The pale yellow colour of human urine is mainly due to the presence of which pigment?

Introduction / Context:

Urine examination is a simple but important diagnostic tool in medicine. One basic observable feature of urine is its colour, which in healthy individuals is typically pale yellow. This colour arises from specific pigments that are products of metabolism and excretion. The question asks which pigment is mainly responsible for the normal pale yellow colour of urine, testing basic knowledge of human excretory system and related biochemistry.

Given Data / Assumptions:

• The question focuses on normal, pale yellow urine in a healthy person.
• We must select the pigment responsible for this colour.
• Options include urochrome, urophyll, chlorophyll, chloroplast, and urobilin.
• We assume standard terminology used in school and entrance exam books.

Concept / Approach:

The normal colour of urine is due to pigments derived from the breakdown of haemoglobin in the body. One widely used term in exam oriented biology is urochrome, which refers to the yellowish pigment that gives urine its characteristic colour. Urobilin is also sometimes mentioned in advanced texts as a related pigment, but standard general knowledge questions usually expect urochrome as the answer. Other options such as chlorophyll and chloroplast are related to plant photosynthesis, not human excretion. Therefore, we identify urochrome as the correct pigment for this question.

Step-by-Step Solution:

Step 1: Recall that urine gets its colour from pigments produced during pigment and haemoglobin breakdown. Step 2: Remember the term commonly used in basic biology to describe the yellow pigment in urine, which is urochrome. Step 3: Compare this term with the options provided. Step 4: Eliminate plant related terms such as chlorophyll and chloroplast, which have no role in urine colour. Step 5: Select Urochrome as the correct answer.

Verification / Alternative check:

Standard biology guide books and exam preparation materials frequently list questions about the pigment of urine and typically give urochrome as the answer. They often mention that the intensity of colour can vary with hydration but the basic pigment remains urochrome. In more detailed physiology texts, urobilin and related pigments may be discussed, but in the context of this level of question, urochrome is treated as the main pigment. This alignment across multiple textbooks supports the selection of urochrome as the correct answer.

Why Other Options Are Wrong:

Option B, Urophyll, is not a standard term for urine pigment in human physiology and appears incorrect in this context. Option C, Chlorophyll, is the green pigment responsible for photosynthesis in plants and has no role in urine colour. Option D, Chloroplast, is the cell organelle in plant cells that contains chlorophyll and is unrelated to human excretory products. Option E, Urobilin, is a related pigment but is not the typical answer expected in school level multiple choice questions, where urochrome is specifically highlighted as the cause of urine colour.

Common Pitfalls:

Some learners may be tempted to choose urobilin if they have encountered it in more advanced readings, or they may confuse similar sounding words such as urochrome and urophyll. Others may not recall the exact name and guess randomly among unfamiliar terms. To avoid these problems, students should explicitly memorise urochrome as the pale yellow urine pigment and associate the prefix “uro” with urine while distinguishing it from plant terms like chlorophyll and chloroplast.

Final Answer:

The pale yellow colour of human urine is mainly due to the pigment Urochrome.