Which organelle is absent in human sperm?

Options

A. ER
B. Nucleus
C. Centriole
D. Mitochondria

Answer

**Step-by-Step Solution:**

1. **Understanding the Structure of Human Sperm:**
- Human sperm is a specialized male gamete that consists of several key structures: the head, middle piece, and tail.

2. **Identifying Key Components:**
- The head contains the acrosome and a haploid nucleus.
- The middle piece is rich in mitochondrial spirals, which provide energy for sperm movement.
- The tail is responsible for the motility of the sperm.

3. **Listing Organelles Present in Sperm:**
- The organelles present in human sperm include:
- Acrosome
- Haploid nucleus
- Centrioles (located in the neck region)
- Mitochondria (in the middle piece)
- Tail (flagellum)

4. **Determining the Absent Organelle:**
- To answer the question, we need to identify which common organelle is not found in human sperm.
- After reviewing the structures and organelles present, it is noted that the endoplasmic reticulum (ER) is absent in human sperm.

5. **Conclusion:**
- The organelle that is absent in human sperm is the endoplasmic reticulum (ER).

**Final Answer:**
The organelle that is absent in human sperm is the endoplasmic reticulum (ER).

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