Question

Scientists performed an experiment on a genus of small aquatic crustaceans called Daphnia. These animals are filter feeders that trap and eat protists and bacteria. Scientists placed different numbers of young Daphnia in similarly-sized tanks. This meant that in some tanks, individuals had a large amount of space, and in other tanks, individuals had less space and were crowded. Scientists gave each group plenty of food to ensure there was enough for every individual.The results showed that during the early juvenile stages, Daphnia in the different tanks grew at similar rates. However, in tanks withfewer Daphnia, adults grew larger than in tanks with more Daphnia. Based on this information, what is the impact of a lack of spaceon Daphnia?A. Lack of space keeps Daphnia from reaching adulthood.B. Lack of space has no impact on how Daphnia grow.C. Lack of space causes Daphnia to grow faster when they are youngD. Lack of space causes Daphnia to grow to smaller sizes as adults.

Answer 1

While they were young, no difference was spotted, therefore C is incorrect.

All of the individuals reached adulthood, therefore A is wrong too.

As the results show, populations in more crowded tanks (with less individual space) resulted in smaller adult individuals. Therefore, B is incorrect as well because there was an impact.