Which of the following is true of vertebrates with four-chambered hearts? there is a partial gas exchange in one chamber of the heart. there is a partial mixing of oxygen-rich and oxygen-poor blood. there is no mixing of oxygen-rich and oxygen-poor blood. there is a complete mixing of oxygen-rich and oxygen-poor blood.

Cathy hypothesized that corn would not grow in mud. to test this hypothesis, she took corn kernels and placed 5 in mud, 3 in soil, and 2 in water. to her surprise, the kernels in the mud grew faster than the kernels in the soil. what error might have caused these unexpected results? a. wrong hypothesis b. not enough variables c. undefined control d. too many variables

Is a measure of the different types of organisms in a community. question options: tertiary secondary primary none of the above

Development has provided electrically for less money but what may be considered a cause of nuclear power