BJC General Science flashcards
BJC General Science · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hypothesis
- A testable, falsifiable prediction about the relationship between variables, stated before the experiment begins so that results can support or reject it.
- Control group
- The group in an experiment that receives no treatment or a placebo, providing a baseline against which the experimental group's results are compared.
- Dependent variable
- The variable that is measured or observed in an experiment; its value depends on the changes made to the independent variable.
- Density
- The mass of a substance per unit volume, calculated as mass divided by volume and measured in grams per cubic centimetre or kilograms per cubic metre.
- Meniscus reading
- The curved surface of a liquid in a measuring cylinder; read its lowest point at eye level to avoid parallax error and obtain an accurate volume.
- Filtration
- A separation technique that passes a mixture through filter paper, trapping an insoluble solid as residue while the liquid filtrate passes through.
- Distillation
- A separation method that boils a liquid mixture and condenses the vapour, recovering the solvent separately from dissolved solids or liquids with different boiling points.
- Chromatography
- A technique separating dissolved substances by their differing solubilities, causing them to travel different distances up a stationary paper or gel.
- Osmosis
- The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to one of lower water concentration.
- Enzyme
- A protein biological catalyst that speeds up reactions; each enzyme has an optimum temperature and pH and is denatured by high temperature.
- Photosynthesis equation
- Carbon dioxide plus water, using light energy absorbed by chlorophyll, produces glucose and oxygen inside plant chloroplasts.
- Alveoli
- Tiny air sacs in the lungs where gas exchange occurs; their thin walls, large surface area, and rich blood supply maximise oxygen and carbon dioxide transfer.
- Double circulation
- A circulatory system in which blood passes through the heart twice per circuit, once to the lungs and once to the body.
- Insulin
- A hormone released by the pancreas that lowers blood glucose by stimulating cells to absorb glucose and the liver to store it as glycogen.
- Dominant allele
- An allele that is expressed in the phenotype even when only one copy is present, masking the effect of a recessive allele.
- Genotype
- The combination of alleles an organism carries for a particular gene, such as homozygous dominant, heterozygous, or homozygous recessive.
- Punnett square
- A grid diagram crossing the possible gametes of two parents to predict the genotypes and phenotype ratios of their offspring.
- Food chain
- A sequence showing the transfer of energy from a producer through primary and secondary consumers, with arrows indicating energy flow direction.
- Eutrophication
- Nutrient runoff into water causes algal blooms; decomposing algae use up oxygen, suffocating fish and other aquatic organisms.
- Bioaccumulation
- The build-up of persistent toxins in organisms over time, becoming more concentrated at each higher trophic level of a food chain.
- Resultant force
- The single force equivalent to all forces acting on an object combined; a zero resultant means balanced forces and unchanged motion.
- Kinetic energy
- The energy an object possesses due to its motion, calculated as one half multiplied by mass multiplied by velocity squared.
- Ohm's law
- The current through a conductor is directly proportional to the voltage across it, provided temperature remains constant; expressed as V equals I times R.
- Parallel circuit
- A circuit in which components are connected in separate branches, so each receives the full supply voltage and current splits between them.
- Electromagnet
- A temporary magnet created by passing current through a coil of wire, often around an iron core; strength increases with more turns and higher current.
- Igneous rock
- Rock formed when molten magma or lava cools and solidifies, either slowly underground producing large crystals or rapidly at the surface producing small crystals.
- Seasons
- Annual variations in daylight and temperature caused by Earth's tilted axis as it orbits the Sun, not by changes in distance from the Sun.
- Neutralisation
- A reaction between an acid and a base producing a salt and water, bringing the pH of the mixture closer to neutral.
- pH scale
- A scale from 0 to 14 measuring acidity or alkalinity; below 7 is acidic, 7 is neutral, above 7 is alkaline, with each step a tenfold change.
- Conservation of mass
- In a chemical reaction, the total mass of reactants equals the total mass of products because atoms are rearranged, not created or destroyed.
- Peer review
- Independent experts examine a study's methods, data, and conclusions before publication, helping to identify errors and improve scientific reliability.
- Correlation and causation
- A correlation shows two variables change together, but it does not prove one causes the other; controlled experiments are needed to establish cause.