Scientists previously thought that frogs and coelacanth are most closely related due to physical characteristics. With DNA evidence, we now know that frogs are more closely related to which of the following?
A. Great white shark
B. Cichlid
C. Lungfish

Researchers randomly divide participants into groups. each group takes a different amount of omega-3 fatty acid supplements daily for a month. one group receives a placebo. the researchers measure the impact on cholesterol levels in the blood. what is the purpose of random assignment in this experiment? a, to produce treatment groups with similar characteristics b, to ensure that all people with high cholesterol have an equal chance of being selected for the study c, to increase the accuracy of the research results and prevent skewness in the data

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important