Egypt STEM Schools Entrance Exam key terms

A symbol representing a quantity whose permitted values must follow the stated domain and the units of the problem rather than an unstated assumption.

The allowed inputs or values for a mathematical statement, including any restrictions from the context, a denominator, an even root or a count.

A claim that two expressions have equal values, whose solutions must make the original relation true and satisfy the declared restrictions.

A comparison describing values above or below a boundary, with inclusion or exclusion of the boundary indicated by the relation used.

A rule or relation assigning each permitted input exactly one output, distinguished from a general relation that may assign multiple outputs to one input.

The change in the vertical variable divided by the change in the horizontal variable between appropriate points on a nonvertical line.

Water chemical potential expressed relative to a defined pure-water reference, often in pressure units. Pure water at reference conditions is assigned zero; positive pressure can raise potential, and water moves toward lower potential.

The net movement of water across a partially permeable membrane from a region of higher water potential to one of lower water potential. It is passive and driven by the water potential gradient.

The component of water potential caused by dissolved solutes, always negative or zero. More concentrated solutions have more negative solute potentials and so attract water.

Shrinking of the protoplast away from the plant cell wall when a cell loses water in a hypertonic solution. It occurs because the protoplast contracts while the rigid wall stays in place.

Passive movement through membrane channels or carriers down an electrochemical gradient. The transport step does not directly hydrolyze ATP, although other processes may use energy to establish the gradient.

Energy-coupled movement against an electrochemical gradient. Primary transport can use ATP directly; secondary transport uses a gradient established by another energy-dependent process.

The number of protons in the nucleus of an atom, which uniquely identifies the element. In a neutral atom it also equals the number of electrons.

The total count of protons plus neutrons in one atom's nucleus. It is a whole number written as a superscript beside the element symbol and differs between isotopes.

One of two or more atoms of the same element that have equal proton counts but different neutron counts, so they differ in mass while sharing nearly identical chemical behaviour.

The weighted average mass of an element's atoms compared with one-twelfth the mass of a carbon-12 atom, taking natural isotopic abundance into account. It is dimensionless and rarely a whole number.

The rule that electrons occupy the lowest-energy available orbitals first when an atom is built up, giving the familiar 1s 2s 2p 3s filling order and the ground-state configuration.

The arrangement of an atom's electrons among its shells, subshells and orbitals, usually written with superscripts such as 1s2 2s2 2p6. It governs chemical behaviour and position in the periodic table.

The way a verb phrase presents an event or state in relation to time, such as ongoing, completed or connected with the present.

A conventional combination of words whose natural use is learned in context, rather than created by substituting any dictionary synonym.

Language choices suited to the situation, audience, purpose and relationship, such as a formal request or an informal message to a friend.

A construction linking a condition with a result, whose forms help express real possibilities, imagined situations or unreal past events.

Creating a suitable grammatical word form, such as a noun or adjective, while preserving the meaning required by the complete sentence.

A conclusion reasonably supported by the given text, distinguished from a directly stated detail or an unrelated assumption based on outside knowledge.