How many years did it take to double between .5 billion and 1 billion?

(drag each tile to the correct identify which questions can be answered by what can be answered by science or which cannot. -is it right or wrong to use genetic engineering to produce new food products? -what are the most common social settings that tend to produce accomplished artists? -if a new gene is added to the genome of a tomato species, will that species be more resistant to insects? -should humans use biotechnology to bring extinct organisms from the fossil record back to life? -do the types of organisms found in the fossil record appear in consistent sequences in different parts of the world? -are michelangelo's paintings more impressive than rembrandt's?

What causes darkening of the skin as melanin production increases

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.