Practice

The following glossary is for 6th grade area3. Here you will find vocabulary related to Biology
according to the institutional programs.
abdomen - (AB-duh-men)
the elongate hind part of the body, behind the thorax
alleles
Alleles are alternate forms of genes. For example, in a plant there might be a gene that codes for flower color. That gene might have two alleles: one that codes for white flowers and one that codes for purple flowers. In a sexually-reproducing species (such as humans or monarchs), an individual has two alleles for each gene, which may be the same or different. One allele comes from its mother and one from its father. Sometimes one allele is dominant, which means that it masks the other allele. If the allele that codes for purple flowers were dominant, for example, and an individual had one purple allele and one white allele, the flowers would be purple. To get white flowers, the individual would have to have two alleles that coded for white flowers. In this example, the white allele is called a recessive allele. In notation, biologists often name dominant alleles with capital letters (A) and recessive alleles with lowercase letters (a). If an individual has two copies of the same allele (e.g., AA or aa), it is called homozygous and that individual is a homozygote. If it has different alleles (e.g., Aa), the individual is called heterozygous and it is a heterozygote. Sometimes neither allele is dominant or recessive; this is called incomplete dominance. When incomplete dominance occurs, heterozygote traits are in between each homozygous alternative. In the example above, the heterozygote would have lavender flowers while homozygotes would be white or purple. Genes often have more than two alleles.
antenna - plural, antennae
sense organ on the head of an insect. In Monarch larvae, these are often confused with the tentacles or filaments. Larval antennae are very small while adult ones are much longer.
aposematic coloration
Aposematic coloration is conspicuous, bright coloration that protects an organism, whether or not the organism contains poisons or other noxious chemicals. This term is often used in the context of mimicry to describe the bright colors of both poisonous species and their palatable mimics. See warning coloration and mimicry.
arachnid
Arachnids, a group of arthropods (invertebrate animals with jointed appendages) which includes spiders, scorpions, ticks, and mites. They have a hard exoskeleton and eight legs.
Asclepias syriaca - (u-SKLEE-pee-us sir-I-uh-kuh) [Photo]
common milkweed. The most common host plant for Monarch larvae in the upper midwestern U.S. Monarchs also eat other members of the genus Asclepias.
bacteria
Bacteria make up the kingdom Monera. These single-celled organisms are the most wide-spread of any type of organism in the world. They are fundamentally different from all others kingdoms because of their structure. Bacteria are prokaryotes (Greek pro, before, and karyon, kernel), which means their DNA sits inside the cell along with everything else; in eukaryotic (Greek eu, true, and karyon, kernel) cells like ours, the DNA is housed inside a membrane-bound organelle called the nucleus. Prokaryotic DNA exists as a long strand that usually forms a ring inside the cell. Bacteria also have a rigid cell wall that helps them maintain their shape.
Bacteria reproduce by binary fission, which means that a single cell grows and divides in two without exchanging genetic material with another individual. This process does not follow a precise sequence of events, as it does for eukaryotic cells, but rather happens as quickly or slowly as the environment allows. Bacteria can also exchange genetic material as part of sexual reproduction. Bacteria can live in a vast range of habitats, including superheated undersea vents and arctic ice.
bottleneck
A bottleneck eckis a specific situation in which genetic drift occurs. A bottleneck occurs when a disaster, such as an earthquake or flood, drastically reduces a population size. The disaster kills individuals unselectively, and the ones that survive are probably not representative of the population as a whole. The survivors' genes, however, serve as the basis for all future generations. When populations get very small, this can reduce variability dramatically. Several examples of this have occurred in the animal world, including the northern elephant seals. Northern elephant seals were hunted until only 20 remained. Through protection, their numbers have risen to more than 30,000, but those 30,000 have no variation in 24 tested genes. Lack of variability makes a population more vulnerable to environmental changes, because there are no options for natural selection to act upon.
braconid wasps
a family of minute, stout-bodied wasps. The female lays one egg inside the host insect. That egg divides up to 5 times, producing up to 32 identical individuals from one egg.
camouflage
Camouflage is concealment by coloration, pattern, or shape that makes something hard to pick out of the background or makes it appear to be something else. In the animal world, camouflage often involves looking like a plant (a leaf, stem, twig, etc.), an inanimate object (a stone, bird droppings, dirt), or a larger animal (e.g., eyespots on wings). Many butterfly species are camouflaged at various stages in their life cycle. Adults from the genera Anaea, Nymphalis, Polygonia, and Libytheana, for example, have undersides that look like dead leaves. They often sit on twigs, which adds to their brown leaf disguise. The pupae of Polygonia and Limenitis also look like dead, curled leaves hanging from a twig. Limenitis caterpillars look like bird droppings, while many other larvae are green and match the foliage they eat. Hairstreak eggs, which overwinter on woody plants, look like bark. What other camouflaged animals and butterflies have you heard about?
cardenolides
- also called Cardiac Glycosides
Cardenolides are a group of heart poison that seriously affects vertebrates. They are related to digitalis, a chemical from the foxglove plant that is used in medicine to treat heart disease but can also be poisonous in large doses. Milkweed plants make these chemicals, probably to protect them from herbivory by vertebrates. Certain insects, including monarch butterflies, have evolved mechanisms to consume the cardenolides and sequester them in their bodies without harming themselves. These insects do not break down the cardenolides they eat. In fact, they gain some protection from vertebrate predation, since the sequestered cardenolides make them poisonous to vertebrates as well. Many species advertise this fact with bright colors and patterns called warning coloration.
cardiac glycosides - (KAR-dee-ak GLI-coh-sides)
Cardiac glycosides (also called cardenolides) are heart poisons that seriously affect vertebrates. They are related to digitalis, a chemical from the foxglove plant that is used in medicine to treat heart disease but can also be poisonous in large doses. Milkweed plants make these chemicals, probably to protect them from being eaten.
chemoreceptors - (KEE-moh-ree-sehp-tors)
cells that sense the presence of chemicals and relay that information to the organism. Taste and smell are sensed through chemoreceptors.
chorion - (KOR-ee-ahn)
the hard outer shell of insect eggs. (In general, the chorion is the outermost membrane enclosing the developing embryo. In reptiles, this layer lies just inside the shell, and in mammals the chorion becomes the placenta.)
chrysalis - (KRISS-uh-lis); plural, chrysalides (KRISS-uh-lids)
another name for a butterfly pupa.
clasper
appendages on the last segment of the male abdomen; they grasp the female tightly during mating.
cocoon - (kuh- KOON)
a silk web that encloses the pupae of many moths, but not butterflies.
conspecific
A conspecific is a member of the same species as the organism in question. Two humans, for example, are conspecifics as are two elm trees, two lake trout, two bluebirds, or two monarchs.
cremaster - (kree-MAS-ter)
the black stem-like appendage that a larva pokes into the silk pad it spins, from which it will hang during the pupa stage.
crochets - (kro-SHAYS)
rows of tiny hooks on the end of each caterpillar's proleg that are used for traction.
cuticle
the hard part of the butterfly's outside skin that is no longer living.
Danaus plexippus - (duh-NAY-us PLEX-ip-us)
the scientific (Latin) name for the Monarch butterfly. Worldwide, there are only ten other species in the genus Danaus, but there are hundreds of species in Danainae, the insect group that contains them, known as the "milkweed butterflies."
Darwin, Charles
Charles Darwin was born in 1809 in England. In 1831, at the age of 22, he joined the crew of the ship Beagle, which sailed around the world and charted poorly known sections of the South American coastline. Darwin was the ship's naturalist, collecting all sorts of animals, plants, rocks, fossils, and other samples from the places they visited. As he collected, Darwin noticed a lot about the flora and fauna that led him to new questions. He observed similarities between South American fossils and living animals, which were quite different from animals in Europe, and he wondered if the living animals were more closely related to the South American fossils than to creatures on other continents. He also observed species in the Galapagos Island that existed no where else on earth, and he wondered how they came to be. By the time he returned to England in 1836, Darwin believed that the world was very old and constantly changing. This voyage became the foundation of his theories and books on evolution.
Even though he had these ideas pretty well formed by the 1840s, Darwin hesitated to publish them because it was against the teachings of the church and the beliefs of the time. Within a decade, however, another scientist had named Alfred Wallace came up with similar ideas and Darwin rushed to present his theories before Wallace beat him. Both naturalists had papers presented in 1858, and Darwin published his book On the Origin of Species by Means of Natural Selection, in 1859. This book and Darwin's theory of natural selection to explain how evolution happens are the main reasons people today still think of Darwin as the father of evolution. Darwin, who published a second book called The Descent of Man, continued to refine his ideas until his death in 1882.
diapause - (DI-uh-pawz)
a period of dormancy between periods of activity.
Diptera
All dipterans are flies. The approximately 80,000 species include fruitflies, houseflies, gnats, and mosquitoes. Flies have one pair of wings; club-shaped organs called halteres replace their hind wings. Halteres help them maintain balance during flight.