Question

Vitamin K cannot be produced by humans. What is true about the presence of vitamin K in the bloodstream even though a person's diet is lacking a vitamin K?
A. Vitamin K is synthesized in the liver using hormones absorbed from ingested plant cells.
B. Vitamin K is a byproduct of proteins degradation during digestion.
C. Vitamin k is synthesized by bacteria that inhabit the colon.
D. Vitamin K can be produced by exposure to sunlight.
E. None of the above

Answer 1

Hint: Vitamin K is an essential vitamin needed for the synthesis of blood clotting factors. And we know that it cannot be synthesized by the body of humans so needs to be taken as a supplement. We all know this vitamin helps in production of proteins that go for the work during the clotting process.

COMPLETE ANSWER-
We all know that vitamin K plays a crucial role in blood clotting. Unlike other proteins, they are not a dietary supplement.
Vitamin K is required for the post synthesis modification of certain proteins that are required for blood coagulation. Chemically, the vitamin K family comprises methyl -1,4 naphthoquinone (3-) derivatives. They are naturally of 2 types- vitamin K1 which is also called a phylloquinone and vitamin K2 which is called menaquinone.
Vitamin K1 is made by plants and is found in the highest amount in green leafy vegetables because they are directly involved in photosynthesis. It is also present in animals in an active form which helps in production of blood -clotting proteins which they convert into Vitamin K2. Only Vitamin K2 can be synthesized by the bacteria that lives in the colon of the large intestine.
Without vitamin K, the body cannot produce prothrombin, a clotting factor that is necessary for blood clotting and for the metabolism of bone.
We know that vitamin K is primarily obtained by plants thus is not synthesized in the liver so option A is incorrect.
 During protein degradation during digestion the byproducts are aminoacids. so option B is incorrect.
Vit. K is produced in plants through photosynthesis which takes place in the presence of sunlight, so option D is also incorrect.

So the correct answer is option C.

Note:
Amongst all the vitamins, vitamin K is one of the most important which is usually extracted from other sources. Scientifically it is said that deficiency of vitamin K may weaken our bones, potentially contributing to osteoporosis and may promote calcification of arteries and many other soft tissues present in our body.