Ocr A level biology paper 2

Efficiency of biomass transfer - answer-Biomass of previous trophic level divided by biomass of current trophic level then x 100 Saprobiotic nutrition - answer-Fungi and bacteria that produces enzymes within the cell which are then transported outside of the cell (extracellular) to digest biochemicals. They then absorb the products. Nitrogen fixation - answer-Taking nitrogen gas and incorporating it into a nitrogen compound. Rhizobium - answer-Found in root nodules. Fix nitrogen into ammonia. Azotobactor - answer-Free living Nitrogen fixing bacteria Ammonification - answer-Decomposition of proteins in dead organic matter to release ammonia. Nitrification - answer-Turning ammonia into nitrate. Nitrosomanas - answer-Bacteria involved in oxidation of ammonia into nitrites Nitrobacter - answer-Bacteria involved in the oxidation of Nitrites to nitrates. Denitrification - answer-Denitrifying bacteria convert nitrates into nitrogen gas ( anaerobic) Primary succession - answer-Sequence of plants colonizing a newly formed environment. e.g. on newly formed volcanic rock. Secondary succession - answer-If an environment has already undergone succession and an event e.g. tree fall removes the climax community and succession starts again - not necessarily from the beginning. Deflected succession - answer-Something prevents the process reaching climax community such as grazing. the result is a plagioclimax community. Taxonomic hierarchy - answer-Classification system based on large groups being subdivided in to smaller groups that do not overlap. Phylogeny - answer-The study of evolutionary relationships between organisms. Phylogenetic tree - answer-Diagram representing the evolutionary relationships of organisms with a common ancestor. Cladistics - answer-Classification system based on an organisms evolutionary history. Domain Bacteria - answer-A domain made up of prokaryotes. Contains the Kingdom Eubacteria. They lack a nucleus and membrane bound organelles. They have a single circular strand of DNA and small 70s ribosomes. Domain - answer-A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya. Domain Archaea - answer-Domain containing single-celled, simple organisms, genetically distinct from bacteria, often thriving in extreme environmental conditions. Domain Eukarya - answer-Domain of all organisms whose cells have membrane bound organelles including nuclei. The domain includes protists, plants, fungi, and animals. Kingdom - answer-Large taxonomic group, consisting of closely related phyla Kingdom Prokaryotae - answer-Bacteria (most recently divided into two kingdoms: Kingdom Eubacteria and Kingdom Archaebacteria/Archaea) Kingdom Protoctista - answer-Includes a diverse collection of single-celled and multicelled organisms that have a nucleus. Includes algae. Kingdom Fungi - answer-Heterotrophic organisms, they secrete enzymes and digest food outside of their bodies then absorb the nutrients, are multicellular, and have cell walls of chitin and often form mulitnucleate hypae. Kingdom Plantae - answer-Multicellular eukaryotes that photosynthesize (photoautotrophs) and have cell walls made of cellulose. Kingdom Animalia - answer-A kingdom a of multicellular, heterotrophic eukaryotic organismsins that are free-moving, lack cell walls Binomial nomenclature - answer-A system for giving each organism a two-word scientific name that consists of the genus name (initial letter written with a capital letter) followed by the species name (Lower case). Written in italics/underlined. Species - answer-A group of similar organisms that can breed and produce fertile offspring. Paleontology - answer-The study of fossils Comparative anatomy - answer-the study of similarities and differences in the anatomy of different species Homologous structures - answer-Features that are similar in structure but appear in different organisms and have different functions. Divergent evolution - answer-A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently, to diverge from their common ancestor. The resulting (new) species may share structural (but not necessarily functional) similarity; divergent evolution produces homologous structures. Convergent evolution - answer-Process by which unrelated organisms independently evolve similarities when adapting to similar environments. Comparative biochemistry - answer-Comparison of organisms proteins/DNA. If amino acid/nucleotide sequence is similar then the organisms are related. Comparative embryology - answer-Among different species, there are similarities in embryo appearance and anatomy. This concept supports the theory of evolution. Inter-specific variation - answer-Variation between members of different species Intra-specific variation - answer-Variation between members within the same species Discontinuous variation - answer-Variation between living organisms within a species, where there are discrete categories and no intermediates, e.g. blood groups A, B, AB or O in humans. This type of variation is determined by one gene. Continuous variation - answer-Variation between living organisms where there is a range of intermediates, such as height, hair colour and intelligence in humans. These characteristics are determined by many genes that interact. The expression of these genes is also influenced by the environment. Genotype - answer-An organism's genetic makeup, or allele combinations. Phenotype - answer-An organisms physical appearance or visible traits Allele - answer-Alternative versions of a gene that produce distinguishable phenotypic effects. Evolution - answer-A change in a species over time, the process by which modern organisms have descended from ancient organisms. Mutation - answer-Any change in the nucleotide sequence of DNA Natural selection - answer-A process in which individuals that have certain alleles/inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. Reproductive success - answer-The likelihood of an individual contributing fertile offspring to the next generation. Standard deviation - answer-A measure of the spread of data around the mean. A measure of the variability in the data. Pathogen - answer-An organism that causes disease Antigen - answer-A molecule that triggers the immune response Antibody - answer-Plasma proteins with specific antigen -binding sites,constant and hinge regions Interleukins - answer-proteins (cytokines) that stimulate the growth of B and T lymphocytes Plasma cells - answer-Cells that develop from B cells and produce antibodies. Clonal selection - answer-the process during the immune responses when specific B cells /T cells interact with antigens displayed by APC Clonal expansion - answer-Mitotic division of a small group of identical cells after clonal selection. Cells differentiate into memory /plasma cells Phagocytosis - answer-process in which neutrophils and macrophages engulf and digest microorganisms and cellular debris. Third line of defence - answer-A response to invading specific pathogens involving lymphocytes and antibodies Callose - answer-A polysaccharide made by plant cells in defence against attack by pests and pathogens Communicable disease - answer-Diseases caused by a pathogen that can be transmitted from one host organism to another Vector - answer-An organism that transfers a pathogen from an infected host to an uninfected host. First line of defence - answer-Physical and chemical defences that prevent entry of pathogens Inflammation - answer-a reaction to injury or infection.Excess tissue fluid forms (swollen). Histamines are released and arterioles dilate ( red). Phagocytes squeeze out of capillaries and engulf pathogens( hot ) Cytokines - answer-Small protein molecules that act as cell-signalling molecules Plasma cell - answer-An activated B cell that makes and releases antibodies during an immune response T helper cell - answer-Type of lymphocyte that coordinates the immune response using chemical signals such as interleukins Agglutination - answer-The clumping together of pathogens using antibodies Opsonisation - answer-the marking of pathogens by antibodies to facilitate phagoctosis Antibiotics - answer-Any substance produced by a microorganism that can harm or kill another microorganisms Autoimmune disease - answer-A disease in which the immune system attacks the organisms own cells antibiotic resistance - answer-Resistance evolving rapidly in many species of prokaryotes due to overuse of antibiotics, especially in agriculture. Neutralisation - answer-Antibodies - Main role = Blood clotting - answer-platelets,cells and fibres form a mesh at a cut preventing blood loss and entry of pathogens. Scab forms Expulsive reflex - answer-sneezing,coughing,vomiting antigen presenting cell - answer-these are cells that recognizes antigens and brings them into the cell by phagocytosis; the cells then breaks up the antigen and present them on the cell surface membrane plasmodesma - answer-A microscopic channel through plant cell walls, connecting the cytoplasm of two cells. These are lined with plasma membrane. (pl: plasmodesmata) Accuracy - answer-How close a measurement is to the true value. However, the true value may not be known Anomaly - answer-All results show variation. This describes a result that lies beyond this variation. Confidence - answer-Is a qualitative judgement expressing the extent to which a conclusion is justified by the quality of the evidence. Error (of measurement) - answer-The Difference between the recorded value and the true value. Precision - answer-The closeness of agreement between independent measurements obtained under the same conditions. It depends only on the distribution of random errors (i.e. the spread of measurements) and does not relate to the true value. Repeatability - answer-The precision obtained when measurement results are produced over a short timescale by one person using the same equipment in the same place. Reproducibility - answer-Is the precision obtained when measurement results are produced over a wider timescale by different people using equivalent equipment in different places. Resolution - answer-Is the smallest change in the quantity being measured that can be detected by an instrument. Uncertainty - answer-An estimate as to where the true value actually lies. This is normally expressed as a range of values such as 44.0 ± 0.4.