Which of the following is a biotic factor that affects distribution of life in aquatic systems?
Salinity
Light
Temperature
Plankton

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

The cretaceous period spanned the time interval between and 65 million years ago. 250 million 144 million 75 million 200 million

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?