Results from multiple experiments suggest that the ActA protein of Listeria, an integral membrane protein expressed on the cell surface, is the only bacterial protein that is required for the movement of the bacterium within its host cell. Which combination of the following observations shows that ActA is both, necessary and sufficient for bacterial movement? I. ActA binds to the Arp2/3 complex
II. E. Coli in which ActA is expressed moves in host cell cytosol
III. Listeria lacking the ActA gene fail to move inside the host cell cytosol.
IV. ActA has 3 transmembrane domains
V. Arp2/3, when activated, nucleates a branched actin network

a. I and II
b. II and III
c. I and III
d. III and IV
e. I and V

An example of internal feedback working to maintain homeostasis is your a. decreased respiration rate when you are studying b. decreased heart rate when you are sad c. increased respiration rate when your muscles need more oxygen d. increased heart rate when your lungs need more oxygen

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.