Controls are defined as ___.
A) variables scientists observe for changes
B) things that change during an experiment
C) variables that are changed by the scientist
D) things that are kept constant during an experiment

Use this diagram of an animal cell to answer the question. where does the first stage of cellular respiration occur? w x y z

What causes darkening of the skin as melanin production increases

Grade 91.)the gravitational pull from the moon words).2.) what is the rate of gravitational 3.)if you drop a hammer, is it more likely to drop handle side down, head side down, or equal chance that it will land either way? why? 4.)a car moves 60km east and 90km west.a.) what is the distance the car traveled? b.) what is the car's displacement5.)what is the average velocity of a car that moved 60 km south in 3 hours? 6.) a car starts from rest and acceleration to 60 m/s over a time of 5 seconds. what is the acceleration of the car? 7.)what is the speed of an object at rest?