Biology Answers

A feature that provides an organism with a selective advantage which makes it more likely to survive and reporiduce is called a(n) _____.

Ventilation helps to supply gases to gas exchange surfaces in animals. a) Other than ventilation, state and explain two features of an effective gas exchange surface in animals.

Explain the structural basis of the high group transfer potential of ATP.

In vitro, is it possible to get back the substrate given to an enzyme?

The ________ controls when the gene is transcribed by RNA polymerase. 

In class we are studying action potentials, repolarization, hyperpolarization, etc.

My teacher told us how once a certain membrane potential is reached and the action potential is fired, potassium channels open and potassium ions flood out of the axon, making it more negative and helping it reach resting potential again. My teacher said that the protein has to be "pumped" out using ATP because it is moving against the concentration gradient. However, looking online it seems like the potassium passes through voltage-gated potassium channels along/following the concentration gradient and therefore doesn't require energy. So does the potassium exiting the cell in repolarization require ATP or no? Does the potassium go through a "pump" or just voltage-gated ion channels?