OCR AS Biology

OCR AS Biology Revision Flashcards

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Magnification
The number of time greater an image is than the object.
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Resolution
The ability to distinguish two separate points as distinct from each other.
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Staining
In microscopy refers to any process that helps to reveal or distinguish different features. In light microscopy, stains may be colours or fluorescent dyes. In electron microscopy, they are metal particles or metal salts.
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Cytoskeleton
The network of protein fibres and microtubules found within the cell that gives structure to the cell and is responsible for the movement of many materials within it.
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Organelle
Structure inside a cell. Each organelle has a specific function.
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Phospholipid
A molecule consisting of a glycerol molecule, two fatty acid molecules and a phosphate group covalently bonded together. Phospholipids form the basis of cell membranes.
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Fluid mosaic
The model of cell membrane structure proposed by Singer and Nicholson – a phospholipid bilayer with proteins ‘floating’ in it.
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Cell signalling
Processes that lead to communication and coordination between cells. Hormones binding to their receptors on the cell surface membrane are an example.
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Diffusion
The net movement of molecules or ions in a gas or liquid from an area of high concentration to an area where they are less concentrated.
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Active transport
Movement of substances across membranes against their concentration gradient, requiring the use of energy in the form of ATP. Active transport usually involves the use of transport proteins.
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Solute
A solid that dissolves in a liquid.
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Solvent
A liquid that dissolves solids.
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Solution
Liquid with dissolved solids.
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The Cell Cycle
The cell cyle describes the events that take place as one parent cell divides to produce two new daughter cells which then each grow to full size.
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Mitosis
Nuclear division that results in the formation of cells that are genetically identical to the parent cell.
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Clones
Genetically identical cells or individuals.
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Differentiation
The development and changes seen in cells as they mature to form specialised cells.
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Tissue
A group of similar cells that perform a particular function.
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Organ
A collection of tissues that work together to perform a specific overall function or set of functions within a multicellular organism.
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Exchange surface
A specialised area adapted to make it easier for molecules to cross from one side of the surface to the other.
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Gaseous exchange
The movement of gases by diffusion across a barrier such as the atreous wall.
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Inspiration (Inhalation) & Expiration (Exhalation)
The terms used to describe breathing in and out.
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Transport
The movement of oxygen, nutrients, hormones, waste and heat around the body.
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Heart
A muscular pump that creates pressure (blood pressure) to propel the blood through the arteries and around the body.
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Cardiac cycle
The sequence of events making up one heartbeat.
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Sinoatrial node (SAN)
The patch of tissue that initiates the heartbeat by sending waves of excitation over the atria.
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Purkyne tissue
Specialised tissue (muscle fibres) in the septum of the heart that conducts the electrical stimulus from the sinoatrial node to the ventricles.
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Septum
The wall separating the ventricles of the heart.
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Ventricles
The lower chambers in the heart.
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Open Circulatory System
The blood is not always in vessels.
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Closed Circulatory System
The blood always remains within vessels.
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Tissue fluid
The fluid, derived from blood plasma, that surrounds the cells in a tissue.
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Lymphatic system
A system of lymph nodes and lacteals with lymph fluid.
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Bohr shift / Bohr effect
The effect of carbon dioxide concentration on the affinity of haemoglobin for oxygen.
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Xylem
A plant tissue containing xylem vessels (and other cells) that are used to transport water in a plant and provide support.
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Phloem
A tissue in plants that is used to transport dissolved sugars and other substances.
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Water potential (Ψ)
A measure of the ability of water molecules to move freely in solution. Measures the potential for a solution to lose water – water moves from a solution with high water potential to one of lower water potential. Water potential is decreased by the p
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Cohesion
The attraction between water molecules due to hydrogen bonding.
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Adhesion
Force of attraction between molecules of two different substances.
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Symplast pathway
The route taken by water through the cytoplasm of cells in a plant.
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Apoplast pathway
The route taken by water between the cells or through the cell walls in a plant.
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Transpiration
The loss of water vapour from the aerial parts of a plant due to evaporation.
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Xerophyte
A plant specially adapted to living in dry areas.
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Translocation
The movement of sucrose and other substances up and down a plant.
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Source
A part of the plant that releases sugars into the phloem.
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Sink
A part of a plant that removes sugars from the phloem.
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Risk factor
A factor that increases the risk or chance that you may develop a particular disease.
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Covalent bond
A chemical bond formed by the sharing of one or more electrons between two atoms.
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Carbohydrate
A class of biological molecules with the general formula Cx(H2O)y. It includes sugars, starches, glycogen and cellulose.
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Polysaccharide
A polymer consisting of many monosaccharide monomers covalently bonded together.
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Cellulose
A carbohydrate polymer (of β-glucose) that forms plant cell walls.
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Amino acid
An organic compound that contains both an amino group (–NH2) and a carboxyl group (–COOH). Amino acids are the monomers of protein molecules.
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Primary structure
The sequence of amino acids found in a protein molecule.
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Secondary structure
The coiling or folding parts of a protein molecule due to the formation of hydrogen bonds formed as the protein is synthesised. The main forms of secondary structure are the α-helix and β-pleated sheets.
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Tertiary structure
The overall three-dimensional shape of a protein molecule. It is the result of interactions between parts of the protein molecule such as hydrogen bonding, formation of disulfide bridges, ionic bonds and hydrophobic interactions.
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Haemoglobin
The protein that carries oxygen in the red blood cells.
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Collagen
A structural fibrous protein found in connective tissue, bones, skin and cartilage. It accounts for 30% of body protein.
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Prosthetic group
A non-protein organic molecule that forms a permanent part of a functioning protein molecule.
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Lipids
A diverse group of chemicals that includes triglycerides, fatty acids and cholesterol.
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Hydrogen bond
A weak bond formed when partially positively charged groups come close to partially negatively charged groups. It is seen in water molecules, and in the secondary and tertiary structure of proteins.
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Food tests
Simple tests that show the presence of various biological molecules in samples or structures.
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Quantitative
A study is quantitative if it involves quantity (numbers). For example, if you count the number of individuals of a species in a selected area, the study is quantitative.
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Assay
The use of comparative studies or samples to determine the concentration or quantity of a substance in a sample.
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Nucleotide
The monomer of nucleic acids consisting of a phosphate, a sugar and an organic base.
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DNA
Deoxyribonucleic acid – a polymer of nucleotide molecules that form the instructions for the synthesis of proteins found within organisms. These nucleotides contain the 5-carbon sugar deoxyribose.
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Gene
A length of DNA that carries the code for the synthesis of one (or more) specific polypeptide.
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Catalyst
A substance that increases the rate of a reaction but does not take part in the reaction, and so is re-usable.
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Extracellular
Outside the cell. Extracellular enzymes/digestion work outside the cell.
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Intracellular
Inside the cell (intracellular enyzmes/digestion are found inside the cell).
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Activation energy
The level of energy required to enable a reaction to take place. Enzymes reduce the amount of energy required to allow a reaction to proceed.
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Denaturation
An irreversible change in the tertiary structure of a protein molecule. It leads to loss of function in most proteins.
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Optimum (temperature / pH)
The condition that gives the fastest rate of reaction in enzyme-controlled reactions.
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Buffer
A chemical system that resists changes in pH by maintaining a constant level of hydrogen ions in solution. Certain chemicals dissolved in the solution are responsible for this.
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Limiting factor
A variable that limits the rate of a process. If it is increased, then the rate of the process will increase.
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Inhibition/inhibitor
The slowing of an enzyme-controlled reaction. An inhibitor slows down or prevents the formation of enzyme–substrate complexes.
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Cofactor
A molecule or ion that helps an enzyme to work. It may be an inorganic ion or an enzyme.
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Anomalous
Describes a result/data point that does not appear to fit the pattern of the other results. It may be assumed to be anomalous if the experimenter has made an error or if the apparatus used is not suitable for the measurements being taken.
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Nutrition
The total substances taken into an animal or plant for use in metabolism (the sum total of its diet).
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Liproproteins
A combination of lipid, cholesterol and protein used to transport fats and cholesterol around the body
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Artificial selection/ Selective breeding
Also called selective breeding – the process of improving a variety of crop plant or domesticated animal by breeding from selected individuals with desired characteristics.
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Antibiotic
A chemical that kills or prevents reproduction in bacteria.
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Health
Complete mental, physical and social wellbeing.
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Disease
A departure from full health.
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Parasite
An organism that lives in or on another living organism (its host), deriving nutrition from the host, benefiting at the expense of its host.
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Pathogen
An organism that causes disease.
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Transmission
The way in which a microorganism or other pathogen travels from one host to another.
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Primary defences
The defences that prevent the entry of a pathogen into the body.
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Immune response
A response to an antigen, which involves the activation of lymphocytes.
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Antibodies
Protein molecules released by the immune system in response to an antigen, which are capable of neutralising the effects of the antigen.
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Cell signalling
Processes that lead to communication and coordination between cells. Hormones binding to their receptors on the cell surface membrane are an example.
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Memory cells
B and T cells that remain in the body after an immune response. Their presence enables a much faster and greater second immune response.
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Lymphocyte
A type of white blood cell activated as part of the immune response.
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Carcinogen
A substance that causes cancer.
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Atherosclerosis / atheroma
The process of deposition of fatty substances in the lining of arteries to form atheroma, which may eventually lead to arteriosclerosis (hardening of the arteries).
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Risk factor
A factor that increases the risk or chance that you may develop a particular disease.
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Epidemiology
The study of patterns of disease and the factors that influence their spread.
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Species
A group of organisms whose members are similar to each other in shape (morphology), physiology, biochemistry and behaviour, and can interbreed to produce fertile offspring.
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Habitat
The place where an organism or population lives. It includes the climatic, topographic and edaphic factors as well as the plants and animals that live there.
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Biodiversity
The number and variety of living things to be found in the world, in an ecosystem or in a habitat.
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Taxonomy
The study of the principles behind classification.
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Phylogeny
The evolutionary relationships between organisms.
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Biological Classification
Process of sorting living things into groups
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Taxonomy
The study of the principles behind classification.
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Phylogeny
The evolutionary relationships between organisms.
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Prokaryote
An organism with cells that do not contain a true nucleus.
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Protoctisis
Include all the organisms that dont fit into the other four kingdoms. Many are single-celled, but some are multicellular
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Fungi
Organisms that are mostly saprophytic.
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Binomial system
A system of naming living things using two Latin words – the genus name and the specific name.
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Dichotomous Key
It is a serious of questions with two alternative answers to help you identify a specimen
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Variation
The differences between individuals.
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Genetic Variation
Cause by differences between the genes and the combination of genes and alleles.
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Continuous Variation
Variation of which there are full range of intermediate phenotype between two extremes
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Discontinuous Variation
Variation in which there are discrete groups of phenotypes with no or very few individuals in between.
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Speciation
The formation of a new species.
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Extinction
The death of the last individual in a species.
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Gene pool
The sum total and variety of all the genes in a population or species at a given time.
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Conservation in situ
Conservation in the natural habitat.
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Conservation ex situ
Conservation in areas other than the natural habitat.
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Environmental impact assessment
An assessment of the damage that may be caused to the (local) environment by a proposed development.
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Other cards in this set

Card 2

Front

Resolution

Back

The ability to distinguish two separate points as distinct from each other.

Card 3

Front

Staining

Back

Preview of the front of card 3

Card 4

Front

Cytoskeleton

Back

Preview of the front of card 4

Card 5

Front

Organelle

Back

Preview of the front of card 5
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sana05

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This was helpful in knowing the relevant definitions :)

Muzyoka

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This was really useful for me.

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