What is the function of the valves in the heart and veins?

Which statement best explains why cattle able to survive on a diet consisting almost entirely of plant material?

Not all poikilotherms are ectotherms.

You are doing a lab experiment on osmosis and are using sugar and water. In osmosis, water moves from an area of high sugar (solute) concentration to an area with lower sugar (solute) concentration. 

Which of the following types of cell-to-cell signaling describes tumor cells that influence surrounding cells by secreting growth factors?

The digestive system processes food, extracts nutrients, and eliminates the residue.  

Homeostasis refers to the property of maintaining particular physiological variables such as body temperature and solute concentrations absolutely constant with no variation.

Which of the following indicates a diagnosis of hypertension (high blood pressure) in human adults?

Which of the following tissue types is specialized to conduct electrical signals? 

Which of the following is an advantage of excreting nitrogenous wastes as urea rather than as ammonia?