According to the phylogenetic tree below, modern-day mammals are most closely related to which modern group of reptiles?

Recent extinctions of species can be attributed to several causes.  Which of the following is not considered a major cause of such extinctions?  

Evidence suggests that an asteroid struck the Gulf of Mexico near what is now the Yucatan Peninsula about 65 million years ago.  What was likely the cause of the cause of the loss of many plants?

What features of charophytes provides evidence for charophytes being the closests relative to land plants?

Which organ system plays the least role in maintaining optimal conditions of the animal body? 

Homeostasis in animals can be generally defined as the _____.

An organism has the following features: diplontic life cycle, protostome development, segmentation, a septate coelom, closed circulatory system, and setae. To which phylum does this organism belong?

When scientists study organisms in nature (i.e. outside of the laboratory), carefully controlled experimentation is not always possible.  In a case involving mating behavior of birds, data might be gathered by

The first stage in the gametophyte generation is  _____.

Considering that the scientific method includes making observations, formulating a hypothesis to explain the observations, testing the hypothesis with experimentation, analyzing data from experiments, and drawing conclusions about the meaning of the data, which of the following statements about a species of flowering plant represents an experiment?