Arrange according to the time they evolved? a) bony fish with jaw b) jawless fishc)fish with leg-like fins

Which statement describes an endocrine function rather than an exocrine function? a. salivary glands release saliva into the mouth. b. sweat glands release sweat onto the skin c. the pineal gland releases melatonin into the blood. d. esophageal glands release mucus into the esophagus.

Which way do the nitrogenous bases in dna pair up? a. a and g; t and c b. a and c; t and g c. a and t; g and c d. a and a; t and t; g and g; c and c

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?