UPMSP High School Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Combination reaction

A reaction in which two or more reactants combine to form a single product, such as calcium oxide reacting with water to give calcium hydroxide with the release of heat.

Decomposition reaction

A reaction in which one compound breaks down into two or more simpler substances, usually driven by heat, light, or electricity, as when calcium carbonate is heated to lime and carbon dioxide.

Redox reaction

A reaction in which oxidation and reduction occur together: one substance loses electrons or gains oxygen while another gains electrons or loses oxygen, as in the reaction of copper oxide with hydrogen.

Rancidity

The oxidation of fats and oils in stored food, producing unpleasant smell and taste; it is slowed by antioxidants, airtight containers, and flushing packets with nitrogen.

pH scale

A 0 to 14 scale measuring hydrogen ion concentration; values below 7 are acidic, 7 is neutral, and above 7 are basic, with each unit representing a tenfold change in concentration.

Neutralisation reaction

The reaction of an acid with a base to produce salt and water, releasing heat, for example hydrochloric acid reacting with sodium hydroxide to give sodium chloride and water.

Chlor-alkali process

Electrolysis of concentrated sodium chloride solution producing chlorine at the anode and hydrogen and sodium hydroxide at the cathode, all three being industrially useful products.

Plaster of Paris

Calcium sulphate hemihydrate, CaSO4·½H2O, made by heating gypsum to about 373 K; mixed with water it sets into a hard solid used for casts and decorative moulds.

Reactivity series

A list of metals ordered by decreasing chemical reactivity, from potassium and sodium down to gold, used to predict displacement reactions and the method of extracting a metal.

Amphoteric oxide

A metal oxide that reacts with both acids and bases to form salts, such as aluminium oxide and zinc oxide, behaving as a base with acid and as an acid with base.

Catenation

The ability of an element, especially carbon, to bond with atoms of itself forming long chains and rings, which explains the very large number of carbon compounds.

Esterification

The reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst to form an ester and water; esters have sweet fruity smells used in perfumes.

Micelle

A spherical cluster formed in water by soap molecules, with hydrocarbon tails pointing inward trapping grease and ionic heads pointing outward interacting with water.

Photosynthesis

The process in green plants using chlorophyll and sunlight to convert carbon dioxide and water into glucose and oxygen, occurring mainly in the chloroplasts of leaf cells.

Double circulation

Blood passing twice through the heart in one complete circuit: pulmonary circulation to the lungs and systemic circulation to the body, keeping oxygenated and deoxygenated blood separate.

Nephron

The functional filtering unit of the kidney, where blood is filtered under pressure in the glomerulus and useful substances are selectively reabsorbed along the tubule.

Reflex arc

The pathway of a reflex action: receptor, sensory neuron, spinal cord relay, motor neuron, and effector muscle, producing a rapid response without waiting for the brain.

Auxin

A plant growth hormone produced at the shoot tip that promotes cell elongation; it accumulates on the shaded side, bending the shoot toward light in phototropism.

Insulin

A hormone secreted by the pancreas that lowers blood glucose by promoting its uptake and storage; its deficiency causes diabetes mellitus with sugar in the urine.

Binary fission

A form of asexual reproduction in which a single-celled organism divides into two daughter cells, each receiving a copy of the genetic material, as in Amoeba.

Vegetative propagation

Asexual reproduction in plants from vegetative parts such as stem, root, or leaf; examples include potato tubers, sugarcane stem cuttings, and buds on Bryophyllum leaves.

Placenta

A disc-like tissue joining the embryo to the uterine wall, allowing glucose and oxygen to pass from the mother's blood and wastes to be removed.

Mendel's segregation law

The two alleles of a gene separate during gamete formation so that each gamete carries only one allele, which reunites randomly at fertilisation.

Homologous organs

Organs with the same basic structure and origin but different functions, such as the forelimbs of humans, whales, and bats, giving evidence of common ancestry.

Sex determination

In humans, the child's sex is set by the father's gamete: an X-bearing sperm gives a girl and a Y-bearing sperm gives a boy.

Concave mirror image rule

A concave mirror gives a real, inverted image when the object is beyond the focus, and a virtual, erect, magnified image when the object lies between the pole and the focus.

Refractive index

The ratio of the speed of light in vacuum to its speed in a medium, also equal to the ratio of the sine of the angle of incidence to the sine of the angle of refraction.

Lens power

The reciprocal of the focal length of a lens measured in metres, expressed in dioptres; a convex lens has positive power and a concave lens negative power.

Dispersion of light

The splitting of white light into its component colours when passing through a prism, because each colour has a different refractive index and bends by a different amount.

Myopia

Short-sightedness in which distant objects appear blurred because the image forms in front of the retina; it is corrected by a concave lens of suitable negative power.

Ohm's law

At constant temperature, the current through a metallic conductor is directly proportional to the potential difference across its ends, giving the relation V equals I times R.

Electric power

The rate at which electrical energy is transferred, given by P equals V times I, or I squared times R, or V squared divided by R, measured in watts.