What do the vessels that are carrying oxygen-poor blood
back to heart have that stops
blood from flowing
backwards?
A. thick muscular walls
B. valves
C. hemoglobin
D. SA nodes

Consider this plant cell which organelle is labeled g

Ronald wants to see if a new shower cleaner works better in removing soap than his old cleaner. he uses the new cleaner on one half of the shower tiles and his old cleaner on the other half. identify the independent and dependent variables in this experiment. enter your answer in the space provided.

What was the purpose of mendel's experiments with dihybrid crosses? a. to determine if dna was a transforming factor b. to determine if traits could be recessive c. to determine if traits affected each other d. to determine if traits had more than one allele