GCSE Biology Comprehensive Revision

Comprehensive vocabulary flashcards covering the seven core units of GCSE Biology: Cell-Level Systems, Scaling Up and Organisation, Health, Disease and the Immune System, Coordination and Control, Photosynthesis and Bioenergetics, Inheritance, Variation and Evolution, and Ecosystems and Material Cycling.

Prokaryotes (Bacterial Cells)

Cells that are much smaller than eukaryotes and lack a true nucleus, possessing a single loop of DNA instead, along with plasmids, cytoplasm, a cell membrane, and sometimes flagella.

Magnification Formula

The relationship used to calculate magnification: $\text{Image size} = \text{Actual size} \times \text{Magnification}$ ($I = A \times M$).

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient; it is a passive process requiring no energy.

Osmosis

The diffusion of water molecules from a dilute solution (high water concentration) to a concentrated solution (low water concentration) across a partially permeable membrane.

Active Transport

The movement of substances against a concentration gradient (from low to high concentration), requiring energy released from respiration (e.g., mineral ion absorption in root hair cells).

Chromosomes

Structures found in the nucleus made of DNA molecules carrying genes; human body cells have 23 pairs ($46$ total).

Mitosis

A type of cell division that produces two identical daughter cells with the same number of chromosomes, used for growth, repair, and asexual reproduction.

Stem Cells

Undifferentiated cells that can divide to produce many more cells of the same type or differentiate into specialised cells.

Enzymes

Biological catalysts made of protein that speed up chemical reactions without being used up.

Active Site

The region on an enzyme where the specific substrate binds, possessing a complementary shape according to the lock and key model.

Denaturing

The disruption of an enzyme's 3D shape caused by high temperatures or incorrect pH, which changes the active site so that the substrate can no longer fit.

Amylase

A digestive enzyme produced in the salivary glands, pancreas, and small intestine that breaks down starch into sugars.

Protease

A digestive enzyme produced in the stomach, pancreas, and small intestine that breaks down proteins into amino acids.

Lipase

A digestive enzyme produced in the pancreas and small intestine that breaks down lipids into fatty acids and glycerol.

Bile

A substance produced in the liver and stored in the gall bladder that neutralises stomach acid and emulsifies fats to increase their surface area.

Arteries

Blood vessels with thick walls and a narrow lumen that carry blood away from the heart under high pressure.

Veins

Blood vessels with thin walls, a wider lumen, and valves to prevent backflow, carrying blood back to the heart under low pressure.

Capillaries

Microscopic blood vessels that are one cell thick to permit the rapid exchange of substances (oxygen, glucose, waste) with body tissues.

Xylem

Plant vascular tissue made of dead cells strengthened with lignin that transports water and mineral ions upwards from the roots to the stem and leaves.

Phloem

Plant transport tissue made of living cells with sieve plates that carries dissolved sugars made by photosynthesis from the leaves to the rest of the plant (translocation).

Transpiration

The evaporation of water from plant leaves through the stomata, which pulls more water upwards through the xylem.

Phagocytosis

The process by which white blood cells defend the body by engulfing and digesting pathogens.

Vaccination

The introduction of dead or inactive forms of a pathogen to stimulate white blood cells to produce specific antibodies, creating memory cells that trigger a rapid secondary immune response upon reinfection.

Synapse

A junction between neurones across which chemical neurotransmitters diffuse to pass nerve impulses.

Reflex Action

A rapid, automatic response to a stimulus that bypasses conscious control from the brain to protect the body from harm.

Homeostasis

The regulation of internal conditions of a cell or body to maintain optimum conditions for function in response to internal and external changes.

Negative Feedback

A regulatory control system that detects a change in conditions and responds by opposing that change to return levels to normal.

Photosynthesis

An endothermic reaction that uses light energy to convert carbon dioxide and water into glucose and oxygen: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.

Aerobic Respiration

An exothermic reaction occurring continuously in living cells that uses oxygen to release a large amount of energy: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$.

Fermentation

Anaerobic respiration in plant and yeast cells that converts glucose into ethanol and carbon dioxide ($\text{Glucose} \rightarrow \text{Ethanol} + \text{Carbon dioxide}$), used in bread and alcohol production.

Gene

A small section of DNA on a chromosome that codes for a specific sequence of amino acids to make a protein.

Genome

The entire genetic material of an organism.

Allele

Different versions of the same gene.

Phenotype

The physical characteristics or appearance expressed by an organism.

Genotype

The genetic makeup of an organism, representing its allele combination.

Natural Selection

The process whereby organisms with characteristics best suited to their environment are more likely to survive, reproduce, and pass on their advantageous alleles.

Genetic Engineering

Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.

Community

Populations of different species living in a habitat and depending on each other (interdependence).

Abiotic Factors

Non-living components of an ecosystem, such as temperature, light intensity, moisture levels, and soil pH.

Biotic Factors

Living components of an ecosystem, such as food availability, predators, pathogens, and competition.

Biodiversity

The variety of all different species of organisms on Earth; high biodiversity ensures ecosystem stability.