The percentage of oxygen in the air is 21.0%, but the percentage in air exhaled while breathing is A. 21.0%
B. 18.0%
C. 16.0%
D. 14.0%
E. none of the above

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

9. technology can bring both good and bad things. building a vertical farm can increase food supplies in cities (good), but it may cause unemployment in rural areas (bad). give another example of both the good and bad sides of a technological advancement (5 noints)

Asample of digestive juice was removed from the stomach of a pig. the juice was placed in a test tube along with some grains of wheat. a second test tube was set up containing an equal number of wheat grains, with distilled water rather than digestive juice. the test tubes were kept for 8 hours at 40 degrees c. after 8 hours, the grains inside the digestive juice had broken into tiny particles. the grains of wheat, in the water, were wet but otherwise unchanged. what is the control group?