Which statements about complex IV are true? 1) This complex catalyzes the reduction of oxygen to water. 2) Despite consuming protons, this complex pumps H+ across the membrane at a rate of 4 per molecule of O2 reduced. 3) The protons flow across a gradient to the inner membrane space. 4) Conformational changes as electrons flow through the complex alter the ability of some residues to bind protons.

In what way do investigations build scientific knowledge? the results of investigations lead to questions that cannot be tested. they reflect the opinions and social values of scientists, ensuring valid information. the results of investigations lead to new questions, which lead to new investigations. they are not influenced by the research of earlier scientists, so they are able to address gaps in understanding.i