Biology definition for relative dating boundaries dating cloud townsend

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PERIODIC TABLE sodium bicarbonate (Na HCO₃ also bicarbonate of soda) /SODE-ee-əm by-KAR-bə-nate/ n. spawn (1) to lay eggs in water (said of an aquatic animal); (2) eggs laid in water by an aquatic animal. However, there is no general consensus among scientists concerning how to decide whether any given group of organisms should be so treated, since there is no general agreement among biologists on the definition of the word species. It lies between the stratum granulosum and stratum corneum. Streptococcus (pl streptococci) /STREP-tə-cock-əs/ n. A genus of gram-positive cocci, of which most strains are harmless. stroma /STRŌ-mə/ (pl stromata /strō-MAWT-ə/) (1) The portion of a chloroplast where the synthesis of organic molecules from carbon dioxide and water occurs; (2) the healthy tissue surrounding a tumor. Large mineral structures formed in shallow water by microorganisms, especially cyanobacteria. sucrose /SOO-krōs, -rōz/ (Suc also saccharose /SACK-ə-rōs, -rōz/) Table sugar (also: cane or beet sugar). Heteropaternal superfecundation occurs when separate fertilizations result from two or more inseminations administered by two or more different males. PICTURE OF SUPERNUMERARY FINGER | PICTURE OF SUPERNUMERARY RAINBOW | PICTURE OF SUPERNUMERARY NIPPLE superorder See: subclass. Symbiosis is of three types: parasitism, mutualism, and commensalism. Of two populations: Occupying overlapping geographic regions. Under such circumstances, it is generally claimed that the trait arose after the divergence of the most recent common ancestor of the taxa in the related group, but before the divergence of those taxa. skullcap Within the context of fossil human remains, a fragment composed of the upper portion of the skull. They also regulate osmotic pressure of cells and protect against excessive water loss from tissues. Any cell in the body except gametes and their precursors. The new genetic material cannot be passed to offspring. somatic mutation (also somatic cell mutation) /sō-MAT-ək, -ik/ n. Used to detect specific fragments by complementary radioactive probes. A given type of organism is treated as a species if it is assigned a binomial name. stratum lucidum /STRAT-əm loo-SEED-dəm/ (pl strata lucida /STRAT-ə loo-SEE-də/) A transparent layer of the skin. (1) an artificial medium on which a microorganism is grown; (2) the molecule on which an enzyme acts. An enzyme that hydrolyzes sucrose into fructose and glucose. superfecundation /SOOP-er-FEK-ən-DAY-shən/ The fertilization of two or more ova from the same ovulation. A relationship, between two distinct types of organisms, in which they live together. synapomorphy /sin-AP-ə-more-fee/ (also synapomorphic character /sin-ap-ə-MORE-fik/) In cladistics, a trait that is: (1) shared by a group of two or more taxa deemed more closely related to each other than to any other taxon under consideration, and (2) not shared with any taxon outside the group. The bulbous structures on the end of an axon, each of which contains many synaptic vesicles. One of the many minute vesicles in a synaptic knob where neurotransmitters are stored. Pertaining to the sacrum and the loins (or lumbar vertebrae). In vertebrates with pelves, the fused portion of the vertebral column to which the pelvis is attached. (1) of or relating to a plane extending from front to back through the body's axis of symmetry, or any plane parallel to that plane; (2) of or relating to the suture between the parietal bones, which runs from front to back down the middle of the top of the skull; (3) arrow-shaped. A ridge of bone running from front to back along the center line of the top of a skull; found in apes and some robust australopithecines. The scala continues to have significant influence on various aspects of modern biological thought. Calcium deposits on the skin are also seen in association with this disease. A pathological hardening of tissue — sclerotic /sklir-RAW-dick/ adj. sodium dodecyl sulfate (SDS) also sodium lauryl sulfate (SLS) /SŌD-ee-əm dō-DECK-əl SƏL-fate/ n. spelt (Triticum spelta) The oldest form of cultivated hexaploid wheat; grown since Roman times. The positive square root of the variance; a commonly used measure of variability. Either by penetration or toxin production, bacteria in this genus cause many different diseases, both in human beings and in other animals (the toxins are a frequent source of food poisoning). It narrows the fauces and blocks off the nasopharynx. The persistence of a fossil form unchanged over geological time. PICTURE 1 | PICTURE 2 stylomandibular /STIGH-lō-man-DIB-yə-ler/ adj. A waxy, waterproof, air-proof substance found in the layers of dead cork cells that sheathe woody stems and mature roots. CHART OF RELATIVE TAXONOMIC RANKS sub-Saharan /sub-sə-HAR-ən/ n. Within the human body, sulfur occurs in many bacterial defense molecules. A medieval system that ordered the various types of organisms existing in nature on a linear scale of perfection. A disorder involving a progressive thickening and hardening of the skin. scolex /SKŌ-leks/ (pl scolices /skō-LEE-seez/ or scoleces /SKŌ-lə-seez/ or scolexes /SKŌ-lex-ehz/) n. A tapeworm attaches itself to the wall of the small intestine with its scolex. In salty solutions water is extracted from cells by osmosis, a process that kills many microorganisms. Salt will also detach feeding leeches and disinfect wounds. A homogeneous mixture, usually a liquid mixture, of two or more substances. PICTURE spectrophotometer /SPECK-trō-fə-TOM-ə-ter/ n. An instrument that measures the intensity of a light beam of a particular wavelength, both before and after passing through a light-absorbing medium. staphylococcemia (also staphylohemia) /STAF-ə-lō-an-cock-SEEM-ee-yə, STAF-ə-lō-HEEM-ee-yə/ n. they are cocci) and form clusters like bunches of grapes. stem cell Undifferentiated, primitive cells with the ability both to multiply and to differentiate into various types of cells. styles Column-shaped structures in flowers, through which the pollen tubes grow. A slender, pointed process on a bone at the attachment point of certain muscles (in particular, the styloid process of the temporal bone). CHART OF RELATIVE TAXONOMIC RANKS subphylum (also superclass) In taxonomy, a division of a phylum; specifically, a category ranking beneath an phylum, but above a class. An essential component of all living cells, sulfur is present in the amino acids cysteine and methionine.

The method of reading the order is called stratigraphy (layers of rock are called strata).

Throughout the history of life, different organisms have appeared, flourished and become extinct.

Many of these organisms have left their remains as fossils in sedimentary rocks.

saccule /SACK-yool/ (1) a small sac; (2) the lesser of two sacs within the vestibule of the inner ear. salpinx (pl salpinges) /SAL-pinks, sal-PIN-jeez/ n. saltation (also saltatory evolution) /sawl-TAY-shən/ n. The production of new types of organisms via rapid, discontinuous processes; used in opposition to the term gradualism. A human spermatozoon is about 0.005 mm (0.002 in) in length. A ring of muscle controlling passage of an orifice. A developmental defect characterized by failure of fusion of vertebral arches, with or without protrusion and dysplasia of the spinal cord or its membranes. Three spirochete genera, Borrelia, Leptospira, and Treponema, contain organisms that are important causative agents of human disease spiroscope /SPIGH-rō-skope/ n. The name is derived from the Latin term lusus naturae, "sport of nature," which expressed the idea that nature was in some way play a game and entertaining itself when it made new organisms in this way.

Saliva contains enzymes that begin the digestive process. salt Sodium chloride (Na Cl); more broadly, any chemical compound composed of a positive ion other than hydrogen, and a negative ion, other than the hydroxyl group. A biologist who believes evolution is a saltatory process. Generally, satellite DNA appears as separate bands because each band contains many copies of a specific highly repetitive sequence with a specific density due to its particular GC-to-AT ratio. During spermatogenesis, spermatozoa form in huge quantities within the seminiferous tubules of the testes. It has an oval, flattened head containing a haploid nucleus. MORE INFORMATION | PICTURE sphincter /SFING-ter/ n. In humans, it gives rise to all the nerves of the trunk and limbs. The prominence at the posterior extremity of a vertebra. A genus of helical microorganism belonging to the family Pseudomonadacea (Spirillum minus is the causative agent of rat-bite fever). Any member of Spirochaetes, a phylum of helical bacteria. splicing The process of joining adjacent exons after the removal of an intervening intron. Inflammation of, and resulting damage to, the vertebrae. A supposed process — that has never actually been observed — in which living things arise from nonliving matter. The term is usually applied to plants, but sometimes, especially in older literature, also to animals (for example, Darwin called the Ancon sheep a sport). Ejected saliva mixed with mucous and sometimes pus. The most diverse order of Class Reptilia; includes the lizards, snakes, and worm lizards. (1) (also: squamate) scale-covered, scaly; (2) scale-like (as in the cells of squamous epithelial tissue); (3) (also: squama) the anterior portion of either temporal bones in humans and many other mammals (PICTURE 1 | PICTURE 2).

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