DAT Natural Sciences flashcards

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

Hardy-Weinberg equilibrium

A population-genetics model in which allele and genotype frequencies remain constant across generations when there is no mutation, migration, selection, or genetic drift and mating is random.

Michaelis constant Km

The substrate concentration at which an enzyme works at half its maximum velocity; a low Km indicates high substrate affinity, and competitive inhibitors raise the apparent Km.

Bohr effect

The shift of the oxygen-hemoglobin dissociation curve to the right when CO2 rises, pH falls, or temperature increases, reducing hemoglobin's affinity for oxygen and enhancing tissue delivery.

Gibbs free energy

A thermodynamic quantity given by ΔG = ΔH − TΔS; a negative ΔG means the reaction releases free energy and proceeds spontaneously under the stated conditions.

Henderson-Hasselbalch equation

pH = pKa + log([A−]/[HA]); it relates buffer pH to the ratio of conjugate base to weak acid and shows maximum buffering near pH = pKa.

Dihybrid cross ratio

The 9:3:3:1 phenotypic ratio in the F2 generation of a cross between two heterozygotes at two independently assorting loci, assuming complete dominance.

Na+/K+ ATPase

A membrane pump that uses ATP to move three sodium ions out and two potassium ions into the cell, maintaining electrochemical gradients and contributing to membrane potential.

Cell cycle checkpoints

Control points at G1/S, G2/M, and metaphase that verify DNA integrity, replication completion, and spindle attachment before the cell proceeds to the next phase.

Newton's second law

F = ma; the net force on an object equals its mass times acceleration, and acceleration is directly proportional to net force and inversely proportional to mass.

Angle ranking strategy

Judge angles by the width of the aperture between the two lines, not by line length; longer lines can make a small angle appear smaller.

Cube counting hidden cubes

Every cube above ground level must be supported by a cube directly beneath it; count visible faces on the surface and add the hidden supporting cubes in each column.

Hole punching reflection rule

Each fold reflects holes across the crease line; to solve, unfold in reverse order, mirroring every hole across the crease created by the corresponding fold.

Opposite faces on a net

In a cube net, faces separated by exactly one face in a straight line, or lying in the alternating pattern, end up opposite each other when folded.

Orthographic projection layout

A standard multi-view drawing places the top view above the front view and the right-side view to the right; features align along shared projection lines across views.

Pattern folding mark orientation

When folding a net into a 3D object, a distinctive mark must retain its orientation relative to adjacent faces; marks cannot cross fold lines.

Aperture width perception

Human vision tends to underestimate small angles and overestimate large ones; comparing apertures directly rather than line lengths improves accuracy.

Hidden line in a view

A dashed line in an orthographic view marks an edge that is not directly visible from that direction, usually because another surface occludes it.

Main idea question

A reading question asking for the passage's central claim; the correct answer must cover the whole passage, while too-narrow or too-broad choices are wrong.

Author's tone

The attitude conveyed by word choice and qualifiers; evaluative adjectives and hedges such as 'arguably' or 'unfortunately' reveal the author's stance toward the subject.

Inference question

A question requiring a conclusion that follows logically from the passage; the answer must be supported by the text, not by outside knowledge or unsupported assumptions.

EXCEPT question

A question in which three choices are supported by the passage and one is not; verify each choice against a specific line to find the exception.

Paraphrase trap

A distractor that restates passage content while changing a key qualifier, such as swapping 'all' for 'some' or 'may' for 'will'.

Transition signals

Words such as 'however', 'therefore', and 'for example' that reveal argument structure; contrast signals often precede the author's main point.

Vocabulary in context

A question asking what a word means as used in the passage; test each choice by substituting it into the sentence and checking that the logic holds.

Comparison passage attribution

In paired passages, track which author holds each claim; the most common distractor attributes a view to the wrong author or blurs their disagreement.

Successive percent change

Percent changes multiply rather than add; a 20% increase followed by a 20% decrease yields a net 4% decrease, not zero change.

Average speed formula

Average speed equals total distance divided by total time; for a round trip at different speeds it is not the arithmetic mean of the two speeds.

Combined work rate

When two workers act together, their rates add: 1/t = 1/t1 + 1/t2, so the time together is the reciprocal of the sum of individual rates.

Probability addition rule

P(A or B) = P(A) + P(B) − P(A and B); for mutually exclusive events the intersection term is zero, so the probabilities simply add.

Pythagorean theorem

For a right triangle, a² + b² = c², where c is the hypotenuse; it is used to find missing side lengths and distances between points.

Exponent product rule

When multiplying powers with the same base, add the exponents: x^a · x^b = x^(a+b); when raising a power to a power, multiply: (x^a)^b = x^(ab).