Which of the following statements on the Red blood cells in human cells in human is/are True?
(a) Measures about `15mum` in diameter.
(b) Do not contain mitochondria.
( c) Have a life span of 120 days in the circulation.
(d) Are released from the bone marrow as mature red blood cells.

Options

A. l and IV are correct.
B. II and III are correct
C. II and IV are correct
D. III and IV are correct

Answer

To determine which statements about red blood cells (RBCs) in humans are true, we will analyze each statement one by one.

**Step 1: Evaluate Statement (a)**
Statement (a) claims that red blood cells measure about 15 micrometers in diameter.
- The typical diameter of human red blood cells is actually between 6 to 8 micrometers. Therefore, this statement is **false**.

**Step 2: Evaluate Statement (b)**
Statement (b) states that red blood cells do not contain mitochondria.
- This statement is **true**. Red blood cells lack mitochondria as they rely on anaerobic respiration for energy, which allows them to efficiently transport oxygen without consuming it.

**Step 3: Evaluate Statement (c)**
Statement (c) claims that red blood cells have a lifespan of 120 days in circulation.
- This statement is **true**. The average lifespan of red blood cells in the human body is approximately 120 days before they are recycled by the spleen and liver.

**Step 4: Evaluate Statement (d)**
Statement (d) states that red blood cells are released from the bone marrow as mature red blood cells.
- This statement is **false**. Red blood cells are released from the bone marrow in an immature form known as reticulocytes. They mature into fully functional red blood cells once they enter the bloodstream.

**Conclusion:**
Based on the evaluations:
- Statement (a) is false.
- Statement (b) is true.
- Statement (c) is true.
- Statement (d) is false.

Thus, the true statements are (b) and (c).

**Final Answer:**
The true statements about red blood cells in humans are (b) and (c).

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