Definitions - Topic 1 Key Concepts in Biology - Edexcel Biology GCSE PDF

Definitions and Concepts for Edexcel Biology GCSE Topic 1: Key Concepts in Biology Definitions in ​bold ​are for higher tier only Definitions marked by ‘*’ are for separate sciences only Acrosome​ - An organelle in the tip of a...

Definitions and Concepts for Edexcel Biology GCSE Topic 1: Key Concepts in Biology Definitions in ​bold ​are for higher tier only Definitions marked by ‘*’ are for separate sciences only Acrosome​ - An organelle in the tip of a sperm that contains enzymes which digest the egg cell membrane. Active site​ - A specific region on an enzyme where the substrate binds and the reaction takes place. Active transport ​- The movement of substances from a low concentration to a higher concentration (against the concentration gradient) across a membrane, with the use of energy from respiration. *Benedict’s test​ - A chemical test used to test for reducing sugars that produces a different colour based on the amount of reducing sugar present. *Biuret test​ - A chemical test that produces a purple colour when it is added to a solution containing protein. *Calorimetry​ - A method of measuring heat transfer during a chemical reaction. Carbohydrases ​- Enzymes that break down carbohydrates into simple sugars. Carbohydrate ​- A large molecule that is synthesised from simple sugars. Cell ​- The basic building block of all living organisms. Cell membrane​ - A partially permeable barrier that surrounds the cell. Cell wall​ - An outer layer made of cellulose that strengthens plant cells. Chloroplast​ - An organelle that is the site of photosynthesis. Chromosome ​- A long, coiled molecule of DNA that carries genetic information in the form of genes. Cilia ​- Hair-like structures found on ciliated epithelial cells which waft substances across the surface of the tissue in one direction. Ciliated epithelial cell​ - A type of epithelial cell that lines the surface of structures such as the respiratory tract and uterus. This work by PMT Education is licensed under https://bit.ly/pmt-cc https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Concentration gradient​ - The difference in concentration between two areas. Denaturation​ - Upon exposure to high temperatures or extremes of pH, the permanent change in the shape of an enzyme’s active site that prevents the binding of a substrate. Diffusion ​- The net spreading out of particles from a high concentration to a lower concentration (down their concentration gradient). Diploid cell​ - A cell that contains two copies of each chromosome (i.e. a full set of chromosomes). Egg cell​ - A specialised female sex cell involved in reproduction. Electron microscope​ - A type of microscope that uses a beam of electrons, focused using magnets, to produce an image of a specimen. It has a greater magnification and resolution than a light microscope. *Emulsion test​ - A chemical test that produces a cloudy emulsion when performed on lipids. Enzyme​ - A biological catalyst that increases the rate of reactions in living organisms. Eukaryotic cell​ -​ ​A type of cell found in plants and animals that contains a nucleus. Flagella​ - A long hair-like structure found on bacterial cells that is used for cell movement. Haploid cell​ - A cell that contains a single copy of each chromosome (i.e. half the number of chromosomes). *Iodine test​ - A chemical test that produces a blue/black colour when iodine solution is added to a sample containing starch. Light microscope​ - A type of microscope that uses a series of lenses to magnify the visible light reflecting off a specimen. It has a lower magnification and resolution than an electron microscope. Lipases​ - Enzymes that break down lipids into fatty acids and glycerol. Lipid ​- A large molecule that is synthesised from fatty acids and glycerol. Lock and key hypothesis ​-​ ​A theory that describes how substrates must be the correct shape to fit the active site of an enzyme. Magnification​ - The number of times bigger an image appears compared to the original object, calculated using the formula: image size = magnification × real size Micrometre (µm) ​- A quantitative unit of length. One micrometre is equal to ×10​-6​ metre. Millimetre (mm) ​- A quantitative unit of length. One millimetre is equal to ×10​-3​ metre. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Mitochondria​ - An organelle that is the site of respiration. Nanometre (nm) ​- A quantitative unit of length. One nanometre is equal to ×10​-9​ metre. Nucleus​ - An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell. Organelle​ - A specialised structure found inside a cell. Osmosis ​- The diffusion of water molecules from a region of high water concentration to a region of lower water concentration across a partially permeable membrane. Percentage change in mass​ - The proportion of the mass of a substance that has changed over a set period, calculated using: Picometre (pm) ​- A quantitative unit of length. One picometre is equal to ×10​-12​ metre. Plasmid ​- Loops of DNA found in the cytoplasm of prokaryotic cells. Prokaryotic cell ​- A type of cell found in bacteria that does not contain a nucleus. Proteases​ - Enzymes that break down proteins into amino acids. Protein ​- A large molecule that is synthesised from amino acids. Rate of reaction ​- The speed at which reactants are converted into products. Resolution​ - The smallest distance between two objects that can be distinguished. Ribosomes​ - Sub-cellular structures that are the site of protein synthesis. Specialised cell ​- A cell that has a structure which makes it adapted to its function. Specificity​ - Describes the ability of an enzyme to catalyse only a particular reaction or set of reactions in which a specific substrate fits the active site of the enzyme. Sperm cell​ - A specialised male sex cell that is involved in reproduction. Vacuole​ - An organelle found in plant cells which stores cell sap and supports the cell. https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc