Which of the following is the best example of a response to external stimuli?
a. pupils of the eyes dilate in the dark.
b. a flu virus infection results in vomiting.
c. when a person is hungry, his/her stomach growls.
d. a fatigued person responds by sleeping.

Eristics do scientists use to distinguish between organisms in different kingdoms

Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above

Asolution of an enzyme and a substrate was placed in a water bath and the temperature of the reaction was raised gradually. the graph shown was plotted at the end of the experiment. what can be concluded from the graph? a) temperature has no effect on the activity of the enzyme. b) the effect of temperature on the enzyme is unpredictable. c) the enzyme shows increased activity up to a certain temperature. d) the activity of the enzyme is inversely proportional to the temperature.