Biology Unit 1

Unit 1 Retake definitions. 

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  • Created by: Sophie
  • Created on: 23-03-13 14:29

Activation Energy

Energy required to bring about a reaction. The activation energy is lowered by the presence of enzymes.

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Active Immunity

Resistance to disease resulting from the activities of an individuals own immune system whereby an antigen induces plasma cells to produce antibodies.

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Active Transport

Movement of a substance from a region where it is in a low concentration to a region where it is in a high concentration. The process requires energy

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Connected with the presence of free oxygen. Aerobic respiration requires free oxygen to release energy from glucose. 

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A normally harmless substance that causes the immune system to produce an immune response.

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The response of an immune system to an allergen. Examples include hayfever and asthma. 

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A substance produced by living organisms that can destroy or inhibit the growth of microorganisms. 

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Antibiotic resistance

The development in microorganisms of mechanisms that prevent antibiotics from killing them. 

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A protein produced by lymphocytes in responce to the presence of the appropriate antigen. 

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A molecule that triggers an immune response by lymphocytes.

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Chemical which reduces or prevents oxidation. Often used as an additive to prolong the shelf life of certain foods. 

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A chronic illness in which there is resistance to air flow to the alveoli of the lungs as a result of the airways becoming inflamed due to an allergic response to an allergen. 

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Fatty deposits in the walls of arteries, often associated with high cholesterol levels in the blood. 

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Nucleotide found in all living organisms, which is produced during respiration and is important in the transfer of energy. 

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B Cell (B Lymphocyte)

Type of white blood cell that is produced and matures within the bone marrow. B lymphocytes produce antibodies as part of their role in immunity. 

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Benedict's Test

A simple biochemical reaction to detect the presence of reducing sugars. When a reducing sugar is heated with benedict's reagent it forms an insoluble red precipitate of copper (I) oxide. 

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Biuret Test

A simple biochemical reaction to detect the presence of protein by detecting peptide links. You add sodium hydroxide solution to the sample, and a few drops of dilute copper sulfate solution and mix gently. A purple colouration indicates the presence of peptide bonds, and hence a protein. If no protein is present, the solution remains blue. 

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Body Mass Index (BMI)

A person's body mass in Kg, divided  by the square of their height in metres. 

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A disease, resulting from mutations, that leads to uncontrolled cell division and the eventual formation of a group of abnormal cells called a tumour, from which cells may break away and form secondary tumours elsewhere in the body. 

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A chemical, a form of radiation, or other agent that causes cancer. 

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Cardiac Cycle

A continuous series of events which make up a single heart beat. 

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Cardiac output

The total volume of blood that the heart can pump each minute. It is calculated as the volume of blood pumped at each beat (stroke volume) multiplied by the number of heart beats per minute (heart rate). 

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Carrier Molecule (Carrier Protein)

A protein on the surface of a cell that helps to transport molecules and ions across plasma membranes. 

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Process of separating out particles of different sizes and densities by spinning them at high speed in a centrifuge. 

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Lipid that is an important component of cell surface membranes. Excess in the blood can lead to atheroma. 

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Fibrous protein that is the main constituent of connective tissue such as tendons, cartilage and bone. 

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Chemical process in which two molecules combine to form a more complex one with the elimination of a simple substance- usually water. Many biological polymers, such as polysaccharides and polypeptides, are formed by condensation. 

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Coronary Arteries

Arteries that supply blood to the cardiac muscle of the heart. 

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Coronary Heart Disease

Any condition, e.g. atheroma and thrombosis, affecting the coronary arteries that supply heart muscle. 

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When a change in one variable is affected by a change in the second variable. 

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Permanent changes due to the unravelling of the 3D structure of a protein as a resulf of factors such as changes in temperature or pH. 

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The movement of molecules or ions from a region where they are in high concentration to one where their concentration is lower. 

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A negatively charged sub-atomic particle that orbits the positively charged nucleus of all atoms. 

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A disease in which the walls of the alveoli break down, reducing the surface area for gaseous exchange, thereby causing breathlessness in the patient. 

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A protein or RNA that acts as a catalyst and so alters the speed of a biochemical reaction. 

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Eukaryotic Cell

A cell that has a membrane bound nucleus and chromosomes, The cell also possesses a variety of other membranous organelles, such as mitochondria and endoplasmic reticulum. 

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Facilitated Diffusion

Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances across plasma membranes. 

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Globular protein in blood that readily combines with oxygen to transport it around the body. It comprises of four polypeptide chains around an iron-containing haem group. 

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High Density Lipoprotein (HDL)

A compound of protein and lipid molecules found in blood plasma. It transports cholesterol from other cells to the liver. 

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Substance released on tissue injury that causes dilation of blood vessels. 

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Hydrogen Bond

Chemical bond formed between the positive charge on a hydrogen atom and the negative charge on another atom of an adjacent molecule, e.g. between the hydrogen atom of one water molecule and the oxygen atom of an adjacent water molecule. 

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The breaking down of large molecules into smaller ones by the addition of water molecules. 

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The means by which the body protects itself  from infection.

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Ion Channel

A passage across a cell surface membrane made up of a protein that spans the membrane and opens and closes to allow ions to pass in and out of the cell. 

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Solutions that possess the same concentration os solutes and therefore have the same water potential. 

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Kinetic Energy

Energy that an object possesses due to its motion. 

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Low-density lipoprotein (LDL)

A compound containing both protein and lipid molecules that occurs in blood plasma and lymph. It carries cholesterol from the liver to other cells in the body.

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The hollow cavity inside a tubular structure such as the gut or xylem vessel. 

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Types of white blood cell responsible for the immune response. They become activated in the presence of antigens. There are two types: B lymphocytes and T lymphocytes. 

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A sudden change in the amount or the arrangement of the genetic material in  the cells.

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Myocardial Infarction

Otherwise known as a heart attack, results from the interruption of the blood supply to the heart muscle, causing damage to an area of the heart with consequent disruption to its function. 

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Oral rehydration solution (ORS)

Means of treating dehydration involving giving, by mouth, a balanced solution of salts and glucose that stimulates the gut to reabsorb water. 

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The passage of water from a region of high water potential to a region where its water potential is lower, through a partially permeable membrane. 

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Degeneration of the cartilage of the joints, causing pain and stiffness of these joints. 

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Passive immunity

Resistance to disease that is acquired from the introduction of antibodies from another individual, rather than an individual's own immune system, e.g. across the placenta or in the mother's milk. It is usually short lived. 

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Any microorganism that causes disease. 

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Peptide bond

The chemical bond formed between two amino acids during condensation. 

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Mechanism by which cells engulf particles to form a vesicle or vacuole. 

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Triglycerides in which one of the three fatty acid molecules is replaced by a phophate molecule. Phospholipids are important in the structure and functioning of membranes. 

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Photograph of an image produced by a microscope. 

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A small circular piece of DNA found in bacterial cells. 

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The shrinkage of cytoplasm away from the cell wall that occurs as a plant cell loses water by osmosis.  

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Large molecules made up of repeating smaller molecules (monomers)

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Group of enzymes that catalyse the formation of long-chain molecules (polymers) from similar basic units (monomers)

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Polyunsaturated fatty acid (PUFA)

Fatty acid that possesses carbon chains with many double bonds. 

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Primary structure of a protein

The sequence of amino acids that makes up the polypeptides of a protein.

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Prokaryotic cell

A cell of an organism belonging to the kingdom Prokaryotae that is characterised by lacking a nucleus and membrane bound organelles, e.g. bacteria. 

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The living portion of a plant cell, i.e. the nucleus and cytoplasm along with the organelles it contains. 

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Quaternary structure of a protein

A number of polypeptide chains linked together, and sometimes associated with non-protein groups, to form a protein. 

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Saturated fatty acid

A fatty acid in which there are no double bonds between the carbon atoms. 

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Secondary structure of a proetin

The way in which the chain of amino acids of the polypeptides of a protein is folded. 

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Sinoatrial node (SAN)

An area of heart muscle in the right atrium that controls and coordinates the contraction of the heart. Also known as the pacemaker. 

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Stroke volume

The volume of blood pumped at each ventricular contraction of the heart. 

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A substance that is acted on or used by another substrate or process. In microbiology, the nutrient medium used to grow microorganisms. 

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Supernatant fluid

The liquid portion of a mixture left at the top of the tube when suspended particles have been separated out at the bottom during centrifugation. 

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Tertiary structure of a protein

The folding of a whole polypeptide chain in a precise way, as determined by the amino acids of which it is composed.

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Formation of a blood clot within a blood vessel that may lead to a blockage. 

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Tidal volume

The volume of air breathed in and out during a single breath when at rest. 

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T Cell (T lymphocyte)

Type of white blood cell that is produced in the bone marrow but matures in the thymus gland. T lymphocytes coordinate the immune response and kill infected cells

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The transfer of a pathogen from one individual to another. 

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An individual lipid molecule made up of a glycerol molecule and three fatty acids. 

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A swelling in an organism that is made up of cells that continue to divide in an abnormal way.  

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A plant cell that is full of water. Additional entry of water is prevented by the cell wall stopping further expansion of the cell. 

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Unsaturated fatty acid

A fatty acid in which there are one or more double bonds between the carbon atoms. 

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The introduction of a vaccine containing appropriate disease antigens into the body, by injection or mouth, in order to induce artificial immunity. 

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Water potential

The pressure created by water molecules. It is the measure of the extent to which a solution gives out water. The greater the number of water molecules present, the higher (less negative) the water potential. Pure water has a water potential of zero. 

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