10. A student planted 50 lima bean seeds and 50 green bean seeds 2 cm deep in soil. She gave them all the same amount of water and light. She measured the height of all seedlings every day to determine which type of seed grew the fastest. What are the constants (controlled variable) in this experiment? The amount of water and light given to the seedlings 1 1. A scientist wanted to determine the best level of light for a certain type of plant. He changed the amount of light and measured the amount of oxygen produced by the plant each time. What is the dependent variable in this experiment? 13. A student set up an experiment to see if soap affects the growth of seeds. Half of the seeds were planted in soapy soil and placed in the sun. The other seeds were planted in soil without soap and placed in the shade. All seeds receive the same amount of water. What is wrong with his experiment? 14. A student is testing how pulse rate changes as length of time spent exercising increases. The dependent variable is 15. Thomas wants to investigate how an object's mass affects the average speed that it falls when dropped from a certain height. Which variable must Thomas change during the experiment? (What is his independent variable?) 16. Catherine must conduct a scientific investigation for a science project. Which step should she complete first? 17. A student times how long it takes for a sheet of paper to fall to the ground from a certain height. The student then crumples the same paper and drops it from the same height The student observes that the paper fell faster the second time. What variable did the student measure? (What was the dependent variable?) 18. A student predicts that similar ice cubes will melt faster in a microwave than in a pot on the stove. How should this hypothesis be tested? 19. A student hypothesized that the amount of light a sunflower receives determines the number of sunflower seeds produced by the plant. In her experiment, the number of seeds is which variable