Question

ADP and ATP differ in the number of:
A. phosphate unit
B. ribose unit
C. adenine base
D. nitrogen atom

Answer 1

Hint: The structure of the two molecules can help in determining the number of each species as mentioned in the question. The structure can also be deduced from their names as :ADP stands for Adenosine diphosphate and ATP stands for adenosine triphosphate.

Complete step by step answer:
ADP stands for Adenosine Diphosphate, whereas ATP stands for adenosine triphosphate.
These are units of energy which are responsible for meeting the energy requirements of the biological processes in the body. In case the body needs energy, the phosphate group breaks out of the molecules to supply energy. The structures of the two molecules are:

If we compare the two structures, we can observe the entire structure is the same except for the phosphate groups attached with a peroxide linkage. Hence, ADP and ATP are different in the number of phosphate groups. ADP has two phosphate groups whereas ATP has three. By observing above two images we get one single point to our mind which is they are differ in one phosphate units
 Each ATP compound consists of Adenine, Ribose and $3$ Phosphate groups.
Each ADP compound consists of Adenine, Ribose and $2$ Phosphate groups. Energy stored in ATPs which is employed by the cells for each energy consuming process. ATS is synthesized in mitochondria

So answer to this question is option”A” which is they differ from phosphate units

Additional information:
ADP and ATP and their importance!
ADP: ADP stands for Adenosine DiPhosphate. Each ADP compound consists of Adenine, Ribose and $2$ Phosphate groups.
ATP: ATP stands for Adenosine TriPhosphate. It is an energy rich molecule which is named currency of energy for living organisms.

Importance of ADP and ATP:-
When the terminal bond is broken the ATP is converted into ADP by enzyme ATPase releasing a phosphate and liberating energy. An ADP is like a discharged battery. When the energy is formed available by oxidation of food, ADP takes this energy to be converted to ATP that's to mention that it becomes charged once more

The structure of ATP may be a nucleoside triphosphate, which contains a nitrogenous base (adenine), a ribose sugar, and $3$ serially bonded phosphate groups. ATP is usually mentioned because the "energy currency" of the cell, because it provides readily releasable energy within the bond between the second and third phosphate groups

The diphosphate group of ADP is attached to the ${5}^{'}$ carbon of the sugar backbone, while the adenosine attaches to the first carbon.

This occurs when a molecule of ADP (ADP) uses the energy released during respiration to bond with a 3rd phosphate group, becoming a molecule of ATP. therefore the energy from respiration is stored within the bond between the\[\;2nd\] and \[3rd\] phosphate groups of ATP.


Note: ADP is converted to ATP for the storing of energy by the addition of a high-energy phosphate group. So ADP is like a discharged battery. Energy is stored within the chemical bond holding atoms together within the sort of molecules.