Burning of fossil fuels has changed the atmosphere by a) producing a hole in the ozone. b) reducing the cfcs in the atmosphere. c) increasing the concentration of carbon dioxide. d) increasing the concentration of ozone in the atmosphere

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.

Ayoung boy has been found and police are trying to locate his family they take a dna sample from him and begin collec dna samples from families who have missing children if police use dna samples only from the fathers, which type of dn technology can they use to identify the boy's parent? y-chromosome analysis omtdna (mitochondrial dna) analysis vntrs (variable tandem repeats) o pcr (polymerase chain reaction) analysis

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