What is the primary factor that limits the population growth of P. caudatum and P. aurelia in a closed culture?

The gizzard is an enlarged chamber of the stomach in which _____________. 

Which organs are primarily responsible for filtering waste products from the frog’s blood, as part of the excretory system?

The aortic arches function as hearts, pumping blood through a closed circulatory system. Therefore, which of the following are true statements about how blood travels in an earthworm? 

Which of the following best describes the structure and function of myomeres? 

Which of the following best describes the concept of competitive exclusion, as demonstrated by the Paramecium experiment?

Which of the following structures is/are associated with the cephalothorax?  

What is/are the primary function(s) of the dermal branches?  

What is the shape of leaf C called?

What is structure H?