Science Revision

Vocabulary flashcards covering core scientific concepts including chemical reactions, the pH scale, experimental variables, evolutionary mechanisms, Newton's laws of motion, genetics, and motion kinematics.

Reactants

The chemicals reacting together in a chemical reaction to form something new.

Products

The chemicals that are produced at the end of a chemical reaction.

The pH Scale

A scale extending from $0$ to $14$ used to measure acidity and alkalinity, where $0\text{--}6$ is acidic, $7$ is neutral, and $8\text{--}14$ is basic (alkaline).

Neutralisation Reaction

A reaction where an acid and a base react to form a salt and water ($\text{acid} + \text{base} \rightarrow \text{salt} + \text{water}$) without producing bubbles.

Acid + Metal Reaction

A reaction in which an acid reacts with a metal to produce a salt and hydrogen gas ($\text{acid} + \text{metal} \rightarrow \text{salt} + \text{hydrogen gas}$), visually indicated by bubbles of hydrogen gas.

Independent Variable

The variable that the experimenter deliberately changes (represented by $x$ in "If I change $x$, what will happen to $y$?").

Dependent Variable

The variable that is measured in an experiment to observe the effect of changes (represented by $y$ in "If I change $x$, what will happen to $y$?").

Controlled Variables

The factors kept constant across repeated trials to ensure an experiment is valid.

Divergent Evolution

The evolutionary process where related species that have separated into different environments evolve different features.

Convergent Evolution

The evolutionary process where unrelated species evolve to suit similar environments, resulting in similar features such as streamlined bodies and fins.

Parallel Evolution

The evolutionary pattern where species in different environments evolve while maintaining the same level of similarity.

Newton's First Law

An object at rest will remain at rest unless acted upon by a force, and an object that is moving will continue to move at the same speed and in the same direction unless an unbalanced force acts upon it.

Newton's Second Law

The principle stating that the force acting on an object is equal to the mass of the object multiplied by its acceleration ($F = m \times a$).

Newton's Third Law of Motion

For every action, there is an equal and opposite reaction; if object A exerts a force on object B, object B exerts an equal and opposite force on object A.

Scalar Quantities

Physical measurements that possess numbers and units where only magnitude is important, such as length, temperature, and time.

Vector Quantities

Physical measurements that have numbers, units, and a direction, where both magnitude and direction are important (e.g., acceleration, displacement, and force).

Nucleotide

The repeating subunit and building block of DNA, consisting of a pentose sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base (A, T, C, or G).

Dominant Trait

The trait that always shows up in the appearance when present and is designated by a capital letter.

Recessive Trait

The trait that is hidden in the presence of a dominant allele and is designated by a lower-case letter.

Phenotype

The physical appearance that results from the interaction of two alleles.

Genotype

The specific combination of alleles that an individual organism possesses.

Homozygous

A genotype description indicating that the two alleles are identical (either both dominant or both recessive).

Heterozygous

A genotype description indicating that two different alleles are present (one dominant and one recessive).

Punnett Square

A grid tool used to determine the probabilities of possible genotypes and phenotypes of offspring using known parent genotypes.

Mutation

A change in the DNA sequence that can occur during mitosis or protein synthesis, which can be inherited if it occurs in sex cells.

Substitution Mutation

A DNA mutation in which one nitrogenous base in the sequence is replaced by another base.

Insertion Mutation

A DNA mutation in which an extra base is added into the sequence.

Deletion Mutation

A DNA mutation in which one base is removed from the sequence.

Mitosis

A form of cell division in somatic cells involving $4$ stages (plus interphase) for cellular proliferation, producing $2$ genetically identical diploid daughter cells.

Meiosis

A form of cell division in germ cells involving $8$ stages (plus interphase) for sexual reproduction, producing $4$ genetically diverse haploid daughter cells with half the original chromosome number.

Archaeopteryx

A fossil organism that acts as a transitional species between feathered dinosaurs and modern avian birds.

Homologous Structures

Similar anatomical structures found in different organisms that indicate common ancestry.

Pentadactyl Limb

A limb structure featuring five digits that is characteristic of tetrapod vertebrates including amphibians, reptiles, birds, and mammals.

Comparative Embryology

The study and comparison of early developmental stages of different organisms, demonstrating similarities such as gill slits and tails in all vertebrate embryos.

Vestigial Structures

Anatomical structures found in an organism that are no longer in functional use but may have been useful at an earlier stage in evolutionary history (e.g., human tailbones, whale pelvis and femur).

Adaptation

An inherited characteristic that increases an organism's ability to survive and reproduce in its environment.

Accuracy

How close experimental results are to the true or correct value, improved by using the most precise measuring tools.

Validity

How suitable an experimental procedure is for fulfilling the aim, achieved by controlling all external variables as much as possible.

Reliability

The degree to which similar results are obtained across similar trials, achieved by repeating the experiment multiple times.

Subscript

A number attached to the bottom right of an element symbol indicating the quantity of that specific atom within the molecule.

Collision Theory

A theory stating that for a chemical reaction to occur, reacting particles must collide with one another.

Catalyst

A substance that affects the rate of a chemical reaction, where a positive catalyst increases the reaction rate and a negative catalyst reduces it.

Neutral Atom

An atom that has an equal number of positively charged protons and negatively charged electrons, canceling each other out to yield no overall net charge.

Compound

A chemical substance composed of two or more elements chemically combined in fixed proportions, classified as either ionic or covalent.

Velocity

A vector quantity defined as the rate of change of displacement travelled by an object ($\text{velocity} = \frac{\text{displacement}}{\text{time}}$), expressed with both magnitude and direction.