What do you mean by symptom ?

The distribution of related animals and plants across the world

Which was most likely an effect on society that resulted from improvements in blood handling during world war i and world war ii?

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?