Deficiency of vitamin K causes :

Increase in blood clotting time

Decrease in blood clotting time

Biomolecules PYQ — JEE Main 2021 · 18 Mar · Shift 2 · Q1 with Solution

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Correct answer: C

Recall the function of Vitamin K

Vitamin K is essential for the synthesis of certain blood clotting factors such as prothrombin and other clotting proteins.
Effect of deficiency

If vitamin K is deficient, the body cannot form clotting factors properly.

Therefore, blood takes longer to clot.
Interpretation in terms of clotting time
- Longer time to clot means increase in blood clotting time.
- So the correct option is C.
Check other options
- A: Cheilosis — associated mainly with deficiency of vitamin $B_2$ (riboflavin), not vitamin K.
- B: Decrease in blood clotting time — opposite of the actual effect.
- D: Increase in fragility of RBC's — associated more with vitamin E deficiency, not vitamin K.
Conclusion

Vitamin K deficiency causes increase in blood clotting time.

$\boxed{\text{Option C}}$