Prior to the time when Luis and Walter Alvarez proposed that an impact led to the extinction of the dinosaurs, it was generally assumed that the dinosaurs had died out over a period of at least thousands to millions of years. Consider each piece of evidence listed below and sort it into the correct bin based on whether it supports a sudden cause for the demise of the dinosaurs or whether it could also be consistent with a gradual cause leading to their demise over many thousands or more years.

Select the situation bellow that would produce a total displacement of zero. a. a trip to the moon and then to mars b. a horse galloping from one end of a field to another c. the criss-crossing path of a bug as it flies from flower to flower d.a round-trip ride to school and back

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time

Scientists are conducting a study on the effectiveness of a new drug on memory loss. they are giving some of the test subjects the new drug to find out if it improves their long-term memory. which are possible limitations of this study? check all that apply. a) test subjects may want to participate in additional experiments. b) test subjects may think they should be paid more. c) test subjects may get bored and want to quit early. d) test subjects may have to travel during the experiment. e) test subjects may have full-time jobs. this is multiple choice. you for the !