A plant root is an exaA plant root is an example of mple of

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the answer will be a) proteins i believe

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.