Sodium and potassium ion channels have several negatively charged residues at the entry to the channel. on what basis do k+ channels specifically select for k+ ions? (in other words, why dont k+ channels enable na+ ions to cross the membrane? )
a. ionic radius, na+ is to smallb. energy cost, it is to energetically costly to dehydrate na+c. charge, na is slightly more electronegative than k and does not interact with the channel carbonyl groupsd. charge, na is slightly less electronegative than k and does not interact with the channel carbonyl groupse. ionic radius, na+ is too big

The phlogiston theory in the 17th century attempted to explain burning. the theory stated that combustable objects contained a material called phlogiston, a substance without mass, color, odor, etc. after objects burned, the objects were dephlogistonated and were then in their true form. the phlogiston theory was accepted until the 18th century, when lavoisier proved that combustion requires a gas that has mass. phlogiston is considered a) to be scientific knowledge b) not to be scientific knowledge c) to be proven by scientific method d) to be accepted in the modern scientific community

When proteins are being produced by a cell, scientist say that the genes are question 2 options: activated turned off replicated deactivated

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.