AQA GCSE Biology Comprehensive Vocabulary Review (B1 - B9)

Vocabulary practice flashcards covering cell biology, organization, diseases, bioenergetics, and human physiology from AQA GCSE Biology Chapters B1 to B9.

Magnification

The degree to which an image appears larger than the actual object, calculated using the formula $\text{Magnification} = \frac{\text{Size of image}}{\text{Size of real object}}$.

Resolution (Resolving Power)

The ability to distinguish between two separate points that are very close to each other in order to observe fine details.

Prokaryotic Cell

A single-celled organism (such as a bacterium) whose genetic material is not enclosed inside a nucleus, containing plasmids and a single circular loop of bacterial chromosome free in the cytoplasm.

Eukaryotic Cell

A complex cell (such as plant, animal, fungal, or protist) whose genetic material ($\text{DNA}$) is enclosed within a distinct nuclear membrane.

Specialised Cell

A cell that has developed specific structural adaptations that enable it to perform a particular function.

Sperm Cell

A specialised male gamete containing a flagellum to swim to the egg, a middle section filled with mitochondria to transfer energy, an acrosome storing digestive enzymes, and a nucleus carrying male genetic information.

Differentiation

The developmental process by which an unspecialised cell acquires specific sub-cellular structures to perform a specialised function.

Diffusion

The net movement of particles from an area of higher concentration to an area of lower concentration along a concentration gradient, requiring no energy.

Osmosis

The movement of water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane without requiring energy.

Active Transport

The movement of substances from an area of lower concentration to an area of higher concentration (against a concentration gradient) via carrier proteins across a membrane, requiring cellular energy.

Mitosis

Nuclear cell division in which a diploid parent cell divides once to produce two genetically identical diploid daughter cells for growth, tissue repair, or asexual reproduction.

Cytokinesis

The final stage of the cell cycle during which the cytoplasm and cell membrane divide to form two separate, identical daughter cells.

Stem Cell

An undifferentiated cell that has the ability to divide and differentiate into specialized cell types within an organism.

Meristem

Undifferentiated plant tissue located in growing shoot and root tips capable of dividing by mitosis throughout the entire lifetime of the plant.

Therapeutic Cloning

A technique where an embryo is produced with the exact same genes as the patient, providing stem cells that can be grown into replacement tissues or organs without immune rejection.

Tissue

A group of specialized cells with similar structures and functions working together to carry out a specific activity.

Organ

A collection of several different tissue types working together to perform a specific physiological function.

Enzyme

A biological catalyst composed of protein that speeds up the rate of a chemical reaction by lowering its activation energy without being altered or consumed in the process.

Lock and Key Hypothesis

A model of enzyme action explaining that the enzyme active site has a specific, complementary shape that binds exclusively to its matching substrate, forming an enzyme-substrate complex.

Denatured Enzyme

An enzyme whose active site has permanently lost its specific three-dimensional conformation due to extremes in temperature or pH, rendering it unable to bind substrates.

Bile

An alkaline substance produced in the liver and stored in the gall bladder that neutralises acidic stomach chyme in the small intestine and emulsifies large lipid droplets into smaller droplets to increase the surface area for lipase.

Biuret Test

A chemical test for proteins using sodium hydroxide and copper sulfate solution; changes from blue to mauve/purple in the presence of protein.

Stent

A metal mesh tube inserted into a blocked coronary artery with a balloon to expand the lumen and ensure continuous blood flow to cardiac muscle cells.

Statins

A class of pharmaceutical drugs that reduce blood cholesterol levels, thereby slowing the deposition of fatty plaques inside coronary arteries.

Pacemaker

A cluster of specialized cells situated in the wall of the right atrium that regulates heart rate by transmitting continuous electrical impulses.

Transpiration

The loss of water vapour from plant leaves via evaporation through the stomata, driving a continuous transpiration stream of water and minerals up the xylem from the roots.

Xerophyte

A plant adapted to arid habitats with very little liquid water, possessing adaptations like spines, thick waxy cuticles, swollen water-storing stems, and stomata sunken in pits.

Human Respiratory System

The gas exchange system comprising the trachea, bronchi, branching bronchioles, and terminal microscopic alveoli where oxygen and carbon dioxide are exchanged with the blood.

Pathogen

A disease-causing microorganism, such as a bacterium, virus, protist, or fungus.

Vector

An organism, such as a female mosquito carrying Plasmodium, that transfers a pathogen from one host organism to another.

Zone of Inhibition

The clear area on an agar plate around an antibiotic or disinfectant paper disc where bacterial colonies cannot grow, reflecting the antimicrobial agent's effectiveness.

Chlorosis

A plant condition characterized by the yellowing of leaves and stunted growth due to a deficiency in magnesium ions ($\text{Mg}^{2+}$), which are essential for synthesizing chlorophyll.

Rose Black Spot

A plant disease caused by a fungus that creates purple or black spots on rose leaves, causing them to turn yellow and drop prematurely, which severely reduces photosynthesis.

Viral Replication

The cycle in which a non-living virus injects genetic material into a host cell, integrates it with the host's DNA to assemble copies of viral proteins, and bursts out, destroying the host cell.

Vaccine

A dead or inactive form of a pathogen administered to stimulate white blood cells to produce specific antibodies and develop immunological memory cells.

Herd Immunity

A high level of immunity within a population achieved when a large proportion is vaccinated, reducing the spread and protection of unvaccinated individuals from transmission.

Antibiotic Resistance

The ability of bacterial strains to survive therapeutic doses of antibiotics, arising through random mutations, natural selection, and overuse or uncompleted courses of antibiotics.

Penicillin

The first widely used antibiotic, discovered by Alexander Fleming from a mould contamination that produced a clear zone of bacterial inhibition on agar, later extracted by Howard Florey and Ernst Chain.

Hybridoma

A hybrid cell produced by fusing a mouse B lymphocyte (which produces specific antibodies) with a rapidly dividing myeloma (tumour) cell to produce monoclonal antibodies.

Monoclonal Antibodies

Identical antibodies produced from a single clone of cells, designed to bind specifically to a single target antigen on cells, hormones, or pathogens.

Double-Blind Trial

A clinical trial design in which neither the volunteer patients nor the administering doctors know who receives the real medication and who receives the placebo, preventing bias.

Benign Tumour

A localized mass of abnormal cells that remains contained within a single membrane and does not invade surrounding healthy tissues or spread to other parts of the body.

Malignant Tumour

An invasive, cancerous growth of abnormal cells that invades neighboring tissues and can shed cells into the bloodstream or lymphatic system to form secondary tumours.

Carcinogen

An environmental agent, chemical, or form of ionizing radiation that damages DNA and induces mutations leading to tumour formation and cancer.

Type 1 Diabetes

An early-onset autoimmune disorder where the immune system destroys pancreatic beta cells, preventing insulin production and requiring daily insulin injections.

Type 2 Diabetes

A metabolic condition linked to obesity, age, and lack of exercise where body cells no longer respond effectively to the insulin produced by the pancreas.

Photosynthesis

An endothermic chemical reaction in plants and algae where sunlight energy converts carbon dioxide and water into glucose and oxygen: $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Limiting Factor

An environmental factor (such as light intensity, carbon dioxide concentration, or temperature) that is in the shortest supply and directly restricts the rate of a physiological reaction.

Inverse Square Law

A law of physics stating that the intensity of light from a source is inversely proportional to the square of the distance from that source ($\text{Light intensity} \propto \frac{1}{d^2}$).

Aerobic Respiration

An exothermic chemical reaction occurring in the mitochondria of cells in the presence of oxygen that releases energy from glucose: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O}$.

Anaerobic Respiration

The incomplete cellular breakdown of glucose occurring in the cytoplasm in the absence of oxygen, producing lactic acid in animals and yielding substantially less energy than aerobic respiration.

Oxygen Debt

The volume of additional oxygen required following vigorous exercise to oxidize and convert built-up lactic acid in the liver back into glucose.

Metabolism

The sum total of all the chemical reactions occurring continuously inside an individual cell or an entire organism.

Glycogen

A complex carbohydrate stored in animal liver and muscle tissues that can be hydrolyzed into glucose to supply substrate for cellular respiration.