152 key terms across all boards. Search for any word to get the definition instantly.
152 terms
A non-living physical or chemical factor affecting organisms. Examples include temperature, light intensity and pH.
The specific region of an enzyme where the substrate binds. Has a shape complementary to the substrate.
Movement of substances from low to high concentration using energy (ATP) and carrier proteins. Against the concentration gradient.
Antidiuretic hormone. Released by the pituitary when blood water content is low. Makes the kidney reabsorb more water, producing concentrated urine.
Hormone from the adrenal glands. Prepares the body for fight or flight - increases heart rate and blood pressure.
The release of energy as ATP from glucose using oxygen. Products are carbon dioxide and water. Occurs in mitochondria.
A version of a gene. Most genes have two alleles, one inherited from each parent.
An enzyme that breaks down starch into sugars. Produced in the salivary glands and pancreas.
Respiration without oxygen. In animals produces lactic acid. In yeast produces ethanol and carbon dioxide. Releases less energy than aerobic.
A drug that kills or inhibits the growth of bacteria. Does NOT work against viruses.
The ability of bacteria to survive antibiotic treatment, evolved through natural selection when resistant bacteria reproduce.
A specific Y-shaped protein produced by lymphocytes that binds to one type of antigen on a pathogen.
A protein on the surface of a pathogen that triggers an immune response.
A blood vessel that carries blood away from the heart. Has thick elastic walls and a small lumen. Carries blood at high pressure.
Build-up of fatty plaques inside artery walls. Narrows the artery and reduces blood flow. Causes coronary heart disease.
Adenosine triphosphate. The universal energy currency of cells. Produced by respiration and used to power cellular processes.
An alkaline liquid produced by the liver and stored in the gall bladder. Emulsifies fats - breaks large fat droplets into small ones. NOT an enzyme.
The variety of different species in an area and the genetic variation within those species.
A living factor affecting organisms. Examples include predation, competition, disease and food availability.
The smallest blood vessel. Walls are one cell thick - the site of exchange of oxygen, carbon dioxide, glucose and waste between blood and tissues.
A reservoir that absorbs more carbon than it releases. Examples include forests and oceans.
The volume of blood pumped by the heart per minute. Equals heart rate multiplied by stroke volume.
A heterozygous individual who carries a recessive allele but shows no symptoms of the condition.
The process by which a cell becomes specialised for a specific function by switching specific genes on or off.
A thin flexible layer surrounding all cells. Controls what enters and leaves. Made of phospholipids and proteins.
A rigid outer layer made of cellulose found in plant cells. Provides structural support and prevents the cell from bursting.
The green pigment in chloroplasts that absorbs light energy for photosynthesis.
Organelle in plant cells containing chlorophyll. The site of photosynthesis.
A long coiled strand of DNA carrying many genes. Humans have 46 chromosomes in 23 pairs in body cells.
Systematic testing of a drug on human volunteers to assess safety and effectiveness. Involves Phase 1, 2 and 3 trials.
When both alleles are expressed equally in the phenotype of a heterozygote. Neither allele is dominant over the other.
A sequence of three mRNA bases that codes for one specific amino acid during translation.
All the populations of different species living in the same area.
The difference in concentration of a substance between two areas. Substances diffuse down the gradient, from high to low.
Narrowing of the coronary arteries by fatty plaques, reducing oxygen supply to the heart muscle.
A recessive genetic disorder causing thick sticky mucus in the lungs and digestive system. Both alleles must be faulty to show the condition.
The gel-like fluid inside a cell where most chemical reactions take place.
An organism such as a bacterium or fungus that breaks down dead organic matter, releasing carbon dioxide and mineral ions.
Irreversible change in the shape of an enzyme active site due to high temperature or extreme pH. The enzyme can no longer function.
Bacteria that convert nitrates back into nitrogen gas, returning nitrogen to the atmosphere.
The net movement of particles from a region of high concentration to low concentration. Passive - no energy required.
Having two complete sets of chromosomes (46 in humans). All body cells are diploid.
Deoxyribonucleic acid. The double-helix molecule that carries genetic information in cells. Made of nucleotides with four bases: A, T, C, G.
An allele that is expressed in the phenotype when only one copy is present. Written as a capital letter.
A trial where neither the patients nor the doctors know who receives the real drug or placebo. Prevents bias in results.
A community of organisms plus the non-living physical environment they interact with.
A muscle or gland that carries out the body response to a stimulus.
A microscope using electrons to create images. Has much higher resolution than a light microscope. Cannot be used on living specimens.
Undifferentiated cell from an early embryo. Totipotent - can develop into any cell type in the body.
The physical process of breaking large fat droplets into smaller ones. Done by bile - increases surface area for lipase.
A biological catalyst - a protein that speeds up chemical reactions without being used up. Specific to one type of substrate.
A cell type with a membrane-bound nucleus. Includes animal, plant and fungal cells.
Nutrient enrichment of water from fertiliser run-off leading to algal blooms, oxygen depletion and death of aquatic organisms.
The change in inherited characteristics of a population over successive generations.
Anaerobic respiration in yeast or bacteria. Glucose is converted to ethanol and carbon dioxide. Used in brewing and bread-making.
A sequence showing the transfer of energy from producer to consumers. Arrows show the direction of energy flow.
Follicle-stimulating hormone. Released by the pituitary gland. Stimulates egg maturation and oestrogen production.
A section of DNA that codes for a specific protein and determines an organism characteristic.
The direct manipulation of genes using restriction enzymes to cut DNA and ligase to join it from different organisms.
The complete set of genetic information in an organism including all genes and non-coding DNA.
The alleles an individual carries for a particular gene, for example Bb.
Rising average global temperatures caused by increased concentrations of greenhouse gases such as carbon dioxide and methane.
Hormone from pancreatic alpha cells. Raises blood glucose by stimulating the liver to break down glycogen into glucose.
The storage form of glucose in animals. An insoluble polysaccharide stored in the liver and muscles.
A gas that absorbs and re-emits infrared radiation, warming the atmosphere. Examples include carbon dioxide and methane.
A specialised plant cell that controls the opening and closing of stomata by becoming turgid or flaccid.
The specific environment where an organism lives.
Red protein in red blood cells that binds oxygen in the lungs and releases it in tissues.
Having one set of chromosomes (23 in humans). Gametes (sperm and eggs) are haploid.
When enough people in a population are immune that the pathogen cannot spread easily, protecting even unvaccinated individuals.
Having two different alleles for a gene, for example Bb.
The maintenance of a stable internal environment within the body such as constant temperature, blood glucose and water balance.
Having two identical alleles for a gene, for example BB or bb.
A region of the brain that monitors blood temperature and coordinates thermoregulatory responses.
The idea that the active site of an enzyme changes shape slightly when the substrate binds, improving the fit. More accurate than lock and key.
Hormone from pancreatic beta cells. Lowers blood glucose by stimulating cells to take up glucose and the liver to store it as glycogen.
Luteinising hormone. Released by the pituitary. A surge in LH on around day 14 of the menstrual cycle triggers ovulation.
An enzyme that joins DNA strands together. Used in genetic engineering to seal a gene into a plasmid.
The factor in shortest supply that controls the rate of a reaction. Increasing other factors has no effect if another is limiting.
An enzyme that breaks down fats into fatty acids and glycerol.
A type of white blood cell that produces specific antibodies in response to antigens. Also produces memory cells.
How many times larger an image appears compared to the real object. Formula: Image size divided by Actual size.
Cell division producing 4 genetically different haploid cells. Used to produce gametes for sexual reproduction.
A long-lived lymphocyte that remains after an immune response. Enables rapid antibody production on re-exposure to the same pathogen.
Organelle where aerobic respiration occurs. Produces ATP. Cells with high energy demands have many mitochondria.
Cell division producing 2 genetically identical diploid cells. Used for growth and repair.
A nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands.
Methicillin-resistant Staphylococcus aureus. A bacterium resistant to most common antibiotics. A major problem in hospitals.
A change in the DNA base sequence. The only source of new alleles. Can be caused by UV radiation, X-rays and certain chemicals.
The process by which individuals with advantageous characteristics survive and reproduce more, passing those traits to offspring.
A control mechanism where the response to a change opposes that change, restoring the system to its set point.
A chemical that carries signals across the synaptic cleft between neurones. Examples include acetylcholine and dopamine.
Bacteria that convert ammonia into nitrites then nitrates in the soil, making nitrogen available for plant uptake.
Conversion of atmospheric nitrogen gas into ammonia or nitrates. Carried out by nitrogen-fixing bacteria in soil and root nodules.
Organelle containing DNA in chromosomes. Controls the cell. Present in eukaryotic cells only.
A hormone produced by the ovaries. Thickens the uterus lining and at high levels triggers the LH surge and inhibits FSH.
The temperature or pH at which an enzyme works at its maximum rate.
A group of different tissues working together to perform a specific function.
A specialised structure within a cell that has a specific function.
The net movement of water molecules from high water potential to low water potential through a partially permeable membrane.
The release of a mature egg from the ovary. Triggered by the LH surge on approximately day 14 of the menstrual cycle.
The extra oxygen needed after anaerobic exercise to break down accumulated lactic acid in the liver.
A membrane that allows water and small molecules through but not large molecules such as sucrose. Essential for osmosis.
A microorganism that causes disease. Can be a bacterium, virus, fungus or protist.
Wave-like muscular contractions that push food through the digestive system.
A type of white blood cell that engulfs and digests pathogens by phagocytosis. A non-specific defence.
The observable characteristics of an individual, produced by the genotype and environment.
Living plant tissue that transports dissolved sugars from leaves to all parts of the plant. Can flow in both directions.
The process by which plants convert carbon dioxide and water into glucose and oxygen using light energy. Occurs in chloroplasts.
An inactive dummy treatment used as a comparison in clinical trials. Contains no active drug.
A small circular ring of extra DNA found in bacterial cells. Used as a vector in genetic engineering.
When a plant cell loses water by osmosis - the membrane pulls away from the cell wall. The cell becomes limp and flaccid.
An inherited condition causing extra digits. Caused by a dominant allele so only one copy is needed to show the condition.
All individuals of one species in a defined area at a given time.
An organism that makes its own food by photosynthesis. Always the first trophic level in a food chain.
Hormone produced by the corpus luteum after ovulation. Maintains the uterus lining. Falls if no pregnancy occurs, leading to menstruation.
A cell type without a membrane-bound nucleus. Bacteria are prokaryotes - DNA floats freely in the cytoplasm.
An enzyme that breaks down proteins into amino acids.
An allele that is only expressed in the phenotype when two copies are present. Written as a lowercase letter.
The rapid automatic neural pathway from stimulus to response. Bypasses the brain and is routed through the spinal cord.
A nerve cell that carries impulses within the CNS, connecting sensory and motor neurones.
The ability of a microscope to distinguish two separate points as distinct. Electron microscopes have higher resolution than light microscopes.
An enzyme that cuts DNA at specific sequences leaving sticky ends. Used in genetic engineering to remove genes.
Tiny organelle found in all cells. The site of protein synthesis.
The process of choosing individuals with desired traits to breed together over many generations to improve characteristics.
A nerve cell that carries electrical impulses from receptors to the CNS.
The formation of a new species through reproductive isolation and independent genetic divergence of two populations.
A group of organisms that can interbreed to produce fertile offspring.
A drug that lowers blood LDL cholesterol levels, slowing the formation of fatty plaques in arteries.
An undifferentiated cell that can divide and differentiate into specialised cell types.
A small mesh tube inserted into a narrowed artery to hold it open and restore blood flow.
Tiny pores in the lower surface of leaves that allow gas exchange. Controlled by guard cells.
The specific molecule that an enzyme acts on. Binds to the active site of the enzyme.
Meeting the needs of the present without compromising the ability of future generations to meet their own needs.
The tiny gap between two neurones. Signals cross it via chemical neurotransmitters.
A group of similar cells working together to perform a function.
Able to differentiate into any cell type in the body. Embryonic stem cells are totipotent.
A poisonous substance produced by bacteria that causes the symptoms of disease.
The transport of dissolved sugars through the phloem from leaves to all parts of a plant.
The evaporation of water vapour from leaves through stomata. Drives the movement of water up through the xylem.
A feeding level in a food chain. Producers are level 1, primary consumers are level 2, and so on.
A plant cell that has absorbed water by osmosis and is firm. The vacuole presses against the cell wall.
An autoimmune condition where beta cells are destroyed and no insulin is produced. Treated with insulin injections.
A condition where body cells become resistant to insulin. Linked to obesity. Managed with diet and exercise.
A preparation containing harmless antigens that trains the immune system to respond to a pathogen without causing disease.
Narrowing of blood vessels near the skin surface. Reduces blood flow and heat loss. The response to cold.
Widening of blood vessels near the skin surface. Increases blood flow and heat loss by radiation. The response to overheating.
An organism that carries and transmits a pathogen between hosts. For example the Anopheles mosquito transmits malaria.
A blood vessel that carries blood towards the heart. Has thin walls, a large lumen and valves to prevent backflow.
A finger-like projection on the inner wall of the small intestine. Increases surface area for absorption of nutrients.
A measure of the tendency of water to move. Pure water has the highest water potential. Adding solutes lowers water potential.
Dead hollow plant tissue with lignified walls. Transports water and mineral ions from roots upward. One-way flow.