasitic on another parasite. Usually, this means it is parasitic on the larval stage of the victim species. Typical examples are members of the Apocrita, and some species in two other insect orders, the Di ...

                                               

Physiology

Physiology is the study of how living things work. Physiologists can study how organs of an organism work together to make things happen. In human beings, for example, the digestion of food hormones and other chemicals are made by the stomach, li ...

                                               

Aestivation

Aestivation, also spelled estivation in the USA, is a state of animal dormancy. It is somewhat similar to hibernation. The animals are inactive and have a lowered metabolic rate. The state is entered in response to high temperatures and dry condi ...

                                               

Allergy

An allergy is something which triggers an allergic reaction. This is the immune system defending the body against attack by bacteria and viruses. Sometimes the systems goes wrong, and is triggered by some quite normal food, or flares up when the ...

                                               

Claude Bernard

Claude Bernard was a French physiologist. He has been called "one of the greatest of all men of science". He was one of the first to suggest blind experiments to get scientific observations more free of bias. He was the first to define the term m ...

                                               

Biological rhythms

Biological rhythms are the repeating cycles of activity which occur in living organisms. The best-known example is the daily of circadian rhythm, which fits the cycle of day and night. Most forms of life have natural rhythms which fit them to nat ...

                                               

Blood substitute

Blood substitute is the name for a number of substances that can perform some functions of blood. Blood substitutes are often used in blood transfusions where real blood is not available. Losing a lot of blood can mean there is not enough blood l ...

                                               

Breathing

Breathing is moving air in and out of the lungs. The air going in and out is called breath. If a person cannot breathe, they will die. Breathing helps people do two very important things: Get oxygen into the body. Every part of the body needs oxy ...

                                               

Circadian rhythm

A circadian rhythm is a rhythm that repeats about every 24 hours. Plants and animals have these built-in cycles which allow them to flower at the right time, sleep at the right time etc. The word "circadian" comes from the Latin circa, "around", ...

                                               

Diapause

Diapause is a delay in development which has evolved in response to regular periods of adverse environmental conditions. It is a physiological state with very specific conditions. Diapause is a mechanism used as a means to survive predictable, un ...

                                               

Electrophysiology

Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electrical current flow on a wide variety of scales from single ion channel proteins, to whole tissues like ...

                                               

Excretion

Excretion is one of the most basic functions of life. It is the process of eliminating waste products of metabolism and other non-useful materials. It is an essential process in all forms of life. It contrasts with secretion, where the substance ...

                                               

Hippocampus

For the small fish, go to seahorse The hippocampus is part of the mammalian brain, and belongs to the limbic system. Humans and other mammals have two, one in each side of the brain. The hippocampus is under the cerebral cortex. It is important i ...

                                               

Hysterical strength

Hysterical strength or superhuman strength is a display of extreme strength by humans beyond the normal. Hysterical strength usually occurs in life or death situations. The usual explanation is a sudden release of adrenaline. There have been nume ...

                                               

Lactation

Lactation describes the secretion of milk from the breasts when a mother feeds her young. It occurs with almost all female mammals after the birth of their young. In humans the process is also called breastfeeding or nursing. In most species, mil ...

                                               

Lateralization of brain function

The human brain has two halves, called the left and right hemispheres. These two halves of the brain are not exactly alike. For most tasks, both sides of the brain work together. But each side of the brain specializes in some things and works har ...

                                               

Muscle atrophy

Muscle atrophy or" muscle wastage” is a medical problem where a person loses muscle tissue. This makes the persons muscles weaker. With muscle atrophy, muscles can waste away completely, or only partly. Many older people have muscular atrophy. Mu ...

                                               

Nerve impulse

A nerve impulse is the way nerve cells communicate with one another. Nerve impulses are mostly electrical signals along the dendrites to produce a nerve impulse or action potential. The action potential is the result of ions moving in and out of ...

                                               

Neurotoxin

A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins and ion channels. Many of the venoms and other toxins that organisms use in defense against vertebrates are neurotoxins. A com ...

                                               

Phagocyte

Phagocytes are the white blood cells that protect the body by eating dirt, bacteria and dead or dying cells. They are important for fighting infections. They are also important for becoming immune. Phagocytes are important in all animals and are ...

                                               

Puberty

Puberty is what happens in childrens bodies that changes them into adults. After puberty, people are able to make children. A girl who has gone through puberty can become pregnant and have a baby. At puberty, a boys body begins making sperm, and ...

                                               

Red blood cell

Red blood cells are cells in the blood which transport oxygen. In women, there are about 4.8 million red blood cells per microliter of blood. In men, there are 5.4 million red blood cells per microliter of blood. Red blood cells are red because t ...

                                               

Rice allergy

Rice allergy is a type of food allergy. People allergic to rice react to some rice proteins after they eat rice or breathe in rice steam. Although some reactions might lead to severe health problems, doctors can diagnose rice allergy with many me ...

                                               

Taurine

Taurine is an organic compound. It is up to 0.1% of total human body weight, and is a main constituent of bile. Taurine is essential for the heart, the skeletal muscles, the retina, and the nerves. The body makes it from the amino acid cysteine. ...

                                               

Thermoregulation

Thermoregulation is the ability of an organism to control its body temperature within certain limits, even when the surrounding temperature is different. This is an aspect of homeostasis: the keeping of a constant internal environment.

                                               

Egg (biology)

An egg results from fertilization of an ovum. The egg is a container for the zygote. It protects the zygote, and feeds the embryo. The animal embryo develops until it can survive on its own, at which point the egg hatches. Most fish, amphibians, ...

                                               

Fecundity

Fecundity, coming from the word fecund, generally means the ability to reproduce. In biology and demography, fecundity is the ability to reproduce of an organism or population, measured by the number of gametes eggs, seed set or asexual propagule ...

                                               

Fertilization

Fertilization is when a males sperm enters a females ovum. Fertilization is also called conception. Biologists call a fertilized egg a zygote. A zygote grows into an embryo. Fertilization occurs in animals, including humans and birds, in plants, ...

                                               

Ovum

An ovum is the name for the haploid female reproductive cell, or gamete. Both animals land plants produce ova.

                                               

Sex

Sex is a type of reproduction common among living things. Sex is used by plants and animals, and also by fungi and various single-celled organisms. It usually needs two individuals which are different sexes from the same species. It works by comb ...

                                               

Sex chromosome

Sex chromosomes are chromosomes which determine the sex of individual organisms. In men, for example, there are 23 pairs of chromosomes, and one of these pairs are sex chromosomes. Females have two X chromosomes, males have one X and one Y. An eg ...

                                               

Sexual intercourse

Sexual intercourse is the insertion and thrusting of a males penis into a females vagina. People and animals that sexually reproduce use sexual intercourse to have an offspring. Sometimes sexual intercourse is called coitus or copulation and is m ...

                                               

Sperm

Sperm are the male reproductive cells. Most animals and plants use sperm to reproduce. They have different ways of making and releasing the sperm. In all cases the sperm meets with the egg of the female and grow into a new organism. The name sper ...

                                               

Twin

Twins are two animal offspring that are born from the same pregnancy. Human twins are two people that shared the uterus during a single pregnancy, and one is normally born quickly after the first. Because of the size of the uterus, multiple pregn ...

                                               

Zygote

A zygote is the fertilized cell that will grow into a new animal or plant. When a females ovum and a males sperm cell join, the cell that results is called the zygote. The zygote then multiplies, and grows into an embryo. So, a zygote is formed f ...

                                               

Biological classification

Biological classification is how biologists group organisms. The classification has its root in the work of Aristotle who invented a multi-ranked system. A great influence was Carolus Linnaeus, who popularized the idea of binomial nomenclature us ...

                                               

Taxonomy

Taxonomy is a branch of science. It is about the laws and principles of classifying things, especially classifying organisms. From one type of taxonomy, many classifications might be produced. The best-known kind of taxonomy is used for the class ...

                                               

Binomial nomenclature

In biology, binomial nomenclature is how species are named. The name of a species is made of two parts: one indicating the genus and one indicating the species. Binomial nomenclature means "two-part name" or "system of two-part names".

                                               

Brachiopod classification

The classification of brachiopods is being discussed at present. The following is an overview of the different schemes which are proposed. The "traditional" classification was defined in 1869. Two further approaches were established in the 1990s: ...

                                               

Domain (biology)

In biological taxonomy, a domain is a taxon in the highest rank of organisms, higher than a kingdom. Domain or its synonyms is the most inclusive of these biological groupings. The arrangement of taxa reflects the fundamental evolutionary differe ...

                                               

Genus

A genus is a rank in the biological classification. It stands above species, and below families. A genus can include more than one species. When biologists talk about a genus, they mean one or more species of animals or plants that are closely re ...

                                               

Kingdom (biology)

Kingdom is the highest rank, after the domain, which is normally used in the biological taxonomy of all organisms. Each kingdom is split into phyla. There are 5 to 7 kingdoms in taxonomy. Every living thing comes under one of these kingdoms and s ...

                                               

Carl Linnaeus

Carl Linnaeus was a Swedish botanist, physician and zoologist who created the binomial nomenclature. In this system, every kind of animal and plant is given a name consisting of two Latin words, for its genus and species. This became used by biol ...

                                               

Neornithes

Neornithes are the most recent common ancestor of all living birds and all their descendants. There are about 9.000 to 10.000 known living species in the world.

                                               

Nomen dubium

A nomen dubium is Latin for "doubtful name". It is a scientific name in zoology which is of unknown or doubtful use. With a nomen dubium it may be impossible to decide whether a specimen belongs to that group or not. This may happen if the origin ...

                                               

Olfactores

Olfactores is a group, called a clade, in taxonomy. Taxonomy is the way scientists put living things in groups to show how they are related to each other. Olfactores is part of the phylum Chordata, animals with notochords. These are rods of tissu ...

                                               

ParaHoxozoa

ParaHoxozoa is a proposed group within taxonomy. It would be above phylum but below a kingdom. It would have the Triploblasts/Bilateria and the Placozoa and Cnidarians in it.

                                               

Race (biology)

In biology, races are distinct populations within the same species with relatively small morphological and genetic differences. The populations are ecological races if they arise from adaptation to different local habitats or geographic races whe ...