What is suggesred when many fossils are found in one rock layer, but none are found in the layer above it

The two tubes contain bromothymol blue. after 24 hours, what will the color of the water be in tube b? a. green (it won't change) b. yellow c. blue d. colorless (clear)

What type of plant is good for a bioassay and where can i buy it? i only have a month.

What is genetic variation? -(a) each individual in a population has slightly different genes. -(b) some individuals in a population have more genes than others. -(c) each population of a species has slightly different genes. -(d)some populations of a species have more genes than others.