4. In humans, a lack of which of these nutrients can cause the condition known as night blindness?
Answer: D
Vitamin A deficiency can cause night blindness in humans.
A lack of Vitamin A in the diet is directly linked to the condition known as night blindness, which impairs the ability to see in low-light conditions.
A) Calcium
Calcium is essential for various bodily functions, including bone health and muscle contraction, but it is not directly related to vision or the ability to see in low light. Therefore, a deficiency in calcium does not cause night blindness.
B) Niacin
Niacin, or Vitamin B3, plays a role in energy metabolism and skin health, but it is not specifically associated with night blindness. While a deficiency can lead to other health issues, it does not affect the ability to see in dim light.
C) Vitamin D
Vitamin D is primarily involved in calcium absorption and bone health. It does not have a direct impact on vision or night blindness. A deficiency in Vitamin D can lead to other health problems but is not related to impaired night vision.
D) Vitamin A
Vitamin A is crucial for the production of rhodopsin, a pigment in the retina that enables vision in low-light conditions. A deficiency in Vitamin A leads to night blindness because the body cannot produce enough rhodopsin to function properly in darkness.
Conclusion
Vitamin A deficiency is the only option that directly causes night blindness due to its critical role in maintaining proper vision in low-light conditions. The other options, while important for various bodily functions, do not impact night vision, making them incorrect choices in this context.