Combined Science GCSE (June 2015) - Vocabulary Flashcards

Vocabulary flashcards covering key terms across biology, chemistry and physics from the GCSE Combined Science subject content (June 2015).

Prokaryotic cell

A simple cell without a true nucleus, e.g., bacteria, whose DNA is not enclosed in a membrane.

Eukaryotic cell

A cell with a true nucleus and membrane‑bound organelles, e.g., plant and animal cells.

Nucleus

The organelle that contains genetic material (DNA) and controls cell activities.

Plasmids

Small circular DNA molecules found in prokaryotes that can carry extra genes.

Mitochondria

Organelles where aerobic respiration occurs to release energy (ATP) in cells.

Chloroplasts

Organelles in plant cells where photosynthesis occurs, containing chlorophyll.

Cell membrane

The phospholipid bilayer that encloses a cell and controls what enters and leaves.

Mitosis

Cell division that results in two genetically identical diploid daughter cells.

Cancer

Uncontrolled cell growth caused by changes in cells.

Stem cells

Cells that can differentiate into other cell types and have potential for medicine.

Meiosis

Cell division that halves the chromosome number to form gametes.

Enzyme

Biological catalyst that speeds up a reaction without being consumed.

Active site

The region of an enzyme where a specific substrate binds.

Substrate

The molecule that binds to an enzyme's active site to undergo a reaction.

Cellular respiration

Metabolic process that releases energy from glucose in cells.

Aerobic respiration

Respiration that uses oxygen to release energy efficiently.

Anaerobic respiration

Respiration without oxygen, producing less energy and often lactic acid or ethanol.

Photosynthesis

Process by which green plants convert light energy into chemical energy (glucose).

Glucose

A simple sugar that is a key source of energy in respiration.

DNA

Deoxyribonucleic acid, the molecule that carries genetic information.

Genome

The complete set of genetic material in an organism.

Allele

Different forms of the same gene at a particular locus.

Dominant

An allele that determines the phenotype even if only one copy is present.

Recessive

An allele that only determines the phenotype if two copies are present.

Genotype

The genetic makeup of an organism (its combination of alleles).

Phenotype

The observable characteristics of an organism resulting from genes and environment.

Mutation

A change in DNA which may lead to variation or different traits.

Natural selection

Process by which organisms with advantageous traits tend to survive and reproduce.

Fossils

Preserved remains or traces of organisms from the past used as evidence for evolution.

Antibiotic resistance

When bacteria evolve to survive antibiotic treatment, reducing drug effectiveness.

Biodiversity

The variety of life in a particular habitat or on Earth as a whole.

Selective breeding

Breeding animals or plants for desirable traits over generations.

Genetic engineering

Modifying an organism’s genome to introduce desirable traits.

Diffusion

Movement of molecules from high to low concentration across a membrane or space.

Osmosis

Diffusion of water through a selectively permeable membrane from high to low water potential.

Active transport

Movement of substances against a concentration gradient requiring energy.

Surface area:volume ratio

Relation between surface area and volume that affects exchange efficiency.

Xylem

Plant tissue that transports water and minerals from roots to shoots; supports structure.

Phloem

Plant tissue that transports sugars from photosynthetic tissues to where needed.

Transpiration

Loss of water from a plant through stomata, drawing water up the plant.

Translocation

Transport of sugars in plants through the phloem from sources to sinks.

Root hair cell

Specialized plant cell with thin walls and root hairs for water uptake.

Red blood cell (RBC)

Blood cell that carries oxygen via haemoglobin.

White blood cell (WBC)

Blood cell involved in immune defense.

Platelets

Blood cell fragments that help blood clotting.

Plasma

Liquid component of blood that carries cells and dissolved substances.

Circulatory system

System that circulates blood and transports nutrients, gases and wastes.

Arteries/Veins/Capillaries

Blood vessels with distinct roles in carrying blood to and from the heart.

Gaseous exchange system

Biological system where gases (O2/CO2) are exchanged between air and blood.

Nervous coordination

Regulation of body activities via the nervous system.

Endocrine system

System that uses hormones to regulate body processes.

Hormone

Chemical messenger produced by glands that regulates body functions.

Negative feedback

A control mechanism where a change triggers a response to reverse it.

Menstrual cycle

Regular hormonal cycle in females, involving FSH, LH, oestrogen and progesterone.

FSH/LH/Oestrogen/Progesterone

Key hormones regulating the menstrual cycle and reproduction.

Insulin

Hormone that lowers blood glucose levels; produced by the pancreas.

Glucagon

Hormone that raises blood glucose levels; works with insulin.

Diabetes (Type 1/Type 2)

Conditions affecting blood glucose regulation; Type 1 is autoimmune, Type 2 is lifestyle-related.

Homeostasis

Maintenance of a stable internal environment within narrow limits.

Photosynthesis rate factors

Temperature, light intensity and carbon dioxide concentration affect rate.

Endothermic

A reaction that absorbs heat from the surroundings.

Ecosystem

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

Carbon cycle

Natural cycling of carbon between living organisms, air, water and soil.

Water cycle

Hydrological cycle including evaporation, condensation, precipitation and collection.

Field investigation

A scientific activity carried out in the natural environment to study organisms or phenomena.

Genetic crosses

Mating experiments used to study inheritance patterns (e.g., Punnett squares).

Polygenic inheritance

Traits controlled by many genes leading to a range of phenotypes.

Force

A push or pull that can change an object's motion or shape.

Weight

Force due to gravity acting on a mass (weight = mass × g).

Free body diagram

A diagram showing all forces acting on an object.

Newton’s laws

Fundamental laws describing motion: inertia (1st), F = ma (2nd), action-reaction (3rd).

Fleming’s left‑hand rule

Rule to determine direction of force on a current-carrying conductor in a magnetic field.

Magnetic field

Region around a magnet where magnetic forces can act.

Electromagnetism

Interaction between electricity and magnetism; builds devices like motors.

Motor effect

Force on a current-carrying conductor in a magnetic field causing motion.

Wave

A transfer of energy through a medium or space without mass transport.

Transverse/Longitudinal waves

Orientation of particle motion relative to wave direction.

Electromagnetic spectrum

Range of EM waves from radio to gamma rays.

Frequency/Wavelength/Speed

Wave properties: frequency (Hz), wavelength (m), speed (m/s).

Light

Visible part of the electromagnetic spectrum; also an EM wave.

Ionising radiation

Radiation capable of ionising atoms, potentially hazardous (e.g., alpha, beta, gamma).

Radioactive decay/Half-life

Unstable nuclei decay over time; half-life is time for half to decay.

SI units

International System of Units used in science (m, kg, s, A, K, mol).

Empirical formula

Smallest whole-number ratio of atoms in a compound.

Molar mass/Avogadro constant

Mass per mole of substance; Avogadro constant relates amount of substance to number of particles.

Stoichiometry

Quantitative relationships in chemical reactions, using balanced equations.

Electrolysis

Splitting compounds using electrical energy at electrodes.

Anode/Cathode

Electrodes: anode is where oxidation occurs; cathode is where reduction occurs.

Oxidation/Reduction (Redox)

Loss/gain of electrons; oxidation is loss, reduction is gain.

Acid/Base; pH; Neutralisation

Acids donate H+, bases accept H; neutralisation forms salt and water.

Fractional distillation

Separation of a mixture into fractions based on boiling points.

Cracking

Breaking long-chain hydrocarbons into shorter, more useful ones.

Reactivity series

Rank of metals by tendency to form positive ions.

Life-cycle assessment

Evaluation of environmental impact of a material/product over its life.

Hydrocarbons

Compounds consisting of hydrogen and carbon, e.g., in crude oil.

Crude oil fractions

Different hydrocarbon mixtures separated by fractional distillation.

Carbon allotropes

Forms of carbon: diamond, graphite, graphene, fullerenes with different bonds.

Bond types (ionic/covalent/metallic)

Different ways atoms bond to form compounds; transfer or share electrons.

Molecular structure models

Ways to represent molecules (dot-and-cross, ball-and-stick) and their limits.

Conservation of mass

Mass remains constant in a closed system during a reaction.