When amino acids are degraded for energy, their amine groups are stripped off and incorporated by the liver into and sent to the kidneys for excretion.

Urea

Explanation:

Amino acids are the monomeric units of proteins. They are bi-functional because they possess both an amino group (-NH₂) and a carboxyl group(-COOH). First class protein are essential ingredients for healthy human diet e.g milk, cheese, fish etc. Such proteins are broken down in the body by enzymatic hydrolysis to their constituent amino acids from which they are degraded into energy which is needed for growth and from which other life function is being synthesized. The result of this effect leads to separation of amine groups which are converted into urea by the liver.

This process is achieved by the deamination of excess amino acids that leads to the formation of urea which are  excreted via the kidneys.

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b