coal v. charcoal

Coal is a dark brown to black rock formed when plant matter is buried and exposed to pressure over geologic time spans. Coal, which consists primarily of carbon, is a fossil fuel that is burned to generate electricity.

Like coal, charcoal is a solid black fuel made mostly of carbon. Charcoal is made by heating wood or other organic substances in the absence of air. Charcoal is also used in drawing, and to absorb odors, gases, and toxins. While coal is usually mined, charcoal is manufactured.

heat v. temperature

Moving Color temperature sensitive tiles. In thermodynamics, heat is the sum of a system’s molecular kinetic energy (arising from particle motion) and its potential energy (stored in its molecular bonds). Heat can be measured in joules, calories, or BTUs.

Temperature is the average kinetic energy of the particles in a substance. Several temperature scales are used throughout the world, including Kelvin, Celsius, and Fahrenheit.

The relationship between heat and temperature is analogous to the relationship between mass and density. A frozen lake (with many slow-moving molecules) contains more heat (and mass) than a hot cup of coffee (with relatively few, fast-moving molecules), but the temperature (and coincidentally, because ice floats, the density) of the coffee is higher.

Under most circumstances, adding heat to a system increases the kinetic energy of its molecules, thereby increasing its temperature. However, when a substance undergoes a phase change (from solid to liquid, or from liquid to gas), the temperature remains constant while the added heat is used to break the molecular bonds.

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resin v. rosin

Resins are clear, yellowish, viscous liquids secreted by plants, especially conifers. Natural resins are primarily hydrocarbons, and are insoluble in water. Synthetic compounds that set into a lacquer-like finish are also called resins. Resins are used in the production of varnish, adhesive, perfume, and incense.

Rosin is a type of solid pine resin obtained by distilling turpentine to remove the oils. Rosin is applied to the bows of stringed instruments, ballet shoes, and gymnasts’ palms to increase friction. Rosin is also used as soldering flux, and is the primary ingredient in mystic smoke.

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vitamins v. minerals

Vitamins

Vitamins are organic (carbon containing) compounds required in minute amounts to sustain normal metabolism. They can not be synthesized in the body, and must be ingested as part of the diet. Vitamins are known by letter names, and are either fat-soluble (vitamins A, D, E, and K) or water-soluble (the vitamin B complex and vitamin C). The recommended dietary allowance of most vitamins ranges from a few micrograms to a few milligrams.

Examples

• Vitamin A, which is found in fish-liver oils, is needed for night vision.
• Vitamin K promotes blood clotting, and can be obtained from leafy green vegetables.

Minerals

Like vitamins, dietary minerals are essential nutrients needed in small quantities for physiological processes, but minerals are simple inorganic chemical elements, not complex organic molecules. Some minerals, such as calcium, sodium, chlorine, and potassium, have RDAs up to several grams. Carbon, hydrogen, nitrogen, and oxygen aren’t considered minerals because they are required in large quantities, not trace amounts, and because they are the constituents of organic molecules.

Examples

• Magnesium is involved in processing adenosine triphosphate. Nuts, soy beans, and chocolate are good sources of magnesium.
• Iron deficiency can result in anemia. Iron is found in red meat, eggs, and oysters.

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DNA v. RNA

A shopping cart model of DNA by Abigail Fallis. DNA (deoxyribonucleic acid) stores the genetic information necessary to maintain and propagate life, and is the main component of chromosomes. DNA is an extremely long, self-replicating molecule consisting of two nucleotide strands coiled around one another in a double helix.

RNA (ribonucleic acid) refers to a group of single-stranded nucleic acids involved in protein synthesis. Messenger RNA carries a transcribed copy of a DNA sequence from the nucleus to the ribosomes, which assemble proteins. Transfer RNA is a small RNA molecule that delivers amino acids to the ribosomes for incorporation into proteins. Ribosomal RNA is a structural element of the ribosomes themselves.

• DNA is usually double-stranded and RNA is usually single-stranded.
• The sugar in the backbone of DNA is deoxyribose; in RNA, ribose is used instead.
• The four chemical bases found in DNA are adenine, cytosine, guanine, and thymine. Thymine is replaced with uracil in RNA.
• RNA is shorter than DNA, and comes in a variety of shapes.
• In eukaryotes, DNA remains within the nucleus, or in some organelles. RNA carries information from the nucleus to the ribosomes.
• While almost all organisms use DNA to encode their genetic information, the majority of viruses have RNA genomes.

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