What is the purpose of photosynthesis

Which are forms of nitrogen that are usable by humans

Which statement best describes lactic acid fermentation? a. lactic acid fermentation is the first step of cellular respiration. o b. lactic acid fermentation is the final step of cellular respiration. re to berate c. in the absence of oxygen, cells release atp by breaking down lactose into glucose. e der lade res o d. in the absence of oxygen, cells release atp by breaking down glucose into lactate. ar

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?