GCSE (9-1) Combined Science Vocabulary Review

Comprehensive vocabulary flashcards covering the key concepts in Biology, Chemistry, and Physics as defined by the Pearson Edexcel Level 1/Level 2 GCSE (9-1) Combined Science specification.

Nucleus (Animal cell)

A sub-cellular structure that contains the genetic material of the cell.

Mitochondria

Sub-cellular structures where aerobic respiration occurs to release energy.

Ribosomes

Sub-cellular structures responsible for the synthesis of proteins.

Chloroplasts

Structures in plant cells that contain chlorophyll for photosynthesis.

Vacuole

A structure in plant cells that stores cell sap.

Plasmid DNA

Small loops of extra DNA found in bacteria cells.

Flagella

Tail-like structures in bacteria used for movement.

Acrosome

A structure in the head of a sperm cell containing enzymes to penetrate an egg cell.

Haploid

A cell or nucleus that contains half the number of chromosomes, such as a gamete.

Ciliated epithelial cells

Specialised cells with hair-like cilia that move substances along surfaces.

Milli

A quantitative unit prefix represented as $10^{-3}$.

Micro

A quantitative unit prefix represented as $10^{-6}$.

Nano

A quantitative unit prefix represented as $10^{-9}$.

Pico

A quantitative unit prefix represented as $10^{-12}$.

Enzyme

A biological catalyst that speeds up reactions in the synthesis or breakdown of substances.

Denatured

A state where an enzyme's active site changes shape, preventing successful substrate binding.

Mitosis

Cell division resulting in two genetically identical diploid body cells for growth and repair.

Cytokinesis

The final stage of the cell cycle where the cell divides into two daughter cells.

Cancer

A result of changes in cells that lead to uncontrolled cell division.

Differentiation

The process by which cells become specialised for a specific function.

Stem cells

Undifferentiated cells that have the capacity to divide and differentiate into specialized cells.

Meristems

Areas in plants containing stem cells for growth and development.

Neurotransmitters

Chemicals that transmit electrical impulses across a synapse between neurones.

Reflex arc

The pathway of neurones (sensory, relay, and motor) involved in a rapid, automatic response.

DNA

A polymer made of two strands coiled to form a double helix, linked by complementary base pairs.

Genome

The entire DNA content of an organism.

Gene

A section of a DNA molecule that codes for a specific protein.

Zygote

The diploid cell formed by the fusion of two haploid gametes at fertilisation.

Charles Darwin

Scientist who developed the theory of evolution by natural selection.

Ardi

Fossil evidence for human evolution dating from $4.4$ million years ago.

Lucy

Fossil evidence for human evolution dating from $3.2$ million years ago.

Richard Leakey

Scientist who discovered human evolution fossils dating from $1.6$ million years ago.

Genetic Engineering

The process of modifying the genome of an organism to introduce desirable characteristics.

Pathogen

A disease-causing organism including viruses, bacteria, fungi, and protists.

BMI (Body Mass Index)

A measurement calculated using the formula: $\text{BMI} = \frac{\text{mass (kg)}}{(\text{height (m)})^2}$.

Photosynthesis

An endothermic reaction in plants and algae that uses light energy to produce glucose and oxygen.

Transpiration

The transport of water and mineral ions through a plant from roots to stomata.

Translocation

The transport of sucrose around a plant through the phloem.

Hormone

A chemical messenger produced by endocrine glands and transported in the blood to target organs.

Insulin

A hormone produced by the pancreas that controls blood glucose concentration.

Glucagon

A hormone that regulates blood glucose levels by stimulating the liver to release glucose.

Homeostasis

The maintenance of a constant internal environment in response to internal and external changes.

Aerobic Respiration

An exothermic reaction occurring in cells that uses oxygen to release energy for metabolic processes.

Anaerobic Respiration

A type of cellular respiration that occurs without oxygen, releasing less energy than aerobic respiration.

Ecosystem

A community of organisms interacting with each other and their abiotic environment.

Dmitri Mendeleev

Scientist who arranged elements in the periodic table by properties and predicted undiscovered elements.

Isotopes

Different atoms of the same element containing the same number of protons but different numbers of neutrons.

Relative Atomic Mass

The weighted average mass of an element's isotopes relative to $1/12$th of the mass of carbon-12.

Covalent Bond

A chemical bond formed when a pair of electrons is shared between two atoms.

Mole

A unit of measurement representing $6.02 \times 10^{23}$ particles (the Avogadro constant).

Empirical Formula

The simplest whole-number ratio of atoms of each element in a compound.

Exothermic

A chemical change or reaction in which heat energy is given out to the surroundings.

Endothermic

A chemical change or reaction in which heat energy is taken in from the surroundings.

Activation Energy

The minimum energy required for a chemical reaction to occur.

Hydrocarbon

A compound that contains carbon and hydrogen atoms only.

Homologous Series

A series of compounds with the same general formula and similar chemical properties.

Cracking

The process of breaking down larger, saturated hydrocarbons into smaller, more useful ones.

Scalar Quantity

A physical quantity that has magnitude (size) but no specific direction.

Vector Quantity

A physical quantity that has both magnitude and a specific direction.

Acceleration

The rate of change in velocity, calculated as $\text{a} = \frac{\text{v} - \text{u}}{\text{t}}$.

Newton’s Second Law

The force on an object is equal to its mass multiplied by its acceleration ($F = m \times a$).

Weight

The force acting on a body due to the gravitational field strength ($W = m \times g$).

Momentum

A property of a moving object calculated as $\text{p} = \text{mass} \times \text{velocity}$.

Conservation of Energy

The principle that energy cannot be created or destroyed, only transferred or dissipated.

Longitudinal Wave

A wave where the oscillations are parallel to the direction of energy transfer, such as sound.

Transverse Wave

A wave where the oscillations are perpendicular to the direction of energy transfer, such as light.

Alpha Particle (\alpha)

A type of ionising radiation equivalent to a helium nucleus.

Half-life

The time taken for half of the undecayed nuclei in a radioactive isotope sample to decay.

Potential Difference

The energy transferred per unit charge passed, measured in volts ($V$).

Resistance

The measure of opposition to current flow in a circuit, defined by $V = I \times R$.

Specific Heat Capacity

The energy needed to raise the temperature of $1\,\text{kg}$ of a substance by $1\,^{\circ}\text{C}$.

Absolute Zero

The theoretical temperature at which particles lack all movement, valued at $-273\,^{\circ}\text{C}$.

Spring Constant

The measure of a spring's stiffness, defined as the force per unit extension ($k = F \div x$).