Pre-Test Questions |78 Questions| With Correct Answers.

indpendent variable {Ans: the experimental factor that is manipulated; the variable whose affect is being studied}A student graphed the position of a cart during a 7-second time interval. Which statement best describes the cart? {Ans: The cart moved at a constant velocity of 0.5 m/s for the entire 7 seconds}As part of an investigation, students combined substances in a beaker to observe chemical reactions. They performed two procedures. They measured the mass of each substance before and after each reaction. The table shows their observations. Assuming the students did not make any careless errors, what likely explains these changes in mass? {Ans: Procedure 1: One of the products was a gas that escaped into the air. Procedure 2: A gas from the air reacted with one of the other reactants}Suppose all the buildings and trees in an area are black. Which color moth would have a better rate of survival? {Ans: Black}Which ecosystem would be most likely to survive if a disease killed the grasses? {Ans: The forest ecosystem, because most the animals can eat other organisms.}Both a chloroplast and a vacuole are enclosed by membranes, but the two organelles serve different functions. Which of