Definitions biology-igcse-biodeluna2011
- 1. DEFINITIONS-Biology Define the term catalyst as a substance that (IGCSE -2011 Syllabus) speeds up a chemical reaction and is not changed by the reaction Define the terms: • nutrition as taking in of nutrients which are organic Define enzymes as proteins that function as substances and mineral ions, containing raw biological catalysts materials or energy for growth and tissue repair, absorbing and assimilating them • excretion as removal from organisms of toxic Define nutrition as taking in of nutrients materials, the waste products of metabolism which are organic substances and mineral (chemical reactions in cells including respiration) ions, containing raw materials or energy and substances in excess of requirements for growth and tissue repair, absorbing and • respiration as the chemical reactions that break assimilating them down nutrient molecules in living cells to release energy • sensitivity as the ability to detect or sense changes Define photosynthesis as the fundamental in the environment (stimuli) and to make responses process by which plants manufacture • reproduction as the processes that make more of carbohydrates from raw materials using energy the same kind of organism from light. • growth as a permanent increase in size and dry mass by an increase in cell number or cell size or both Define the term limiting factor as something • movement as an action by an organism or part of present in the environment in such short an organism causing a change of position or place. supply that it restricts life processes. Define the binomial system of naming Define ingestion as taking substances (e.g. species as a system in which the scientific name of an food, drink) into the body through the mouth organism is made up of two parts showing the genus and species. Define egestion as passing out of food that has not been digested, as faeces, through the anus Define: • tissue as a group of cells with similar Define digestion as the break-down of large, structures, working together to perform a insoluble food molecules into small, watersoluble shared function molecules using mechanical and • organ as a structure made up of a group of chemical processes tissues, working together to perform specific functions • organ system as a group of organs with related functions, working together to Define absorption as movement of digested perform body functions. food molecules through the wall of the intestine into the blood or lymph Define diffusion as the net movement of molecules from a region of their higher Define assimilation as movement of digested concentration to a region of their lower food molecules into the cells of the body where concentration down a concentration gradient, they are used, becoming part of the cells as a result of their random movement. Define active transport as movement of ions in or Define deamination as removal of the out of a cell through the cell membrane, from a nitrogencontaining region of their lower concentration to a region of part of amino acids to form urea, their higher concentration against a concentration followed by release of energy from the gradient, using energy released during respiration. remainder of the amino acid Biology definitions (IGCSE) - IES Pedro de Luna - 1
- 2. Define transpiration as evaporation of water at Define the surfaces of the mesophyll cells followed by geotropism (as a loss of water vapour from plant leaves, through response in which a plant grows towards or the stomata away from gravity) and phototropism (as a response in which a plant grows towards or away from the direction from which light is coming) Define translocation in terms of the movement of sucrose and amino acids in phloem; • from regions of production Define homeostasis as the maintenance of a • to regions of storage OR to regions of constant internal environment utilisation in respiration or growth Define a drug as any substance taken into the body that modifies or affects chemical reactions in the body Define respiration as the chemical reactions that break down nutrient molecules in living cells to release energy Define asexual reproduction as the process resulting in the production of genetically identical offspring from one parent Define aerobic respiration as the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen Define sexual reproduction as the process involving the fusion of haploid nuclei to form a diploid zygote and the production of genetically dissimilar offspring Define anaerobic respiration as the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen Define pollination as the transfer of pollen grains from the male part of the plant (anther of stamen) to the female part of the plant Define excretion as the removal from (stigma) organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements. Substances should Define growth in terms of a permanent include carbon dioxide, urea and salts increase in size and dry mass by an increase in cell number or cell size or both Define development in terms of increase in Define sense organs as groups of receptor cells complexity responding to specific stimuli: light, sound, touch, temperature and chemicals Define inheritance as the transmission of genetic information from generation to generation Define a hormone as a chemical substance, Define the terms: produced by a gland, carried by the blood, which • chromosome as a thread of DNA, made up alters the activity of one or more specific target of a string of genes organs and is then destroyed by the liver • gene as a length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation Biology definitions (IGCSE) - IES Pedro de Luna - 2
- 3. • allele as any of two or more alternative Define the terms: forms of a gene • food chain as a chart showing the flow of • haploid nucleus as a nucleus containing a energy (food) from one organism to the next single set of unpaired chromosomes (e.g. beginning with a producer (e.g. mahogany sperm and egg) tree → caterpillar → song bird → hawk) • diploid nucleus as a nucleus containing • food web as a network of interconnected two sets of chromosomes (e.g. in body food chains showing the energy flow through cells) part of an ecosystem • producer as an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis • consumer as an organism that gets its energy by feeding on other organisms Define mitosis as nuclear division giving rise • herbivore as an animal that gets its energy to genetically identical cells in which the by eating plants chromosome number is maintained by the • carnivore as an animal that gets its energy by exact duplication of chromosomes eating other animals • decomposer as an organism that gets its Define meiosis as reduction division in which energy from dead or waste organic matter the chromosome number is halved from • ecosystem as a unit containing all of the diploid to haploid organisms and their environment, interacting together, in a given area e.g. decomposing log or a lake • trophic level as the position of an organism Define the terms: in a food chain, food web or pyramid of • genotype as genetic makeup of an biomass, numbers or energy organism in terms of the alleles present (e.g. Tt or GG) • phenotype as the physical or other features of an organism due to both its Define population as a group of organisms of genotype and its environment (e.g. tall one species, living in the same area at the same plant or green seed) time • homozygous as having two identical alleles of a particular gene (e.g. TT or gg). Two identical homozygous individuals that breed together will be pure-breeding • heterozygous as having two different alleles of a particular gene (e.g. Tt or Gg), not pure-breeding • dominant as an allele that is expressed if it is present (e.g. T or G) • recessive as an allele that is only expressed when there is no dominant http://biodeluna.wordpress.com allele of the gene present (e.g. t or g) Define natural selection as the greater chance of passing on of genes by the best adapted organisms Define genetic engineering as taking a gene from one species and putting it into another species Biology definitions (IGCSE) - IES Pedro de Luna - 3