Question

water fleas (cladocera) are small freshwater crustaceans. they are filter feeders and measure approximately 3 - 5mm in length. the outer carapace of a water flea is transparent, so the internal organs can be observed. caffeine raises the heart rate of humans. hanna predicts caffeine will have the same effect on other organisms. she uses the water flea as her test subject in an experiment. hanna introduces varying amounts of caffeine to water flea populations. using a microscope, she measures the heart rate of the sample water fleas in beats per second. she records the data in a table. as the concentration of caffeine increases, hanna observes that the water fleas heart rate also increases. what is the hypothesis in hannas experiment? a caffeine raises the heart rate of humans. b water fleas prefer caffeine over plain water. c caffeine increases the heart rate of the water flea. d the effects of caffeine are the same on all organisms.

Explanation:

A hypothesis is a proposed explanation made on the basis of limited evidence as a starting - point for further investigation. Hanna predicts caffeine will have the same effect on other organisms as it does on humans. Her experiment with water fleas is to test this prediction. The most relevant hypothesis here is that caffeine has the same effect on all organisms as it does on humans.

Answer:

D. The effects of caffeine are the same on all organisms.