All of the answer choices given in this question are true statements, and they are all reasons why endergonic reactions can occur within living things.

Oftentimes, reactions that require a large input of energy are thermodynamically coupled to the hydrolysis of ATP, the energy currency of the cell. As a result, ATP is able to provide the fuel, so to speak, for powering the reaction.

Also, it's important to note that standard free energy changes are much different than the free energy changes that occur under physiological conditions. Standard state assumes that all reactants and all products of a reaction start out at a concentration of , but this concentration is absurdly high for just about any compound found within cells.

Lastly, the products of some endergonic reactions are often used up quite readily. As a result of this, the concentration of product is kept at a low level, which means that the reactions becomes favored toward making more product.

A nucleoside triphosphate - as its name suggests - is a DNA base with three phosphate groups. During polymerization, these base groups will be continuously connected to each other in order to form a DNA strand. This is thermodynamically favorable because during the polymerization, two of the three phosphate groups on the nucleoside triphosphate will detach as a pyrophosphate. This will then be hydrolyzed which is extremely thermodynamically favorable. And so, the polymerization itself is considered to be thermodynamically favorable.

The R (relaxed) state hemoglobin is triggered by hemoglobin binding to oxygen. The heme group in R state hemoglobin is perfectly planar. By nature, R state hemoglobin is stabilized in the presence of oxygen, not in the absence of oxygen. 

To answer this question, it's important to know how the standard free energy change of a reaction is related to other various parameters of the reaction.

The standard free energy change of a reaction can be presented in different expressions.

For the purposes of this question, the bottom expression is the one we need. If we set the change in standard enthalpy term equal to zero, we can solve for our answer.

Phosphoanhydride bonds contain lots of stored energy, with a  of . This energy, when released during ATP hydrolysis, can then be used for various anabolic pathways.

Diffusion and facilitated diffusion are methods by which molecules can pass through membranes without the use of ATP. Even though facilitated diffusion does require a channel to function, movement is still controlled by differences in concentration gradients. Primary active transport uses ATP directly to drive molecules against their concentration gradients, and secondary active transport uses the pre-established electrochemical gradient from primary transport to create movement for other molecules - so it still does require ATP to function even though it is indirect.

Fick's law describes the factors that influence diffusion of molecules through a membrane. All of the variables listed as answer choices, if changed, can influence the level of diffusion that can occur through the membrane.

The correct Nernst potential for sodium is  and the correct Nernst potential for potassium is . The resting membrane potential for the cell membrane as a whole is about . 

For this question, we're asked to identify the correct measure that allows us to predict the direction of a chemical reaction. Let's take a look at each answer choice.

The change in enthalpy of a reaction, , represents the amount of heat energy absorbed by or given off in a chemical reaction. Generally, chemical reactions that give off heat tend to go in the forward reaction. However, by itself, enthalpy cannot predict the direction of a chemical reaction.

The change in entropy of a reaction, , represents the change in disorder of a chemical reaction. Generally, chemical reactions that become more disordered as they progress tend to be driven in the forward direction. However, this alone is not enough to predict the direction of a chemical reaction.

The temperature at which a reaction occurs is another important factor to take into account when deciding the direction in which a chemical reaction will take. Reactions tend to be driven forward when they give off heat in low temperature environments. Also, reactions tend to be driven forward when they absorb heat in high temperature environments. But, by itself, temperature is not sufficient to predict the direction of a chemical reaction.

The activation energy of a reaction represents the amount of energy that must be put into a reaction in order for the reactants to reach the high-energy transition state. However, activation energy only affects the rate of a reaction and not its direction. Reactions that have higher activation energies will necessarily have a harder time reaching the transition state, which is necessary in order for the reaction to progress. But activation energy does not affect the change in energy of the reactants and products themselves. In other words, activation energy is not concerned with the thermodynamics of a reaction, but rather with the kinetics. Thus, activation energy will not allow us to predict the direction of a chemical reaction.

Finally, let's take a look at the change in Gibb's free energy, . This measurement takes into account several other variables, including , , and temperature. In doing so, the  term allows us to accurately predict the direction of a chemical reaction, since it takes these other important factors into account. When the value of  is negative, this indicates a reaction that will be driven in the forward direction, because the reactants are losing free energy as they are converted into products. Conversely, a positive  indicates a reaction that is driven in the reverse direction. Put into the form of an equation,  takes the following form.

When  is negative, the reaction will occur spontaneously. So, if the change in enthalpy  and the change in entropy  are both positive,  will only be negative when temperature is high enough to make  greater than .