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Biology Key Terms
It is important to know all the key terms for each topic so that you can apply it in question answering. The most important ones are the ones that are bolded or underlined in past paper marking schemes because its what examiners are looking for and will give marks for. This is a list of each topic with its key terms:
Characteristics and Cla ification of Living Organisms
MRS GREN: An acronym for the seven life processes: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition. Binomial Nomenclature: A system of naming species using two names: the genus and the species. Taxonomic Hierarchy: The classification of organisms in the following order: Kingdom, Phylum, Class, Order, Family, Genus, Species. Vertebrates: Animals with a backbone. Invertebrates: Animals without a backbone. Pathogens: Microorganisms that cause disease, such as bacteria, viruses, fungi, and protoctists.
Organisation of the Organism
Cell: The basic structural and functional unit of all living organisms. Tissue: A group of similar cells that perform a specific function. Organ: A structure made up of different tissues working together to perform a specific function. Organ System: A group of organs that work together to carry out a particular function. Specialized Cells: Cells that have adapted to perform a particular function, e.g., red blood cells, root hair cells, ciliated cells.
Movement In and Out of Ces
Diffusion: The net movement of molecules from a region of higher concentration to a region of lower concentration down a concentration gradient.
Osmosis: The diffusion of water molecules through a partially permeable membrane from a region of higher water potential to a region of lower water potential. Active Transport: The movement of molecules or ions against a concentration gradient, using energy from respiration. Concentration Gradient: The difference in concentration of a substance between two regions. Partially Permeable Membrane: A membrane that allows some substances to pass through but not others.
Biological Molecules
Carbohydrates: Organic compounds made up of carbon, hydrogen, and oxygen; examples include glucose, starch, and glycogen. Proteins: Large molecules made up of amino acids; they perform various functions including structural roles and as enzymes. Lipids: Organic compounds made up of fatty acids and glycerol; they are used for energy storage and insulation. Enzymes: Biological catalysts that speed up chemical reactions without being used up. Substrate: The molecule upon which an enzyme acts. Active Site: The region on an enzyme where the substrate binds. Denaturation: The structural change in a protein (e.g., enzyme) that results in the loss of its biological properties. Benedict’s Test: A chemical test for reducing sugars; a positive result turns from blue to brick-red upon heating. Iodine Test: A test for starch; a positive result turns from brown to blue-black. Biuret Test: A test for proteins; a positive result turns from blue to purple. Ethanol Emulsion Test: A test for lipids; a positive result forms a milky-white emulsion.
Enzymes
Catalyst: A substance that increases the rate of a chemical reaction without undergoing permanent change. Lock and Key Model: A model explaining how enzymes and substrates fit together based on specific shapes. Temperature and pH Effects: Enzymes have optimal temperature and pH ranges; deviations can reduce activity or denature the enzyme.
Plant Nutrition
Photosynthesis: The process by which green plants use sunlight to synthesize nutrients from carbon dioxide and water.
Capillaries: Microscopic vessels where exchange of substances occurs between blood and tissues. Red Blood Cells: Carry oxygen using haemoglobin. White Blood Cells: Defend the body against disease (e.g., phagocytes and lymphocytes). Platelets: Help with blood clotting. Plasma: Liquid part of blood that transports carbon dioxide, nutrients, hormones, and urea.
Diseases and Immunity
Disease: A condition that impairs normal functioning of the body. Pathogen: Disease-causing organism (e.g., bacteria, viruses, fungi, protoctists). Immune Response: The body’s defense mechanism against pathogens. Antibodies: Proteins produced by lymphocytes to neutralize pathogens. Antigens: Molecules on pathogens that trigger immune response. Phagocytosis: The process by which white blood cells engulf and digest pathogens. Vaccination: Introducing antigens to stimulate production of memory cells. Memory Cells: Long-lived cells that provide immunity by remembering antigens.
Gas Exchange in Humans
Gas Exchange: The process of swapping oxygen and carbon dioxide between alveoli and blood. Alveoli: Tiny air sacs in lungs where gas exchange occurs. Ventilation: Breathing; includes inhalation and exhalation. Diaphragm: Muscle that contracts and relaxes to aid breathing. Intercostal Muscles: Muscles between ribs that assist with ventilation. Carbon Monoxide: A toxic gas in cigarette smoke that reduces oxygen transport. Tar: Sticky substance in cigarette smoke that damages lungs and cilia.
Respiration
Respiration: The chemical process that releases energy from glucose. Aerobic Respiration: Respiration using oxygen (glucose + oxygen → CO₂ + water + energy). Anaerobic Respiration: Respiration without oxygen (produces less energy; e.g., lactic acid in humans). Lactic Acid: Waste product of anaerobic respiration in muscles. Oxygen Debt: The extra oxygen needed after exercise to remove lactic acid.
Excretion in Humans
Excretion: Removal of metabolic waste from the body. Urea: Waste product formed in the liver from excess amino acids. Kidneys: Organs that filter blood and produce urine. Urine: Liquid waste excreted by kidneys, containing urea, water, and salts. Dialysis: Artificial method of removing waste from the blood. Homeostasis: Maintaining a constant internal environment.
C rdination and Response
Stimulus: A change in the environment that causes a response. Receptor: Detects stimuli (e.g., eyes, skin). Effector: Carries out a response (e.g., muscles or glands). Central Nervous System (CNS): Brain and spinal cord. Reflex Arc: Pathway of nerve impulses in a reflex action. Synapse: Gap between two neurons; neurotransmitters transmit signals. Hormones: Chemical messengers produced by glands (e.g., insulin, adrenaline). Endocrine System: Glands that secrete hormones directly into the blood.
Drugs
Medicinal Drugs: Used to treat diseases (e.g., antibiotics). Antibiotics: Kill bacteria but not viruses. Drug Abuse: Use of substances in a way that is harmful. Addiction: Dependence on a drug. Withdrawal Symptoms: Effects when stopping an addictive drug.
Reproduction
Asexual Reproduction: One parent, no gametes, offspring genetically identical. Sexual Reproduction: Two parents, fusion of gametes, offspring genetically varied. Fertilisation: Fusion of male and female gametes. Pollination: Transfer of pollen from anther to stigma. Ovule: Female gamete in plants. Zygote: Fertilised egg cell. Menstrual Cycle: Monthly cycle preparing uterus for pregnancy. Contraception: Preventing fertilisation or implantation.
Inheritance
Biotechnology and Genetic Modification
Biotechnology: Use of living organisms in industrial processes (e.g., brewing, baking). Fermentation: Anaerobic respiration in microbes producing ethanol or carbon dioxide. Genetic Engineering: Modifying an organism’s DNA by adding foreign genes. Insulin Production: Using genetically modified bacteria to produce human insulin. GMOs: Organisms with altered DNA to enhance traits (e.g., pest resistance in crops).
