Electron transport is coupled to ATP synthesis in mitochondria, in chloroplasts, and in thermophilic bacterium Methanococcus. Which of the following is likely to affect the coupling of the electron transport chain to ATP synthesis in all of these systems?

A) A potent inhibitor of cytochrome c oxidase
B) The removal of oxygen
C) The absence of light
D) An ADP analog that inhibits ATP synthase

I know that D is the correct answer but why? Could you please make it very detailed?

The correct answer is option D.

Explanation:

Each of the chemiosmotic coupling systems comprises a proton gradient, which is utilized by the enzyme ATP synthase to combine with ADP and phosphorylate it. Thus, any component that obstructs the binding of ATP with the synthase or that prevents the formation of the proton gradient will surely influence all the chemiosmotic systems.  

On the other hand, the element like oxygen and cytochrome c are needed only for aerobic bacteria and for mitochondria, they have no function in methanococcus, and light is needed only for the photosynthetic bacteria and for chloroplasts, and thus, have no role for methanococcus.  

question#1

ans:

cell is the basic unit of organization of all living things. cells are often called the building block of life and it is the smallest unit of life. the study of cell is called cell biology. cell consists of cytoplasm enclosed within membrane, which contain bio-molecules such as proteins and nucleic acid.

two third of cell is water, which means that two-third of your whole body is water. the rest is the mixture of molecules, mainly proteins, lipids and carbohydrates.

question#2

ans:

organ:

an organ is a group of tissues specialized to form a functional unit. an example is the heart in animals.

organ system:

an organ system is a group of several organs whose functions are synchronized to release an effective action in a living organism. an example is digestive system.

question#3

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#4

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system—working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#5

our body works because of the interactions that happen between organs and organ systems.  

for example:  

the heart to regulate blood flow throughout the body. the blood carries oxygen and nutrients to the cells and carries carbon dioxide and waste away from the cells. body systems work together in maintaining a constant internal environment. when this balance is disrupted, the body systems may not function properly, and human health can suffer.   you start to feel bad.